1 files changed, 71 insertions, 0 deletions
diff --git a/src/math/s_modf.c b/src/math/s_modf.c
new file mode 100644
index 00000000..a5528d6b
--- /dev/null
+++ b/src/math/s_modf.c
@@ -0,0 +1,71 @@
+/* @(#)s_modf.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.
+ * ====================================================
+ */
+
+/*
+ * modf(double x, double *iptr)
+ * return fraction part of x, and return x's integral part in *iptr.
+ * Method:
+ *      Bit twiddling.
+ *
+ * Exception:
+ *      No exception.
+ */
+
+#include <math.h>
+#include "math_private.h"
+
+static const double one = 1.0;
+
+double
+modf(double x, double *iptr)
+{
+        int32_t i0,i1,j0;
+        uint32_t i;
+        EXTRACT_WORDS(i0,i1,x);
+        j0 = ((i0>>20)&0x7ff)-0x3ff;    /* exponent of x */
+        if(j0<20) {                     /* integer part in high x */
+            if(j0<0) {                  /* |x|<1 */
+                INSERT_WORDS(*iptr,i0&0x80000000,0);    /* *iptr = +-0 */
+                return x;
+            } else {
+                i = (0x000fffff)>>j0;
+                if(((i0&i)|i1)==0) {            /* x is integral */
+                    uint32_t high;
+                    *iptr = x;
+                    GET_HIGH_WORD(high,x);
+                    INSERT_WORDS(x,high&0x80000000,0);  /* return +-0 */
+                    return x;
+                } else {
+                    INSERT_WORDS(*iptr,i0&(~i),0);
+                    return x - *iptr;
+                }
+            }
+        } else if (j0>51) {             /* no fraction part */
+            uint32_t high;
+            *iptr = x*one;
+            GET_HIGH_WORD(high,x);
+            INSERT_WORDS(x,high&0x80000000,0);  /* return +-0 */
+            return x;
+        } else {                        /* fraction part in low x */
+            i = ((uint32_t)(0xffffffff))>>(j0-20);
+            if((i1&i)==0) {             /* x is integral */
+                uint32_t high;
+                *iptr = x;
+                GET_HIGH_WORD(high,x);
+                INSERT_WORDS(x,high&0x80000000,0);      /* return +-0 */
+                return x;
+            } else {
+                INSERT_WORDS(*iptr,i0,i1&(~i));
+                return x - *iptr;
+            }
+        }
+}