altos: Add floating point math functions from newlib

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

diff --git a/src/math/sf_scalbn.c b/src/math/sf_scalbn.c
new file mode 100644 (file)
index 0000000..7000600
--- /dev/null
+++ b/src/math/sf_scalbn.c
@@ -0,0 +1,86 @@
+/* sf_scalbn.c -- float version of s_scalbn.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"
+#include <limits.h>
+#include <float.h>
+
+#if INT_MAX > 50000
+#define OVERFLOW_INT 50000
+#else
+#define OVERFLOW_INT 30000
+#endif
+
+#ifdef __STDC__
+static const float
+#else
+static float
+#endif
+two25   =  3.355443200e+07,    /* 0x4c000000 */
+twom25  =  2.9802322388e-08,   /* 0x33000000 */
+huge   = 1.0e+30,
+tiny   = 1.0e-30;
+
+#ifdef __STDC__
+       float scalbnf (float x, int n)
+#else
+       float scalbnf (x,n)
+       float x; int n;
+#endif
+{
+       __int32_t  k,ix;
+       __uint32_t hx;
+
+       GET_FLOAT_WORD(ix,x);
+       hx = ix&0x7fffffff;
+        k = hx>>23;            /* extract exponent */
+       if (FLT_UWORD_IS_ZERO(hx))
+           return x;
+        if (!FLT_UWORD_IS_FINITE(hx))
+           return x+x;         /* NaN or Inf */
+        if (FLT_UWORD_IS_SUBNORMAL(hx)) {
+           x *= two25;
+           GET_FLOAT_WORD(ix,x);
+           k = ((ix&0x7f800000)>>23) - 25; 
+            if (n< -50000) return tiny*x;      /*underflow*/
+        }
+        k = k+n; 
+        if (k > FLT_LARGEST_EXP) return huge*copysignf(huge,x); /* overflow  */
+        if (k > 0)                             /* normal result */
+           {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;}
+        if (k < FLT_SMALLEST_EXP) {
+            if (n > OVERFLOW_INT)      /* in case integer overflow in n+k */
+               return huge*copysignf(huge,x);  /*overflow*/
+           else return tiny*copysignf(tiny,x); /*underflow*/
+        }
+        k += 25;                               /* subnormal result */
+       SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23));
+        return x*twom25;
+}
+
+#ifdef _DOUBLE_IS_32BITS
+
+#ifdef __STDC__
+       double scalbn(double x, int n)
+#else
+       double scalbn(x,n)
+       double x;
+       int n;
+#endif
+{
+       return (double) scalbnf((float) x, n);
+}
+
+#endif /* defined(_DOUBLE_IS_32BITS) */