sync with Plan 9

1 files changed, 104 insertions, 101 deletions

diff --git a/lib9/rune.c b/lib9/rune.c
index 3dcff0b4..f969a2e6 100644
--- a/lib9/rune.c
+++ b/lib9/rune.c
@@ -1,75 +1,66 @@
 #include	"lib9.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
 {
-	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
+	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, c1, c2;
-	long l;
+	int c[UTFmax], i;
+	Rune l;
 
 	/*
-	 * one character sequence
+	 * N character sequence
 	 *	00000-0007F => T1
+	 *	00080-007FF => T2 Tx
+	 *	00800-0FFFF => T3 Tx Tx
+	 *	10000-10FFFF => T4 Tx Tx Tx
 	 */
-	c = *(uchar*)str;
-	if(c < Tx) {
-		*rune = c;
+
+	c[0] = *(uchar*)(str);
+	if(c[0] < Tx){
+		*rune = c[0];
 		return 1;
 	}
+	l = c[0];
 
-	/*
-	 * 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)
+	for(i = 1; i < UTFmax; i++) {
+		c[i] = *(uchar*)(str+i);
+		c[i] ^= Tx;
+		if(c[i] & Testx)
 			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;
+		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;
+		}
 	}
 
 	/*
@@ -83,12 +74,9 @@ bad:
 int
 runetochar(char *str, Rune *rune)
 {
-	long c;
+	int i, j;
+	Rune c;
 
-	/*
-	 * one character sequence
-	 *	00000-0007F => 00-7F
-	 */
 	c = *rune;
 	if(c <= Rune1) {
 		str[0] = c;
@@ -96,67 +84,82 @@ runetochar(char *str, Rune *rune)
 	}
 
 	/*
+	 * one character sequence
+	 *	00000-0007F => 00-7F
 	 * 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
+	 * 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.
 	 */
-	str[0] = T3 |  (c >> 2*Bitx);
-	str[1] = Tx | ((c >> 1*Bitx) & Maskx);
-	str[2] = Tx |  (c & Maskx);
-	return 3;
+	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)
 {
-	if(c <= Rune1)
-		return 1;
-	if(c <= Rune2)
-		return 2;
-	return 3;
+	Rune rune;
+	char str[10];
+
+	rune = c;
+	return runetochar(str, &rune);
 }
 
 int
-runenlen(Rune *r, int l)
+runenlen(Rune *r, int nrune)
 {
-	int n;
-	long c;
+	int nb, i;
+	Rune c;
 
-	n = 0;
-	while(l--) {
+	nb = 0;
+	while(nrune--) {
 		c = *r++;
-		if(c <= Rune1)
-			n += 1;
-		else
-		if(c <= Rune2)
-			n += 2;
-		else
-			n += 3;
+		if(c <= Rune1){
+			nb++;
+		} else {
+			for(i = 2; i < UTFmax + 1; i++)
+				if(c <= RuneX(i) || i == UTFmax){
+					nb += i;
+					break;
+				}
+		}
 	}
-	return n;
+	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;
+	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;
 }