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/s_trunc.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 src/math/s_trunc.c

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

diff --git a/src/math/s_trunc.c b/src/math/s_trunc.c
new file mode 100644
index 00000000..02c65567
--- /dev/null
+++ b/src/math/s_trunc.c
@@ -0,0 +1,58 @@
+/* @(#)s_floor.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+/*
+ * trunc(x)
+ * Return x rounded toward 0 to integral value
+ * Method:
+ *      Bit twiddling.
+ * Exception:
+ *      Inexact flag raised if x not equal to trunc(x).
+ */
+
+#include <math.h>
+#include "math_private.h"
+
+static const double huge = 1.0e300;
+
+double
+trunc(double x)
+{
+        int32_t i0,i1,j0;
+        uint32_t i,j;
+        EXTRACT_WORDS(i0,i1,x);
+        j0 = ((i0>>20)&0x7ff)-0x3ff;
+        if(j0<20) {
+            if(j0<0) {  /* raise inexact if x != 0 */
+                if(huge+x>0.0) {/* |x|<1, so return 0*sign(x) */
+                    i0 &= 0x80000000U;
+                    i1 = 0;
+                }
+            } else {
+                i = (0x000fffff)>>j0;
+                if(((i0&i)|i1)==0) return x; /* x is integral */
+                if(huge+x>0.0) {        /* raise inexact flag */
+                    i0 &= (~i); i1=0;
+                }
+            }
+        } else if (j0>51) {
+            if(j0==0x400) return x+x;   /* inf or NaN */
+            else return x;              /* x is integral */
+        } else {
+            i = ((uint32_t)(0xffffffff))>>(j0-20);
+            if((i1&i)==0) return x;     /* x is integral */
+            if(huge+x>0.0)              /* raise inexact flag */
+                i1 &= (~i);
+        }
+        INSERT_WORDS(x,i0,i1);
+        return x;
+}
-- 
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