ref: 7bdaff72afb4d43d327387ed40e24c83f5381b4c
dir: /libc/rune.c/
#include <u.h> #include <libc.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 = *(uchar*)str; if(c < Tx) { *rune = c; return 1; } /* * two character sequence * 0080-07FF => T2 Tx */ c1 = *(uchar*)(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 = *(uchar*)(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 runenlen(Rune *r, int nrune) { int nb, c; nb = 0; while(nrune--) { c = *r++; if(c <= Rune1) nb++; else if(c <= Rune2) nb += 2; else nb += 3; } return nb; } int fullrune(char *str, int n) { int c; if(n > 0) { c = *(uchar*)str; if(c < Tx) return 1; if(n > 1) if(c < T3 || n > 2) return 1; } return 0; }