diff libquadmath/math/fmodq.c @ 68:561a7518be6b

update gcc-4.6
author Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp>
date Sun, 21 Aug 2011 07:07:55 +0900
parents
children 04ced10e8804
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libquadmath/math/fmodq.c	Sun Aug 21 07:07:55 2011 +0900
@@ -0,0 +1,129 @@
+/* e_fmodl.c -- long double version of e_fmod.c.
+ * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
+ */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+/* 
+ * fmodq(x,y)
+ * Return x mod y in exact arithmetic
+ * Method: shift and subtract
+ */
+
+#include "quadmath-imp.h"
+
+static const __float128 one = 1.0, Zero[] = {0.0, -0.0,};
+
+__float128
+fmodq (__float128 x, __float128 y)
+{
+  int64_t n,hx,hy,hz,ix,iy,sx,i;
+  uint64_t lx,ly,lz;
+
+  GET_FLT128_WORDS64(hx,lx,x);
+  GET_FLT128_WORDS64(hy,ly,y);
+  sx = hx&0x8000000000000000ULL;	/* sign of x */
+  hx ^=sx;				/* |x| */
+  hy &= 0x7fffffffffffffffLL;		/* |y| */
+
+  /* purge off exception values */
+  if((hy|ly)==0||(hx>=0x7fff000000000000LL)|| /* y=0,or x not finite */
+    ((hy|((ly|-ly)>>63))>0x7fff000000000000LL))	/* or y is NaN */
+      return (x*y)/(x*y);
+  if(hx<=hy) {
+      if((hx<hy)||(lx<ly)) return x;	/* |x|<|y| return x */
+      if(lx==ly) 
+	  return Zero[(uint64_t)sx>>63];	/* |x|=|y| return x*0*/
+  }
+
+  /* determine ix = ilogb(x) */
+  if(hx<0x0001000000000000LL) {	/* subnormal x */
+      if(hx==0) {
+	  for (ix = -16431, i=lx; i>0; i<<=1) ix -=1;
+      } else {
+	  for (ix = -16382, i=hx<<15; i>0; i<<=1) ix -=1;
+      }
+  } else ix = (hx>>48)-0x3fff;
+
+  /* determine iy = ilogb(y) */
+      if(hy<0x0001000000000000LL) {	/* subnormal y */
+	  if(hy==0) {
+	      for (iy = -16431, i=ly; i>0; i<<=1) iy -=1;
+	  } else {
+	      for (iy = -16382, i=hy<<15; i>0; i<<=1) iy -=1;
+	  }
+      } else iy = (hy>>48)-0x3fff;
+
+  /* set up {hx,lx}, {hy,ly} and align y to x */
+      if(ix >= -16382) 
+	  hx = 0x0001000000000000LL|(0x0000ffffffffffffLL&hx);
+      else {		/* subnormal x, shift x to normal */
+	  n = -16382-ix;
+	  if(n<=63) {
+	      hx = (hx<<n)|(lx>>(64-n));
+	      lx <<= n;
+	  } else {
+	      hx = lx<<(n-64);
+	      lx = 0;
+	  }
+      }
+      if(iy >= -16382) 
+	  hy = 0x0001000000000000LL|(0x0000ffffffffffffLL&hy);
+      else {		/* subnormal y, shift y to normal */
+	  n = -16382-iy;
+	  if(n<=63) {
+	      hy = (hy<<n)|(ly>>(64-n));
+	      ly <<= n;
+	  } else {
+	      hy = ly<<(n-64);
+	      ly = 0;
+	  }
+      }
+
+  /* fix point fmod */
+      n = ix - iy;
+      while(n--) {
+	  hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
+	  if(hz<0){hx = hx+hx+(lx>>63); lx = lx+lx;}
+	  else {
+	      if((hz|lz)==0) 		/* return sign(x)*0 */
+		  return Zero[(uint64_t)sx>>63];
+	      hx = hz+hz+(lz>>63); lx = lz+lz;
+	  }
+      }
+      hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
+      if(hz>=0) {hx=hz;lx=lz;}
+
+  /* convert back to floating value and restore the sign */
+      if((hx|lx)==0) 			/* return sign(x)*0 */
+	  return Zero[(uint64_t)sx>>63];	
+      while(hx<0x0001000000000000LL) {	/* normalize x */
+	  hx = hx+hx+(lx>>63); lx = lx+lx;
+	  iy -= 1;
+      }
+      if(iy>= -16382) {	/* normalize output */
+	  hx = ((hx-0x0001000000000000LL)|((iy+16383)<<48));
+	  SET_FLT128_WORDS64(x,hx|sx,lx);
+      } else {		/* subnormal output */
+	  n = -16382 - iy;
+	  if(n<=48) {
+	      lx = (lx>>n)|((uint64_t)hx<<(64-n));
+	      hx >>= n;
+	  } else if (n<=63) {
+	      lx = (hx<<(64-n))|(lx>>n); hx = sx;
+	  } else {
+	      lx = hx>>(n-64); hx = sx;
+	  }
+	  SET_FLT128_WORDS64(x,hx|sx,lx);
+	  x *= one;		/* create necessary signal */
+      }
+      return x;		/* exact output */
+}