_fixunstfdi.c revision 1.1.1.2
1/* Definitions of target machine for GNU compiler, for IBM S/390 2 Copyright (C) 1999-2013 Free Software Foundation, Inc. 3 Contributed by Hartmut Penner (hpenner@de.ibm.com) and 4 Ulrich Weigand (uweigand@de.ibm.com). 5 6This file is part of GCC. 7 8GCC is free software; you can redistribute it and/or modify it under 9the terms of the GNU General Public License as published by the Free 10Software Foundation; either version 3, or (at your option) any later 11version. 12 13GCC is distributed in the hope that it will be useful, but WITHOUT ANY 14WARRANTY; without even the implied warranty of MERCHANTABILITY or 15FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 16for more details. 17 18Under Section 7 of GPL version 3, you are granted additional 19permissions described in the GCC Runtime Library Exception, version 203.1, as published by the Free Software Foundation. 21 22You should have received a copy of the GNU General Public License and 23a copy of the GCC Runtime Library Exception along with this program; 24see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 25<http://www.gnu.org/licenses/>. */ 26 27#define EXPD(fp) (((fp.l.i[0]) >> 16) & 0x7FFF) 28#define EXPONENT_BIAS 16383 29#define MANTISSA_BITS 112 30#define PRECISION (MANTISSA_BITS + 1) 31#define SIGNBIT 0x80000000 32#define SIGND(fp) ((fp.l.i[0]) & SIGNBIT) 33#define MANTD_HIGH_LL(fp) ((fp.ll[0] & HIGH_LL_FRAC_MASK) | HIGH_LL_UNIT_BIT) 34#define MANTD_LOW_LL(fp) (fp.ll[1]) 35#define FRACD_ZERO_P(fp) (!fp.ll[1] && !(fp.ll[0] & HIGH_LL_FRAC_MASK)) 36#define HIGH_LL_FRAC_BITS 48 37#define HIGH_LL_UNIT_BIT ((UDItype_x)1 << HIGH_LL_FRAC_BITS) 38#define HIGH_LL_FRAC_MASK (HIGH_LL_UNIT_BIT - 1) 39 40typedef int DItype_x __attribute__ ((mode (DI))); 41typedef unsigned int UDItype_x __attribute__ ((mode (DI))); 42typedef int SItype_x __attribute__ ((mode (SI))); 43typedef unsigned int USItype_x __attribute__ ((mode (SI))); 44 45union double_long { 46 long double d; 47 struct { 48 SItype_x i[4]; /* 32 bit parts: 0 upper ... 3 lowest */ 49 } l; 50 UDItype_x ll[2]; /* 64 bit parts: 0 upper, 1 lower */ 51}; 52 53UDItype_x __fixunstfdi (long double a1); 54 55/* convert double to unsigned int */ 56UDItype_x 57__fixunstfdi (long double a1) 58{ 59 register union double_long dl1; 60 register int exp; 61 register UDItype_x l; 62 63 dl1.d = a1; 64 65 /* +/- 0, denormalized, negative */ 66 if (!EXPD (dl1) || SIGND(dl1)) 67 return 0; 68 69 /* The exponent - considered the binary point at the right end of 70 the mantissa. */ 71 exp = EXPD (dl1) - EXPONENT_BIAS - MANTISSA_BITS; 72 73 /* number < 1: If the mantissa would need to be right-shifted more bits than 74 its size (plus the implied one bit on the left) the result would be 75 zero. */ 76 if (exp <= -PRECISION) 77 return 0; 78 79 /* NaN: All exponent bits set and a nonzero fraction. */ 80 if ((EXPD(dl1) == 0x7fff) && !FRACD_ZERO_P (dl1)) 81 return 0x0ULL; 82 83 /* One extra bit is needed for the unit bit which is appended by 84 MANTD_HIGH_LL on the left of the matissa. */ 85 exp += HIGH_LL_FRAC_BITS + 1; 86 87 /* If the result would still need a left shift it will be too large 88 to be represented. */ 89 if (exp > 0) 90 return 0xFFFFFFFFFFFFFFFFULL; 91 92 l = MANTD_LOW_LL (dl1) >> (HIGH_LL_FRAC_BITS + 1) 93 | MANTD_HIGH_LL (dl1) << (64 - (HIGH_LL_FRAC_BITS + 1)); 94 95 return l >> -exp; 96} 97