encoding_rs/ascii.rs
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922
// Copyright Mozilla Foundation. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// It's assumed that in due course Rust will have explicit SIMD but will not
// be good at run-time selection of SIMD vs. no-SIMD. In such a future,
// x86_64 will always use SSE2 and 32-bit x86 will use SSE2 when compiled with
// a Mozilla-shipped rustc. SIMD support and especially detection on ARM is a
// mess. Under the circumstances, it seems to make sense to optimize the ALU
// case for ARMv7 rather than x86. Annoyingly, I was unable to get useful
// numbers of the actual ARMv7 CPU I have access to, because (thermal?)
// throttling kept interfering. Since Raspberry Pi 3 (ARMv8 core but running
// ARMv7 code) produced reproducible performance numbers, that's the ARM
// computer that this code ended up being optimized for in the ALU case.
// Less popular CPU architectures simply get the approach that was chosen based
// on Raspberry Pi 3 measurements. The UTF-16 and UTF-8 ALU cases take
// different approaches based on benchmarking on Raspberry Pi 3.
#[cfg(all(
feature = "simd-accel",
any(
target_feature = "sse2",
all(target_endian = "little", target_arch = "aarch64"),
all(target_endian = "little", target_feature = "neon")
)
))]
use crate::simd_funcs::*;
cfg_if! {
if #[cfg(feature = "simd-accel")] {
#[allow(unused_imports)]
use ::core::intrinsics::unlikely;
#[allow(unused_imports)]
use ::core::intrinsics::likely;
} else {
#[allow(dead_code)]
#[inline(always)]
fn unlikely(b: bool) -> bool {
b
}
#[allow(dead_code)]
#[inline(always)]
fn likely(b: bool) -> bool {
b
}
}
}
// Safety invariants for masks: data & mask = 0 for valid ASCII or basic latin utf-16
// `as` truncates, so works on 32-bit, too.
#[allow(dead_code)]
pub const ASCII_MASK: usize = 0x8080_8080_8080_8080u64 as usize;
// `as` truncates, so works on 32-bit, too.
#[allow(dead_code)]
pub const BASIC_LATIN_MASK: usize = 0xFF80_FF80_FF80_FF80u64 as usize;
#[allow(unused_macros)]
macro_rules! ascii_naive {
($name:ident, $src_unit:ty, $dst_unit:ty) => {
/// Safety: src and dst must have len_unit elements and be aligned
/// Safety-usable invariant: will return Some() when it fails
/// to convert. The first value will be a u8 that is > 127.
#[inline(always)]
pub unsafe fn $name(
src: *const $src_unit,
dst: *mut $dst_unit,
len: usize,
) -> Option<($src_unit, usize)> {
// Yes, manually omitting the bound check here matters
// a lot for perf.
for i in 0..len {
// Safety: len invariant used here
let code_unit = *(src.add(i));
// Safety: Upholds safety-usable invariant here
if code_unit > 127 {
return Some((code_unit, i));
}
// Safety: len invariant used here
*(dst.add(i)) = code_unit as $dst_unit;
}
return None;
}
};
}
#[allow(unused_macros)]
macro_rules! ascii_alu {
($name:ident,
// safety invariant: src/dst MUST be u8
$src_unit:ty,
$dst_unit:ty,
// Safety invariant: stride_fn must consume and produce two usizes, and return the index of the first non-ascii when it fails
$stride_fn:ident) => {
/// Safety: src and dst must have len elements, src is valid for read, dst is valid for
/// write
/// Safety-usable invariant: will return Some() when it fails
/// to convert. The first value will be a u8 that is > 127.
#[cfg_attr(feature = "cargo-clippy", allow(never_loop, cast_ptr_alignment))]
#[inline(always)]
pub unsafe fn $name(
src: *const $src_unit,
dst: *mut $dst_unit,
len: usize,
) -> Option<($src_unit, usize)> {
let mut offset = 0usize;
// This loop is only broken out of as a `goto` forward
loop {
// Safety: until_alignment becomes the number of bytes we need to munch until we are aligned to usize
let mut until_alignment = {
// Check if the other unit aligns if we move the narrower unit
// to alignment.
// if ::core::mem::size_of::<$src_unit>() == ::core::mem::size_of::<$dst_unit>() {
// ascii_to_ascii
let src_alignment = (src as usize) & ALU_ALIGNMENT_MASK;
let dst_alignment = (dst as usize) & ALU_ALIGNMENT_MASK;
if src_alignment != dst_alignment {
// Safety: bails early and ends up in the naïve branch where usize-alignment doesn't matter
break;
}
(ALU_ALIGNMENT - src_alignment) & ALU_ALIGNMENT_MASK
// } else if ::core::mem::size_of::<$src_unit>() < ::core::mem::size_of::<$dst_unit>() {
// ascii_to_basic_latin
// let src_until_alignment = (ALIGNMENT - ((src as usize) & ALIGNMENT_MASK)) & ALIGNMENT_MASK;
// if (dst.add(src_until_alignment) as usize) & ALIGNMENT_MASK != 0 {
// break;
// }
// src_until_alignment
// } else {
// basic_latin_to_ascii
// let dst_until_alignment = (ALIGNMENT - ((dst as usize) & ALIGNMENT_MASK)) & ALIGNMENT_MASK;
// if (src.add(dst_until_alignment) as usize) & ALIGNMENT_MASK != 0 {
// break;
// }
// dst_until_alignment
// }
};
if until_alignment + ALU_STRIDE_SIZE <= len {
// Moving pointers to alignment seems to be a pessimization on
// x86_64 for operations that have UTF-16 as the internal
// Unicode representation. However, since it seems to be a win
// on ARM (tested ARMv7 code running on ARMv8 [rpi3]), except
// mixed results when encoding from UTF-16 and since x86 and
// x86_64 should be using SSE2 in due course, keeping the move
// to alignment here. It would be good to test on more ARM CPUs
// and on real MIPS and POWER hardware.
//
// Safety: This is the naïve code once again, for `until_alignment` bytes
while until_alignment != 0 {
let code_unit = *(src.add(offset));
if code_unit > 127 {
// Safety: Upholds safety-usable invariant here
return Some((code_unit, offset));
}
*(dst.add(offset)) = code_unit as $dst_unit;
// Safety: offset is the number of bytes copied so far
offset += 1;
until_alignment -= 1;
}
let len_minus_stride = len - ALU_STRIDE_SIZE;
loop {
// Safety: num_ascii is known to be a byte index of a non-ascii byte due to stride_fn's invariant
if let Some(num_ascii) = $stride_fn(
// Safety: These are known to be valid and aligned since we have at
// least ALU_STRIDE_SIZE data in these buffers, and offset is the
// number of elements copied so far, which according to the
// until_alignment calculation above will cause both src and dst to be
// aligned to usize after this add
src.add(offset) as *const usize,
dst.add(offset) as *mut usize,
) {
offset += num_ascii;
// Safety: Upholds safety-usable invariant here by indexing into non-ascii byte
return Some((*(src.add(offset)), offset));
}
// Safety: offset continues to be the number of bytes copied so far, and
// maintains usize alignment for the next loop iteration
offset += ALU_STRIDE_SIZE;
// Safety: This is `offset > len - stride. This loop will continue as long as
// `offset <= len - stride`, which means there are `stride` bytes to still be read.
if offset > len_minus_stride {
break;
}
}
}
break;
}
// Safety: This is the naïve code, same as ascii_naive, and has no requirements
// other than src/dst being valid for the the right lens
while offset < len {
// Safety: len invariant used here
let code_unit = *(src.add(offset));
if code_unit > 127 {
// Safety: Upholds safety-usable invariant here
return Some((code_unit, offset));
}
// Safety: len invariant used here
*(dst.add(offset)) = code_unit as $dst_unit;
offset += 1;
}
None
}
};
}
#[allow(unused_macros)]
macro_rules! basic_latin_alu {
($name:ident,
// safety invariant: use u8 for src/dest for ascii, and u16 for basic_latin
$src_unit:ty,
$dst_unit:ty,
// safety invariant: stride function must munch ALU_STRIDE_SIZE*size(src_unit) bytes off of src and
// write ALU_STRIDE_SIZE*size(dst_unit) bytes to dst
$stride_fn:ident) => {
/// Safety: src and dst must have len elements, src is valid for read, dst is valid for
/// write
/// Safety-usable invariant: will return Some() when it fails
/// to convert. The first value will be a u8 that is > 127.
#[cfg_attr(
feature = "cargo-clippy",
allow(never_loop, cast_ptr_alignment, cast_lossless)
)]
#[inline(always)]
pub unsafe fn $name(
src: *const $src_unit,
dst: *mut $dst_unit,
len: usize,
) -> Option<($src_unit, usize)> {
let mut offset = 0usize;
// This loop is only broken out of as a `goto` forward
loop {
// Safety: until_alignment becomes the number of bytes we need to munch from src/dest until we are aligned to usize
// We ensure basic-latin has the same alignment as ascii, starting with ascii since it is smaller.
let mut until_alignment = {
// Check if the other unit aligns if we move the narrower unit
// to alignment.
// if ::core::mem::size_of::<$src_unit>() == ::core::mem::size_of::<$dst_unit>() {
// ascii_to_ascii
// let src_alignment = (src as usize) & ALIGNMENT_MASK;
// let dst_alignment = (dst as usize) & ALIGNMENT_MASK;
// if src_alignment != dst_alignment {
// break;
// }
// (ALIGNMENT - src_alignment) & ALIGNMENT_MASK
// } else
if ::core::mem::size_of::<$src_unit>() < ::core::mem::size_of::<$dst_unit>() {
// ascii_to_basic_latin
let src_until_alignment = (ALU_ALIGNMENT
- ((src as usize) & ALU_ALIGNMENT_MASK))
& ALU_ALIGNMENT_MASK;
if (dst.wrapping_add(src_until_alignment) as usize) & ALU_ALIGNMENT_MASK
!= 0
{
break;
}
src_until_alignment
} else {
// basic_latin_to_ascii
let dst_until_alignment = (ALU_ALIGNMENT
- ((dst as usize) & ALU_ALIGNMENT_MASK))
& ALU_ALIGNMENT_MASK;
if (src.wrapping_add(dst_until_alignment) as usize) & ALU_ALIGNMENT_MASK
!= 0
{
break;
}
dst_until_alignment
}
};
if until_alignment + ALU_STRIDE_SIZE <= len {
// Moving pointers to alignment seems to be a pessimization on
// x86_64 for operations that have UTF-16 as the internal
// Unicode representation. However, since it seems to be a win
// on ARM (tested ARMv7 code running on ARMv8 [rpi3]), except
// mixed results when encoding from UTF-16 and since x86 and
// x86_64 should be using SSE2 in due course, keeping the move
// to alignment here. It would be good to test on more ARM CPUs
// and on real MIPS and POWER hardware.
//
// Safety: This is the naïve code once again, for `until_alignment` bytes
while until_alignment != 0 {
let code_unit = *(src.add(offset));
if code_unit > 127 {
// Safety: Upholds safety-usable invariant here
return Some((code_unit, offset));
}
*(dst.add(offset)) = code_unit as $dst_unit;
// Safety: offset is the number of bytes copied so far
offset += 1;
until_alignment -= 1;
}
let len_minus_stride = len - ALU_STRIDE_SIZE;
loop {
if !$stride_fn(
// Safety: These are known to be valid and aligned since we have at
// least ALU_STRIDE_SIZE data in these buffers, and offset is the
// number of elements copied so far, which according to the
// until_alignment calculation above will cause both src and dst to be
// aligned to usize after this add
src.add(offset) as *const usize,
dst.add(offset) as *mut usize,
) {
break;
}
// Safety: offset continues to be the number of bytes copied so far, and
// maintains usize alignment for the next loop iteration
offset += ALU_STRIDE_SIZE;
// Safety: This is `offset > len - stride. This loop will continue as long as
// `offset <= len - stride`, which means there are `stride` bytes to still be read.
if offset > len_minus_stride {
break;
}
}
}
break;
}
// Safety: This is the naïve code once again, for leftover bytes
while offset < len {
// Safety: len invariant used here
let code_unit = *(src.add(offset));
if code_unit > 127 {
// Safety: Upholds safety-usable invariant here
return Some((code_unit, offset));
}
// Safety: len invariant used here
*(dst.add(offset)) = code_unit as $dst_unit;
offset += 1;
}
None
}
};
}
#[allow(unused_macros)]
macro_rules! latin1_alu {
// safety invariant: stride function must munch ALU_STRIDE_SIZE*size(src_unit) bytes off of src and
// write ALU_STRIDE_SIZE*size(dst_unit) bytes to dst
($name:ident, $src_unit:ty, $dst_unit:ty, $stride_fn:ident) => {
/// Safety: src and dst must have len elements, src is valid for read, dst is valid for
/// write
#[cfg_attr(
feature = "cargo-clippy",
allow(never_loop, cast_ptr_alignment, cast_lossless)
)]
#[inline(always)]
pub unsafe fn $name(src: *const $src_unit, dst: *mut $dst_unit, len: usize) {
let mut offset = 0usize;
// This loop is only broken out of as a `goto` forward
loop {
// Safety: until_alignment becomes the number of bytes we need to munch from src/dest until we are aligned to usize
// We ensure the UTF-16 side has the same alignment as the Latin-1 side, starting with Latin-1 since it is smaller.
let mut until_alignment = {
if ::core::mem::size_of::<$src_unit>() < ::core::mem::size_of::<$dst_unit>() {
// unpack
let src_until_alignment = (ALU_ALIGNMENT
- ((src as usize) & ALU_ALIGNMENT_MASK))
& ALU_ALIGNMENT_MASK;
if (dst.wrapping_add(src_until_alignment) as usize) & ALU_ALIGNMENT_MASK
!= 0
{
break;
}
src_until_alignment
} else {
// pack
let dst_until_alignment = (ALU_ALIGNMENT
- ((dst as usize) & ALU_ALIGNMENT_MASK))
& ALU_ALIGNMENT_MASK;
if (src.wrapping_add(dst_until_alignment) as usize) & ALU_ALIGNMENT_MASK
!= 0
{
break;
}
dst_until_alignment
}
};
if until_alignment + ALU_STRIDE_SIZE <= len {
// Safety: This is the naïve code once again, for `until_alignment` bytes
while until_alignment != 0 {
let code_unit = *(src.add(offset));
*(dst.add(offset)) = code_unit as $dst_unit;
// Safety: offset is the number of bytes copied so far
offset += 1;
until_alignment -= 1;
}
let len_minus_stride = len - ALU_STRIDE_SIZE;
loop {
$stride_fn(
// Safety: These are known to be valid and aligned since we have at
// least ALU_STRIDE_SIZE data in these buffers, and offset is the
// number of elements copied so far, which according to the
// until_alignment calculation above will cause both src and dst to be
// aligned to usize after this add
src.add(offset) as *const usize,
dst.add(offset) as *mut usize,
);
// Safety: offset continues to be the number of bytes copied so far, and
// maintains usize alignment for the next loop iteration
offset += ALU_STRIDE_SIZE;
// Safety: This is `offset > len - stride. This loop will continue as long as
// `offset <= len - stride`, which means there are `stride` bytes to still be read.
if offset > len_minus_stride {
break;
}
}
}
break;
}
// Safety: This is the naïve code once again, for leftover bytes
while offset < len {
// Safety: len invariant used here
let code_unit = *(src.add(offset));
*(dst.add(offset)) = code_unit as $dst_unit;
offset += 1;
}
}
};
}
#[allow(unused_macros)]
macro_rules! ascii_simd_check_align {
(
$name:ident,
$src_unit:ty,
$dst_unit:ty,
// Safety: This function must require aligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_both_aligned:ident,
// Safety: This function must require aligned/unaligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_src_aligned:ident,
// Safety: This function must require unaligned/aligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_dst_aligned:ident,
// Safety: This function must require unaligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_neither_aligned:ident
) => {
/// Safety: src/dst must be valid for reads/writes of `len` elements of their units.
///
/// Safety-usable invariant: will return Some() when it encounters non-ASCII, with the first element in the Some being
/// guaranteed to be non-ASCII (> 127), and the second being the offset where it is found
#[inline(always)]
pub unsafe fn $name(
src: *const $src_unit,
dst: *mut $dst_unit,
len: usize,
) -> Option<($src_unit, usize)> {
let mut offset = 0usize;
// Safety: if this check succeeds we're valid for reading/writing at least `SIMD_STRIDE_SIZE` elements.
if SIMD_STRIDE_SIZE <= len {
let len_minus_stride = len - SIMD_STRIDE_SIZE;
// XXX Should we first process one stride unconditionally as unaligned to
// avoid the cost of the branchiness below if the first stride fails anyway?
// XXX Should we just use unaligned SSE2 access unconditionally? It seems that
// on Haswell, it would make sense to just use unaligned and not bother
// checking. Need to benchmark older architectures before deciding.
let dst_masked = (dst as usize) & SIMD_ALIGNMENT_MASK;
// Safety: checking whether src is aligned
if ((src as usize) & SIMD_ALIGNMENT_MASK) == 0 {
// Safety: Checking whether dst is aligned
if dst_masked == 0 {
loop {
// Safety: We're valid to read/write SIMD_STRIDE_SIZE elements and have the appropriate alignments
if !$stride_both_aligned(src.add(offset), dst.add(offset)) {
break;
}
offset += SIMD_STRIDE_SIZE;
// Safety: This is `offset > len - SIMD_STRIDE_SIZE` which means we always have at least `SIMD_STRIDE_SIZE` elements to munch next time.
if offset > len_minus_stride {
break;
}
}
} else {
loop {
// Safety: We're valid to read/write SIMD_STRIDE_SIZE elements and have the appropriate alignments
if !$stride_src_aligned(src.add(offset), dst.add(offset)) {
break;
}
offset += SIMD_STRIDE_SIZE;
// Safety: This is `offset > len - SIMD_STRIDE_SIZE` which means we always have at least `SIMD_STRIDE_SIZE` elements to munch next time.
if offset > len_minus_stride {
break;
}
}
}
} else {
if dst_masked == 0 {
loop {
// Safety: We're valid to read/write SIMD_STRIDE_SIZE elements and have the appropriate alignments
if !$stride_dst_aligned(src.add(offset), dst.add(offset)) {
break;
}
offset += SIMD_STRIDE_SIZE;
// Safety: This is `offset > len - SIMD_STRIDE_SIZE` which means we always have at least `SIMD_STRIDE_SIZE` elements to munch next time.
if offset > len_minus_stride {
break;
}
}
} else {
loop {
// Safety: We're valid to read/write SIMD_STRIDE_SIZE elements and have the appropriate alignments
if !$stride_neither_aligned(src.add(offset), dst.add(offset)) {
break;
}
offset += SIMD_STRIDE_SIZE;
// Safety: This is `offset > len - SIMD_STRIDE_SIZE` which means we always have at least `SIMD_STRIDE_SIZE` elements to munch next time.
if offset > len_minus_stride {
break;
}
}
}
}
}
while offset < len {
// Safety: uses len invariant here and below
let code_unit = *(src.add(offset));
if code_unit > 127 {
// Safety: upholds safety-usable invariant
return Some((code_unit, offset));
}
*(dst.add(offset)) = code_unit as $dst_unit;
offset += 1;
}
None
}
};
}
#[allow(unused_macros)]
macro_rules! ascii_simd_check_align_unrolled {
(
$name:ident,
$src_unit:ty,
$dst_unit:ty,
// Safety: This function must require aligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_both_aligned:ident,
// Safety: This function must require aligned/unaligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_src_aligned:ident,
// Safety: This function must require unaligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_neither_aligned:ident,
// Safety: This function must require aligned src/dest that are valid for reading/writing 2*SIMD_STRIDE_SIZE src_unit/dst_unit
$double_stride_both_aligned:ident,
// Safety: This function must require aligned/unaligned src/dest that are valid for reading/writing 2*SIMD_STRIDE_SIZE src_unit/dst_unit
$double_stride_src_aligned:ident
) => {
/// Safety: src/dst must be valid for reads/writes of `len` elements of their units.
///
/// Safety-usable invariant: will return Some() when it encounters non-ASCII, with the first element in the Some being
/// guaranteed to be non-ASCII (> 127), and the second being the offset where it is found #[inline(always)]
pub unsafe fn $name(
src: *const $src_unit,
dst: *mut $dst_unit,
len: usize,
) -> Option<($src_unit, usize)> {
let unit_size = ::core::mem::size_of::<$src_unit>();
let mut offset = 0usize;
// This loop is only broken out of as a goto forward without
// actually looping
'outer: loop {
// Safety: if this check succeeds we're valid for reading/writing at least `SIMD_STRIDE_SIZE` elements.
if SIMD_STRIDE_SIZE <= len {
// First, process one unaligned
// Safety: this is safe to call since we're valid for this read/write
if !$stride_neither_aligned(src, dst) {
break 'outer;
}
offset = SIMD_STRIDE_SIZE;
// We have now seen 16 ASCII bytes. Let's guess that
// there will be enough more to justify more expense
// in the case of non-ASCII.
// Use aligned reads for the sake of old microachitectures.
//
// Safety: this correctly calculates the number of src_units that need to be read before the remaining list is aligned.
// This is less that SIMD_ALIGNMENT, which is also SIMD_STRIDE_SIZE (as documented)
let until_alignment = ((SIMD_ALIGNMENT
- ((src.add(offset) as usize) & SIMD_ALIGNMENT_MASK))
& SIMD_ALIGNMENT_MASK)
/ unit_size;
// Safety: This addition won't overflow, because even in the 32-bit PAE case the
// address space holds enough code that the slice length can't be that
// close to address space size.
// offset now equals SIMD_STRIDE_SIZE, hence times 3 below.
//
// Safety: if this check succeeds we're valid for reading/writing at least `2 * SIMD_STRIDE_SIZE` elements plus `until_alignment`.
// The extra SIMD_STRIDE_SIZE in the condition is because `offset` is already `SIMD_STRIDE_SIZE`.
if until_alignment + (SIMD_STRIDE_SIZE * 3) <= len {
if until_alignment != 0 {
// Safety: this is safe to call since we're valid for this read/write (and more), and don't care about alignment
// This will copy over bytes that get decoded twice since it's not incrementing `offset` by SIMD_STRIDE_SIZE. This is fine.
if !$stride_neither_aligned(src.add(offset), dst.add(offset)) {
break;
}
offset += until_alignment;
}
// Safety: At this point we're valid for reading/writing 2*SIMD_STRIDE_SIZE elements
// Safety: Now `offset` is aligned for `src`
let len_minus_stride_times_two = len - (SIMD_STRIDE_SIZE * 2);
// Safety: This is whether dst is aligned
let dst_masked = (dst.add(offset) as usize) & SIMD_ALIGNMENT_MASK;
if dst_masked == 0 {
loop {
// Safety: both are aligned, we can call the aligned function. We're valid for reading/writing double stride from the initial condition
// and the loop break condition below
if let Some(advance) =
$double_stride_both_aligned(src.add(offset), dst.add(offset))
{
offset += advance;
let code_unit = *(src.add(offset));
// Safety: uses safety-usable invariant on ascii_to_ascii_simd_double_stride to return
// guaranteed non-ascii
return Some((code_unit, offset));
}
offset += SIMD_STRIDE_SIZE * 2;
// Safety: This is `offset > len - 2 * SIMD_STRIDE_SIZE` which means we always have at least `2 * SIMD_STRIDE_SIZE` elements to munch next time.
if offset > len_minus_stride_times_two {
break;
}
}
// Safety: We're valid for reading/writing one more, and can still assume alignment
if offset + SIMD_STRIDE_SIZE <= len {
if !$stride_both_aligned(src.add(offset), dst.add(offset)) {
break 'outer;
}
offset += SIMD_STRIDE_SIZE;
}
} else {
loop {
// Safety: only src is aligned here. We're valid for reading/writing double stride from the initial condition
// and the loop break condition below
if let Some(advance) =
$double_stride_src_aligned(src.add(offset), dst.add(offset))
{
offset += advance;
let code_unit = *(src.add(offset));
// Safety: uses safety-usable invariant on ascii_to_ascii_simd_double_stride to return
// guaranteed non-ascii
return Some((code_unit, offset));
}
offset += SIMD_STRIDE_SIZE * 2;
// Safety: This is `offset > len - 2 * SIMD_STRIDE_SIZE` which means we always have at least `2 * SIMD_STRIDE_SIZE` elements to munch next time.
if offset > len_minus_stride_times_two {
break;
}
}
// Safety: We're valid for reading/writing one more, and can still assume alignment
if offset + SIMD_STRIDE_SIZE <= len {
if !$stride_src_aligned(src.add(offset), dst.add(offset)) {
break 'outer;
}
offset += SIMD_STRIDE_SIZE;
}
}
} else {
// At most two iterations, so unroll
if offset + SIMD_STRIDE_SIZE <= len {
// Safety: The check above ensures we're allowed to read/write this, and we don't use alignment
if !$stride_neither_aligned(src.add(offset), dst.add(offset)) {
break;
}
offset += SIMD_STRIDE_SIZE;
if offset + SIMD_STRIDE_SIZE <= len {
// Safety: The check above ensures we're allowed to read/write this, and we don't use alignment
if !$stride_neither_aligned(src.add(offset), dst.add(offset)) {
break;
}
offset += SIMD_STRIDE_SIZE;
}
}
}
}
break 'outer;
}
while offset < len {
// Safety: relies straightforwardly on the `len` invariant
let code_unit = *(src.add(offset));
if code_unit > 127 {
// Safety-usable invariant upheld here
return Some((code_unit, offset));
}
*(dst.add(offset)) = code_unit as $dst_unit;
offset += 1;
}
None
}
};
}
#[allow(unused_macros)]
macro_rules! latin1_simd_check_align {
(
$name:ident,
$src_unit:ty,
$dst_unit:ty,
// Safety: This function must require aligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_both_aligned:ident,
// Safety: This function must require aligned/unaligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_src_aligned:ident,
// Safety: This function must require unaligned/aligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_dst_aligned:ident,
// Safety: This function must require unaligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_neither_aligned:ident
) => {
/// Safety: src/dst must be valid for reads/writes of `len` elements of their units.
#[inline(always)]
pub unsafe fn $name(src: *const $src_unit, dst: *mut $dst_unit, len: usize) {
let mut offset = 0usize;
// Safety: if this check succeeds we're valid for reading/writing at least `SIMD_STRIDE_SIZE` elements.
if SIMD_STRIDE_SIZE <= len {
let len_minus_stride = len - SIMD_STRIDE_SIZE;
// Whether dst is aligned
let dst_masked = (dst as usize) & SIMD_ALIGNMENT_MASK;
// Whether src is aligned
if ((src as usize) & SIMD_ALIGNMENT_MASK) == 0 {
if dst_masked == 0 {
loop {
// Safety: Both were aligned, we can use the aligned function
$stride_both_aligned(src.add(offset), dst.add(offset));
offset += SIMD_STRIDE_SIZE;
// Safety: This is `offset > len - SIMD_STRIDE_SIZE`, which means in the next iteration we're valid for
// reading/writing at least SIMD_STRIDE_SIZE elements.
if offset > len_minus_stride {
break;
}
}
} else {
loop {
// Safety: src was aligned, dst was not
$stride_src_aligned(src.add(offset), dst.add(offset));
offset += SIMD_STRIDE_SIZE;
// Safety: This is `offset > len - SIMD_STRIDE_SIZE`, which means in the next iteration we're valid for
// reading/writing at least SIMD_STRIDE_SIZE elements.
if offset > len_minus_stride {
break;
}
}
}
} else {
if dst_masked == 0 {
loop {
// Safety: src was aligned, dst was not
$stride_dst_aligned(src.add(offset), dst.add(offset));
offset += SIMD_STRIDE_SIZE;
// Safety: This is `offset > len - SIMD_STRIDE_SIZE`, which means in the next iteration we're valid for
// reading/writing at least SIMD_STRIDE_SIZE elements.
if offset > len_minus_stride {
break;
}
}
} else {
loop {
// Safety: Neither were aligned
$stride_neither_aligned(src.add(offset), dst.add(offset));
offset += SIMD_STRIDE_SIZE;
// Safety: This is `offset > len - SIMD_STRIDE_SIZE`, which means in the next iteration we're valid for
// reading/writing at least SIMD_STRIDE_SIZE elements.
if offset > len_minus_stride {
break;
}
}
}
}
}
while offset < len {
// Safety: relies straightforwardly on the `len` invariant
let code_unit = *(src.add(offset));
*(dst.add(offset)) = code_unit as $dst_unit;
offset += 1;
}
}
};
}
#[allow(unused_macros)]
macro_rules! latin1_simd_check_align_unrolled {
(
$name:ident,
$src_unit:ty,
$dst_unit:ty,
// Safety: This function must require aligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_both_aligned:ident,
// Safety: This function must require aligned/unaligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_src_aligned:ident,
// Safety: This function must require unaligned/aligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_dst_aligned:ident,
// Safety: This function must require unaligned src/dest that are valid for reading/writing SIMD_STRIDE_SIZE src_unit/dst_unit
$stride_neither_aligned:ident
) => {
/// Safety: src/dst must be valid for reads/writes of `len` elements of their units.
#[inline(always)]
pub unsafe fn $name(src: *const $src_unit, dst: *mut $dst_unit, len: usize) {
let unit_size = ::core::mem::size_of::<$src_unit>();
let mut offset = 0usize;
// Safety: if this check succeeds we're valid for reading/writing at least `SIMD_STRIDE_SIZE` elements.
if SIMD_STRIDE_SIZE <= len {
// Safety: this correctly calculates the number of src_units that need to be read before the remaining list is aligned.
// This is by definition less than SIMD_STRIDE_SIZE.
let mut until_alignment = ((SIMD_STRIDE_SIZE
- ((src as usize) & SIMD_ALIGNMENT_MASK))
& SIMD_ALIGNMENT_MASK)
/ unit_size;
while until_alignment != 0 {
// Safety: This is a straightforward copy, since until_alignment is < SIMD_STRIDE_SIZE < len, this is in-bounds
*(dst.add(offset)) = *(src.add(offset)) as $dst_unit;
offset += 1;
until_alignment -= 1;
}
// Safety: here offset will be `until_alignment`, i.e. enough to align `src`.
let len_minus_stride = len - SIMD_STRIDE_SIZE;
// Safety: if this check succeeds we're valid for reading/writing at least `2 * SIMD_STRIDE_SIZE` elements.
if offset + SIMD_STRIDE_SIZE * 2 <= len {
let len_minus_stride_times_two = len_minus_stride - SIMD_STRIDE_SIZE;
// Safety: at this point src is known to be aligned at offset, dst is not.
if (dst.add(offset) as usize) & SIMD_ALIGNMENT_MASK == 0 {
loop {
// Safety: We checked alignment of dst above, we can use the alignment functions. We're allowed to read/write 2*SIMD_STRIDE_SIZE elements, which we do.
$stride_both_aligned(src.add(offset), dst.add(offset));
offset += SIMD_STRIDE_SIZE;
$stride_both_aligned(src.add(offset), dst.add(offset));
offset += SIMD_STRIDE_SIZE;
// Safety: This is `offset > len - 2 * SIMD_STRIDE_SIZE` which means we always have at least `2 * SIMD_STRIDE_SIZE` elements to munch next time.
if offset > len_minus_stride_times_two {
break;
}
}
} else {
loop {
// Safety: we ensured alignment of src already.
$stride_src_aligned(src.add(offset), dst.add(offset));
offset += SIMD_STRIDE_SIZE;
$stride_src_aligned(src.add(offset), dst.add(offset));
offset += SIMD_STRIDE_SIZE;
// Safety: This is `offset > len - 2 * SIMD_STRIDE_SIZE` which means we always have at least `2 * SIMD_STRIDE_SIZE` elements to munch next time.
if offset > len_minus_stride_times_two {
break;
}
}
}
}
// Safety: This is `offset > len - SIMD_STRIDE_SIZE` which means we are valid to munch SIMD_STRIDE_SIZE more elements, which we do
if offset < len_minus_stride {
$stride_src_aligned(src.add(offset), dst.add(offset));
offset += SIMD_STRIDE_SIZE;
}
}
while offset < len {
// Safety: uses len invariant here and below
let code_unit = *(src.add(offset));
// On x86_64, this loop autovectorizes but in the pack
// case there are instructions whose purpose is to make sure
// each u16 in the vector is truncated before packing. However,
// since we don't care about saturating behavior of SSE2 packing
// when the input isn't Latin1, those instructions are useless.
// Unfortunately, using the `assume` intrinsic to lie to the
// optimizer doesn't make LLVM omit the trunctation that we
// don't need. Possibly this loop could be manually optimized
// to do the sort of thing that LLVM does but without the
// ANDing the read vectors of u16 with a constant that discards
// the high half of each u16. As far as I can tell, the
// optimization assumes that doing a SIMD read past the end of
// the array is OK.
*(dst.add(offset)) = code_unit as $dst_unit;
offset += 1;
}
}
};
}
#[allow(unused_macros)]
macro_rules! ascii_simd_unalign {
// Safety: stride_neither_aligned must be a function that requires src/dest be valid for unaligned reads/writes for SIMD_STRIDE_SIZE elements of type src_unit/dest_unit
($name:ident, $src_unit:ty, $dst_unit:ty, $stride_neither_aligned:ident) => {
/// Safety: src and dst must be valid for reads/writes of len elements of type src_unit/dst_unit
///
/// Safety-usable invariant: will return Some() when it encounters non-ASCII, with the first element in the Some being
/// guaranteed to be non-ASCII (> 127), and the second being the offset where it is found
#[inline(always)]
pub unsafe fn $name(
src: *const $src_unit,
dst: *mut $dst_unit,
len: usize,
) -> Option<($src_unit, usize)> {
let mut offset = 0usize;
// Safety: if this check succeeds we're valid for reading/writing at least `stride` elements.
if SIMD_STRIDE_SIZE <= len {
let len_minus_stride = len - SIMD_STRIDE_SIZE;
loop {
// Safety: We know we're valid for `stride` reads/writes, so we can call this function. We don't need alignment.
if !$stride_neither_aligned(src.add(offset), dst.add(offset)) {
break;
}
offset += SIMD_STRIDE_SIZE;
// This is `offset > len - stride` which means we always have at least `stride` elements to munch next time.
if offset > len_minus_stride {
break;
}
}
}
while offset < len {
// Safety: Uses len invariant here and below
let code_unit = *(src.add(offset));
if code_unit > 127 {
// Safety-usable invariant upheld here
return Some((code_unit, offset));
}
*(dst.add(offset)) = code_unit as $dst_unit;
offset += 1;
}
None
}
};
}
#[allow(unused_macros)]
macro_rules! latin1_simd_unalign {
// Safety: stride_neither_aligned must be a function that requires src/dest be valid for unaligned reads/writes for SIMD_STRIDE_SIZE elements of type src_unit/dest_unit
($name:ident, $src_unit:ty, $dst_unit:ty, $stride_neither_aligned:ident) => {
/// Safety: src and dst must be valid for unaligned reads/writes of len elements of type src_unit/dst_unit
#[inline(always)]
pub unsafe fn $name(src: *const $src_unit, dst: *mut $dst_unit, len: usize) {
let mut offset = 0usize;
// Safety: if this check succeeds we're valid for reading/writing at least `stride` elements.
if SIMD_STRIDE_SIZE <= len {
let len_minus_stride = len - SIMD_STRIDE_SIZE;
loop {
// Safety: We know we're valid for `stride` reads/writes, so we can call this function. We don't need alignment.
$stride_neither_aligned(src.add(offset), dst.add(offset));
offset += SIMD_STRIDE_SIZE;
// This is `offset > len - stride` which means we always have at least `stride` elements to munch next time.
if offset > len_minus_stride {
break;
}
}
}
while offset < len {
// Safety: Uses len invariant here
let code_unit = *(src.add(offset));
*(dst.add(offset)) = code_unit as $dst_unit;
offset += 1;
}
}
};
}
#[allow(unused_macros)]
macro_rules! ascii_to_ascii_simd_stride {
// Safety: load/store must be valid for 16 bytes of read/write, which may be unaligned. (candidates: `(load|store)(16|8)_(unaligned|aligned)` functions)
($name:ident, $load:ident, $store:ident) => {
/// Safety: src and dst must be valid for 16 bytes of read/write according to
/// the $load/$store fn, which may allow for unaligned reads/writes or require
/// alignment to either 16x8 or u8x16.
#[inline(always)]
pub unsafe fn $name(src: *const u8, dst: *mut u8) -> bool {
let simd = $load(src);
if !simd_is_ascii(simd) {
return false;
}
$store(dst, simd);
true
}
};
}
#[allow(unused_macros)]
macro_rules! ascii_to_ascii_simd_double_stride {
// Safety: store must be valid for 32 bytes of write, which may be unaligned (candidates: `store(8|16)_(aligned|unaligned)`)
($name:ident, $store:ident) => {
/// Safety: src must be valid for 32 bytes of aligned u8x16 read
/// dst must be valid for 32 bytes of unaligned write according to
/// the $store fn, which may allow for unaligned writes or require
/// alignment to either 16x8 or u8x16.
///
/// Safety-usable invariant: Returns Some(index) if the element at `index` is invalid ASCII
#[inline(always)]
pub unsafe fn $name(src: *const u8, dst: *mut u8) -> Option<usize> {
let first = load16_aligned(src);
let second = load16_aligned(src.add(SIMD_STRIDE_SIZE));
$store(dst, first);
if unlikely(!simd_is_ascii(first | second)) {
// Safety: mask_ascii produces a mask of all the high bits.
let mask_first = mask_ascii(first);
if mask_first != 0 {
// Safety: on little endian systems this will be the number of ascii bytes
// before the first non-ascii, i.e. valid for indexing src
// TODO SAFETY: What about big-endian systems?
return Some(mask_first.trailing_zeros() as usize);
}
$store(dst.add(SIMD_STRIDE_SIZE), second);
let mask_second = mask_ascii(second);
// Safety: on little endian systems this will be the number of ascii bytes
// before the first non-ascii, i.e. valid for indexing src
return Some(SIMD_STRIDE_SIZE + mask_second.trailing_zeros() as usize);
}
$store(dst.add(SIMD_STRIDE_SIZE), second);
None
}
};
}
#[allow(unused_macros)]
macro_rules! ascii_to_basic_latin_simd_stride {
// Safety: load/store must be valid for 16 bytes of read/write, which may be unaligned. (candidates: `(load|store)(16|8)_(unaligned|aligned)` functions)
($name:ident, $load:ident, $store:ident) => {
/// Safety: src and dst must be valid for 16/32 bytes of read/write according to
/// the $load/$store fn, which may allow for unaligned reads/writes or require
/// alignment to either 16x8 or u8x16.
#[inline(always)]
pub unsafe fn $name(src: *const u8, dst: *mut u16) -> bool {
let simd = $load(src);
if !simd_is_ascii(simd) {
return false;
}
let (first, second) = simd_unpack(simd);
$store(dst, first);
$store(dst.add(8), second);
true
}
};
}
#[allow(unused_macros)]
macro_rules! ascii_to_basic_latin_simd_double_stride {
// Safety: store must be valid for 16 bytes of write, which may be unaligned
($name:ident, $store:ident) => {
/// Safety: src must be valid for 2*SIMD_STRIDE_SIZE bytes of aligned reads,
/// aligned to either 16x8 or u8x16.
/// dst must be valid for 2*SIMD_STRIDE_SIZE bytes of aligned or unaligned reads
#[inline(always)]
pub unsafe fn $name(src: *const u8, dst: *mut u16) -> Option<usize> {
let first = load16_aligned(src);
let second = load16_aligned(src.add(SIMD_STRIDE_SIZE));
let (a, b) = simd_unpack(first);
$store(dst, a);
// Safety: divide by 2 since it's a u16 pointer
$store(dst.add(SIMD_STRIDE_SIZE / 2), b);
if unlikely(!simd_is_ascii(first | second)) {
let mask_first = mask_ascii(first);
if mask_first != 0 {
return Some(mask_first.trailing_zeros() as usize);
}
let (c, d) = simd_unpack(second);
$store(dst.add(SIMD_STRIDE_SIZE), c);
$store(dst.add(SIMD_STRIDE_SIZE + (SIMD_STRIDE_SIZE / 2)), d);
let mask_second = mask_ascii(second);
return Some(SIMD_STRIDE_SIZE + mask_second.trailing_zeros() as usize);
}
let (c, d) = simd_unpack(second);
$store(dst.add(SIMD_STRIDE_SIZE), c);
$store(dst.add(SIMD_STRIDE_SIZE + (SIMD_STRIDE_SIZE / 2)), d);
None
}
};
}
#[allow(unused_macros)]
macro_rules! unpack_simd_stride {
// Safety: load/store must be valid for 16 bytes of read/write, which may be unaligned. (candidates: `(load|store)(16|8)_(unaligned|aligned)` functions)
($name:ident, $load:ident, $store:ident) => {
/// Safety: src and dst must be valid for 16 bytes of read/write according to
/// the $load/$store fn, which may allow for unaligned reads/writes or require
/// alignment to either 16x8 or u8x16.
#[inline(always)]
pub unsafe fn $name(src: *const u8, dst: *mut u16) {
let simd = $load(src);
let (first, second) = simd_unpack(simd);
$store(dst, first);
$store(dst.add(8), second);
}
};
}
#[allow(unused_macros)]
macro_rules! basic_latin_to_ascii_simd_stride {
// Safety: load/store must be valid for 16 bytes of read/write, which may be unaligned. (candidates: `(load|store)(16|8)_(unaligned|aligned)` functions)
($name:ident, $load:ident, $store:ident) => {
/// Safety: src and dst must be valid for 32/16 bytes of read/write according to
/// the $load/$store fn, which may allow for unaligned reads/writes or require
/// alignment to either 16x8 or u8x16.
#[inline(always)]
pub unsafe fn $name(src: *const u16, dst: *mut u8) -> bool {
let first = $load(src);
let second = $load(src.add(8));
if simd_is_basic_latin(first | second) {
$store(dst, simd_pack(first, second));
true
} else {
false
}
}
};
}
#[allow(unused_macros)]
macro_rules! pack_simd_stride {
// Safety: load/store must be valid for 16 bytes of read/write, which may be unaligned. (candidates: `(load|store)(16|8)_(unaligned|aligned)` functions)
($name:ident, $load:ident, $store:ident) => {
/// Safety: src and dst must be valid for 32/16 bytes of read/write according to
/// the $load/$store fn, which may allow for unaligned reads/writes or require
/// alignment to either 16x8 or u8x16.
#[inline(always)]
pub unsafe fn $name(src: *const u16, dst: *mut u8) {
let first = $load(src);
let second = $load(src.add(8));
$store(dst, simd_pack(first, second));
}
};
}
cfg_if! {
if #[cfg(all(feature = "simd-accel", target_endian = "little", target_arch = "aarch64"))] {
// SIMD with the same instructions for aligned and unaligned loads and stores
pub const SIMD_STRIDE_SIZE: usize = 16;
pub const MAX_STRIDE_SIZE: usize = 16;
// pub const ALIGNMENT: usize = 8;
pub const ALU_STRIDE_SIZE: usize = 16;
pub const ALU_ALIGNMENT: usize = 8;
pub const ALU_ALIGNMENT_MASK: usize = 7;
// Safety for stride macros: We stick to the load8_aligned/etc family of functions. We consistently produce
// neither_unaligned variants using only unaligned inputs.
ascii_to_ascii_simd_stride!(ascii_to_ascii_stride_neither_aligned, load16_unaligned, store16_unaligned);
ascii_to_basic_latin_simd_stride!(ascii_to_basic_latin_stride_neither_aligned, load16_unaligned, store8_unaligned);
unpack_simd_stride!(unpack_stride_neither_aligned, load16_unaligned, store8_unaligned);
basic_latin_to_ascii_simd_stride!(basic_latin_to_ascii_stride_neither_aligned, load8_unaligned, store16_unaligned);
pack_simd_stride!(pack_stride_neither_aligned, load8_unaligned, store16_unaligned);
// Safety for conversion macros: We use the unalign macro with unalign functions above. All stride functions were produced
// by stride macros that universally munch a single SIMD_STRIDE_SIZE worth of elements.
ascii_simd_unalign!(ascii_to_ascii, u8, u8, ascii_to_ascii_stride_neither_aligned);
ascii_simd_unalign!(ascii_to_basic_latin, u8, u16, ascii_to_basic_latin_stride_neither_aligned);
ascii_simd_unalign!(basic_latin_to_ascii, u16, u8, basic_latin_to_ascii_stride_neither_aligned);
latin1_simd_unalign!(unpack_latin1, u8, u16, unpack_stride_neither_aligned);
latin1_simd_unalign!(pack_latin1, u16, u8, pack_stride_neither_aligned);
} else if #[cfg(all(feature = "simd-accel", target_endian = "little", target_feature = "neon"))] {
// SIMD with different instructions for aligned and unaligned loads and stores.
//
// Newer microarchitectures are not supposed to have a performance difference between
// aligned and unaligned SSE2 loads and stores when the address is actually aligned,
// but the benchmark results I see don't agree.
pub const SIMD_STRIDE_SIZE: usize = 16;
pub const MAX_STRIDE_SIZE: usize = 16;
pub const SIMD_ALIGNMENT_MASK: usize = 15;
// Safety for stride macros: We stick to the load8_aligned/etc family of functions. We consistently name
// aligned/unaligned functions according to src/dst being aligned/unaligned
ascii_to_ascii_simd_stride!(ascii_to_ascii_stride_both_aligned, load16_aligned, store16_aligned);
ascii_to_ascii_simd_stride!(ascii_to_ascii_stride_src_aligned, load16_aligned, store16_unaligned);
ascii_to_ascii_simd_stride!(ascii_to_ascii_stride_dst_aligned, load16_unaligned, store16_aligned);
ascii_to_ascii_simd_stride!(ascii_to_ascii_stride_neither_aligned, load16_unaligned, store16_unaligned);
ascii_to_basic_latin_simd_stride!(ascii_to_basic_latin_stride_both_aligned, load16_aligned, store8_aligned);
ascii_to_basic_latin_simd_stride!(ascii_to_basic_latin_stride_src_aligned, load16_aligned, store8_unaligned);
ascii_to_basic_latin_simd_stride!(ascii_to_basic_latin_stride_dst_aligned, load16_unaligned, store8_aligned);
ascii_to_basic_latin_simd_stride!(ascii_to_basic_latin_stride_neither_aligned, load16_unaligned, store8_unaligned);
unpack_simd_stride!(unpack_stride_both_aligned, load16_aligned, store8_aligned);
unpack_simd_stride!(unpack_stride_src_aligned, load16_aligned, store8_unaligned);
unpack_simd_stride!(unpack_stride_dst_aligned, load16_unaligned, store8_aligned);
unpack_simd_stride!(unpack_stride_neither_aligned, load16_unaligned, store8_unaligned);
basic_latin_to_ascii_simd_stride!(basic_latin_to_ascii_stride_both_aligned, load8_aligned, store16_aligned);
basic_latin_to_ascii_simd_stride!(basic_latin_to_ascii_stride_src_aligned, load8_aligned, store16_unaligned);
basic_latin_to_ascii_simd_stride!(basic_latin_to_ascii_stride_dst_aligned, load8_unaligned, store16_aligned);
basic_latin_to_ascii_simd_stride!(basic_latin_to_ascii_stride_neither_aligned, load8_unaligned, store16_unaligned);
pack_simd_stride!(pack_stride_both_aligned, load8_aligned, store16_aligned);
pack_simd_stride!(pack_stride_src_aligned, load8_aligned, store16_unaligned);
pack_simd_stride!(pack_stride_dst_aligned, load8_unaligned, store16_aligned);
pack_simd_stride!(pack_stride_neither_aligned, load8_unaligned, store16_unaligned);
// Safety for conversion macros: We use the correct pattern of both/src/dst/neither here. All stride functions were produced
// by stride macros that universally munch a single SIMD_STRIDE_SIZE worth of elements.
ascii_simd_check_align!(ascii_to_ascii, u8, u8, ascii_to_ascii_stride_both_aligned, ascii_to_ascii_stride_src_aligned, ascii_to_ascii_stride_dst_aligned, ascii_to_ascii_stride_neither_aligned);
ascii_simd_check_align!(ascii_to_basic_latin, u8, u16, ascii_to_basic_latin_stride_both_aligned, ascii_to_basic_latin_stride_src_aligned, ascii_to_basic_latin_stride_dst_aligned, ascii_to_basic_latin_stride_neither_aligned);
ascii_simd_check_align!(basic_latin_to_ascii, u16, u8, basic_latin_to_ascii_stride_both_aligned, basic_latin_to_ascii_stride_src_aligned, basic_latin_to_ascii_stride_dst_aligned, basic_latin_to_ascii_stride_neither_aligned);
latin1_simd_check_align!(unpack_latin1, u8, u16, unpack_stride_both_aligned, unpack_stride_src_aligned, unpack_stride_dst_aligned, unpack_stride_neither_aligned);
latin1_simd_check_align!(pack_latin1, u16, u8, pack_stride_both_aligned, pack_stride_src_aligned, pack_stride_dst_aligned, pack_stride_neither_aligned);
} else if #[cfg(all(feature = "simd-accel", target_feature = "sse2"))] {
// SIMD with different instructions for aligned and unaligned loads and stores.
//
// Newer microarchitectures are not supposed to have a performance difference between
// aligned and unaligned SSE2 loads and stores when the address is actually aligned,
// but the benchmark results I see don't agree.
pub const SIMD_STRIDE_SIZE: usize = 16;
/// Safety-usable invariant: This should be identical to SIMD_STRIDE_SIZE (used by ascii_simd_check_align_unrolled)
pub const SIMD_ALIGNMENT: usize = 16;
pub const MAX_STRIDE_SIZE: usize = 16;
pub const SIMD_ALIGNMENT_MASK: usize = 15;
// Safety for stride macros: We stick to the load8_aligned/etc family of functions. We consistently name
// aligned/unaligned functions according to src/dst being aligned/unaligned
ascii_to_ascii_simd_double_stride!(ascii_to_ascii_simd_double_stride_both_aligned, store16_aligned);
ascii_to_ascii_simd_double_stride!(ascii_to_ascii_simd_double_stride_src_aligned, store16_unaligned);
ascii_to_basic_latin_simd_double_stride!(ascii_to_basic_latin_simd_double_stride_both_aligned, store8_aligned);
ascii_to_basic_latin_simd_double_stride!(ascii_to_basic_latin_simd_double_stride_src_aligned, store8_unaligned);
ascii_to_ascii_simd_stride!(ascii_to_ascii_stride_both_aligned, load16_aligned, store16_aligned);
ascii_to_ascii_simd_stride!(ascii_to_ascii_stride_src_aligned, load16_aligned, store16_unaligned);
ascii_to_ascii_simd_stride!(ascii_to_ascii_stride_neither_aligned, load16_unaligned, store16_unaligned);
ascii_to_basic_latin_simd_stride!(ascii_to_basic_latin_stride_both_aligned, load16_aligned, store8_aligned);
ascii_to_basic_latin_simd_stride!(ascii_to_basic_latin_stride_src_aligned, load16_aligned, store8_unaligned);
ascii_to_basic_latin_simd_stride!(ascii_to_basic_latin_stride_neither_aligned, load16_unaligned, store8_unaligned);
unpack_simd_stride!(unpack_stride_both_aligned, load16_aligned, store8_aligned);
unpack_simd_stride!(unpack_stride_src_aligned, load16_aligned, store8_unaligned);
basic_latin_to_ascii_simd_stride!(basic_latin_to_ascii_stride_both_aligned, load8_aligned, store16_aligned);
basic_latin_to_ascii_simd_stride!(basic_latin_to_ascii_stride_src_aligned, load8_aligned, store16_unaligned);
basic_latin_to_ascii_simd_stride!(basic_latin_to_ascii_stride_dst_aligned, load8_unaligned, store16_aligned);
basic_latin_to_ascii_simd_stride!(basic_latin_to_ascii_stride_neither_aligned, load8_unaligned, store16_unaligned);
pack_simd_stride!(pack_stride_both_aligned, load8_aligned, store16_aligned);
pack_simd_stride!(pack_stride_src_aligned, load8_aligned, store16_unaligned);
// Safety for conversion macros: We use the correct pattern of both/src/dst/neither/double_both/double_src here. All stride functions were produced
// by stride macros that universally munch a single SIMD_STRIDE_SIZE worth of elements.
ascii_simd_check_align_unrolled!(ascii_to_ascii, u8, u8, ascii_to_ascii_stride_both_aligned, ascii_to_ascii_stride_src_aligned, ascii_to_ascii_stride_neither_aligned, ascii_to_ascii_simd_double_stride_both_aligned, ascii_to_ascii_simd_double_stride_src_aligned);
ascii_simd_check_align_unrolled!(ascii_to_basic_latin, u8, u16, ascii_to_basic_latin_stride_both_aligned, ascii_to_basic_latin_stride_src_aligned, ascii_to_basic_latin_stride_neither_aligned, ascii_to_basic_latin_simd_double_stride_both_aligned, ascii_to_basic_latin_simd_double_stride_src_aligned);
ascii_simd_check_align!(basic_latin_to_ascii, u16, u8, basic_latin_to_ascii_stride_both_aligned, basic_latin_to_ascii_stride_src_aligned, basic_latin_to_ascii_stride_dst_aligned, basic_latin_to_ascii_stride_neither_aligned);
latin1_simd_check_align_unrolled!(unpack_latin1, u8, u16, unpack_stride_both_aligned, unpack_stride_src_aligned, unpack_stride_dst_aligned, unpack_stride_neither_aligned);
latin1_simd_check_align_unrolled!(pack_latin1, u16, u8, pack_stride_both_aligned, pack_stride_src_aligned, pack_stride_dst_aligned, pack_stride_neither_aligned);
} else if #[cfg(all(target_endian = "little", target_pointer_width = "64"))] {
// Aligned ALU word, little-endian, 64-bit
/// Safety invariant: this is the amount of bytes consumed by
/// unpack_alu. This will be twice the pointer width, as it consumes two usizes.
/// This is also the number of bytes produced by pack_alu.
/// This is also the number of u16 code units produced/consumed by unpack_alu/pack_alu respectively.
pub const ALU_STRIDE_SIZE: usize = 16;
pub const MAX_STRIDE_SIZE: usize = 16;
// Safety invariant: this is the pointer width in bytes
pub const ALU_ALIGNMENT: usize = 8;
// Safety invariant: this is a mask for getting the bits of a pointer not aligned to ALU_ALIGNMENT
pub const ALU_ALIGNMENT_MASK: usize = 7;
/// Safety: dst must point to valid space for writing four `usize`s
#[inline(always)]
unsafe fn unpack_alu(word: usize, second_word: usize, dst: *mut usize) {
let first = ((0x0000_0000_FF00_0000usize & word) << 24) |
((0x0000_0000_00FF_0000usize & word) << 16) |
((0x0000_0000_0000_FF00usize & word) << 8) |
(0x0000_0000_0000_00FFusize & word);
let second = ((0xFF00_0000_0000_0000usize & word) >> 8) |
((0x00FF_0000_0000_0000usize & word) >> 16) |
((0x0000_FF00_0000_0000usize & word) >> 24) |
((0x0000_00FF_0000_0000usize & word) >> 32);
let third = ((0x0000_0000_FF00_0000usize & second_word) << 24) |
((0x0000_0000_00FF_0000usize & second_word) << 16) |
((0x0000_0000_0000_FF00usize & second_word) << 8) |
(0x0000_0000_0000_00FFusize & second_word);
let fourth = ((0xFF00_0000_0000_0000usize & second_word) >> 8) |
((0x00FF_0000_0000_0000usize & second_word) >> 16) |
((0x0000_FF00_0000_0000usize & second_word) >> 24) |
((0x0000_00FF_0000_0000usize & second_word) >> 32);
// Safety: fn invariant used here
*dst = first;
*(dst.add(1)) = second;
*(dst.add(2)) = third;
*(dst.add(3)) = fourth;
}
/// Safety: dst must point to valid space for writing two `usize`s
#[inline(always)]
unsafe fn pack_alu(first: usize, second: usize, third: usize, fourth: usize, dst: *mut usize) {
let word = ((0x00FF_0000_0000_0000usize & second) << 8) |
((0x0000_00FF_0000_0000usize & second) << 16) |
((0x0000_0000_00FF_0000usize & second) << 24) |
((0x0000_0000_0000_00FFusize & second) << 32) |
((0x00FF_0000_0000_0000usize & first) >> 24) |
((0x0000_00FF_0000_0000usize & first) >> 16) |
((0x0000_0000_00FF_0000usize & first) >> 8) |
(0x0000_0000_0000_00FFusize & first);
let second_word = ((0x00FF_0000_0000_0000usize & fourth) << 8) |
((0x0000_00FF_0000_0000usize & fourth) << 16) |
((0x0000_0000_00FF_0000usize & fourth) << 24) |
((0x0000_0000_0000_00FFusize & fourth) << 32) |
((0x00FF_0000_0000_0000usize & third) >> 24) |
((0x0000_00FF_0000_0000usize & third) >> 16) |
((0x0000_0000_00FF_0000usize & third) >> 8) |
(0x0000_0000_0000_00FFusize & third);
// Safety: fn invariant used here
*dst = word;
*(dst.add(1)) = second_word;
}
} else if #[cfg(all(target_endian = "little", target_pointer_width = "32"))] {
// Aligned ALU word, little-endian, 32-bit
/// Safety invariant: this is the amount of bytes consumed by
/// unpack_alu. This will be twice the pointer width, as it consumes two usizes.
/// This is also the number of bytes produced by pack_alu.
/// This is also the number of u16 code units produced/consumed by unpack_alu/pack_alu respectively.
pub const ALU_STRIDE_SIZE: usize = 8;
pub const MAX_STRIDE_SIZE: usize = 8;
// Safety invariant: this is the pointer width in bytes
pub const ALU_ALIGNMENT: usize = 4;
// Safety invariant: this is a mask for getting the bits of a pointer not aligned to ALU_ALIGNMENT
pub const ALU_ALIGNMENT_MASK: usize = 3;
/// Safety: dst must point to valid space for writing four `usize`s
#[inline(always)]
unsafe fn unpack_alu(word: usize, second_word: usize, dst: *mut usize) {
let first = ((0x0000_FF00usize & word) << 8) |
(0x0000_00FFusize & word);
let second = ((0xFF00_0000usize & word) >> 8) |
((0x00FF_0000usize & word) >> 16);
let third = ((0x0000_FF00usize & second_word) << 8) |
(0x0000_00FFusize & second_word);
let fourth = ((0xFF00_0000usize & second_word) >> 8) |
((0x00FF_0000usize & second_word) >> 16);
// Safety: fn invariant used here
*dst = first;
*(dst.add(1)) = second;
*(dst.add(2)) = third;
*(dst.add(3)) = fourth;
}
/// Safety: dst must point to valid space for writing two `usize`s
#[inline(always)]
unsafe fn pack_alu(first: usize, second: usize, third: usize, fourth: usize, dst: *mut usize) {
let word = ((0x00FF_0000usize & second) << 8) |
((0x0000_00FFusize & second) << 16) |
((0x00FF_0000usize & first) >> 8) |
(0x0000_00FFusize & first);
let second_word = ((0x00FF_0000usize & fourth) << 8) |
((0x0000_00FFusize & fourth) << 16) |
((0x00FF_0000usize & third) >> 8) |
(0x0000_00FFusize & third);
// Safety: fn invariant used here
*dst = word;
*(dst.add(1)) = second_word;
}
} else if #[cfg(all(target_endian = "big", target_pointer_width = "64"))] {
// Aligned ALU word, big-endian, 64-bit
/// Safety invariant: this is the amount of bytes consumed by
/// unpack_alu. This will be twice the pointer width, as it consumes two usizes.
/// This is also the number of bytes produced by pack_alu.
/// This is also the number of u16 code units produced/consumed by unpack_alu/pack_alu respectively.
pub const ALU_STRIDE_SIZE: usize = 16;
pub const MAX_STRIDE_SIZE: usize = 16;
// Safety invariant: this is the pointer width in bytes
pub const ALU_ALIGNMENT: usize = 8;
// Safety invariant: this is a mask for getting the bits of a pointer not aligned to ALU_ALIGNMENT
pub const ALU_ALIGNMENT_MASK: usize = 7;
/// Safety: dst must point to valid space for writing four `usize`s
#[inline(always)]
unsafe fn unpack_alu(word: usize, second_word: usize, dst: *mut usize) {
let first = ((0xFF00_0000_0000_0000usize & word) >> 8) |
((0x00FF_0000_0000_0000usize & word) >> 16) |
((0x0000_FF00_0000_0000usize & word) >> 24) |
((0x0000_00FF_0000_0000usize & word) >> 32);
let second = ((0x0000_0000_FF00_0000usize & word) << 24) |
((0x0000_0000_00FF_0000usize & word) << 16) |
((0x0000_0000_0000_FF00usize & word) << 8) |
(0x0000_0000_0000_00FFusize & word);
let third = ((0xFF00_0000_0000_0000usize & second_word) >> 8) |
((0x00FF_0000_0000_0000usize & second_word) >> 16) |
((0x0000_FF00_0000_0000usize & second_word) >> 24) |
((0x0000_00FF_0000_0000usize & second_word) >> 32);
let fourth = ((0x0000_0000_FF00_0000usize & second_word) << 24) |
((0x0000_0000_00FF_0000usize & second_word) << 16) |
((0x0000_0000_0000_FF00usize & second_word) << 8) |
(0x0000_0000_0000_00FFusize & second_word);
// Safety: fn invariant used here
*dst = first;
*(dst.add(1)) = second;
*(dst.add(2)) = third;
*(dst.add(3)) = fourth;
}
/// Safety: dst must point to valid space for writing two `usize`s
#[inline(always)]
unsafe fn pack_alu(first: usize, second: usize, third: usize, fourth: usize, dst: *mut usize) {
let word = ((0x00FF0000_00000000usize & first) << 8) |
((0x000000FF_00000000usize & first) << 16) |
((0x00000000_00FF0000usize & first) << 24) |
((0x00000000_000000FFusize & first) << 32) |
((0x00FF0000_00000000usize & second) >> 24) |
((0x000000FF_00000000usize & second) >> 16) |
((0x00000000_00FF0000usize & second) >> 8) |
(0x00000000_000000FFusize & second);
let second_word = ((0x00FF0000_00000000usize & third) << 8) |
((0x000000FF_00000000usize & third) << 16) |
((0x00000000_00FF0000usize & third) << 24) |
((0x00000000_000000FFusize & third) << 32) |
((0x00FF0000_00000000usize & fourth) >> 24) |
((0x000000FF_00000000usize & fourth) >> 16) |
((0x00000000_00FF0000usize & fourth) >> 8) |
(0x00000000_000000FFusize & fourth);
// Safety: fn invariant used here
*dst = word;
*(dst.add(1)) = second_word;
}
} else if #[cfg(all(target_endian = "big", target_pointer_width = "32"))] {
// Aligned ALU word, big-endian, 32-bit
/// Safety invariant: this is the amount of bytes consumed by
/// unpack_alu. This will be twice the pointer width, as it consumes two usizes.
/// This is also the number of bytes produced by pack_alu.
/// This is also the number of u16 code units produced/consumed by unpack_alu/pack_alu respectively.
pub const ALU_STRIDE_SIZE: usize = 8;
pub const MAX_STRIDE_SIZE: usize = 8;
// Safety invariant: this is the pointer width in bytes
pub const ALU_ALIGNMENT: usize = 4;
// Safety invariant: this is a mask for getting the bits of a pointer not aligned to ALU_ALIGNMENT
pub const ALU_ALIGNMENT_MASK: usize = 3;
/// Safety: dst must point to valid space for writing four `usize`s
#[inline(always)]
unsafe fn unpack_alu(word: usize, second_word: usize, dst: *mut usize) {
let first = ((0xFF00_0000usize & word) >> 8) |
((0x00FF_0000usize & word) >> 16);
let second = ((0x0000_FF00usize & word) << 8) |
(0x0000_00FFusize & word);
let third = ((0xFF00_0000usize & second_word) >> 8) |
((0x00FF_0000usize & second_word) >> 16);
let fourth = ((0x0000_FF00usize & second_word) << 8) |
(0x0000_00FFusize & second_word);
// Safety: fn invariant used here
*dst = first;
*(dst.add(1)) = second;
*(dst.add(2)) = third;
*(dst.add(3)) = fourth;
}
/// Safety: dst must point to valid space for writing two `usize`s
#[inline(always)]
unsafe fn pack_alu(first: usize, second: usize, third: usize, fourth: usize, dst: *mut usize) {
let word = ((0x00FF_0000usize & first) << 8) |
((0x0000_00FFusize & first) << 16) |
((0x00FF_0000usize & second) >> 8) |
(0x0000_00FFusize & second);
let second_word = ((0x00FF_0000usize & third) << 8) |
((0x0000_00FFusize & third) << 16) |
((0x00FF_0000usize & fourth) >> 8) |
(0x0000_00FFusize & fourth);
// Safety: fn invariant used here
*dst = word;
*(dst.add(1)) = second_word;
}
} else {
ascii_naive!(ascii_to_ascii, u8, u8);
ascii_naive!(ascii_to_basic_latin, u8, u16);
ascii_naive!(basic_latin_to_ascii, u16, u8);
}
}
cfg_if! {
// Safety-usable invariant: this counts the zeroes from the "first byte" of utf-8 data packed into a usize
// with the target endianness
if #[cfg(target_endian = "little")] {
#[allow(dead_code)]
#[inline(always)]
fn count_zeros(word: usize) -> u32 {
word.trailing_zeros()
}
} else {
#[allow(dead_code)]
#[inline(always)]
fn count_zeros(word: usize) -> u32 {
word.leading_zeros()
}
}
}
cfg_if! {
if #[cfg(all(feature = "simd-accel", target_endian = "little", target_arch = "disabled"))] {
/// Safety-usable invariant: Will return the value and position of the first non-ASCII byte in the slice in a Some if found.
/// In other words, the first element of the Some is always `> 127`
#[inline(always)]
pub fn validate_ascii(slice: &[u8]) -> Option<(u8, usize)> {
let src = slice.as_ptr();
let len = slice.len();
let mut offset = 0usize;
// Safety: if this check succeeds we're valid for reading/writing at least `stride` elements.
if SIMD_STRIDE_SIZE <= len {
let len_minus_stride = len - SIMD_STRIDE_SIZE;
loop {
// Safety: src at offset is valid for a `SIMD_STRIDE_SIZE` read
let simd = unsafe { load16_unaligned(src.add(offset)) };
if !simd_is_ascii(simd) {
break;
}
offset += SIMD_STRIDE_SIZE;
// This is `offset > len - SIMD_STRIDE_SIZE` which means we always have at least `SIMD_STRIDE_SIZE` elements to munch next time.
if offset > len_minus_stride {
break;
}
}
}
while offset < len {
let code_unit = slice[offset];
if code_unit > 127 {
// Safety: Safety-usable invariant upheld here
return Some((code_unit, offset));
}
offset += 1;
}
None
}
} else if #[cfg(all(feature = "simd-accel", target_feature = "sse2"))] {
/// Safety-usable invariant: will return Some() when it encounters non-ASCII, with the first element in the Some being
/// guaranteed to be non-ASCII (> 127), and the second being the offset where it is found
#[inline(always)]
pub fn validate_ascii(slice: &[u8]) -> Option<(u8, usize)> {
let src = slice.as_ptr();
let len = slice.len();
let mut offset = 0usize;
// Safety: if this check succeeds we're valid for reading at least `stride` elements.
if SIMD_STRIDE_SIZE <= len {
// First, process one unaligned vector
// Safety: src is valid for a `SIMD_STRIDE_SIZE` read
let simd = unsafe { load16_unaligned(src) };
let mask = mask_ascii(simd);
if mask != 0 {
offset = mask.trailing_zeros() as usize;
let non_ascii = unsafe { *src.add(offset) };
return Some((non_ascii, offset));
}
offset = SIMD_STRIDE_SIZE;
// Safety: Now that offset has changed we don't yet know how much it is valid for
// We have now seen 16 ASCII bytes. Let's guess that
// there will be enough more to justify more expense
// in the case of non-ASCII.
// Use aligned reads for the sake of old microachitectures.
// Safety: this correctly calculates the number of src_units that need to be read before the remaining list is aligned.
// This is by definition less than SIMD_ALIGNMENT, which is defined to be equal to SIMD_STRIDE_SIZE.
let until_alignment = unsafe { (SIMD_ALIGNMENT - ((src.add(offset) as usize) & SIMD_ALIGNMENT_MASK)) & SIMD_ALIGNMENT_MASK };
// This addition won't overflow, because even in the 32-bit PAE case the
// address space holds enough code that the slice length can't be that
// close to address space size.
// offset now equals SIMD_STRIDE_SIZE, hence times 3 below.
//
// Safety: if this check succeeds we're valid for reading at least `2 * SIMD_STRIDE_SIZE` elements plus `until_alignment`.
// The extra SIMD_STRIDE_SIZE in the condition is because `offset` is already `SIMD_STRIDE_SIZE`.
if until_alignment + (SIMD_STRIDE_SIZE * 3) <= len {
if until_alignment != 0 {
// Safety: this is safe to call since we're valid for this read (and more), and don't care about alignment
// This will copy over bytes that get decoded twice since it's not incrementing `offset` by SIMD_STRIDE_SIZE. This is fine.
let simd = unsafe { load16_unaligned(src.add(offset)) };
let mask = mask_ascii(simd);
if mask != 0 {
offset += mask.trailing_zeros() as usize;
let non_ascii = unsafe { *src.add(offset) };
return Some((non_ascii, offset));
}
offset += until_alignment;
}
// Safety: At this point we're valid for reading 2*SIMD_STRIDE_SIZE elements
// Safety: Now `offset` is aligned for `src`
let len_minus_stride_times_two = len - (SIMD_STRIDE_SIZE * 2);
loop {
// Safety: We were valid for this read, and were aligned.
let first = unsafe { load16_aligned(src.add(offset)) };
let second = unsafe { load16_aligned(src.add(offset + SIMD_STRIDE_SIZE)) };
if !simd_is_ascii(first | second) {
// Safety: mask_ascii produces a mask of all the high bits.
let mask_first = mask_ascii(first);
if mask_first != 0 {
// Safety: on little endian systems this will be the number of ascii bytes
// before the first non-ascii, i.e. valid for indexing src
// TODO SAFETY: What about big-endian systems?
offset += mask_first.trailing_zeros() as usize;
} else {
let mask_second = mask_ascii(second);
// Safety: on little endian systems this will be the number of ascii bytes
// before the first non-ascii, i.e. valid for indexing src
offset += SIMD_STRIDE_SIZE + mask_second.trailing_zeros() as usize;
}
// Safety: We know this is non-ASCII, and can uphold the safety-usable invariant here
let non_ascii = unsafe { *src.add(offset) };
return Some((non_ascii, offset));
}
offset += SIMD_STRIDE_SIZE * 2;
// Safety: This is `offset > len - 2 * SIMD_STRIDE_SIZE` which means we always have at least `2 * SIMD_STRIDE_SIZE` elements to munch next time.
if offset > len_minus_stride_times_two {
break;
}
}
// Safety: if this check succeeds we're valid for reading at least `SIMD_STRIDE_SIZE`
if offset + SIMD_STRIDE_SIZE <= len {
// Safety: We were valid for this read, and were aligned.
let simd = unsafe { load16_aligned(src.add(offset)) };
// Safety: mask_ascii produces a mask of all the high bits.
let mask = mask_ascii(simd);
if mask != 0 {
// Safety: on little endian systems this will be the number of ascii bytes
// before the first non-ascii, i.e. valid for indexing src
offset += mask.trailing_zeros() as usize;
let non_ascii = unsafe { *src.add(offset) };
// Safety: We know this is non-ASCII, and can uphold the safety-usable invariant here
return Some((non_ascii, offset));
}
offset += SIMD_STRIDE_SIZE;
}
} else {
// Safety: this is the unaligned branch
// At most two iterations, so unroll
// Safety: if this check succeeds we're valid for reading at least `SIMD_STRIDE_SIZE`
if offset + SIMD_STRIDE_SIZE <= len {
// Safety: We're valid for this read but must use an unaligned read
let simd = unsafe { load16_unaligned(src.add(offset)) };
let mask = mask_ascii(simd);
if mask != 0 {
offset += mask.trailing_zeros() as usize;
let non_ascii = unsafe { *src.add(offset) };
// Safety-usable invariant upheld here (same as above)
return Some((non_ascii, offset));
}
offset += SIMD_STRIDE_SIZE;
// Safety: if this check succeeds we're valid for reading at least `SIMD_STRIDE_SIZE`
if offset + SIMD_STRIDE_SIZE <= len {
// Safety: We're valid for this read but must use an unaligned read
let simd = unsafe { load16_unaligned(src.add(offset)) };
let mask = mask_ascii(simd);
if mask != 0 {
offset += mask.trailing_zeros() as usize;
let non_ascii = unsafe { *src.add(offset) };
// Safety-usable invariant upheld here (same as above)
return Some((non_ascii, offset));
}
offset += SIMD_STRIDE_SIZE;
}
}
}
}
while offset < len {
// Safety: relies straightforwardly on the `len` invariant
let code_unit = unsafe { *(src.add(offset)) };
if code_unit > 127 {
// Safety-usable invariant upheld here
return Some((code_unit, offset));
}
offset += 1;
}
None
}
} else {
// Safety-usable invariant: returns byte index of first non-ascii byte
#[inline(always)]
fn find_non_ascii(word: usize, second_word: usize) -> Option<usize> {
let word_masked = word & ASCII_MASK;
let second_masked = second_word & ASCII_MASK;
if (word_masked | second_masked) == 0 {
// Both are ascii, invariant upheld
return None;
}
if word_masked != 0 {
let zeros = count_zeros(word_masked);
// `zeros` now contains 0 to 7 (for the seven bits of masked ASCII in little endian,
// or up to 7 bits of non-ASCII in big endian if the first byte is non-ASCII)
// plus 8 times the number of ASCII in text order before the
// non-ASCII byte in the little-endian case or 8 times the number of ASCII in
// text order before the non-ASCII byte in the big-endian case.
let num_ascii = (zeros >> 3) as usize;
// Safety-usable invariant upheld here
return Some(num_ascii);
}
let zeros = count_zeros(second_masked);
// `zeros` now contains 0 to 7 (for the seven bits of masked ASCII in little endian,
// or up to 7 bits of non-ASCII in big endian if the first byte is non-ASCII)
// plus 8 times the number of ASCII in text order before the
// non-ASCII byte in the little-endian case or 8 times the number of ASCII in
// text order before the non-ASCII byte in the big-endian case.
let num_ascii = (zeros >> 3) as usize;
// Safety-usable invariant upheld here
Some(ALU_ALIGNMENT + num_ascii)
}
/// Safety: `src` must be valid for the reads of two `usize`s
///
/// Safety-usable invariant: will return byte index of first non-ascii byte
#[inline(always)]
unsafe fn validate_ascii_stride(src: *const usize) -> Option<usize> {
let word = *src;
let second_word = *(src.add(1));
find_non_ascii(word, second_word)
}
/// Safety-usable invariant: will return Some() when it encounters non-ASCII, with the first element in the Some being
/// guaranteed to be non-ASCII (> 127), and the second being the offset where it is found
#[cfg_attr(feature = "cargo-clippy", allow(cast_ptr_alignment))]
#[inline(always)]
pub fn validate_ascii(slice: &[u8]) -> Option<(u8, usize)> {
let src = slice.as_ptr();
let len = slice.len();
let mut offset = 0usize;
let mut until_alignment = (ALU_ALIGNMENT - ((src as usize) & ALU_ALIGNMENT_MASK)) & ALU_ALIGNMENT_MASK;
// Safety: If this check fails we're valid to read `until_alignment + ALU_STRIDE_SIZE` elements
if until_alignment + ALU_STRIDE_SIZE <= len {
while until_alignment != 0 {
let code_unit = slice[offset];
if code_unit > 127 {
// Safety-usable invairant upheld here
return Some((code_unit, offset));
}
offset += 1;
until_alignment -= 1;
}
// Safety: At this point we have read until_alignment elements and
// are valid for `ALU_STRIDE_SIZE` more.
let len_minus_stride = len - ALU_STRIDE_SIZE;
loop {
// Safety: we were valid for this read
let ptr = unsafe { src.add(offset) as *const usize };
if let Some(num_ascii) = unsafe { validate_ascii_stride(ptr) } {
offset += num_ascii;
// Safety-usable invairant upheld here using the invariant from validate_ascii_stride()
return Some((unsafe { *(src.add(offset)) }, offset));
}
offset += ALU_STRIDE_SIZE;
// Safety: This is `offset > ALU_STRIDE_SIZE` which means we always have at least `2 * ALU_STRIDE_SIZE` elements to munch next time.
if offset > len_minus_stride {
break;
}
}
}
while offset < len {
let code_unit = slice[offset];
if code_unit > 127 {
// Safety-usable invairant upheld here
return Some((code_unit, offset));
}
offset += 1;
}
None
}
}
}
cfg_if! {
if #[cfg(all(feature = "simd-accel", any(target_feature = "sse2", all(target_endian = "little", target_arch = "aarch64"))))] {
} else if #[cfg(all(feature = "simd-accel", target_endian = "little", target_feature = "neon"))] {
// Even with NEON enabled, we use the ALU path for ASCII validation, because testing
// on Exynos 5 indicated that using NEON isn't worthwhile where there are only
// vector reads without vector writes.
pub const ALU_STRIDE_SIZE: usize = 8;
pub const ALU_ALIGNMENT: usize = 4;
pub const ALU_ALIGNMENT_MASK: usize = 3;
} else {
// Safety: src points to two valid `usize`s, dst points to four valid `usize`s
#[inline(always)]
unsafe fn unpack_latin1_stride_alu(src: *const usize, dst: *mut usize) {
// Safety: src safety invariant used here
let word = *src;
let second_word = *(src.add(1));
// Safety: dst safety invariant passed down
unpack_alu(word, second_word, dst);
}
// Safety: src points to four valid `usize`s, dst points to two valid `usize`s
#[inline(always)]
unsafe fn pack_latin1_stride_alu(src: *const usize, dst: *mut usize) {
// Safety: src safety invariant used here
let first = *src;
let second = *(src.add(1));
let third = *(src.add(2));
let fourth = *(src.add(3));
// Safety: dst safety invariant passed down
pack_alu(first, second, third, fourth, dst);
}
// Safety: src points to two valid `usize`s, dst points to four valid `usize`s
#[inline(always)]
unsafe fn ascii_to_basic_latin_stride_alu(src: *const usize, dst: *mut usize) -> bool {
// Safety: src safety invariant used here
let word = *src;
let second_word = *(src.add(1));
// Check if the words contains non-ASCII
if (word & ASCII_MASK) | (second_word & ASCII_MASK) != 0 {
return false;
}
// Safety: dst safety invariant passed down
unpack_alu(word, second_word, dst);
true
}
// Safety: src points four valid `usize`s, dst points to two valid `usize`s
#[inline(always)]
unsafe fn basic_latin_to_ascii_stride_alu(src: *const usize, dst: *mut usize) -> bool {
// Safety: src safety invariant used here
let first = *src;
let second = *(src.add(1));
let third = *(src.add(2));
let fourth = *(src.add(3));
if (first & BASIC_LATIN_MASK) | (second & BASIC_LATIN_MASK) | (third & BASIC_LATIN_MASK) | (fourth & BASIC_LATIN_MASK) != 0 {
return false;
}
// Safety: dst safety invariant passed down
pack_alu(first, second, third, fourth, dst);
true
}
// Safety: src, dst both point to two valid `usize`s each
// Safety-usable invariant: Will return byte index of first non-ascii byte.
#[inline(always)]
unsafe fn ascii_to_ascii_stride(src: *const usize, dst: *mut usize) -> Option<usize> {
// Safety: src safety invariant used here
let word = *src;
let second_word = *(src.add(1));
// Safety: src safety invariant used here
*dst = word;
*(dst.add(1)) = second_word;
// Relies on safety-usable invariant here
find_non_ascii(word, second_word)
}
basic_latin_alu!(ascii_to_basic_latin, u8, u16, ascii_to_basic_latin_stride_alu);
basic_latin_alu!(basic_latin_to_ascii, u16, u8, basic_latin_to_ascii_stride_alu);
latin1_alu!(unpack_latin1, u8, u16, unpack_latin1_stride_alu);
latin1_alu!(pack_latin1, u16, u8, pack_latin1_stride_alu);
// Safety invariant upheld: ascii_to_ascii_stride will return byte index of first non-ascii if found
ascii_alu!(ascii_to_ascii, u8, u8, ascii_to_ascii_stride);
}
}
pub fn ascii_valid_up_to(bytes: &[u8]) -> usize {
match validate_ascii(bytes) {
None => bytes.len(),
Some((_, num_valid)) => num_valid,
}
}
pub fn iso_2022_jp_ascii_valid_up_to(bytes: &[u8]) -> usize {
for (i, b_ref) in bytes.iter().enumerate() {
let b = *b_ref;
if b >= 0x80 || b == 0x1B || b == 0x0E || b == 0x0F {
return i;
}
}
bytes.len()
}
// Any copyright to the test code below this comment is dedicated to the
// Public Domain. http://creativecommons.org/publicdomain/zero/1.0/
#[cfg(all(test, feature = "alloc"))]
mod tests {
use super::*;
use alloc::vec::Vec;
macro_rules! test_ascii {
($test_name:ident, $fn_tested:ident, $src_unit:ty, $dst_unit:ty) => {
#[test]
fn $test_name() {
let mut src: Vec<$src_unit> = Vec::with_capacity(32);
let mut dst: Vec<$dst_unit> = Vec::with_capacity(32);
for i in 0..32 {
src.clear();
dst.clear();
dst.resize(32, 0);
for j in 0..32 {
let c = if i == j { 0xAA } else { j + 0x40 };
src.push(c as $src_unit);
}
match unsafe { $fn_tested(src.as_ptr(), dst.as_mut_ptr(), 32) } {
None => unreachable!("Should always find non-ASCII"),
Some((non_ascii, num_ascii)) => {
assert_eq!(non_ascii, 0xAA);
assert_eq!(num_ascii, i);
for j in 0..i {
assert_eq!(dst[j], (j + 0x40) as $dst_unit);
}
}
}
}
}
};
}
test_ascii!(test_ascii_to_ascii, ascii_to_ascii, u8, u8);
test_ascii!(test_ascii_to_basic_latin, ascii_to_basic_latin, u8, u16);
test_ascii!(test_basic_latin_to_ascii, basic_latin_to_ascii, u16, u8);
}