ref: b5e697fda5842e1bf9016b983dfbff17f53683f6
dir: /libc/rune.c/
#include <u.h> #include <libc.h> #define Bit(i) (7-(i)) /* N 0's preceded by i 1's, T(Bit(2)) is 1100 0000 */ #define T(i) (((1 << (Bit(i)+1))-1) ^ 0xFF) /* 0000 0000 0000 0111 1111 1111 */ #define RuneX(i) ((1 << (Bit(i) + ((i)-1)*Bitx))-1) enum { Bitx = Bit(1), Tx = T(1), /* 1000 0000 */ Rune1 = (1<<(Bit(0)+0*Bitx))-1, /* 0000 0000 0000 0000 0111 1111 */ Maskx = (1<<Bitx)-1, /* 0011 1111 */ Testx = Maskx ^ 0xFF, /* 1100 0000 */ SurrogateMin = 0xD800, SurrogateMax = 0xDFFF, Bad = Runeerror, }; int chartorune(Rune *rune, char *str) { int c[UTFmax], i; Rune l; /* * N character sequence * 00000-0007F => T1 * 00080-007FF => T2 Tx * 00800-0FFFF => T3 Tx Tx * 10000-10FFFF => T4 Tx Tx Tx */ c[0] = *(uchar*)(str); if(c[0] < Tx){ *rune = c[0]; return 1; } l = c[0]; for(i = 1; i < UTFmax; i++) { c[i] = *(uchar*)(str+i); c[i] ^= Tx; if(c[i] & Testx) goto bad; l = (l << Bitx) | c[i]; if(c[0] < T(i + 2)) { l &= RuneX(i + 1); if(i == 1) { if(c[0] < T(2) || l <= Rune1) goto bad; } else if(l <= RuneX(i) || l > Runemax) goto bad; if (i == 2 && SurrogateMin <= l && l <= SurrogateMax) goto bad; *rune = l; return i + 1; } } /* * bad decoding */ bad: *rune = Bad; return 1; } int runetochar(char *str, Rune *rune) { int i, j; Rune c; c = *rune; if(c <= Rune1) { str[0] = c; return 1; } /* * one character sequence * 00000-0007F => 00-7F * two character sequence * 0080-07FF => T2 Tx * three character sequence * 0800-FFFF => T3 Tx Tx * four character sequence (21-bit value) * 10000-1FFFFF => T4 Tx Tx Tx * If the Rune is out of range or a surrogate half, * convert it to the error rune. * Do this test when i==3 because the error rune encodes to three bytes. * Doing it earlier would duplicate work, since an out of range * Rune wouldn't have fit in one or two bytes. */ for(i = 2; i < UTFmax + 1; i++){ if(i == 3){ if(c > Runemax) c = Runeerror; if(SurrogateMin <= c && c <= SurrogateMax) c = Runeerror; } if (c <= RuneX(i) || i == UTFmax ) { str[0] = T(i) | (c >> (i - 1)*Bitx); for(j = 1; j < i; j++) str[j] = Tx | ((c >> (i - j - 1)*Bitx) & Maskx); return i; } } return UTFmax; } int runelen(long c) { Rune rune; char str[10]; rune = c; return runetochar(str, &rune); } int runenlen(Rune *r, int nrune) { int nb, i; Rune c; nb = 0; while(nrune--) { c = *r++; if(c <= Rune1){ nb++; } else { for(i = 2; i < UTFmax + 1; i++) if(c <= RuneX(i) || i == UTFmax){ nb += i; break; } } } return nb; } int fullrune(char *str, int n) { int i; Rune c; if(n <= 0) return 0; c = *(uchar*)str; if(c < Tx) return 1; for(i = 3; i < UTFmax + 1; i++) if(c < T(i)) return n >= i - 1; return n >= UTFmax; }