1 files changed, 79 insertions, 0 deletions
diff --git a/libkern/frexp-power.c b/libkern/frexp-power.c
new file mode 100644
index 00000000..b13bbead
--- /dev/null
+++ b/libkern/frexp-power.c
@@ -0,0 +1,79 @@
+#include <lib9.h>
+
+#define	MASK	0x7ffL
+#define	SHIFT	20
+#define	BIAS	1022L
+
+typedef	union
+{
+	double	d;
+	struct
+	{
+		long	ms;
+		long	ls;
+	};
+} Cheat;
+
+double
+frexp(double d, int *ep)
+{
+	Cheat x;
+
+	if(d == 0) {
+		*ep = 0;
+		return 0;
+	}
+	x.d = d;
+	*ep = ((x.ms >> SHIFT) & MASK) - BIAS;
+	x.ms &= ~(MASK << SHIFT);
+	x.ms |= BIAS << SHIFT;
+	return x.d;
+}
+
+double
+ldexp(double d, int e)
+{
+	Cheat x;
+
+	if(d == 0)
+		return 0;
+	x.d = d;
+	e += (x.ms >> SHIFT) & MASK;
+	if(e <= 0)
+		return 0;	/* underflow */
+	if(e >= MASK){		/* overflow */
+		if(d < 0)
+			return Inf(-1);
+		return Inf(1);
+	}
+	x.ms &= ~(MASK << SHIFT);
+	x.ms |= (long)e << SHIFT;
+	return x.d;
+}
+
+double
+modf(double d, double *ip)
+{
+	Cheat x;
+	int e;
+
+	if(d < 1) {
+		if(d < 0) {
+			x.d = modf(-d, ip);
+			*ip = -*ip;
+			return -x.d;
+		}
+		*ip = 0;
+		return d;
+	}
+	x.d = d;
+	e = ((x.ms >> SHIFT) & MASK) - BIAS;
+	if(e <= SHIFT+1) {
+		x.ms &= ~(0x1fffffL >> e);
+		x.ls = 0;
+	} else
+	if(e <= SHIFT+33)
+		x.ls &= ~(0x7fffffffL >> (e-SHIFT-2));
+	*ip = x.d;
+	return d - x.d;
+}