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