[PATCH v2 04/22] sim/erc32: Use fenv.h for host FPU access

Jiri Gaisler
2015-02-19T22:32:28Z

* float.c (get_accex, clear_accex, set_fsr) Use functions from fenv.h
instead of custom assembly.
---
sim/erc32/float.c | 191 +++++++++---------------------------------------------
1 file changed, 30 insertions(+), 161 deletions(-)

diff --git a/sim/erc32/float.c b/sim/erc32/float.c
index 598b7cc..40c133b 100644
--- a/sim/erc32/float.c
+++ b/sim/erc32/float.c
@@ -28,53 +28,38 @@
* 4. Clear host exception bits
*
*
- * This can also be done using ieee_flags() library routine on sun.
*/

#include "config.h"
#include "sis.h"
+#include <fenv.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 */
+/* This 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);
+ int fexc, accx;
+
+ fexc = fetestexcept(FE_ALL_EXCEPT);
+ accx = 0;
+ if (fexc & FE_INEXACT)
+ accx |= 1;
+ if (fexc & FE_DIVBYZERO)
+ accx |= 2;
+ if (fexc & FE_UNDERFLOW)
+ accx |= 4;
+ if (fexc & FE_OVERFLOW)
+ accx |= 8;
+ if (fexc & FE_INVALID)
+ accx |= 0x10;
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
+ feclearexcept(FE_ALL_EXCEPT);
}

/* How to map SPARC FSR onto the host */
@@ -82,138 +67,22 @@ void
set_fsr(fsr)
uint32 fsr;
{
-#ifdef sparc
- _set_fsr_raw(fsr & ~0x0f800000);
-#elif i386
- void __setfpucw(unsigned short fpu_control);
- uint32 rawfsr;
+ int fround;

- fsr >>= 30;
- switch (fsr) {
+ fsr >>= 30;
+ switch (fsr) {
case 0:
- case 2:
- break;
-
+ fround = FE_TONEAREST;
+ break;
case 1:
- fsr = 3;
- break;
-
+ fround = FE_TOWARDZERO;
+ break;
+ case 2:
+ fround = FE_UPWARD;
+ break;
case 3:
- fsr = 1;
- break;
+ fround = FE_DOWNWARD;
+ 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));
+ fesetround(fround);
}
-/* #endif */
-#endif
--
2.1.0