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Diffstat (limited to 'cross/lib/fpucw.h')
| -rw-r--r-- | cross/lib/fpucw.h | 108 |
1 files changed, 0 insertions, 108 deletions
diff --git a/cross/lib/fpucw.h b/cross/lib/fpucw.h deleted file mode 100644 index 7dcb310eaf5..00000000000 --- a/cross/lib/fpucw.h +++ /dev/null @@ -1,108 +0,0 @@ -/* Manipulating the FPU control word. -*- coding: utf-8 -*- - Copyright (C) 2007-2023 Free Software Foundation, Inc. - Written by Bruno Haible <bruno@clisp.org>, 2007. - - This file is free software: you can redistribute it and/or modify - it under the terms of the GNU Lesser General Public License as - published by the Free Software Foundation; either version 2.1 of the - License, or (at your option) any later version. - - This file is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - GNU Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public License - along with this program. If not, see <https://www.gnu.org/licenses/>. */ - -#ifndef _FPUCW_H -#define _FPUCW_H - -/* The i386 floating point hardware (the 387 compatible FPU, not the modern - SSE/SSE2 hardware) has a controllable rounding precision. It is specified - through the 'PC' bits in the FPU control word ('fctrl' register). (See - the GNU libc i386 <fpu_control.h> header for details.) - - On some platforms, such as Linux or Solaris, the default precision setting - is set to "extended precision". This means that 'long double' instructions - operate correctly, but 'double' computations often produce slightly - different results as on strictly IEEE 754 conforming systems. - - On some platforms, such as NetBSD, the default precision is set to - "double precision". This means that 'long double' instructions will operate - only as 'double', i.e. lead to wrong results. Similarly on FreeBSD 6.4, at - least for the division of 'long double' numbers. - - The FPU control word is under control of the application, i.e. it is - not required to be set either way by the ABI. (In fact, the i386 ABI - https://www.linux-mips.org/pub/linux/mips/doc/ABI/abi386-4.pdf page 3-12 = page 38 - is not clear about it. But in any case, gcc treats the control word - like a "preserved" register: it emits code that assumes that the control - word is preserved across calls, and it restores the control word at the - end of functions that modify it.) - - See Vincent Lefèvre's page https://www.vinc17.net/research/extended.en.html - for a good explanation. - See https://web.archive.org/web/20060905133417/http://www.uwsg.iu.edu/hypermail/linux/kernel/0103.0/0453.html - some argumentation which setting should be the default. */ - -/* This header file provides the following facilities: - fpucw_t integral type holding the value of 'fctrl' - FPU_PC_MASK bit mask denoting the precision control - FPU_PC_DOUBLE precision control for 53 bits mantissa - FPU_PC_EXTENDED precision control for 64 bits mantissa - GET_FPUCW () yields the current FPU control word - SET_FPUCW (word) sets the FPU control word - DECL_LONG_DOUBLE_ROUNDING variable declaration for - BEGIN/END_LONG_DOUBLE_ROUNDING - BEGIN_LONG_DOUBLE_ROUNDING () starts a sequence of instructions with - 'long double' safe operation precision - END_LONG_DOUBLE_ROUNDING () ends a sequence of instructions with - 'long double' safe operation precision - */ - -/* Inline assembler like this works only with GNU C and clang. */ -#if (defined __i386__ || defined __x86_64__) && (defined __GNUC__ || defined __clang__) - -typedef unsigned short fpucw_t; /* glibc calls this fpu_control_t */ - -# define FPU_PC_MASK 0x0300 -# define FPU_PC_DOUBLE 0x200 /* glibc calls this _FPU_DOUBLE */ -# define FPU_PC_EXTENDED 0x300 /* glibc calls this _FPU_EXTENDED */ - -# define GET_FPUCW() __extension__ \ - ({ fpucw_t _cw; \ - __asm__ __volatile__ ("fnstcw %0" : "=m" (*&_cw)); \ - _cw; \ - }) -# define SET_FPUCW(word) __extension__ \ - (void)({ fpucw_t _ncw = (word); \ - __asm__ __volatile__ ("fldcw %0" : : "m" (*&_ncw)); \ - }) - -# define DECL_LONG_DOUBLE_ROUNDING \ - fpucw_t oldcw; -# define BEGIN_LONG_DOUBLE_ROUNDING() \ - (void)(oldcw = GET_FPUCW (), \ - SET_FPUCW ((oldcw & ~FPU_PC_MASK) | FPU_PC_EXTENDED)) -# define END_LONG_DOUBLE_ROUNDING() \ - SET_FPUCW (oldcw) - -#else - -typedef unsigned int fpucw_t; - -# define FPU_PC_MASK 0 -# define FPU_PC_DOUBLE 0 -# define FPU_PC_EXTENDED 0 - -# define GET_FPUCW() 0 -# define SET_FPUCW(word) (void)(word) - -# define DECL_LONG_DOUBLE_ROUNDING -# define BEGIN_LONG_DOUBLE_ROUNDING() -# define END_LONG_DOUBLE_ROUNDING() - -#endif - -#endif /* _FPUCW_H */ |