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Diffstat (limited to 'sim/erc32/float.c')
| -rw-r--r-- | sim/erc32/float.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/sim/erc32/float.c b/sim/erc32/float.c new file mode 100644 index 0000000..fe2f41e --- /dev/null +++ b/sim/erc32/float.c @@ -0,0 +1,212 @@ +/* + * 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 2 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, write to the Free Software Foundation, Inc., 675 + * Mass Ave, Cambridge, MA 02139, USA. + * + * + * 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 "sis.h" + +/* Forward declarations */ + +extern uint32 _get_sw PARAMS ((void)); +extern uint32 _get_cw PARAMS ((void)); +static void __setfpucw PARAMS ((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(" +.text + fnclex + + "); +#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; + case 3: fsr = 1; + } + 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(" + +.text + .align 4 + .global __set_fsr_raw,_set_fsr_raw +__set_fsr_raw: +_set_fsr_raw: + save %sp,-104,%sp + st %i0,[%fp+68] + ld [%fp+68], %fsr + mov 0,%i0 + ret + restore + + .align 4 + .global __get_fsr_raw + .global _get_fsr_raw +__get_fsr_raw: +_get_fsr_raw: + save %sp,-104,%sp + st %fsr,[%fp+68] + ld [%fp+68], %i0 + ret + restore + + "); + +#elif i386 + + asm(" + +.text + .align 8 +.globl _get_sw,__get_sw +__get_sw: +_get_sw: + pushl %ebp + movl %esp,%ebp + movl $0,%eax + fnstsw %ax + movl %ebp,%esp + popl %ebp + ret + + .align 8 +.globl _get_cw,__get_cw +__get_cw: +_get_cw: + pushl %ebp + movl %esp,%ebp + subw $2,%esp + fnstcw -2(%ebp) + movw -2(%ebp),%eax + movl %ebp,%esp + popl %ebp + ret + + + "); + + +#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 |