1 files changed, 69 insertions, 0 deletions
diff --git a/src/math/s_floor.c b/src/math/s_floor.c
new file mode 100644
index 00000000..273cf6f4
--- /dev/null
+++ b/src/math/s_floor.c
@@ -0,0 +1,69 @@
+/* @(#)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.
+ * ====================================================
+ */
+
+/*
+ * floor(x)
+ * Return x rounded toward -inf to integral value
+ * Method:
+ *      Bit twiddling.
+ * Exception:
+ *      Inexact flag raised if x not equal to floor(x).
+ */
+
+#include <math.h>
+#include "math_private.h"
+
+static const double huge = 1.0e300;
+
+double
+floor(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) {/* return 0*sign(x) if |x|<1 */
+                    if(i0>=0) {i0=i1=0;}
+                    else if(((i0&0x7fffffff)|i1)!=0)
+                        { i0=0xbff00000;i1=0;}
+                }
+            } else {
+                i = (0x000fffff)>>j0;
+                if(((i0&i)|i1)==0) return x; /* x is integral */
+                if(huge+x>0.0) {        /* raise inexact flag */
+                    if(i0<0) i0 += (0x00100000)>>j0;
+                    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 */
+                if(i0<0) {
+                    if(j0==20) i0+=1;
+                    else {
+                        j = i1+(1<<(52-j0));
+                        if(j<i1) i0 +=1 ;       /* got a carry */
+                        i1=j;
+                    }
+                }
+                i1 &= (~i);
+            }
+        }
+        INSERT_WORDS(x,i0,i1);
+        return x;
+}