altos: Add floating point math functions from newlib

These are all BSD licensed, so we can simply include them directly

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 86 insertions, 0 deletions

diff --git a/src/math/sf_scalbn.c b/src/math/sf_scalbn.c
new file mode 100644
index 00000000..70006001
--- /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) */