#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,}; intchartorune(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;} intrunetochar(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;} intrunelen(long c){	Rune rune;	char str[10]; 	rune = c;	return runetochar(str, &rune);} intrunenlen(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;} intfullrune(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;}