altos: Add floating point math functions from newlib

[fw/altos] / src / math / ef_acos.c

diff --git a/src/math/ef_acos.c b/src/math/ef_acos.c
new file mode 100644 (file)
index 0000000..f73f97d
--- /dev/null
+++ b/src/math/ef_acos.c
@@ -0,0 +1,84 @@
+/* ef_acos.c -- float version of e_acos.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 "fdlibm.h"
+
+#ifdef __STDC__
+static const float 
+#else
+static float 
+#endif
+one =  1.0000000000e+00, /* 0x3F800000 */
+pi =  3.1415925026e+00, /* 0x40490fda */
+pio2_hi =  1.5707962513e+00, /* 0x3fc90fda */
+pio2_lo =  7.5497894159e-08, /* 0x33a22168 */
+pS0 =  1.6666667163e-01, /* 0x3e2aaaab */
+pS1 = -3.2556581497e-01, /* 0xbea6b090 */
+pS2 =  2.0121252537e-01, /* 0x3e4e0aa8 */
+pS3 = -4.0055535734e-02, /* 0xbd241146 */
+pS4 =  7.9153501429e-04, /* 0x3a4f7f04 */
+pS5 =  3.4793309169e-05, /* 0x3811ef08 */
+qS1 = -2.4033949375e+00, /* 0xc019d139 */
+qS2 =  2.0209457874e+00, /* 0x4001572d */
+qS3 = -6.8828397989e-01, /* 0xbf303361 */
+qS4 =  7.7038154006e-02; /* 0x3d9dc62e */
+
+#ifdef __STDC__
+       float __ieee754_acosf(float x)
+#else
+       float __ieee754_acosf(x)
+       float x;
+#endif
+{
+       float z,p,q,r,w,s,c,df;
+       __int32_t hx,ix;
+       GET_FLOAT_WORD(hx,x);
+       ix = hx&0x7fffffff;
+       if(ix==0x3f800000) {            /* |x|==1 */
+           if(hx>0) return 0.0;        /* acos(1) = 0  */
+           else return pi+(float)2.0*pio2_lo;  /* acos(-1)= pi */
+       } else if(ix>0x3f800000) {      /* |x| >= 1 */
+           return (x-x)/(x-x);         /* acos(|x|>1) is NaN */
+       }
+       if(ix<0x3f000000) {     /* |x| < 0.5 */
+           if(ix<=0x23000000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/
+           z = x*x;
+           p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
+           q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
+           r = p/q;
+           return pio2_hi - (x - (pio2_lo-x*r));
+       } else  if (hx<0) {             /* x < -0.5 */
+           z = (one+x)*(float)0.5;
+           p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
+           q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
+           s = __ieee754_sqrtf(z);
+           r = p/q;
+           w = r*s-pio2_lo;
+           return pi - (float)2.0*(s+w);
+       } else {                        /* x > 0.5 */
+           __int32_t idf;
+           z = (one-x)*(float)0.5;
+           s = __ieee754_sqrtf(z);
+           df = s;
+           GET_FLOAT_WORD(idf,df);
+           SET_FLOAT_WORD(df,idf&0xfffff000);
+           c  = (z-df*df)/(s+df);
+           p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
+           q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
+           r = p/q;
+           w = r*s+c;
+           return (float)2.0*(df+w);
+       }
+}