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#include "rune.h"
enum
{
Bit1 = 7,
Bitx = 6,
Bit2 = 5,
Bit3 = 4,
Bit4 = 3,
T1 = ((1<<(Bit1+1))-1) ^ 0xFF, /* 0000 0000 */
Tx = ((1<<(Bitx+1))-1) ^ 0xFF, /* 1000 0000 */
T2 = ((1<<(Bit2+1))-1) ^ 0xFF, /* 1100 0000 */
T3 = ((1<<(Bit3+1))-1) ^ 0xFF, /* 1110 0000 */
T4 = ((1<<(Bit4+1))-1) ^ 0xFF, /* 1111 0000 */
Rune1 = (1<<(Bit1+0*Bitx))-1, /* 0000 0000 0111 1111 */
Rune2 = (1<<(Bit2+1*Bitx))-1, /* 0000 0111 1111 1111 */
Rune3 = (1<<(Bit3+2*Bitx))-1, /* 1111 1111 1111 1111 */
Maskx = (1<<Bitx)-1, /* 0011 1111 */
Testx = Maskx ^ 0xFF, /* 1100 0000 */
Bad = Runeerror
};
int
chartorune(Rune *rune, char *str)
{
int c, c1, c2;
long l;
/*
* one character sequence
* 00000-0007F => T1
*/
c = *(unsigned char*)str;
if(c < Tx) {
*rune = c;
return 1;
}
/*
* two character sequence
* 0080-07FF => T2 Tx
*/
c1 = *(unsigned char*)(str+1) ^ Tx;
if(c1 & Testx)
goto bad;
if(c < T3) {
if(c < T2)
goto bad;
l = ((c << Bitx) | c1) & Rune2;
if(l <= Rune1)
goto bad;
*rune = l;
return 2;
}
/*
* three character sequence
* 0800-FFFF => T3 Tx Tx
*/
c2 = *(unsigned char*)(str+2) ^ Tx;
if(c2 & Testx)
goto bad;
if(c < T4) {
l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
if(l <= Rune2)
goto bad;
*rune = l;
return 3;
}
/*
* bad decoding
*/
bad:
*rune = Bad;
return 1;
}
int
runetochar(char *str, Rune *rune)
{
long c;
/*
* one character sequence
* 00000-0007F => 00-7F
*/
c = *rune;
if(c <= Rune1) {
str[0] = c;
return 1;
}
/*
* two character sequence
* 0080-07FF => T2 Tx
*/
if(c <= Rune2) {
str[0] = T2 | (c >> 1*Bitx);
str[1] = Tx | (c & Maskx);
return 2;
}
/*
* three character sequence
* 0800-FFFF => T3 Tx Tx
*/
str[0] = T3 | (c >> 2*Bitx);
str[1] = Tx | ((c >> 1*Bitx) & Maskx);
str[2] = Tx | (c & Maskx);
return 3;
}
int
runelen(long c)
{
Rune rune;
char str[10];
rune = c;
return runetochar(str, &rune);
}
int
fullrune(char *str, int n)
{
int c;
if(n > 0) {
c = *(unsigned char*)str;
if(c < Tx)
return 1;
if(n > 1)
if(c < T3 || n > 2)
return 1;
}
return 0;
}
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