129 lines · cpp
1//===-- lib/runtime/utf.cpp -------------------------------------*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "flang-rt/runtime/utf.h"10 11namespace Fortran::runtime {12 13#ifndef FLANG_RUNTIME_NO_GLOBAL_VAR_DEFS14// clang-format off15RT_OFFLOAD_VAR_GROUP_BEGIN16const RT_CONST_VAR_ATTRS std::uint8_t UTF8FirstByteTable[256]{17 /* 00 - 7F: 7 bit payload in single byte */18 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,19 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,20 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,21 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,22 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,23 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,24 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,25 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,26 /* 80 - BF: invalid first byte, valid later byte */27 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,28 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,29 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,30 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,31 /* C0 - DF: 11 bit payload */32 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,33 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,34 /* E0 - EF: 16 bit payload */35 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,36 /* F0 - F7: 21 bit payload */ 4, 4, 4, 4, 4, 4, 4, 4,37 /* F8 - FB: 26 bit payload */ 5, 5, 5, 5,38 /* FC - FD: 31 bit payload */ 6, 6,39 /* FE: 32 bit payload */ 7,40 /* FF: invalid */ 041};42RT_OFFLOAD_VAR_GROUP_END43// clang-format on44#endif // FLANG_RUNTIME_NO_GLOBAL_VAR_DEFS45 46RT_OFFLOAD_API_GROUP_BEGIN47 48std::size_t MeasurePreviousUTF8Bytes(const char *end, std::size_t limit) {49 // Scan back over UTF-8 continuation bytes, if any50 for (std::size_t n{1}; n <= limit; ++n) {51 if ((end[-n] & 0xc0) != 0x80) {52 return n;53 }54 }55 return limit;56}57 58// Non-minimal encodings are accepted.59common::optional<char32_t> DecodeUTF8(const char *p0) {60 const std::uint8_t *p{reinterpret_cast<const std::uint8_t *>(p0)};61 std::size_t bytes{MeasureUTF8Bytes(*p0)};62 if (bytes == 1) {63 return char32_t{*p};64 } else if (bytes > 1) {65 std::uint64_t result{char32_t{*p} & (0x7f >> bytes)};66 for (std::size_t j{1}; j < bytes; ++j) {67 std::uint8_t next{p[j]};68 if (next < 0x80 || next > 0xbf) {69 return common::nullopt;70 }71 result = (result << 6) | (next & 0x3f);72 }73 if (result <= 0xffffffff) {74 return static_cast<char32_t>(result);75 }76 }77 return common::nullopt;78}79 80std::size_t EncodeUTF8(char *p0, char32_t ucs) {81 std::uint8_t *p{reinterpret_cast<std::uint8_t *>(p0)};82 if (ucs <= 0x7f) {83 p[0] = ucs;84 return 1;85 } else if (ucs <= 0x7ff) {86 p[0] = 0xc0 | (ucs >> 6);87 p[1] = 0x80 | (ucs & 0x3f);88 return 2;89 } else if (ucs <= 0xffff) {90 p[0] = 0xe0 | (ucs >> 12);91 p[1] = 0x80 | ((ucs >> 6) & 0x3f);92 p[2] = 0x80 | (ucs & 0x3f);93 return 3;94 } else if (ucs <= 0x1fffff) {95 p[0] = 0xf0 | (ucs >> 18);96 p[1] = 0x80 | ((ucs >> 12) & 0x3f);97 p[2] = 0x80 | ((ucs >> 6) & 0x3f);98 p[3] = 0x80 | (ucs & 0x3f);99 return 4;100 } else if (ucs <= 0x3ffffff) {101 p[0] = 0xf8 | (ucs >> 24);102 p[1] = 0x80 | ((ucs >> 18) & 0x3f);103 p[2] = 0x80 | ((ucs >> 12) & 0x3f);104 p[3] = 0x80 | ((ucs >> 6) & 0x3f);105 p[4] = 0x80 | (ucs & 0x3f);106 return 5;107 } else if (ucs <= 0x7ffffff) {108 p[0] = 0xf8 | (ucs >> 30);109 p[1] = 0x80 | ((ucs >> 24) & 0x3f);110 p[2] = 0x80 | ((ucs >> 18) & 0x3f);111 p[3] = 0x80 | ((ucs >> 12) & 0x3f);112 p[4] = 0x80 | ((ucs >> 6) & 0x3f);113 p[5] = 0x80 | (ucs & 0x3f);114 return 6;115 } else {116 p[0] = 0xfe;117 p[1] = 0x80 | ((ucs >> 30) & 0x3f);118 p[2] = 0x80 | ((ucs >> 24) & 0x3f);119 p[3] = 0x80 | ((ucs >> 18) & 0x3f);120 p[4] = 0x80 | ((ucs >> 12) & 0x3f);121 p[5] = 0x80 | ((ucs >> 6) & 0x3f);122 p[6] = 0x80 | (ucs & 0x3f);123 return 7;124 }125}126RT_OFFLOAD_API_GROUP_END127 128} // namespace Fortran::runtime129