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// Copyright (c) 2015 Ryan Prichard
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
#ifndef UNICODE_ENCODING_H
#define UNICODE_ENCODING_H
#include <stdint.h>
// Encode the Unicode codepoint with UTF-8. The buffer must be at least 4
// bytes in size.
static inline int encodeUtf8(char *out, uint32_t code) {
if (code < 0x80) {
out[0] = code;
return 1;
} else if (code < 0x800) {
out[0] = ((code >> 6) & 0x1F) | 0xC0;
out[1] = ((code >> 0) & 0x3F) | 0x80;
return 2;
} else if (code < 0x10000) {
if (code >= 0xD800 && code <= 0xDFFF) {
// The code points 0xD800 to 0xDFFF are reserved for UTF-16
// surrogate pairs and do not have an encoding in UTF-8.
return 0;
}
out[0] = ((code >> 12) & 0x0F) | 0xE0;
out[1] = ((code >> 6) & 0x3F) | 0x80;
out[2] = ((code >> 0) & 0x3F) | 0x80;
return 3;
} else if (code < 0x110000) {
out[0] = ((code >> 18) & 0x07) | 0xF0;
out[1] = ((code >> 12) & 0x3F) | 0x80;
out[2] = ((code >> 6) & 0x3F) | 0x80;
out[3] = ((code >> 0) & 0x3F) | 0x80;
return 4;
} else {
// Encoding error
return 0;
}
}
// Encode the Unicode codepoint with UTF-16. The buffer must be large enough
// to hold the output -- either 1 or 2 elements.
static inline int encodeUtf16(wchar_t *out, uint32_t code) {
if (code < 0x10000) {
if (code >= 0xD800 && code <= 0xDFFF) {
// The code points 0xD800 to 0xDFFF are reserved for UTF-16
// surrogate pairs and do not have an encoding in UTF-16.
return 0;
}
out[0] = code;
return 1;
} else if (code < 0x110000) {
code -= 0x10000;
out[0] = 0xD800 | (code >> 10);
out[1] = 0xDC00 | (code & 0x3FF);
return 2;
} else {
// Encoding error
return 0;
}
}
// Return the byte size of a UTF-8 character using the value of the first
// byte.
static inline int utf8CharLength(char firstByte) {
// This code would probably be faster if it used __builtin_clz.
if ((firstByte & 0x80) == 0) {
return 1;
} else if ((firstByte & 0xE0) == 0xC0) {
return 2;
} else if ((firstByte & 0xF0) == 0xE0) {
return 3;
} else if ((firstByte & 0xF8) == 0xF0) {
return 4;
} else {
// Malformed UTF-8.
return 0;
}
}
// The pointer must point to 1-4 bytes, as indicated by the first byte.
// Returns -1 on decoding error.
static inline uint32_t decodeUtf8(const char *in) {
const uint32_t kInvalid = static_cast<uint32_t>(-1);
switch (utf8CharLength(in[0])) {
case 1: {
return in[0];
}
case 2: {
if ((in[1] & 0xC0) != 0x80) {
return kInvalid;
}
uint32_t tmp = 0;
tmp = (in[0] & 0x1F) << 6;
tmp |= (in[1] & 0x3F);
return tmp <= 0x7F ? kInvalid : tmp;
}
case 3: {
if ((in[1] & 0xC0) != 0x80 ||
(in[2] & 0xC0) != 0x80) {
return kInvalid;
}
uint32_t tmp = 0;
tmp = (in[0] & 0x0F) << 12;
tmp |= (in[1] & 0x3F) << 6;
tmp |= (in[2] & 0x3F);
if (tmp <= 0x07FF || (tmp >= 0xD800 && tmp <= 0xDFFF)) {
return kInvalid;
} else {
return tmp;
}
}
case 4: {
if ((in[1] & 0xC0) != 0x80 ||
(in[2] & 0xC0) != 0x80 ||
(in[3] & 0xC0) != 0x80) {
return kInvalid;
}
uint32_t tmp = 0;
tmp = (in[0] & 0x07) << 18;
tmp |= (in[1] & 0x3F) << 12;
tmp |= (in[2] & 0x3F) << 6;
tmp |= (in[3] & 0x3F);
if (tmp <= 0xFFFF || tmp > 0x10FFFF) {
return kInvalid;
} else {
return tmp;
}
}
default: {
return kInvalid;
}
}
}
static inline uint32_t decodeSurrogatePair(wchar_t ch1, wchar_t ch2) {
return ((ch1 - 0xD800) << 10) + (ch2 - 0xDC00) + 0x10000;
}
#endif // UNICODE_ENCODING_H
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