95 static int DecodeUtf8Char(uint8 *data, size_t length, uint32 *codepoint)
96 {
97  if (length < 1) return 0;
98  uint32 value = *data;
99  data++;
100  if ((value & 0x80) == 0) {
101  *codepoint = value;
102  return 1;
103  }
104  int size;
105  uint32 min_value;
106  if ((value & 0xE0) == 0xC0) {
107  size = 2;
108  min_value = 0x80;
109  value &= 0x1F;
110  } else if ((value & 0xF0) == 0xE0) {
111  size = 3;
112  min_value = 0x800;
113  value &= 0x0F;
114  } else if ((value & 0xF8) == 0xF0) {
115  size = 4;
116  min_value = 0x10000;
117  value &= 0x07;
118  } else {
119  return 0;
120  }
121 
122  if (length < static_cast<size_t>(size)) return 0;
123  for (int n = 1; n < size; n++) {
124  uint8 val = *data;
125  data++;
126  if ((val & 0xC0) != 0x80) return 0;
127  value = (value << 6) | (val & 0x3F);
128  }
129  if (value < min_value || (value >= 0xD800 && value <= 0xDFFF) || value > 0x10FFFF) return 0;
130  *codepoint = value;
131  return size;
132 }