1 files changed, 138 insertions, 0 deletions
diff --git a/lib/libc/gen/modf.c b/lib/libc/gen/modf.c
new file mode 100644
index 0000000..d67b441
--- /dev/null
+++ b/lib/libc/gen/modf.c
@@ -0,0 +1,138 @@
+/* @(#)s_modf.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * 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 <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+/*
+ * modf(double x, double *iptr)
+ * return fraction part of x, and return x's integral part in *iptr.
+ * Method:
+ *	Bit twiddling.
+ *
+ * Exception:
+ *	No exception.
+ */
+
+#include <sys/types.h>
+#include <machine/endian.h>
+#include <math.h>
+
+/* Bit fiddling routines copied from msun/src/math_private.h,v 1.15 */
+
+#if BYTE_ORDER == BIG_ENDIAN
+
+typedef union
+{
+  double value;
+  struct
+  {
+    u_int32_t msw;
+    u_int32_t lsw;
+  } parts;
+} ieee_double_shape_type;
+
+#endif
+
+#if BYTE_ORDER == LITTLE_ENDIAN
+
+typedef union
+{
+  double value;
+  struct
+  {
+    u_int32_t lsw;
+    u_int32_t msw;
+  } parts;
+} ieee_double_shape_type;
+
+#endif
+
+/* Get two 32 bit ints from a double.  */
+
+#define EXTRACT_WORDS(ix0,ix1,d)				\
+do {								\
+  ieee_double_shape_type ew_u;					\
+  ew_u.value = (d);						\
+  (ix0) = ew_u.parts.msw;					\
+  (ix1) = ew_u.parts.lsw;					\
+} while (0)
+
+/* Get the more significant 32 bit int from a double.  */
+
+#define GET_HIGH_WORD(i,d)					\
+do {								\
+  ieee_double_shape_type gh_u;					\
+  gh_u.value = (d);						\
+  (i) = gh_u.parts.msw;						\
+} while (0)
+
+/* Set a double from two 32 bit ints.  */
+
+#define INSERT_WORDS(d,ix0,ix1)					\
+do {								\
+  ieee_double_shape_type iw_u;					\
+  iw_u.parts.msw = (ix0);					\
+  iw_u.parts.lsw = (ix1);					\
+  (d) = iw_u.value;						\
+} while (0)
+
+static const double one = 1.0;
+
+double
+modf(double x, double *iptr)
+{
+	int32_t i0,i1,j0;
+	u_int32_t i;
+	EXTRACT_WORDS(i0,i1,x);
+	j0 = ((i0>>20)&0x7ff)-0x3ff;	/* exponent of x */
+	if(j0<20) {			/* integer part in high x */
+	    if(j0<0) {			/* |x|<1 */
+	        INSERT_WORDS(*iptr,i0&0x80000000,0);	/* *iptr = +-0 */
+		return x;
+	    } else {
+		i = (0x000fffff)>>j0;
+		if(((i0&i)|i1)==0) {		/* x is integral */
+		    u_int32_t high;
+		    *iptr = x;
+		    GET_HIGH_WORD(high,x);
+		    INSERT_WORDS(x,high&0x80000000,0);	/* return +-0 */
+		    return x;
+		} else {
+		    INSERT_WORDS(*iptr,i0&(~i),0);
+		    return x - *iptr;
+		}
+	    }
+	} else if (j0>51) {		/* no fraction part */
+	    u_int32_t high;
+	    if (j0 == 0x400) {		/* inf/NaN */
+		*iptr = x;
+		return 0.0 / x;
+	    }
+	    *iptr = x*one;
+	    GET_HIGH_WORD(high,x);
+	    INSERT_WORDS(x,high&0x80000000,0);	/* return +-0 */
+	    return x;
+	} else {			/* fraction part in low x */
+	    i = ((u_int32_t)(0xffffffff))>>(j0-20);
+	    if((i1&i)==0) { 		/* x is integral */
+	        u_int32_t high;
+		*iptr = x;
+		GET_HIGH_WORD(high,x);
+		INSERT_WORDS(x,high&0x80000000,0);	/* return +-0 */
+		return x;
+	    } else {
+	        INSERT_WORDS(*iptr,i0,i1&(~i));
+		return x - *iptr;
+	    }
+	}
+}