first commit of the new libm!

[musl] / src / math / remainderf.c

diff --git a/src/math/remainderf.c b/src/math/remainderf.c
new file mode 100644 (file)
index 0000000..c17bb4f
--- /dev/null
+++ b/src/math/remainderf.c
@@ -0,0 +1,64 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/e_remainderf.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 "libm.h"
+
+static const float zero = 0.0;
+
+float remainderf(float x, float p)
+{
+       int32_t hx,hp;
+       uint32_t sx;
+       float p_half;
+
+       GET_FLOAT_WORD(hx, x);
+       GET_FLOAT_WORD(hp, p);
+       sx = hx & 0x80000000;
+       hp &= 0x7fffffff;
+       hx &= 0x7fffffff;
+
+       /* purge off exception values */
+       if (hp == 0)  /* p = 0 */
+               return (x*p)/(x*p);
+       if (hx >= 0x7f800000 || hp > 0x7f800000)  /* x not finite, p is NaN */
+               // FIXME: why long double?
+               return ((long double)x*p)/((long double)x*p);
+
+       if (hp <= 0x7effffff)
+               x = fmodf(x, p + p);  /* now x < 2p */
+       if (hx - hp == 0)
+               return zero*x;
+       x = fabsf(x);
+       p = fabsf(p);
+       if (hp < 0x01000000) {
+               if (x + x > p) {
+                       x -= p;
+                       if (x + x >= p)
+                               x -= p;
+               }
+       } else {
+               p_half = (float)0.5*p;
+               if (x > p_half) {
+                       x -= p;
+                       if (x >= p_half)
+                               x -= p;
+               }
+       }
+       GET_FLOAT_WORD(hx, x);
+       if ((hx & 0x7fffffff) == 0)
+               hx = 0;
+       SET_FLOAT_WORD(x, hx ^ sx);
+       return x;
+}