111 lines
2.7 KiB
C
111 lines
2.7 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <inttypes.h>
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typedef struct {
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char mask; /* char data will be bitwise AND with this */
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char lead; /* start bytes of current char in utf-8 encoded character */
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uint32_t beg; /* beginning of codepoint range */
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uint32_t end; /* end of codepoint range */
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int bits_stored; /* the number of bits from the codepoint that fits in char */
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}utf_t;
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utf_t * utf[] = {
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/* mask lead beg end bits */
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[0] = &(utf_t){0b00111111, 0b10000000, 0, 0, 6 },
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[1] = &(utf_t){0b01111111, 0b00000000, 0000, 0177, 7 },
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[2] = &(utf_t){0b00011111, 0b11000000, 0200, 03777, 5 },
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[3] = &(utf_t){0b00001111, 0b11100000, 04000, 0177777, 4 },
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[4] = &(utf_t){0b00000111, 0b11110000, 0200000, 04177777, 3 },
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&(utf_t){0},
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};
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/* All lengths are in bytes */
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int codepoint_len(const uint32_t cp); /* len of associated utf-8 char */
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int utf8_len(const char ch); /* len of utf-8 encoded char */
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char *to_utf8(const uint32_t cp);
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uint32_t to_cp(const char chr[4]);
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int codepoint_len(const uint32_t cp)
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{
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int len = 0;
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for(utf_t **u = utf; *u; ++u) {
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if((cp >= (*u)->beg) && (cp <= (*u)->end)) {
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break;
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}
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++len;
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}
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if(len > 4) /* Out of bounds */
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exit(1);
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return len;
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}
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int utf8_len(const char ch)
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{
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int len = 0;
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for(utf_t **u = utf; *u; ++u) {
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if((ch & ~(*u)->mask) == (*u)->lead) {
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break;
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}
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++len;
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}
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if(len > 4) { /* Malformed leading byte */
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exit(1);
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}
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return len;
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}
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char *to_utf8(const uint32_t cp)
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{
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static char ret[5];
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const int bytes = codepoint_len(cp);
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int shift = utf[0]->bits_stored * (bytes - 1);
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ret[0] = (cp >> shift & utf[bytes]->mask) | utf[bytes]->lead;
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shift -= utf[0]->bits_stored;
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for(int i = 1; i < bytes; ++i) {
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ret[i] = (cp >> shift & utf[0]->mask) | utf[0]->lead;
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shift -= utf[0]->bits_stored;
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}
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ret[bytes] = '\0';
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return ret;
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}
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uint32_t to_cp(const char chr[4])
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{
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int bytes = utf8_len(*chr);
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int shift = utf[0]->bits_stored * (bytes - 1);
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uint32_t codep = (*chr++ & utf[bytes]->mask) << shift;
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for(int i = 1; i < bytes; ++i, ++chr) {
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shift -= utf[0]->bits_stored;
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codep |= ((char)*chr & utf[0]->mask) << shift;
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}
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return codep;
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}
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int main(void)
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{
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const uint32_t *in, input[] = {0x0041, 0x00f6, 0x0416, 0x20ac, 0x1d11e, 0x0};
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printf("Character Unicode UTF-8 encoding (hex)\n");
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printf("----------------------------------------\n");
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char *utf8;
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uint32_t codepoint;
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for(in = input; *in; ++in) {
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utf8 = to_utf8(*in);
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codepoint = to_cp(utf8);
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printf("%s U+%-7.4x", utf8, codepoint);
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for(int i = 0; utf8[i] && i < 4; ++i) {
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printf("%hhx ", utf8[i]);
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}
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printf("\n");
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}
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return 0;
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}
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