first commit of the new libm!

[musl] / src / math / truncf.c

diff --git a/src/math/truncf.c b/src/math/truncf.c
new file mode 100644 (file)
index 0000000..209586e
--- /dev/null
+++ b/src/math/truncf.c
@@ -0,0 +1,52 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/s_truncf.c */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+/*
+ * truncf(x)
+ * Return x rounded toward 0 to integral value
+ * Method:
+ *      Bit twiddling.
+ * Exception:
+ *      Inexact flag raised if x not equal to truncf(x).
+ */
+
+#include "libm.h"
+
+static const float huge = 1.0e30F;
+
+float truncf(float x)
+{
+       int32_t i0,j0;
+       uint32_t i;
+
+       GET_FLOAT_WORD(i0, x);
+       j0 = ((i0>>23)&0xff) - 0x7f;
+       if (j0 < 23) {
+               if (j0 < 0) {  /* |x|<1, return 0*sign(x) */
+                       /* raise inexact if x != 0 */
+                       if (huge+x > 0.0F)
+                               i0 &= 0x80000000;
+               } else {
+                       i = 0x007fffff>>j0;
+                       if ((i0&i) == 0)
+                               return x; /* x is integral */
+                       /* raise inexact */
+                       if (huge+x > 0.0F)
+                               i0 &= ~i;
+               }
+       } else {
+               if (j0 == 0x80)
+                       return x + x;  /* inf or NaN */
+               return x;              /* x is integral */
+       }
+       SET_FLOAT_WORD(x, i0);
+       return x;
+}