math: rewrite remainder functions (remainder, remquo, fmod, modf)

* results are exact
* modfl follows truncl (raises inexact flag spuriously now)
* modf and modff only had cosmetic cleanup
* remainder is just a wrapper around remquo now
* using iterative shift+subtract for remquo and fmod
* ld80 and ld128 are supported as well

1 files changed, 4 insertions, 56 deletions

diff --git a/src/math/remainderf.c b/src/math/remainderf.c
index 77671039..b418bbff 100644
--- a/src/math/remainderf.c
+++ b/src/math/remainderf.c
@@ -1,59 +1,7 @@
-/* origin: FreeBSD /usr/src/lib/msun/src/e_remainderf.c */
-/*
- * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
- */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
+#include <math.h>
 
-#include "libm.h"
-
-float remainderf(float x, float p)
+float remainderf(float x, float y)
 {
-	int32_t hx,hp;
-	uint32_t sx;
-	float p_half;
-
-	GET_FLOAT_WORD(hx, x);
-	GET_FLOAT_WORD(hp, p);
-	sx = hx & 0x80000000;
-	hp &= 0x7fffffff;
-	hx &= 0x7fffffff;
-
-	/* purge off exception values */
-	if (hp == 0 || hx >= 0x7f800000 || hp > 0x7f800000)  /* p = 0, x not finite, p is NaN */
-		return (x*p)/(x*p);
-
-	if (hp <= 0x7effffff)
-		x = fmodf(x, p + p);  /* now x < 2p */
-	if (hx - hp == 0)
-		return 0.0f*x;
-	x = fabsf(x);
-	p = fabsf(p);
-	if (hp < 0x01000000) {
-		if (x + x > p) {
-			x -= p;
-			if (x + x >= p)
-				x -= p;
-		}
-	} else {
-		p_half = 0.5f*p;
-		if (x > p_half) {
-			x -= p;
-			if (x >= p_half)
-				x -= p;
-		}
-	}
-	GET_FLOAT_WORD(hx, x);
-	if ((hx & 0x7fffffff) == 0)
-		hx = 0;
-	SET_FLOAT_WORD(x, hx ^ sx);
-	return x;
+	int q;
+	return remquof(x, y, &q);
 }