utf8.c

   1 #include "termbox.h"
   2
   3 static const unsigned char utf8_length[256] = { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
   4         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
   5         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
   6         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
   7         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
   8         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
   9         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  10         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
  11         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
  12         2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3,
  13         3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5,
  14         5, 6, 6, 1, 1 };
  15
  16 static const unsigned char utf8_mask[6] = { 0x7F, 0x1F, 0x0F, 0x07, 0x03,
  17         0x01 };
  18
  19 int
  20 tb_utf8_char_length(char c)
  21 {
  22         return utf8_length[(unsigned char)c];
  23 }
  24
  25 int
  26 tb_utf8_char_to_unicode(uint32_t *out, const char *c)
  27 {
  28         if (*c == 0)
  29                 return TB_EOF;
  30
  31         int i;
  32         unsigned char len = tb_utf8_char_length(*c);
  33         unsigned char mask = utf8_mask[len - 1];
  34         uint32_t result = c[0] & mask;
  35         for (i = 1; i < len; ++i) {
  36                 result <<= 6;
  37                 result |= c[i] & 0x3f;
  38         }
  39
  40         *out = result;
  41         return (int)len;
  42 }
  43
  44 int
  45 tb_utf8_unicode_to_char(char *out, uint32_t c)
  46 {
  47         int len = 0;
  48         int first;
  49         int i;
  50
  51         if (c < 0x80) {
  52                 first = 0;
  53                 len = 1;
  54         } else if (c < 0x800) {
  55                 first = 0xc0;
  56                 len = 2;
  57         } else if (c < 0x10000) {
  58                 first = 0xe0;
  59                 len = 3;
  60         } else if (c < 0x200000) {
  61                 first = 0xf0;
  62                 len = 4;
  63         } else if (c < 0x4000000) {
  64                 first = 0xf8;
  65                 len = 5;
  66         } else {
  67                 first = 0xfc;
  68                 len = 6;
  69         }
  70
  71         for (i = len - 1; i > 0; --i) {
  72                 out[i] = (c & 0x3f) | 0x80;
  73                 c >>= 6;
  74         }
  75         out[0] = c | first;
  76
  77         return len;
  78 }