Implement remquol() based on remquo().

svn path=/head/; revision=177764

lib/msun/src/s_remquo.c

@@ -13,6 +13,8 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include <float.h>
+
 #include "math.h"
 #include "math_private.h"
 
@@ -150,3 +152,7 @@ remquo(double x, double y, int *quo)
 	*quo = (sxy ? -q : q);
 	return x;
 }
+
+#if LDBL_MANT_DIG == 53
+__weak_reference(remquo, remquol);
+#endif

lib/msun/src/s_remquol.c

@@ -0,0 +1,177 @@
+/* @(#)e_fmod.c 1.3 95/01/18 */
+/*-
+ * ====================================================
+ * 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 <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <float.h>
+#include <stdint.h>
+
+#include "fpmath.h"
+#include "math.h"
+#include "math_private.h"
+
+#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<(1U<<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;
+}