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Diffstat (limited to 'lib/msun/src/s_truncl.c')
-rw-r--r-- | lib/msun/src/s_truncl.c | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/lib/msun/src/s_truncl.c b/lib/msun/src/s_truncl.c new file mode 100644 index 0000000..9e2b511 --- /dev/null +++ b/lib/msun/src/s_truncl.c @@ -0,0 +1,68 @@ +/* + * ==================================================== + * 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 + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +/* + * 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 <float.h> +#include <math.h> +#include <stdint.h> + +#include "fpmath.h" + +#ifdef LDBL_IMPLICIT_NBIT +#define MANH_SIZE (LDBL_MANH_SIZE + 1) +#else +#define MANH_SIZE LDBL_MANH_SIZE +#endif + +static const long double huge = 1.0e300; +static const float zero[] = { 0.0, -0.0 }; + +long double +truncl(long double x) +{ + union IEEEl2bits u = { .e = x }; + int e = u.bits.exp - LDBL_MAX_EXP + 1; + + if (e < MANH_SIZE - 1) { + if (e < 0) { /* raise inexact if x != 0 */ + if (huge + x > 0.0) + u.e = zero[u.bits.sign]; + } else { + uint64_t m = ((1llu << MANH_SIZE) - 1) >> (e + 1); + if (((u.bits.manh & m) | u.bits.manl) == 0) + return (x); /* x is integral */ + if (huge + x > 0.0) { /* raise inexact flag */ + u.bits.manh &= ~m; + u.bits.manl = 0; + } + } + } else if (e < LDBL_MANT_DIG - 1) { + uint64_t m = (uint64_t)-1 >> (64 - LDBL_MANT_DIG + e + 1); + if ((u.bits.manl & m) == 0) + return (x); /* x is integral */ + if (huge + x > 0.0) /* raise inexact flag */ + u.bits.manl &= ~m; + } + return (u.e); +} |