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#include "../../include/mgl/system/utf8.h"
/* TODO: Optimize (remove branching, etc) */
bool mgl_utf8_is_valid(const unsigned char *str, size_t size) {
size_t i = 0;
while(i < size) {
size_t codepoint_length = 0;
const unsigned char b = str[i];
if((b & 0x80) == 0)
codepoint_length = 1;
else if((b & 0xE0) == 0xC0)
codepoint_length = 2;
else if((b & 0xF0) == 0xE0)
codepoint_length = 3;
else if((b & 0xF8) == 0xF0)
codepoint_length = 4;
else
return false;
const size_t next = i + codepoint_length;
if(next > size)
return false;
/* TODO: Remove this overflow check? */
/* Check overflow */
if(next <= i)
return false;
++i;
for(; i < next; ++i) {
if((str[i] & 0xC0) != 0x80)
return false;
}
}
return true;
}
static inline size_t utf8_get_codepoint_length(unsigned char b) {
const unsigned int length1 = b >> 7;
const unsigned int length2 = length1 & ((b & 0x40) >> 6);
const unsigned int length3 = length2 & ((b & 0x20) >> 5);
const unsigned int length4 = length3 & ((b & 0x10) >> 4);
return (length1 ^ 0x01) + length1 + length2 + length3 + length4;
}
/* TODO: Optimize (remove branching, etc) */
size_t mgl_utf8_decode(const unsigned char *str, uint32_t *decoded_codepoint) {
const size_t length = utf8_get_codepoint_length(str[0]);
uint32_t codepoint;
switch(length) {
case 1:
codepoint = (uint32_t)(str[0] & 0x7F);
break;
case 2:
codepoint = ((uint32_t)(str[0] & 0x1F) << 6);
codepoint |= (uint32_t)(str[1] & 0x3F);
break;
case 3:
codepoint = ((uint32_t)(str[0] & 0x0F) << 12);
codepoint |= ((uint32_t)(str[1] & 0x3F) << 6);
codepoint |= (uint32_t)(str[2] & 0x3F);
break;
case 4:
codepoint = ((uint32_t)(str[0] & 0x07) << 18);
codepoint |= ((uint32_t)(str[1] & 0x3F) << 12);
codepoint |= ((uint32_t)(str[2] & 0x3F) << 6);
codepoint |= (uint32_t)(str[3] & 0x3F);
break;
}
*decoded_codepoint = codepoint;
return length;
}
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