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authorRich Felker <dalias@aerifal.cx>2012-03-13 01:17:53 -0400
committerRich Felker <dalias@aerifal.cx>2012-03-13 01:17:53 -0400
commitb69f695acedd4ce2798ef9ea28d834ceccc789bd (patch)
treeeafd98b9b75160210f3295ac074d699f863d958e /src/math/__rem_pio2f.c
parentd46cf2e14cc4df7cc75e77d7009fcb6df1f48a33 (diff)
downloadmusl-b69f695acedd4ce2798ef9ea28d834ceccc789bd.tar.gz
first commit of the new libm!
thanks to the hard work of Szabolcs Nagy (nsz), identifying the best (from correctness and license standpoint) implementations from freebsd and openbsd and cleaning them up! musl should now fully support c99 float and long double math functions, and has near-complete complex math support. tgmath should also work (fully on gcc-compatible compilers, and mostly on any c99 compiler). based largely on commit 0376d44a890fea261506f1fc63833e7a686dca19 from nsz's libm git repo, with some additions (dummy versions of a few missing long double complex functions, etc.) by me. various cleanups still need to be made, including re-adding (if they're correct) some asm functions that were dropped.
Diffstat (limited to 'src/math/__rem_pio2f.c')
-rw-r--r--src/math/__rem_pio2f.c78
1 files changed, 78 insertions, 0 deletions
diff --git a/src/math/__rem_pio2f.c b/src/math/__rem_pio2f.c
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+++ b/src/math/__rem_pio2f.c
@@ -0,0 +1,78 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/e_rem_pio2f.c */
+/*
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ * Debugged and optimized by Bruce D. Evans.
+ */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+/* __rem_pio2f(x,y)
+ *
+ * return the remainder of x rem pi/2 in *y
+ * use double precision for everything except passing x
+ * use __rem_pio2_large() for large x
+ */
+
+#include "libm.h"
+
+/*
+ * invpio2: 53 bits of 2/pi
+ * pio2_1: first 33 bit of pi/2
+ * pio2_1t: pi/2 - pio2_1
+ */
+static const double
+invpio2 = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */
+pio2_1 = 1.57079631090164184570e+00, /* 0x3FF921FB, 0x50000000 */
+pio2_1t = 1.58932547735281966916e-08; /* 0x3E5110b4, 0x611A6263 */
+
+int __rem_pio2f(float x, double *y)
+{
+ double w,r,fn;
+ double tx[1],ty[1];
+ float z;
+ int32_t e0,n,ix,hx;
+
+ GET_FLOAT_WORD(hx, x);
+ ix = hx & 0x7fffffff;
+ /* 33+53 bit pi is good enough for medium size */
+ if (ix < 0x4dc90fdb) { /* |x| ~< 2^28*(pi/2), medium size */
+ /* Use a specialized rint() to get fn. Assume round-to-nearest. */
+ STRICT_ASSIGN(double, fn, x*invpio2 + 0x1.8p52);
+ fn = fn - 0x1.8p52;
+// FIXME
+#ifdef HAVE_EFFICIENT_IRINT
+ n = irint(fn);
+#else
+ n = (int32_t)fn;
+#endif
+ r = x - fn*pio2_1;
+ w = fn*pio2_1t;
+ *y = r - w;
+ return n;
+ }
+ /*
+ * all other (large) arguments
+ */
+ if(ix>=0x7f800000) { /* x is inf or NaN */
+ *y = x-x;
+ return 0;
+ }
+ /* set z = scalbn(|x|,ilogb(|x|)-23) */
+ e0 = (ix>>23) - 150; /* e0 = ilogb(|x|)-23; */
+ SET_FLOAT_WORD(z, ix - ((int32_t)(e0<<23)));
+ tx[0] = z;
+ n = __rem_pio2_large(tx,ty,e0,1,0);
+ if (hx < 0) {
+ *y = -ty[0];
+ return -n;
+ }
+ *y = ty[0];
+ return n;
+}