first commit of the new libm!

[musl] / src / math / modff.c

diff --git a/src/math/modff.c b/src/math/modff.c
new file mode 100644 (file)
index 0000000..d535314
--- /dev/null
+++ b/src/math/modff.c
@@ -0,0 +1,51 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/s_modff.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 one = 1.0;
+
+float modff(float x, float *iptr)
+{
+       int32_t i0,j0;
+       uint32_t i;
+
+       GET_FLOAT_WORD(i0, x);
+       j0 = ((i0>>23) & 0xff) - 0x7f;  /* exponent of x */
+       if (j0 < 23) {  /* integer part in x */
+               if (j0 < 0) {  /* |x| < 1 */
+                       SET_FLOAT_WORD(*iptr, i0 & 0x80000000);  /* *iptr = +-0 */
+                       return x;
+               }
+               i = 0x007fffff >> j0;
+               if ((i0&i) == 0) {  /* x is integral */
+                       uint32_t ix;
+                       *iptr = x;
+                       GET_FLOAT_WORD(ix, x);
+                       SET_FLOAT_WORD(x, ix & 0x80000000);  /* return +-0 */
+                       return x;
+               }
+               SET_FLOAT_WORD(*iptr, i0&~i);
+               return x - *iptr;
+       } else {        /* no fraction part */
+               uint32_t ix;
+               *iptr = x*one;
+               if (x != x)  /* NaN */
+                       return x;
+               GET_FLOAT_WORD(ix, x);
+               SET_FLOAT_WORD(x, ix & 0x80000000);  /* return +-0 */
+               return x;
+       }
+}