2 * Copyright (C) 2012, 2013
5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
6 * this software and associated documentation files (the "Software"), to deal in
7 * the Software without restriction, including without limitation the rights to
8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
9 * of the Software, and to permit persons to whom the Software is furnished to do
10 * so, subject to the following conditions:
12 * The above copyright notice and this permission notice shall be included in all
13 * copies or substantial portions of the Software.
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
26 * Based on the flexible and economical utf8 decoder:
27 * http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
29 * This is slightly more economical, the fastest way to decode utf8 is
30 * with a lookup table as in:
33 * if that fails, 2-byte lookup
34 * if that fails, 3-byte lookup
35 * if that fails, 4-byte lookup
37 * The following table can be generated with some interval trickery.
38 * consider an interval [a, b):
40 * a must be 0x80 or b must be 0xc0, lower 3 bits
42 * interval(a,b) = ((uint32_t)((a==0x80?0x40-b:-a)<<23))
44 * The failstate can be represented as interval(0x80,0x80), it's
45 * odd to see but this is a full state machine.
47 * The table than maps the corresponding sections as a serise of
50 * In this table the transition values are pre-multiplied with 16 to
51 * save a shift instruction for every byte, we throw away fillers
52 * which makes the table smaller.
54 * The first section of the table handles bytes with leading C
55 * The second section of the table handles bytes with leading D
56 * The third section of the table handles bytes with leading E
57 * The last section of the table handles bytes with leading F
59 * The values themselfs in the table are arranged so that when you
60 * left shift them by 6 to shift continuation characters into place, the
61 * new top bits tell you:
63 * 1 - if you keep going
64 * 2 - the range of valid values for the next byte
66 static const uint32_t utf8_tab[] = {
67 0xC0000002, 0xC0000003, 0xC0000004, 0xC0000005, 0xC0000006,
68 0xC0000007, 0xC0000008, 0xC0000009, 0xC000000A, 0xC000000B,
69 0xC000000C, 0xC000000D, 0xC000000E, 0xC000000F, 0xC0000010,
70 0xC0000011, 0xC0000012, 0xC0000013, 0xC0000014, 0xC0000015,
71 0xC0000016, 0xC0000017, 0xC0000018, 0xC0000019, 0xC000001A,
72 0xC000001B, 0xC000001C, 0xC000001D, 0xC000001E, 0xC000001F,
73 0xB3000000, 0xC3000001, 0xC3000002, 0xC3000003, 0xC3000004,
74 0xC3000005, 0xC3000006, 0xC3000007, 0xC3000008, 0xC3000009,
75 0xC300000A, 0xC300000B, 0xC300000C, 0xD300000D, 0xC300000E,
76 0xC300000F, 0xBB0C0000, 0xC30C0001, 0xC30C0002, 0xC30C0003,
80 int utf8_from(char *s, utf8ch_t ch) {
84 if ((unsigned)ch < 0x80) {
87 } else if ((unsigned)ch < 0x800) {
88 *s++ = 0xC0 | (ch >> 6);
89 *s = 0x80 | (ch & 0x3F);
91 } else if ((unsigned)ch < 0xD800 || (unsigned)ch - 0xE000 < 0x2000) {
92 *s++ = 0xE0 | (ch >> 12);
93 *s++ = 0x80 | ((ch >> 6) & 0x3F);
94 *s = 0x80 | (ch & 0x3F);
96 } else if ((unsigned)ch - 0x10000 < 0x100000) {
97 *s++ = 0xF0 | (ch >> 18);
98 *s++ = 0x80 | ((ch >> 12) & 0x3F);
99 *s++ = 0x80 | ((ch >> 6) & 0x3F);
100 *s = 0x80 | (ch & 0x3F);
106 int utf8_to(utf8ch_t *i, const unsigned char *s, size_t n) {
112 /* This is consistent with mbtowc behaviour. */
114 i = (utf8ch_t*)(void*)&i;
121 c = utf8_tab[*s++-0xC2U];
124 * Avoid excessive checks against n.
126 * When shifting state `n-1` times does not clear the high bit,
127 * then the value of `n` won't satisfy the condition to read a
128 * character as it will be insufficent.
130 if (n < 4 && ((c<<(6*n-6)) & (1U << 31)))
134 * The upper 6 state bits are negitive integer offset to a bound-check
135 * next byte equivlant to: ((b-0x80)+(b+offset))&~0x3f
137 if ((((*s>>3)-0x10)|((*s>>3)+((int32_t)c>>26))) & ~7)
140 for (j=2; j<3; j++) {
141 if (!((c = c<<6 | (*s++-0x80))&(1U<<31))) {
145 if (*s-0x80U >= 0x40)
149 *i = c<<6 | (*s++-0x80);