1998-07-28 01:52:34 +08:00
|
|
|
/* FPU control word definitions. ARM version.
|
2000-03-27 02:40:17 +08:00
|
|
|
Copyright (C) 1996, 1997, 1998, 2000 Free Software Foundation, Inc.
|
1998-07-28 01:52:34 +08:00
|
|
|
This file is part of the GNU C Library.
|
|
|
|
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
2001-07-06 12:56:23 +08:00
|
|
|
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.
|
1998-07-28 01:52:34 +08:00
|
|
|
|
|
|
|
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
|
2001-07-06 12:56:23 +08:00
|
|
|
Lesser General Public License for more details.
|
1998-07-28 01:52:34 +08:00
|
|
|
|
2001-07-06 12:56:23 +08:00
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
|
|
License along with the GNU C Library; if not, write to the Free
|
|
|
|
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
|
|
|
02111-1307 USA. */
|
1998-07-28 01:52:34 +08:00
|
|
|
|
|
|
|
#ifndef _FPU_CONTROL_H
|
|
|
|
#define _FPU_CONTROL_H
|
|
|
|
|
|
|
|
/* We have a slight terminology confusion here. On the ARM, the register
|
|
|
|
* we're interested in is actually the FPU status word - the FPU control
|
|
|
|
* word is something different (which is implementation-defined and only
|
2000-03-27 02:40:17 +08:00
|
|
|
* accessible from supervisor mode.)
|
1998-07-28 01:52:34 +08:00
|
|
|
*
|
|
|
|
* The FPSR looks like this:
|
|
|
|
*
|
|
|
|
* 31-24 23-16 15-8 7-0
|
2000-03-27 02:40:17 +08:00
|
|
|
* | system ID | trap enable | system control | exception flags |
|
1998-07-28 01:52:34 +08:00
|
|
|
*
|
|
|
|
* We ignore the system ID bits; for interest's sake they are:
|
|
|
|
*
|
|
|
|
* 0000 "old" FPE
|
|
|
|
* 1000 FPPC hardware
|
|
|
|
* 0001 FPE 400
|
|
|
|
* 1001 FPA hardware
|
|
|
|
*
|
|
|
|
* The trap enable and exception flags are both structured like this:
|
|
|
|
*
|
|
|
|
* 7 - 5 4 3 2 1 0
|
2000-03-27 02:40:17 +08:00
|
|
|
* | reserved | INX | UFL | OFL | DVZ | IVO |
|
1998-07-28 01:52:34 +08:00
|
|
|
*
|
|
|
|
* where a `1' bit in the enable byte means that the trap can occur, and
|
|
|
|
* a `1' bit in the flags byte means the exception has occurred.
|
|
|
|
*
|
|
|
|
* The exceptions are:
|
|
|
|
*
|
|
|
|
* IVO - invalid operation
|
|
|
|
* DVZ - divide by zero
|
|
|
|
* OFL - overflow
|
|
|
|
* UFL - underflow
|
|
|
|
* INX - inexact (do not use; implementations differ)
|
|
|
|
*
|
|
|
|
* The system control byte looks like this:
|
|
|
|
*
|
|
|
|
* 7-5 4 3 2 1 0
|
|
|
|
* | reserved | AC | EP | SO | NE | ND |
|
2000-03-27 02:40:17 +08:00
|
|
|
*
|
1998-07-28 01:52:34 +08:00
|
|
|
* where the bits mean
|
|
|
|
*
|
|
|
|
* ND - no denormalised numbers (force them all to zero)
|
|
|
|
* NE - enable NaN exceptions
|
|
|
|
* SO - synchronous operation
|
|
|
|
* EP - use expanded packed-decimal format
|
|
|
|
* AC - use alternate definition for C flag on compare operations
|
|
|
|
*/
|
|
|
|
|
2000-03-27 02:40:17 +08:00
|
|
|
/* masking of interrupts */
|
|
|
|
#define _FPU_MASK_IM 0x00010000 /* invalid operation */
|
|
|
|
#define _FPU_MASK_ZM 0x00020000 /* divide by zero */
|
|
|
|
#define _FPU_MASK_OM 0x00040000 /* overflow */
|
|
|
|
#define _FPU_MASK_UM 0x00080000 /* underflow */
|
|
|
|
#define _FPU_MASK_PM 0x00100000 /* inexact */
|
|
|
|
#define _FPU_MASK_DM 0x00000000 /* denormalized operation */
|
|
|
|
|
|
|
|
/* The system id bytes cannot be changed.
|
|
|
|
Only the bottom 5 bits in the trap enable byte can be changed.
|
|
|
|
Only the bottom 5 bits in the system control byte can be changed.
|
|
|
|
Only the bottom 5 bits in the exception flags are used.
|
|
|
|
The exception flags are set by the fpu, but can be zeroed by the user. */
|
|
|
|
#define _FPU_RESERVED 0xffe0e0e0 /* These bits are reserved. */
|
1998-07-28 01:52:34 +08:00
|
|
|
|
2000-03-27 02:40:17 +08:00
|
|
|
/* The fdlibm code requires strict IEEE double precision arithmetic,
|
|
|
|
no interrupts for exceptions, rounding to nearest. Changing the
|
|
|
|
rounding mode will break long double I/O. Turn on the AC bit,
|
|
|
|
the compiler generates code that assumes it is on. */
|
|
|
|
#define _FPU_DEFAULT 0x00001000 /* Default value. */
|
|
|
|
#define _FPU_IEEE 0x001f1000 /* Default + exceptions enabled. */
|
1998-07-28 01:52:34 +08:00
|
|
|
|
|
|
|
/* Type of the control word. */
|
|
|
|
typedef unsigned int fpu_control_t;
|
|
|
|
|
|
|
|
/* Macros for accessing the hardware control word. */
|
|
|
|
#define _FPU_GETCW(cw) __asm__ ("rfs %0" : "=r" (cw))
|
|
|
|
#define _FPU_SETCW(cw) __asm__ ("wfs %0" : : "r" (cw))
|
|
|
|
|
|
|
|
/* Default control word set at startup. */
|
|
|
|
extern fpu_control_t __fpu_control;
|
|
|
|
|
|
|
|
#endif /* _FPU_CONTROL_H */
|