#include	<u.h>#include	<libc.h> enum{	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,}; intchartorune(Rune *rune, char *str){	int c, c1, c2, c3;	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;	}  	/*	 * four character sequence	 *	10000-10FFFF => T4 Tx Tx Tx	 */	if(UTFmax >= 4) {		c3 = *(uchar*)(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;} intrunetochar(char *str, Rune *rune){	long c; 	c = *rune;	if(c > Runemax)		c = Runeerror; 	/*	 * one character sequence	 *	00000-0007F => 00-7F	 */	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	 */	if(c <= Rune3) {		str[0] = T3 |  (c >> 2*Bitx);		str[1] = Tx | ((c >> 1*Bitx) & Maskx);		str[2] = Tx |  (c & Maskx);		return 3;	} 	/*	 * four character sequence	 *	10000-1FFFFF => T4 Tx Tx Tx	 */	str[0] = T4 |  (c >> 3*Bitx);	str[1] = Tx | ((c >> 2*Bitx) & Maskx);	str[2] = Tx | ((c >> 1*Bitx) & Maskx);	str[3] = Tx |  (c & Maskx);	return 4;} intrunelen(long c){	Rune rune;	char str[UTFmax]; 	rune = c;	return runetochar(str, &rune);} intrunenlen(Rune *r, int nrune){	int nb, c; 	nb = 0;	while(nrune--) {		c = *r++;		if(c <= Rune1)			nb++;		else		if(c <= Rune2)			nb += 2;		else		if(c <= Rune3 || c > Runemax)			nb += 3;		else			nb += 4;	}	return nb;} intfullrune(char *str, int n){	int c; 	if(n <= 0)		return 0;	c = *(uchar*)str;	if(c < Tx)		return 1;	if(c < T3)		return n >= 2;	if(UTFmax == 3 || c < T4)		return n >= 3;	return n >= 4;}