X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Finternal%2Ffloatscan.c;h=da209e278e14e5abe0a39aa5cf59854696207df8;hb=bdeb184c3d08ea5017e1570e0f0431e9d7fd02fd;hp=d5444daaff8e03cf61ae93f9648e6f92129dd293;hpb=1bdd5c8b9868ebc092074e078604acb80546e43f;p=musl

diff --git a/src/internal/floatscan.c b/src/internal/floatscan.c
index d5444daa..da209e27 100644
--- a/src/internal/floatscan.c
+++ b/src/internal/floatscan.c
@@ -59,12 +59,15 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 	int i, j, k, a, z;
 	long long lrp=-1, dc=0;
 	long long e10=0;
+	int lnz = 0;
 	int gotdig = 0;
 	int rp;
 	int e2;
 	long double y;
 	long double frac=0;
 	long double bias=0;
+	static const int p10s[] = { 10, 100, 1000, 10000,
+		100000, 1000000, 10000000, 100000000 };
 
 	j=0;
 	k=0;
@@ -77,8 +80,9 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 		if (c == '.') {
 			if (lrp!=-1) break;
 			lrp = dc;
-		} else if (k < KMAX) {
+		} else if (k < KMAX-2) {
 			dc++;
+			if (c!='0') lnz = dc;
 			if (j) x[k] = x[k]*10 + c-'0';
 			else x[k] = c-'0';
 			if (++j==9) {
@@ -88,7 +92,7 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 			gotdig=1;
 		} else {
 			dc++;
-			x[KMAX-1] |= c-'0';
+			if (c!='0') x[KMAX-3] |= 1;
 		}
 	}
 	if (lrp==-1) lrp=dc;
@@ -114,9 +118,11 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 		return 0;
 	}
 
-	if (!x[0])
-		return sign * 0.0;
-	if (lrp==dc && (!k || (k==1 && !j)) && (bits>30 || x[0]>>bits==0))
+	/* Handle zero specially to avoid nasty special cases later */
+	if (!x[0]) return sign * 0.0;
+
+	/* Optimize small integers (w/no exponent) and over/under-flow */
+	if (lrp==dc && dc<10 && (bits>30 || x[0]>>bits==0))
 		return sign * (long double)x[0];
 	if (lrp > -emin/2) {
 		errno = ERANGE;
@@ -127,6 +133,7 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 		return sign * LDBL_MIN * LDBL_MIN;
 	}
 
+	/* Align incomplete final B1B digit */
 	if (k<KMAX && j) {
 		for (; j<9; j++) x[k]*=10;
 		k++;
@@ -138,15 +145,21 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 	e2 = 0;
 	rp = lrp;
 
+	/* Optimize small to mid-size integers (even in exp. notation) */
+	if (lnz<9 && lnz<=rp && rp < 18) {
+		if (rp == 9) return sign * (long double)x[0];
+		if (rp < 9) return sign * (long double)x[0] / p10s[8-rp];
+		int bitlim = bits-3*(int)(rp-9);
+		if (bitlim>30 || x[0]>>bitlim==0)
+			return sign * (long double)x[0] * p10s[rp-10];
+	}
+
+	/* Align radix point to B1B digit boundary */
 	if (rp % 9) {
-		static const int p10s[] = {
-			100000000, 10000000, 1000000, 100000,
-			10000, 1000, 100, 10
-		};
 		int rpm9 = rp>=0 ? rp%9 : rp%9+9;
-		int p10 = p10s[rpm9-1];
+		int p10 = p10s[8-rpm9];
 		uint32_t carry = 0;
-		for (k=a; k!=z; k=(k+1 & MASK)) {
+		for (k=a; k!=z; k++) {
 			uint32_t tmp = x[k] % p10;
 			x[k] = x[k]/p10 + carry;
 			carry = 1000000000/p10 * tmp;
@@ -155,16 +168,12 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 				rp -= 9;
 			}
 		}
-		if (carry) {
-			if ((z+1 & MASK) != a) {
-				x[z] = carry;
-				z = (z+1 & MASK);
-			} else x[z-1 & MASK] |= 1;
-		}
+		if (carry) x[z++] = carry;
 		rp += 9-rpm9;
 	}
 
-	while (rp < 9*LD_B1B_DIG || (rp == 9*LD_B1B_DIG && x[0]<th[0])) {
+	/* Upscale until desired number of bits are left of radix point */
+	while (rp < 9*LD_B1B_DIG || (rp == 9*LD_B1B_DIG && x[a]<th[0])) {
 		uint32_t carry = 0;
 		e2 -= 29;
 		for (k=(z-1 & MASK); ; k=(k-1 & MASK)) {
@@ -190,6 +199,7 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 		}
 	}
 
+	/* Downscale until exactly number of bits are left of radix point */
 	for (;;) {
 		uint32_t carry = 0;
 		int sh = 1;
@@ -211,6 +221,7 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 			carry = (1000000000>>sh) * tmp;
 			if (k==a && !x[k]) {
 				a = (a+1 & MASK);
+				i--;
 				rp -= 9;
 			}
 		}
@@ -222,6 +233,7 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 		}
 	}
 
+	/* Assemble desired bits into floating point variable */
 	for (y=i=0; i<LD_B1B_DIG; i++) {
 		if ((a+i & MASK)==z) x[z=(z+1 & MASK)] = 0;
 		y = 1000000000.0L * y + x[a+i & MASK];
@@ -229,11 +241,13 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 
 	y *= sign;
 
+	/* Limit precision for denormal results */
 	if (bits > LDBL_MANT_DIG+e2-emin) {
 		bits = LDBL_MANT_DIG+e2-emin;
 		if (bits<0) bits=0;
 	}
 
+	/* Calculate bias term to force rounding, move out lower bits */
 	if (bits < LDBL_MANT_DIG) {
 		bias = copysignl(scalbn(1, 2*LDBL_MANT_DIG-bits-1), y);
 		frac = fmodl(y, scalbn(1, LDBL_MANT_DIG-bits));
@@ -241,6 +255,7 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 		y += bias;
 	}
 
+	/* Process tail of decimal input so it can affect rounding */
 	if ((a+i & MASK) != z) {
 		uint32_t t = x[a+i & MASK];
 		if (t < 500000000 && (t || (a+i+1 & MASK) != z))
@@ -388,16 +403,16 @@ long double __floatscan(FILE *f, int c, int prec, int pok)
 
 	switch (prec) {
 	case 0:
-		bits = 24;
-		emin = -149;
+		bits = FLT_MANT_DIG;
+		emin = FLT_MIN_EXP-bits;
 		break;
 	case 1:
-		bits = 53;
-		emin = -1074;
+		bits = DBL_MANT_DIG;
+		emin = DBL_MIN_EXP-bits;
 		break;
 	case 2:
 		bits = LDBL_MANT_DIG;
-		emin = -16445;
+		emin = LDBL_MIN_EXP-bits;
 		break;
 	default:
 		return 0;
@@ -413,9 +428,10 @@ long double __floatscan(FILE *f, int c, int prec, int pok)
 	for (i=0; i<8 && (c|32)=="infinity"[i]; i++)
 		if (i<7) c = shgetc(f);
 	if (i==3 || i==8 || (i>3 && pok)) {
-		if (i==3) shunget(f);
-		if (pok) for (; i>3; i--) shunget(f);
-		else shlim(f, 0);
+		if (i!=8) {
+			shunget(f);
+			if (pok) for (; i>3; i--) shunget(f);
+		}
 		return sign * INFINITY;
 	}
 	if (!i) for (i=0; i<3 && (c|32)=="nan"[i]; i++)