--- /dev/null
+/* origin: FreeBSD /usr/src/lib/msun/src/s_remquol.c */
+/*-
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunSoft, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double remquol(long double x, long double y, int *quo)
+{
+ return remquo(x, y, quo);
+}
+#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
+
+#define BIAS (LDBL_MAX_EXP - 1)
+
+#if LDBL_MANL_SIZE > 32
+typedef uint64_t manl_t;
+#else
+typedef uint32_t manl_t;
+#endif
+
+#if LDBL_MANH_SIZE > 32
+typedef uint64_t manh_t;
+#else
+typedef uint32_t manh_t;
+#endif
+
+/*
+ * These macros add and remove an explicit integer bit in front of the
+ * fractional mantissa, if the architecture doesn't have such a bit by
+ * default already.
+ */
+#ifdef LDBL_IMPLICIT_NBIT
+#define SET_NBIT(hx) ((hx) | (1ULL << LDBL_MANH_SIZE))
+#define HFRAC_BITS LDBL_MANH_SIZE
+#else
+#define SET_NBIT(hx) (hx)
+#define HFRAC_BITS (LDBL_MANH_SIZE - 1)
+#endif
+
+#define MANL_SHIFT (LDBL_MANL_SIZE - 1)
+
+static const long double Zero[] = {0.0L, -0.0L};
+
+/*
+ * Return the IEEE remainder and set *quo to the last n bits of the
+ * quotient, rounded to the nearest integer. We choose n=31 because
+ * we wind up computing all the integer bits of the quotient anyway as
+ * a side-effect of computing the remainder by the shift and subtract
+ * method. In practice, this is far more bits than are needed to use
+ * remquo in reduction algorithms.
+ *
+ * Assumptions:
+ * - The low part of the mantissa fits in a manl_t exactly.
+ * - The high part of the mantissa fits in an int64_t with enough room
+ * for an explicit integer bit in front of the fractional bits.
+ */
+long double remquol(long double x, long double y, int *quo)
+{
+ union IEEEl2bits ux, uy;
+ int64_t hx,hz; /* We need a carry bit even if LDBL_MANH_SIZE is 32. */
+ manh_t hy;
+ manl_t lx,ly,lz;
+ int ix,iy,n,q,sx,sxy;
+
+ ux.e = x;
+ uy.e = y;
+ sx = ux.bits.sign;
+ sxy = sx ^ uy.bits.sign;
+ ux.bits.sign = 0; /* |x| */
+ uy.bits.sign = 0; /* |y| */
+ x = ux.e;
+
+ /* purge off exception values */
+ if ((uy.bits.exp|uy.bits.manh|uy.bits.manl)==0 || /* y=0 */
+ (ux.bits.exp == BIAS + LDBL_MAX_EXP) || /* or x not finite */
+ (uy.bits.exp == BIAS + LDBL_MAX_EXP &&
+ ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl)!=0)) /* or y is NaN */
+ return (x*y)/(x*y);
+ if (ux.bits.exp <= uy.bits.exp) {
+ if ((ux.bits.exp < uy.bits.exp) ||
+ (ux.bits.manh <= uy.bits.manh &&
+ (ux.bits.manh < uy.bits.manh ||
+ ux.bits.manl < uy.bits.manl))) {
+ q = 0;
+ goto fixup; /* |x|<|y| return x or x-y */
+ }
+ if (ux.bits.manh == uy.bits.manh && ux.bits.manl == uy.bits.manl) {
+ *quo = 1;
+ return Zero[sx]; /* |x|=|y| return x*0*/
+ }
+ }
+
+ /* determine ix = ilogb(x) */
+ if (ux.bits.exp == 0) { /* subnormal x */
+ ux.e *= 0x1.0p512;
+ ix = ux.bits.exp - (BIAS + 512);
+ } else {
+ ix = ux.bits.exp - BIAS;
+ }
+
+ /* determine iy = ilogb(y) */
+ if (uy.bits.exp == 0) { /* subnormal y */
+ uy.e *= 0x1.0p512;
+ iy = uy.bits.exp - (BIAS + 512);
+ } else {
+ iy = uy.bits.exp - BIAS;
+ }
+
+ /* set up {hx,lx}, {hy,ly} and align y to x */
+ hx = SET_NBIT(ux.bits.manh);
+ hy = SET_NBIT(uy.bits.manh);
+ lx = ux.bits.manl;
+ ly = uy.bits.manl;
+
+ /* fix point fmod */
+ n = ix - iy;
+ q = 0;
+
+ while (n--) {
+ hz = hx - hy;
+ lz = lx - ly;
+ if (lx < ly)
+ hz -= 1;
+ if (hz < 0) {
+ hx = hx + hx + (lx>>MANL_SHIFT);
+ lx = lx + lx;
+ } else {
+ hx = hz + hz + (lz>>MANL_SHIFT);
+ lx = lz + lz;
+ q++;
+ }
+ q <<= 1;
+ }
+ hz = hx - hy;
+ lz = lx - ly;
+ if (lx < ly)
+ hz -= 1;
+ if (hz >= 0) {
+ hx = hz;
+ lx = lz;
+ q++;
+ }
+
+ /* convert back to floating value and restore the sign */
+ if ((hx|lx) == 0) { /* return sign(x)*0 */
+ *quo = sxy ? -q : q;
+ return Zero[sx];
+ }
+ while (hx < (1ULL<<HFRAC_BITS)) { /* normalize x */
+ hx = hx + hx + (lx>>MANL_SHIFT);
+ lx = lx + lx;
+ iy -= 1;
+ }
+ ux.bits.manh = hx; /* The integer bit is truncated here if needed. */
+ ux.bits.manl = lx;
+ if (iy < LDBL_MIN_EXP) {
+ ux.bits.exp = iy + (BIAS + 512);
+ ux.e *= 0x1p-512;
+ } else {
+ ux.bits.exp = iy + BIAS;
+ }
+ ux.bits.sign = 0;
+ x = ux.e;
+fixup:
+ y = fabsl(y);
+ if (y < LDBL_MIN * 2) {
+ if (x + x > y || (x + x == y && (q & 1))) {
+ q++;
+ x-=y;
+ }
+ } else if (x > 0.5*y || (x == 0.5*y && (q & 1))) {
+ q++;
+ x-=y;
+ }
+
+ ux.e = x;
+ ux.bits.sign ^= sx;
+ x = ux.e;
+
+ q &= 0x7fffffff;
+ *quo = sxy ? -q : q;
+ return x;
+}
+#endif
projects / musl / blobdiff