Meta: Add OpenLibm

src/openlibm/ld80/s_truncl.c

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+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ *
+ * From: @(#)s_floor.c 5.1 93/09/24
+ */
+
+/*
+ * truncl(x)
+ * Return x rounded toward 0 to integral value
+ * Method:
+ *	Bit twiddling.
+ * Exception:
+ *	Inexact flag raised if x not equal to truncl(x).
+ */
+
+#include <sys/types.h>
+//#include <machine/ieee.h>
+
+#include <float.h>
+#include <openlibm_math.h>
+#include <stdint.h>
+
+#include "math_private.h"
+
+#ifdef LDBL_IMPLICIT_NBIT
+#define	MANH_SIZE	(EXT_FRACHBITS + 1)
+#else
+#define	MANH_SIZE	EXT_FRACHBITS
+#endif
+
+static const long double huge = 1.0e300;
+static const float zero[] = { 0.0, -0.0 };
+
+long double
+truncl(long double x)
+{
+	int e, es;
+	uint32_t ix0, ix1;
+
+	GET_LDOUBLE_WORDS(es,ix0,ix1,x);
+	e = (es&0x7fff) - LDBL_MAX_EXP + 1;
+
+	if (e < MANH_SIZE - 1) {
+		if (e < 0) {			/* raise inexact if x != 0 */
+			if (huge + x > 0.0)
+				return (zero[(es&0x8000)!=0]);
+		} else {
+			uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1);
+			if (((ix0 & m) | ix1) == 0)
+				return (x);	/* x is integral */
+			if (huge + x > 0.0) {	/* raise inexact flag */
+				ix0 &= ~m;
+				ix1 = 0;
+			}
+		}
+	} else if (e < LDBL_MANT_DIG - 1) {
+		uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1);
+		if ((ix1 & m) == 0)
+			return (x);	/* x is integral */
+		if (huge + x > 0.0)		/* raise inexact flag */
+			ix1 &= ~m;
+	}
+	SET_LDOUBLE_WORDS(x,es,ix0,ix1);
+	return (x);
+}