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* isValidUtf8 function, tests * Cleanup, change to forAll * Fix accidentally-correct generation of wrong test cases * Increase test count, fix segfault on Clang * Try fixing Windows * Eliminate block-checking for ASCII in fallback mode * Use GHC 8.10 for CI on Windows * Namespace externally-visible C function better * Link to libgcc on Windows * Fix error accumulation in AVX2 check * Fix use of <> on older GHCs * Repair Drone config to deal with older Cabal * Ensure non-SSE2 x86 can still build * License information and contact for C code * Fix test name typo, allow more than pre-set count of tests * Stop using MagicHash for FFI wrapper * Revert change to 8.10 for Windows CI * Use existing license verbatim for C code * Explain the use of gcc and gcc_s * More concise implementation of isValidUtf8 * Document AVX2 block-checking function
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,139 @@ | ||
| /* | ||
| Copyright (c) Koz Ross 2021 | ||
| All rights reserved. | ||
| Redistribution and use in source and binary forms, with or without | ||
| modification, are permitted provided that the following conditions | ||
| are met: | ||
| 1. Redistributions of source code must retain the above copyright | ||
| notice, this list of conditions and the following disclaimer. | ||
| 2. Redistributions in binary form must reproduce the above copyright | ||
| notice, this list of conditions and the following disclaimer in the | ||
| documentation and/or other materials provided with the distribution. | ||
| 3. Neither the name of the author nor the names of his contributors | ||
| may be used to endorse or promote products derived from this software | ||
| without specific prior written permission. | ||
| THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | ||
| ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | ||
| IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | ||
| ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE | ||
| FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | ||
| DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | ||
| OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | ||
| HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | ||
| LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | ||
| OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | ||
| SUCH DAMAGE. | ||
| */ | ||
| #pragma GCC push_options | ||
| #pragma GCC optimize("-O2") | ||
| #include <stdbool.h> | ||
| #include <stddef.h> | ||
| #include <stdint.h> | ||
|
|
||
| // 0x80 in every 'lane'. | ||
| static uint64_t const high_bits_mask = 0x8080808080808080ULL; | ||
|
|
||
| int bytestring_is_valid_utf8(uint8_t const *const src, size_t const len) { | ||
| uint8_t const *ptr = (uint8_t const *)src; | ||
| // This is 'one past the end' to make loop termination and bounds checks | ||
| // easier. | ||
| uint8_t const *const end = ptr + len; | ||
| while (ptr < end) { | ||
| uint8_t const byte = *ptr; | ||
| // Check if the byte is ASCII. | ||
| if (byte <= 0x7F) { | ||
| ptr++; | ||
| /* | ||
| // If we saw one ASCII byte, as long as it's not whitespace, it's quite | ||
| // likely we'll see more. | ||
| bool is_not_whitespace = byte > 32; | ||
| // If possible, do a block-check ahead. | ||
| if ((ptr + 32 < end) && is_not_whitespace) { | ||
| uint64_t const *big_ptr = (uint64_t const *)ptr; | ||
| // Non-ASCII bytes have a set MSB. Thus, if we AND with 0x80 in every | ||
| // 'lane', we will get 0 if everything is ASCII, and something else | ||
| // otherwise. | ||
| uint64_t results[4] = {(*big_ptr) & high_bits_mask, | ||
| (*(big_ptr + 1)) & high_bits_mask, | ||
| (*(big_ptr + 2)) & high_bits_mask, | ||
| (*(big_ptr + 3)) & high_bits_mask}; | ||
| if (results[0] == 0) { | ||
| ptr += 8; | ||
| if (results[1] == 0) { | ||
| ptr += 8; | ||
| if (results[2] == 0) { | ||
| ptr += 8; | ||
| if (results[3] == 0) { | ||
| ptr += 8; | ||
| } else { | ||
| ptr += (__builtin_ctzl(results[3]) / 8); | ||
| } | ||
| } else { | ||
| ptr += (__builtin_ctzl(results[2]) / 8); | ||
| } | ||
| } else { | ||
| ptr += (__builtin_ctzl(results[1]) / 8); | ||
| } | ||
| } else { | ||
| ptr += (__builtin_ctzl(results[0]) / 8); | ||
| } | ||
| } | ||
| */ | ||
| } | ||
| // Check for a valid 2-byte sequence. | ||
| // | ||
| // We use a signed comparison to avoid an extra comparison with 0x80, since | ||
| // _signed_ 0x80 is -128. | ||
| else if (ptr + 1 < end && byte >= 0xC2 && byte <= 0xDF && | ||
| ((int8_t) * (ptr + 1)) <= (int8_t)0xBF) { | ||
| ptr += 2; | ||
| } | ||
| // Check for a valid 3-byte sequence. | ||
| else if (ptr + 2 < end && byte >= 0xE0 && byte <= 0xEF) { | ||
| uint8_t const byte2 = *(ptr + 1); | ||
| bool byte2_valid = (int8_t)byte2 <= (int8_t)0xBF; | ||
| bool byte3_valid = ((int8_t) * (ptr + 2)) <= (int8_t)0xBF; | ||
| if (byte2_valid && byte3_valid && | ||
| // E0, A0..BF, 80..BF | ||
| ((byte == 0xE0 && byte2 >= 0xA0) || | ||
| // E1..EC, 80..BF, 80..BF | ||
| (byte >= 0xE1 && byte <= 0xEC) || | ||
| // ED, 80..9F, 80..BF | ||
| (byte == 0xED && byte2 <= 0x9F) || | ||
| // EE..EF, 80..BF, 80..BF | ||
| (byte >= 0xEE && byte <= 0xEF))) { | ||
| ptr += 3; | ||
| } else { | ||
| return 0; | ||
| } | ||
| } | ||
| // Check for a valid 4-byte sequence. | ||
| else if (ptr + 3 < end) { | ||
| uint8_t const byte2 = *(ptr + 1); | ||
| bool byte2_valid = (int8_t)byte2 <= (int8_t)0xBF; | ||
| bool byte3_valid = ((int8_t) * (ptr + 2)) <= (int8_t)0xBF; | ||
| bool byte4_valid = ((int8_t) * (ptr + 3)) <= (int8_t)0xBF; | ||
| if (byte2_valid && byte3_valid && byte4_valid && | ||
| // F0, 90..BF, 80..BF, 80..BF | ||
| ((byte == 0xF0 && byte2 >= 0x90) || | ||
| // F1..F3, 80..BF, 80..BF, 80..BF | ||
| (byte >= 0xF1 && byte <= 0xF3) || | ||
| // F4, 80..8F, 80..BF, 80..BF | ||
| (byte == 0xF4 && byte2 <= 0x8F))) { | ||
| ptr += 4; | ||
| } else { | ||
| return 0; | ||
| } | ||
| } | ||
| // Otherwise, invalid. | ||
| else { | ||
| return 0; | ||
| } | ||
| } | ||
| // If we got this far, we're valid. | ||
| return 1; | ||
| } | ||
| #pragma GCC pop_options |
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