Import sources from 2011-03-30 iso image

1 files changed, 53 insertions, 0 deletions

diff --git a/sys/src/ape/lib/ap/math/modf.c b/sys/src/ape/lib/ap/math/modf.c
new file mode 100755
index 000000000..4326cf44a
--- /dev/null
+++ b/sys/src/ape/lib/ap/math/modf.c
@@ -0,0 +1,53 @@
+#include <math.h>
+#include <errno.h>
+
+/* modf suitable for IEEE double-precision */
+
+#define	MASK	0x7ffL
+#define SIGN	0x80000000
+#define	SHIFT	20
+#define	BIAS	1022L
+
+typedef	union
+{
+	double	d;
+	struct
+	{
+		long	ms;
+		long	ls;
+	} i;
+} Cheat;
+
+double
+modf(double d, double *ip)
+{
+	Cheat x;
+	int e;
+
+	if(-1 < d && d < 1) {
+		*ip = 0;
+		return d;
+	}
+	x.d = d;
+	x.i.ms &= ~SIGN;
+	e = (x.i.ms >> SHIFT) & MASK;
+	if(e == MASK || e == 0){
+		errno = EDOM;
+		*ip = (d > 0)? HUGE_VAL : -HUGE_VAL;
+		return 0;
+	}
+	e -= BIAS;
+	if(e <= SHIFT+1) {
+		x.i.ms &= ~(0x1fffffL >> e);
+		x.i.ls = 0;
+	} else
+	if(e <= SHIFT+33)
+		x.i.ls &= ~(0x7fffffffL >> (e-SHIFT-2));
+	if(d > 0){
+		*ip = x.d;
+		return d - x.d;
+	}else{
+		*ip = -x.d;
+		return d + x.d;
+	}
+}