_fixunstfdi.c revision 1.1.1.1.8.2
1/* Definitions of target machine for GNU compiler, for IBM S/390 2 Copyright (C) 1999, 2000, 2001, 2007, 2008 and 2009 3 Free Software Foundation, Inc. 4 Contributed by Hartmut Penner (hpenner@de.ibm.com) and 5 Ulrich Weigand (uweigand@de.ibm.com). 6 7This file is part of GCC. 8 9GCC is free software; you can redistribute it and/or modify it under 10the terms of the GNU General Public License as published by the Free 11Software Foundation; either version 3, or (at your option) any later 12version. 13 14GCC is distributed in the hope that it will be useful, but WITHOUT ANY 15WARRANTY; without even the implied warranty of MERCHANTABILITY or 16FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 17for more details. 18 19Under Section 7 of GPL version 3, you are granted additional 20permissions described in the GCC Runtime Library Exception, version 213.1, as published by the Free Software Foundation. 22 23You should have received a copy of the GNU General Public License and 24a copy of the GCC Runtime Library Exception along with this program; 25see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 26<http://www.gnu.org/licenses/>. */ 27 28#define EXPD(fp) (((fp.l.i[0]) >> 16) & 0x7FFF) 29#define EXPONENT_BIAS 16383 30#define MANTISSA_BITS 112 31#define PRECISION (MANTISSA_BITS + 1) 32#define SIGNBIT 0x80000000 33#define SIGND(fp) ((fp.l.i[0]) & SIGNBIT) 34#define MANTD_HIGH_LL(fp) ((fp.ll[0] & HIGH_LL_FRAC_MASK) | HIGH_LL_UNIT_BIT) 35#define MANTD_LOW_LL(fp) (fp.ll[1]) 36#define FRACD_ZERO_P(fp) (!fp.ll[1] && !(fp.ll[0] & HIGH_LL_FRAC_MASK)) 37#define HIGH_LL_FRAC_BITS 48 38#define HIGH_LL_UNIT_BIT ((UDItype_x)1 << HIGH_LL_FRAC_BITS) 39#define HIGH_LL_FRAC_MASK (HIGH_LL_UNIT_BIT - 1) 40 41typedef int DItype_x __attribute__ ((mode (DI))); 42typedef unsigned int UDItype_x __attribute__ ((mode (DI))); 43typedef int SItype_x __attribute__ ((mode (SI))); 44typedef unsigned int USItype_x __attribute__ ((mode (SI))); 45 46union double_long { 47 long double d; 48 struct { 49 SItype_x i[4]; /* 32 bit parts: 0 upper ... 3 lowest */ 50 } l; 51 UDItype_x ll[2]; /* 64 bit parts: 0 upper, 1 lower */ 52}; 53 54UDItype_x __fixunstfdi (long double a1); 55 56/* convert double to unsigned int */ 57UDItype_x 58__fixunstfdi (long double a1) 59{ 60 register union double_long dl1; 61 register int exp; 62 register UDItype_x l; 63 64 dl1.d = a1; 65 66 /* +/- 0, denormalized, negative */ 67 if (!EXPD (dl1) || SIGND(dl1)) 68 return 0; 69 70 /* The exponent - considered the binary point at the right end of 71 the mantissa. */ 72 exp = EXPD (dl1) - EXPONENT_BIAS - MANTISSA_BITS; 73 74 /* number < 1: If the mantissa would need to be right-shifted more bits than 75 its size (plus the implied one bit on the left) the result would be 76 zero. */ 77 if (exp <= -PRECISION) 78 return 0; 79 80 /* NaN: All exponent bits set and a nonzero fraction. */ 81 if ((EXPD(dl1) == 0x7fff) && !FRACD_ZERO_P (dl1)) 82 return 0x0ULL; 83 84 /* One extra bit is needed for the unit bit which is appended by 85 MANTD_HIGH_LL on the left of the matissa. */ 86 exp += HIGH_LL_FRAC_BITS + 1; 87 88 /* If the result would still need a left shift it will be too large 89 to be represented. */ 90 if (exp > 0) 91 return 0xFFFFFFFFFFFFFFFFULL; 92 93 l = MANTD_LOW_LL (dl1) >> (HIGH_LL_FRAC_BITS + 1) 94 | MANTD_HIGH_LL (dl1) << (64 - (HIGH_LL_FRAC_BITS + 1)); 95 96 return l >> -exp; 97} 98