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

fusl/src/internal/floatscan.c

+#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);
+}