ref: 3582b9cc27bf2a83800c00b4a84873037e99642d
dir: /unix/rune.c/
/*
Copyright © 2021 Plan 9 Foundation
Copyright © 20XX 9front authors
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#include "otfsys.h"
enum
{
UTFmax = 4,
Runemax = 0x10ffff,
Bit1 = 7,
Bitx = 6,
Bit2 = 5,
Bit3 = 4,
Bit4 = 3,
Bit5 = 2,
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 */
T5 = ((1<<(Bit5+1))-1) ^ 0xFF, /* 1111 1000 */
Rune1 = (1<<(Bit1+0*Bitx))-1, /* 0000 0000 0000 0000 0111 1111 */
Rune2 = (1<<(Bit2+1*Bitx))-1, /* 0000 0000 0000 0111 1111 1111 */
Rune3 = (1<<(Bit3+2*Bitx))-1, /* 0000 0000 1111 1111 1111 1111 */
Rune4 = (1<<(Bit4+3*Bitx))-1, /* 0011 1111 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, c3;
long l;
/*
* one character sequence
* 00000-0007F => T1
*/
c = *(uint8_t*)str;
if(c < Tx) {
*rune = c;
return 1;
}
/*
* two character sequence
* 0080-07FF => T2 Tx
*/
c1 = *(uint8_t*)(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 = *(uint8_t*)(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;
}
/*
* four character sequence
* 10000-10FFFF => T4 Tx Tx Tx
*/
if(UTFmax >= 4) {
c3 = *(uint8_t*)(str+3) ^ Tx;
if(c3 & Testx)
goto bad;
if(c < T5) {
l = ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4;
if(l <= Rune3)
goto bad;
if(l > Runemax)
goto bad;
*rune = l;
return 4;
}
}
/*
* bad decoding
*/
bad:
*rune = Bad;
return 1;
}