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_sqrtf.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 src/math/e_sqrtf.c

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

diff --git a/src/math/e_sqrtf.c b/src/math/e_sqrtf.c
new file mode 100644
index 00000000..03a15beb
--- /dev/null
+++ b/src/math/e_sqrtf.c
@@ -0,0 +1,85 @@
+/* e_sqrtf.c -- float version of e_sqrt.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 "math_private.h"
+
+static  const float     one     = 1.0, tiny=1.0e-30;
+
+float
+sqrtf(float x)
+{
+        float z;
+        int32_t sign = (int)0x80000000;
+        int32_t ix,s,q,m,t,i;
+        uint32_t r;
+
+        GET_FLOAT_WORD(ix,x);
+
+    /* take care of Inf and NaN */
+        if((ix&0x7f800000)==0x7f800000) {
+            return x*x+x;               /* sqrt(NaN)=NaN, sqrt(+inf)=+inf
+                                           sqrt(-inf)=sNaN */
+        }
+    /* take care of zero */
+        if(ix<=0) {
+            if((ix&(~sign))==0) return x;/* sqrt(+-0) = +-0 */
+            else if(ix<0)
+                return (x-x)/(x-x);             /* sqrt(-ve) = sNaN */
+        }
+    /* normalize x */
+        m = (ix>>23);
+        if(m==0) {                              /* subnormal x */
+            for(i=0;(ix&0x00800000)==0;i++) ix<<=1;
+            m -= i-1;
+        }
+        m -= 127;       /* unbias exponent */
+        ix = (ix&0x007fffff)|0x00800000;
+        if(m&1) /* odd m, double x to make it even */
+            ix += ix;
+        m >>= 1;        /* m = [m/2] */
+
+    /* generate sqrt(x) bit by bit */
+        ix += ix;
+        q = s = 0;              /* q = sqrt(x) */
+        r = 0x01000000;         /* r = moving bit from right to left */
+
+        while(r!=0) {
+            t = s+r;
+            if(t<=ix) {
+                s    = t+r;
+                ix  -= t;
+                q   += r;
+            }
+            ix += ix;
+            r>>=1;
+        }
+
+    /* use floating add to find out rounding direction */
+        if(ix!=0) {
+            z = one-tiny; /* trigger inexact flag */
+            if (z>=one) {
+                z = one+tiny;
+                if (z>one)
+                    q += 2;
+                else
+                    q += (q&1);
+            }
+        }
+        ix = (q>>1)+0x3f000000;
+        ix += (m <<23);
+        SET_FLOAT_WORD(z,ix);
+        return z;
+}
-- 
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