1 files changed, 70 insertions, 0 deletions
diff --git a/src/math/modf.c b/src/math/modf.c
new file mode 100644
index 00000000..ff85b2a3
--- /dev/null
+++ b/src/math/modf.c
@@ -0,0 +1,70 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/s_modf.c */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+/*
+ * 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 "libm.h"
+
+static const double one = 1.0;
+
+double modf(double x, double *iptr)
+{
+	int32_t i0,i1,j0;
+	uint32_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;
+		}
+		i = 0x000fffff >> j0;
+		if (((i0&i)|i1) == 0) {  /* x is integral */
+			uint32_t high;
+			*iptr = x;
+			GET_HIGH_WORD(high, x);
+			INSERT_WORDS(x, high & 0x80000000, 0);  /* return +-0 */
+			return x;
+		}
+		INSERT_WORDS(*iptr, i0&~i, 0);
+		return x - *iptr;
+	} else if (j0 > 51) {  /* no fraction part */
+		uint32_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 = (uint32_t)0xffffffff >> (j0 - 20);
+		if ((i1&i) == 0) {  /* x is integral */
+			uint32_t high;
+			*iptr = x;
+			GET_HIGH_WORD(high, x);
+			INSERT_WORDS(x, high & 0x80000000, 0);  /* return +-0 */
+			return x;
+		}
+		INSERT_WORDS(*iptr, i0, i1&~i);
+		return x - *iptr;
+	}
+}