mirror of
https://github.com/ziglang/zig.git
synced 2024-11-27 07:32:44 +00:00
108 lines
3.5 KiB
C
Vendored
108 lines
3.5 KiB
C
Vendored
/* FPU control word bits. x86 version.
|
|
Copyright (C) 1993-2024 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library 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.
|
|
|
|
The GNU C Library 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 the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#ifndef _FPU_CONTROL_H
|
|
#define _FPU_CONTROL_H 1
|
|
|
|
/* Note that this file sets on x86-64 only the x87 FPU, it does not
|
|
touch the SSE unit. */
|
|
|
|
/* Here is the dirty part. Set up your 387 through the control word
|
|
* (cw) register.
|
|
*
|
|
* 15-13 12 11-10 9-8 7-6 5 4 3 2 1 0
|
|
* | reserved | IC | RC | PC | reserved | PM | UM | OM | ZM | DM | IM
|
|
*
|
|
* IM: Invalid operation mask
|
|
* DM: Denormalized operand mask
|
|
* ZM: Zero-divide mask
|
|
* OM: Overflow mask
|
|
* UM: Underflow mask
|
|
* PM: Precision (inexact result) mask
|
|
*
|
|
* Mask bit is 1 means no interrupt.
|
|
*
|
|
* PC: Precision control
|
|
* 11 - round to extended precision
|
|
* 10 - round to double precision
|
|
* 00 - round to single precision
|
|
*
|
|
* RC: Rounding control
|
|
* 00 - rounding to nearest
|
|
* 01 - rounding down (toward - infinity)
|
|
* 10 - rounding up (toward + infinity)
|
|
* 11 - rounding toward zero
|
|
*
|
|
* IC: Infinity control
|
|
* That is for 8087 and 80287 only.
|
|
*
|
|
* The hardware default is 0x037f which we use.
|
|
*/
|
|
|
|
#include <features.h>
|
|
|
|
/* masking of interrupts */
|
|
#define _FPU_MASK_IM 0x01
|
|
#define _FPU_MASK_DM 0x02
|
|
#define _FPU_MASK_ZM 0x04
|
|
#define _FPU_MASK_OM 0x08
|
|
#define _FPU_MASK_UM 0x10
|
|
#define _FPU_MASK_PM 0x20
|
|
|
|
/* precision control */
|
|
#define _FPU_EXTENDED 0x300 /* libm requires double extended precision. */
|
|
#define _FPU_DOUBLE 0x200
|
|
#define _FPU_SINGLE 0x0
|
|
|
|
/* rounding control */
|
|
#define _FPU_RC_NEAREST 0x0 /* RECOMMENDED */
|
|
#define _FPU_RC_DOWN 0x400
|
|
#define _FPU_RC_UP 0x800
|
|
#define _FPU_RC_ZERO 0xC00
|
|
|
|
#define _FPU_RESERVED 0xF0C0 /* Reserved bits in cw */
|
|
|
|
|
|
/* The fdlibm code requires strict IEEE double precision arithmetic,
|
|
and no interrupts for exceptions, rounding to nearest. */
|
|
|
|
#define _FPU_DEFAULT 0x037f
|
|
|
|
/* IEEE: same as above. */
|
|
#define _FPU_IEEE 0x037f
|
|
|
|
/* Type of the control word. */
|
|
typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__HI__)));
|
|
|
|
/* Macros for accessing the hardware control word. "*&" is used to
|
|
work around a bug in older versions of GCC. __volatile__ is used
|
|
to support combination of writing the control register and reading
|
|
it back. Without __volatile__, the old value may be used for reading
|
|
back under compiler optimization.
|
|
|
|
Note that the use of these macros is not sufficient anymore with
|
|
recent hardware nor on x86-64. Some floating point operations are
|
|
executed in the SSE/SSE2 engines which have their own control and
|
|
status register. */
|
|
#define _FPU_GETCW(cw) __asm__ __volatile__ ("fnstcw %0" : "=m" (*&cw))
|
|
#define _FPU_SETCW(cw) __asm__ __volatile__ ("fldcw %0" : : "m" (*&cw))
|
|
|
|
/* Default control word set at startup. */
|
|
extern fpu_control_t __fpu_control;
|
|
|
|
#endif /* fpu_control.h */ |