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#include <stdio.h>
#include <assert.h>
#include "jv_unicode.h"
#include "jv_utf8_tables.h"
const char* jvp_utf8_next(const char* in, const char* end, int* codepoint) {
if (in == end) {
codepoint = 0;
return 0;
}
unsigned char first = (unsigned char)in[0];
int length = utf8_coding_length[first];
if (length == 0 || length == UTF8_CONTINUATION_BYTE || in + length > end) {
*codepoint = -1;
return 0;
}
*codepoint = ((unsigned)in[0]) & utf8_coding_bits[first];
for (int i=1; i<length; i++) {
int ch = (unsigned char)in[i];
if (utf8_coding_length[(unsigned char)in[i]] != UTF8_CONTINUATION_BYTE){
*codepoint = -1;
return 0;
}
*codepoint = (*codepoint << 6) | (ch & 0x3f);
}
return in + length;
}
int jvp_utf8_verify(const char* in, const char* end) {
int codepoint = 0;
while ((in = jvp_utf8_next(in, end, &codepoint))) {
if (codepoint == -1) return 0;
}
return codepoint != -1;
}
int jvp_utf8_encode_length(int codepoint) {
if (codepoint <= 0x7F) return 1;
else if (codepoint <= 0x7FF) return 2;
else if (codepoint <= 0xFFFF) return 3;
else return 4;
}
int jvp_utf8_encode(int codepoint, char* out) {
assert(codepoint >= 0 && codepoint <= 0x10FFFF);
char* start = out;
if (codepoint <= 0x7F) {
*out++ = codepoint;
} else if (codepoint <= 0x7FF) {
*out++ = 0xC0 + ((codepoint & 0x7C0) >> 6);
*out++ = 0x80 + ((codepoint & 0x03F));
} else if(codepoint <= 0xFFFF) {
*out++ = 0xE0 + ((codepoint & 0xF000) >> 12);
*out++ = 0x80 + ((codepoint & 0x0FC0) >> 6);
*out++ = 0x80 + ((codepoint & 0x003F));
} else {
*out++ = 0xF0 + ((codepoint & 0x1C0000) >> 18);
*out++ = 0x80 + ((codepoint & 0x03F000) >> 12);
*out++ = 0x80 + ((codepoint & 0x000FC0) >> 6);
*out++ = 0x80 + ((codepoint & 0x00003F));
}
assert(out - start == jvp_utf8_encode_length(codepoint));
return out - start;
}
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