_fixtfdi.c revision 1.1.1.1.4.2
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 54DItype_x __fixtfdi (long double a1); 55 56/* convert double to unsigned int */ 57DItype_x 58__fixtfdi (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 */ 67 if (!EXPD (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 the result would be 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 0x8000000000000000ULL; 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. Compared to the unsigned variant we have to 89 take care that there is still space for the sign bit to be 90 applied. So we can only go on if there is a right-shift by one 91 or more. */ 92 if (exp >= 0) 93 { 94 l = 1ULL << 63; /* long long min */ 95 return SIGND (dl1) ? l : l - 1; 96 } 97 98 l = MANTD_LOW_LL (dl1) >> (HIGH_LL_FRAC_BITS + 1) 99 | MANTD_HIGH_LL (dl1) << (64 - (HIGH_LL_FRAC_BITS + 1)); 100 101 return SIGND (dl1) ? -(l >> -exp) : l >> -exp; 102} 103