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/*
* utf8.c
*
* Copyright (c) Chris Putnam 2004-5
*
* Source code released under the GPL
*
*/
#include <stdio.h>
#include "utf8.h"
/* UTF-8 encryption
U-00000000 - U-0000007F: 0xxxxxxx
U-00000080 - U-000007FF: 110xxxxx 10xxxxxx
U-00000800 - U-0000FFFF: 1110xxxx 10xxxxxx 10xxxxxx
U-00010000 - U-001FFFFF: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
U-00200000 - U-03FFFFFF: 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
U-04000000 - U-7FFFFFFF: 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
*/
static void
utf8_build( unsigned int value, unsigned char out[6], int in_pos, int out_pos )
{
unsigned int in_mask, out_mask;
int byte = 0;
while ( in_pos < 32 ) {
in_mask = 1 << ( 31 - in_pos );
out_mask = 1 << ( 7 - out_pos );
if ( value & in_mask ) out[byte] |= out_mask;
in_pos++;
out_pos++;
if ( out_pos > 7 ) {
out_pos=2;
byte++;
}
}
}
/* int utf8( in, out[6] );
*
* in is character code 0x0 -> 0x7FFFFFFF
* int is number of characters for output
*
*/
int
utf8_encode( unsigned int value, unsigned char out[6] )
{
int i;
for ( i=1; i<6; ++i ) out[i] = 0x80; /* 10xxxxxx */
if ( value < 0x80 ) {
out[0] = 0x0; /* 0xxxxxxx */
utf8_build( value, out, 25, 1 );
return 1;
} else if ( value < 0x800 ) {
out[0] = 0xC0; /* 110xxxxx */
utf8_build( value, out, 21, 3 );
return 2;
} else if ( value < 0x10000 ) {
out[0] = 0xE0; /* 1110xxxx */
utf8_build( value, out, 16, 4 );
return 3;
} else if ( value < 0x200000 ) {
out[0] = 0xF0; /* 11110xxx */
utf8_build( value, out, 11, 5 );
return 4;
} else if ( value < 0x4000000 ) {
out[0] = 0xF8; /* 111110xx */
utf8_build( value, out, 6, 6 );
return 5;
} else if ( value < (unsigned int ) 0x80000000 ) {
out[0] = 0xFC; /* 1111110x */
utf8_build( value, out, 1, 7 );
return 6;
} else {
/* error, above 2^31 bits encodable by UTF-8 */
return 0;
}
}
unsigned int
utf8_decode( char *s, unsigned int *pi )
{
unsigned int c;
int i = *pi;
/* one digit utf-8 */
if ((s[i] & 128)== 0 ) {
c = (unsigned int) s[i];
i += 1;
} else if ((s[i] & 224)== 192 ) { /* 110xxxxx & 111xxxxx == 110xxxxx */
c = (( (unsigned int) s[i] & 31 ) << 6) +
( (unsigned int) s[i+1] & 63 );
i += 2;
} else if ((s[i] & 240)== 224 ) { /* 1110xxxx & 1111xxxx == 1110xxxx */
c = ( ( (unsigned int) s[i] & 15 ) << 12 ) +
( ( (unsigned int) s[i+1] & 63 ) << 6 ) +
( (unsigned int) s[i+2] & 63 );
i += 3;
} else if ((s[i] & 248)== 240 ) { /* 11110xxx & 11111xxx == 11110xxx */
c = ( ( (unsigned int) s[i] & 7 ) << 18 ) +
( ( (unsigned int) s[i+1] & 63 ) << 12 ) +
( ( (unsigned int) s[i+2] & 63 ) << 6 ) +
( (unsigned int) s[i+3] & 63 );
i+= 4;
} else if ((s[i] & 252)== 248 ) { /* 111110xx & 111111xx == 111110xx */
c = ( ( (unsigned int) s[i] & 3 ) << 24 ) +
( ( (unsigned int) s[i+1] & 63 ) << 18 ) +
( ( (unsigned int) s[i+2] & 63 ) << 12 ) +
( ( (unsigned int) s[i+3] & 63 ) << 6 ) +
( (unsigned int) s[i+4] & 63 );
i += 5;
} else if ((s[i] & 254)== 252 ) { /* 1111110x & 1111111x == 1111110x */
c = ( ( (unsigned int) s[i] & 1 ) << 30 ) +
( ( (unsigned int) s[i+1] & 63 ) << 24 ) +
( ( (unsigned int) s[i+2] & 63 ) << 18 ) +
( ( (unsigned int) s[i+3] & 63 ) << 12 ) +
( ( (unsigned int) s[i+4] & 63 ) << 6 ) +
( (unsigned int) s[i+5] & 63 );
i += 6;
} else {
c = '?';
i++;
}
*pi = i;
return c;
}
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