From 0b44a0315b47dd8eced9f3b7f31580cf14bbfc01 Mon Sep 17 00:00:00 2001
From: Rich Felker <dalias@aerifal.cx>
Date: Sat, 12 Feb 2011 00:22:29 -0500
Subject: initial check-in, version 0.5.0

---
 src/math/e_fmodf.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 src/math/e_fmodf.c

(limited to 'src/math/e_fmodf.c')

diff --git a/src/math/e_fmodf.c b/src/math/e_fmodf.c
new file mode 100644
index 00000000..fe86cb04
--- /dev/null
+++ b/src/math/e_fmodf.c
@@ -0,0 +1,101 @@
+/* e_fmodf.c -- float version of e_fmod.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.
+ * ====================================================
+ */
+
+/*
+ * fmodf(x,y)
+ * Return x mod y in exact arithmetic
+ * Method: shift and subtract
+ */
+
+#include <math.h>
+#include "math_private.h"
+
+static const float one = 1.0, Zero[] = {0.0, -0.0,};
+
+float
+fmodf(float x, float y)
+{
+        int32_t n,hx,hy,hz,ix,iy,sx,i;
+
+        GET_FLOAT_WORD(hx,x);
+        GET_FLOAT_WORD(hy,y);
+        sx = hx&0x80000000;             /* sign of x */
+        hx ^=sx;                /* |x| */
+        hy &= 0x7fffffff;       /* |y| */
+
+    /* purge off exception values */
+        if(hy==0||(hx>=0x7f800000)||            /* y=0,or x not finite */
+           (hy>0x7f800000))                     /* or y is NaN */
+            return (x*y)/(x*y);
+        if(hx<hy) return x;                     /* |x|<|y| return x */
+        if(hx==hy)
+            return Zero[(uint32_t)sx>>31];     /* |x|=|y| return x*0*/
+
+    /* determine ix = ilogb(x) */
+        if(hx<0x00800000) {     /* subnormal x */
+            for (ix = -126,i=(hx<<8); i>0; i<<=1) ix -=1;
+        } else ix = (hx>>23)-127;
+
+    /* determine iy = ilogb(y) */
+        if(hy<0x00800000) {     /* subnormal y */
+            for (iy = -126,i=(hy<<8); i>=0; i<<=1) iy -=1;
+        } else iy = (hy>>23)-127;
+
+    /* set up {hx,lx}, {hy,ly} and align y to x */
+        if(ix >= -126)
+            hx = 0x00800000|(0x007fffff&hx);
+        else {          /* subnormal x, shift x to normal */
+            n = -126-ix;
+            hx = hx<<n;
+        }
+        if(iy >= -126)
+            hy = 0x00800000|(0x007fffff&hy);
+        else {          /* subnormal y, shift y to normal */
+            n = -126-iy;
+            hy = hy<<n;
+        }
+
+    /* fix point fmod */
+        n = ix - iy;
+        while(n--) {
+            hz=hx-hy;
+            if(hz<0){hx = hx+hx;}
+            else {
+                if(hz==0)               /* return sign(x)*0 */
+                    return Zero[(uint32_t)sx>>31];
+                hx = hz+hz;
+            }
+        }
+        hz=hx-hy;
+        if(hz>=0) {hx=hz;}
+
+    /* convert back to floating value and restore the sign */
+        if(hx==0)                       /* return sign(x)*0 */
+            return Zero[(uint32_t)sx>>31];
+        while(hx<0x00800000) {          /* normalize x */
+            hx = hx+hx;
+            iy -= 1;
+        }
+        if(iy>= -126) {         /* normalize output */
+            hx = ((hx-0x00800000)|((iy+127)<<23));
+            SET_FLOAT_WORD(x,hx|sx);
+        } else {                /* subnormal output */
+            n = -126 - iy;
+            hx >>= n;
+            SET_FLOAT_WORD(x,hx|sx);
+            x *= one;           /* create necessary signal */
+        }
+        return x;               /* exact output */
+}
-- 
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