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/*
* This file is part of SIS.
*
* SIS, SPARC instruction simulator. Copyright (C) 1995 Jiri Gaisler, European
* Space Agency
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 3 of the License, or (at your option)
* any later version.
*
* This program 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 General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, see <http://www.gnu.org/licenses/>.
*
*
* This file implements the interface between the host and the simulated
* FPU. IEEE trap handling is done as follows:
* 1. In the host, all IEEE traps are masked
* 2. After each simulated FPU instruction, check if any exception occured
* by reading the exception bits from the host FPU status register
* (get_accex()).
* 3. Propagate any exceptions to the simulated FSR.
* 4. Clear host exception bits
*
*
* This can also be done using ieee_flags() library routine on sun.
*/
#include "config.h"
#include "sis.h"
/* Forward declarations */
extern uint32 _get_sw (void);
extern uint32 _get_cw (void);
static void __setfpucw (unsigned short fpu_control);
/* This host dependent routine should return the accrued exceptions */
int
get_accex()
{
#ifdef sparc
return ((_get_fsr_raw() >> 5) & 0x1F);
#elif i386
uint32 accx;
accx = _get_sw() & 0x3f;
accx = ((accx & 1) << 4) | ((accx & 2) >> 1) | ((accx & 4) >> 1) |
(accx & 8) | ((accx & 16) >> 2) | ((accx & 32) >> 5);
return(accx);
#else
return(0);
#warning no fpu trap support for this target
#endif
}
/* How to clear the accrued exceptions */
void
clear_accex()
{
#ifdef sparc
set_fsr((_get_fsr_raw() & ~0x3e0));
#elif i386
asm("\n"
".text\n"
" fnclex\n"
"\n"
" ");
#else
#warning no fpu trap support for this target
#endif
}
/* How to map SPARC FSR onto the host */
void
set_fsr(fsr)
uint32 fsr;
{
#ifdef sparc
_set_fsr_raw(fsr & ~0x0f800000);
#elif i386
void __setfpucw(unsigned short fpu_control);
uint32 rawfsr;
fsr >>= 30;
switch (fsr) {
case 0:
case 2:
break;
case 1:
fsr = 3;
break;
case 3:
fsr = 1;
break;
}
rawfsr = _get_cw();
rawfsr |= (fsr << 10) | 0x3ff;
__setfpucw(rawfsr);
#else
#warning no fpu trap support for this target
#endif
}
/* Host dependent support functions */
#ifdef sparc
asm("\n"
"\n"
".text\n"
" .align 4\n"
" .global __set_fsr_raw,_set_fsr_raw\n"
"__set_fsr_raw:\n"
"_set_fsr_raw:\n"
" save %sp,-104,%sp\n"
" st %i0,[%fp+68]\n"
" ld [%fp+68], %fsr\n"
" mov 0,%i0\n"
" ret\n"
" restore\n"
"\n"
" .align 4\n"
" .global __get_fsr_raw\n"
" .global _get_fsr_raw\n"
"__get_fsr_raw:\n"
"_get_fsr_raw:\n"
" save %sp,-104,%sp\n"
" st %fsr,[%fp+68]\n"
" ld [%fp+68], %i0\n"
" ret\n"
" restore\n"
"\n"
" ");
#elif i386
asm("\n"
"\n"
".text\n"
" .align 8\n"
".globl _get_sw,__get_sw\n"
"__get_sw:\n"
"_get_sw:\n"
" pushl %ebp\n"
" movl %esp,%ebp\n"
" movl $0,%eax\n"
" fnstsw %ax\n"
" movl %ebp,%esp\n"
" popl %ebp\n"
" ret\n"
"\n"
" .align 8\n"
".globl _get_cw,__get_cw\n"
"__get_cw:\n"
"_get_cw:\n"
" pushl %ebp\n"
" movl %esp,%ebp\n"
" subw $2,%esp\n"
" fnstcw -2(%ebp)\n"
" movw -2(%ebp),%eax\n"
" movl %ebp,%esp\n"
" popl %ebp\n"
" ret\n"
"\n"
"\n"
" ");
#else
#warning no fpu trap support for this target
#endif
#if i386
/* #if defined _WIN32 || defined __GO32__ */
/* This is so floating exception handling works on NT
These definitions are from the linux fpu_control.h, which
doesn't exist on NT.
default to:
- extended precision
- rounding to nearest
- exceptions on overflow, zero divide and NaN
*/
#define _FPU_DEFAULT 0x1372
#define _FPU_RESERVED 0xF0C0 /* Reserved bits in cw */
static void
__setfpucw(unsigned short fpu_control)
{
volatile unsigned short cw;
/* If user supplied _fpu_control, use it ! */
if (!fpu_control)
{
/* use defaults */
fpu_control = _FPU_DEFAULT;
}
/* Get Control Word */
__asm__ volatile ("fnstcw %0" : "=m" (cw) : );
/* mask in */
cw &= _FPU_RESERVED;
cw = cw | (fpu_control & ~_FPU_RESERVED);
/* set cw */
__asm__ volatile ("fldcw %0" :: "m" (cw));
}
/* #endif */
#endif
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