Add a "fork" of musl as //fusl.

fusl/src/internal/floatscan.c

Index: fusl/src/internal/floatscan.c
diff --git a/fusl/src/internal/floatscan.c b/fusl/src/internal/floatscan.c
new file mode 100644
index 0000000000000000000000000000000000000000..eef70df9d6bc03ac463ae8eaa6419c9b8577e78f
--- /dev/null
+++ b/fusl/src/internal/floatscan.c
@@ -0,0 +1,504 @@
+#include <stdint.h>
+#include <stdio.h>
+#include <math.h>
+#include <float.h>
+#include <limits.h>
+#include <errno.h>
+#include <ctype.h>
+
+#include "shgetc.h"
+#include "floatscan.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+
+#define LD_B1B_DIG 2
+#define LD_B1B_MAX 9007199, 254740991
+#define KMAX 128
+
+#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
+
+#define LD_B1B_DIG 3
+#define LD_B1B_MAX 18, 446744073, 709551615
+#define KMAX 2048
+
+#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
+
+#define LD_B1B_DIG 4
+#define LD_B1B_MAX 10384593, 717069655, 257060992, 658440191
+#define KMAX 2048
+
+#else
+#error Unsupported long double representation
+#endif
+
+#define MASK (KMAX-1)
+
+#define CONCAT2(x,y) x ## y
+#define CONCAT(x,y) CONCAT2(x,y)
+
+static long long scanexp(FILE *f, int pok)
+{
+	int c;
+	int x;
+	long long y;
+	int neg = 0;
+	
+	c = shgetc(f);
+	if (c=='+' || c=='-') {
+		neg = (c=='-');
+		c = shgetc(f);
+		if (c-'0'>=10U && pok) shunget(f);
+	}
+	if (c-'0'>=10U) {
+		shunget(f);
+		return LLONG_MIN;
+	}
+	for (x=0; c-'0'<10U && x<INT_MAX/10; c = shgetc(f))
+		x = 10*x + c-'0';
+	for (y=x; c-'0'<10U && y<LLONG_MAX/100; c = shgetc(f))
+		y = 10*y + c-'0';
+	for (; c-'0'<10U; c = shgetc(f));
+	shunget(f);
+	return neg ? -y : y;
+}
+
+
+static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int pok)
+{
+	uint32_t x[KMAX];
+	static const uint32_t th[] = { LD_B1B_MAX };
+	int i, j, k, a, z;
+	long long lrp=0, dc=0;
+	long long e10=0;
+	int lnz = 0;
+	int gotdig = 0, gotrad = 0;
+	int rp;
+	int e2;
+	int emax = -emin-bits+3;
+	int denormal = 0;
+	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;
+
+	/* Don't let leading zeros consume buffer space */
+	for (; c=='0'; c = shgetc(f)) gotdig=1;
+	if (c=='.') {
+		gotrad = 1;
+		for (c = shgetc(f); c=='0'; c = shgetc(f)) gotdig=1, lrp--;
+	}
+
+	x[0] = 0;
+	for (; c-'0'<10U || c=='.'; c = shgetc(f)) {
+		if (c == '.') {
+			if (gotrad) break;
+			gotrad = 1;
+			lrp = dc;
+		} else if (k < KMAX-3) {
+			dc++;
+			if (c!='0') lnz = dc;
+			if (j) x[k] = x[k]*10 + c-'0';
+			else x[k] = c-'0';
+			if (++j==9) {
+				k++;
+				j=0;
+			}
+			gotdig=1;
+		} else {
+			dc++;
+			if (c!='0') x[KMAX-4] |= 1;
+		}
+	}
+	if (!gotrad) lrp=dc;
+
+	if (gotdig && (c|32)=='e') {
+		e10 = scanexp(f, pok);
+		if (e10 == LLONG_MIN) {
+			if (pok) {
+				shunget(f);
+			} else {
+				shlim(f, 0);
+				return 0;
+			}
+			e10 = 0;
+		}
+		lrp += e10;
+	} else if (c>=0) {
+		shunget(f);
+	}
+	if (!gotdig) {
+		errno = EINVAL;
+		shlim(f, 0);
+		return 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;
+		return sign * LDBL_MAX * LDBL_MAX;
+	}
+	if (lrp < emin-2*LDBL_MANT_DIG) {
+		errno = ERANGE;
+		return sign * LDBL_MIN * LDBL_MIN;
+	}
+
+	/* Align incomplete final B1B digit */
+	if (j) {
+		for (; j<9; j++) x[k]*=10;
+		k++;
+		j=0;
+	}
+
+	a = 0;
+	z = k;
+	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) {
+		int rpm9 = rp>=0 ? rp%9 : rp%9+9;
+		int p10 = p10s[8-rpm9];
+		uint32_t carry = 0;
+		for (k=a; k!=z; k++) {
+			uint32_t tmp = x[k] % p10;
+			x[k] = x[k]/p10 + carry;
+			carry = 1000000000/p10 * tmp;
+			if (k==a && !x[k]) {
+				a = (a+1 & MASK);
+				rp -= 9;
+			}
+		}
+		if (carry) x[z++] = carry;
+		rp += 9-rpm9;
+	}
+
+	/* 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)) {
+			uint64_t tmp = ((uint64_t)x[k] << 29) + carry;
+			if (tmp > 1000000000) {
+				carry = tmp / 1000000000;
+				x[k] = tmp % 1000000000;
+			} else {
+				carry = 0;
+				x[k] = tmp;
+			}
+			if (k==(z-1 & MASK) && k!=a && !x[k]) z = k;
+			if (k==a) break;
+		}
+		if (carry) {
+			rp += 9;
+			a = (a-1 & MASK);
+			if (a == z) {
+				z = (z-1 & MASK);
+				x[z-1 & MASK] |= x[z];
+			}
+			x[a] = carry;
+		}
+	}
+
+	/* Downscale until exactly number of bits are left of radix point */
+	for (;;) {
+		uint32_t carry = 0;
+		int sh = 1;
+		for (i=0; i<LD_B1B_DIG; i++) {
+			k = (a+i & MASK);
+			if (k == z || x[k] < th[i]) {
+				i=LD_B1B_DIG;
+				break;
+			}
+			if (x[a+i & MASK] > th[i]) break;
+		}
+		if (i==LD_B1B_DIG && rp==9*LD_B1B_DIG) break;
+		/* FIXME: find a way to compute optimal sh */
+		if (rp > 9+9*LD_B1B_DIG) sh = 9;
+		e2 += sh;
+		for (k=a; k!=z; k=(k+1 & MASK)) {
+			uint32_t tmp = x[k] & (1<<sh)-1;
+			x[k] = (x[k]>>sh) + carry;
+			carry = (1000000000>>sh) * tmp;
+			if (k==a && !x[k]) {
+				a = (a+1 & MASK);
+				i--;
+				rp -= 9;
+			}
+		}
+		if (carry) {
+			if ((z+1 & MASK) != a) {
+				x[z] = carry;
+				z = (z+1 & MASK);
+			} else x[z-1 & MASK] |= 1;
+		}
+	}
+
+	/* 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))-1] = 0;
+		y = 1000000000.0L * y + x[a+i & MASK];
+	}
+
+	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;
+		denormal = 1;
+	}
+
+	/* 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));
+		y -= frac;
+		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))
+			frac += 0.25*sign;
+		else if (t > 500000000)
+			frac += 0.75*sign;
+		else if (t == 500000000) {
+			if ((a+i+1 & MASK) == z)
+				frac += 0.5*sign;
+			else
+				frac += 0.75*sign;
+		}
+		if (LDBL_MANT_DIG-bits >= 2 && !fmodl(frac, 1))
+			frac++;
+	}
+
+	y += frac;
+	y -= bias;
+
+	if ((e2+LDBL_MANT_DIG & INT_MAX) > emax-5) {
+		if (fabs(y) >= CONCAT(0x1p, LDBL_MANT_DIG)) {
+			if (denormal && bits==LDBL_MANT_DIG+e2-emin)
+				denormal = 0;
+			y *= 0.5;
+			e2++;
+		}
+		if (e2+LDBL_MANT_DIG>emax || (denormal && frac))
+			errno = ERANGE;
+	}
+
+	return scalbnl(y, e2);
+}
+
+static long double hexfloat(FILE *f, int bits, int emin, int sign, int pok)
+{
+	uint32_t x = 0;
+	long double y = 0;
+	long double scale = 1;
+	long double bias = 0;
+	int gottail = 0, gotrad = 0, gotdig = 0;
+	long long rp = 0;
+	long long dc = 0;
+	long long e2 = 0;
+	int d;
+	int c;
+
+	c = shgetc(f);
+
+	/* Skip leading zeros */
+	for (; c=='0'; c = shgetc(f)) gotdig = 1;
+
+	if (c=='.') {
+		gotrad = 1;
+		c = shgetc(f);
+		/* Count zeros after the radix point before significand */
+		for (rp=0; c=='0'; c = shgetc(f), rp--) gotdig = 1;
+	}
+
+	for (; c-'0'<10U || (c|32)-'a'<6U || c=='.'; c = shgetc(f)) {
+		if (c=='.') {
+			if (gotrad) break;
+			rp = dc;
+			gotrad = 1;
+		} else {
+			gotdig = 1;
+			if (c > '9') d = (c|32)+10-'a';
+			else d = c-'0';
+			if (dc<8) {
+				x = x*16 + d;
+			} else if (dc < LDBL_MANT_DIG/4+1) {
+				y += d*(scale/=16);
+			} else if (d && !gottail) {
+				y += 0.5*scale;
+				gottail = 1;
+			}
+			dc++;
+		}
+	}
+	if (!gotdig) {
+		shunget(f);
+		if (pok) {
+			shunget(f);
+			if (gotrad) shunget(f);
+		} else {
+			shlim(f, 0);
+		}
+		return sign * 0.0;
+	}
+	if (!gotrad) rp = dc;
+	while (dc<8) x *= 16, dc++;
+	if ((c|32)=='p') {
+		e2 = scanexp(f, pok);
+		if (e2 == LLONG_MIN) {
+			if (pok) {
+				shunget(f);
+			} else {
+				shlim(f, 0);
+				return 0;
+			}
+			e2 = 0;
+		}
+	} else {
+		shunget(f);
+	}
+	e2 += 4*rp - 32;
+
+	if (!x) return sign * 0.0;
+	if (e2 > -emin) {
+		errno = ERANGE;
+		return sign * LDBL_MAX * LDBL_MAX;
+	}
+	if (e2 < emin-2*LDBL_MANT_DIG) {
+		errno = ERANGE;
+		return sign * LDBL_MIN * LDBL_MIN;
+	}
+
+	while (x < 0x80000000) {
+		if (y>=0.5) {
+			x += x + 1;
+			y += y - 1;
+		} else {
+			x += x;
+			y += y;
+		}
+		e2--;
+	}
+
+	if (bits > 32+e2-emin) {
+		bits = 32+e2-emin;
+		if (bits<0) bits=0;
+	}
+
+	if (bits < LDBL_MANT_DIG)
+		bias = copysignl(scalbn(1, 32+LDBL_MANT_DIG-bits-1), sign);
+
+	if (bits<32 && y && !(x&1)) x++, y=0;
+
+	y = bias + sign*(long double)x + sign*y;
+	y -= bias;
+
+	if (!y) errno = ERANGE;
+
+	return scalbnl(y, e2);
+}
+
+long double __floatscan(FILE *f, int prec, int pok)
+{
+	int sign = 1;
+	size_t i;
+	int bits;
+	int emin;
+	int c;
+
+	switch (prec) {
+	case 0:
+		bits = FLT_MANT_DIG;
+		emin = FLT_MIN_EXP-bits;
+		break;
+	case 1:
+		bits = DBL_MANT_DIG;
+		emin = DBL_MIN_EXP-bits;
+		break;
+	case 2:
+		bits = LDBL_MANT_DIG;
+		emin = LDBL_MIN_EXP-bits;
+		break;
+	default:
+		return 0;
+	}
+
+	while (isspace((c=shgetc(f))));
+
+	if (c=='+' || c=='-') {
+		sign -= 2*(c=='-');
+		c = shgetc(f);
+	}
+
+	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!=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++)
+		if (i<2) c = shgetc(f);
+	if (i==3) {
+		if (shgetc(f) != '(') {
+			shunget(f);
+			return NAN;
+		}
+		for (i=1; ; i++) {
+			c = shgetc(f);
+			if (c-'0'<10U || c-'A'<26U || c-'a'<26U || c=='_')
+				continue;
+			if (c==')') return NAN;
+			shunget(f);
+			if (!pok) {
+				errno = EINVAL;
+				shlim(f, 0);
+				return 0;
+			}
+			while (i--) shunget(f);
+			return NAN;
+		}
+		return NAN;
+	}
+
+	if (i) {
+		shunget(f);
+		errno = EINVAL;
+		shlim(f, 0);
+		return 0;
+	}
+
+	if (c=='0') {
+		c = shgetc(f);
+		if ((c|32) == 'x')
+			return hexfloat(f, bits, emin, sign, pok);
+		shunget(f);
+		c = '0';
+	}
+
+	return decfloat(f, c, bits, emin, sign, pok);
+}