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arm64: simplify the fenv implementation a bit.

Browse source 
The macOS man page was helpful in advancing my understanding of
feupdateenv() in particular.

Test: treehugger
Change-Id: I511e8b31ac16f3fdf08b42eee5a2e6558ec3b70b
This commit is contained in:
Elliott Hughes 2022-10-14 20:38:35 +00:00
parent 4c2de1fccc
commit a93431ca4c
1 changed files with 12 additions and 41 deletions
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53
libm/arm64/fenv.c
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@ -59,7 +59,6 @@ int fegetenv(fenv_t* envp) {
int fesetenv(const fenv_t* envp) {
fpu_control_t fpcr;
__get_fpcr(fpcr);
if (envp->__control != fpcr) {
__set_fpcr(envp->__control);
@ -70,27 +69,22 @@ int fesetenv(const fenv_t* envp) {
int feclearexcept(int excepts) {
fpu_status_t fpsr;
excepts &= FE_ALL_EXCEPT;
__get_fpsr(fpsr);
fpsr &= ~excepts;
fpsr &= ~(excepts & FE_ALL_EXCEPT);
__set_fpsr(fpsr);
return 0;
}
int fegetexceptflag(fexcept_t* flagp, int excepts) {
fpu_status_t fpsr;
excepts &= FE_ALL_EXCEPT;
__get_fpsr(fpsr);
*flagp = fpsr & excepts;
*flagp = fpsr & (excepts & FE_ALL_EXCEPT);
return 0;
}
int fesetexceptflag(const fexcept_t* flagp, int excepts) {
fpu_status_t fpsr;
excepts &= FE_ALL_EXCEPT;
fpu_status_t fpsr;
__get_fpsr(fpsr);
fpsr &= ~excepts;
fpsr |= *flagp & excepts;
@ -100,32 +94,27 @@ int fesetexceptflag(const fexcept_t* flagp, int excepts) {
int feraiseexcept(int excepts) {
fexcept_t ex = excepts;
fesetexceptflag(&ex, excepts);
return 0;
}
int fetestexcept(int excepts) {
fpu_status_t fpsr;
excepts &= FE_ALL_EXCEPT;
__get_fpsr(fpsr);
return (fpsr & excepts);
return (fpsr & (excepts & FE_ALL_EXCEPT));
}
int fegetround(void) {
fpu_control_t fpcr;
__get_fpcr(fpcr);
return ((fpcr >> FPCR_RMODE_SHIFT) & FE_TOWARDZERO);
}
int fesetround(int round) {
fpu_control_t fpcr, new_fpcr;
round &= FE_TOWARDZERO;
if (round < FE_TONEAREST || round > FE_UPWARD) return -1;
fpu_control_t fpcr;
__get_fpcr(fpcr);
new_fpcr = fpcr & ~(FE_TOWARDZERO << FPCR_RMODE_SHIFT);
fpu_control_t new_fpcr = fpcr & ~(FE_TOWARDZERO << FPCR_RMODE_SHIFT);
new_fpcr |= (round << FPCR_RMODE_SHIFT);
if (new_fpcr != fpcr) {
__set_fpcr(new_fpcr);
@ -134,33 +123,15 @@ int fesetround(int round) {
}
int feholdexcept(fenv_t* envp) {
fpu_status_t fpsr;
__get_fpsr(fpsr);
fpu_control_t fpcr;
__get_fpcr(fpcr);
fenv_t env = { .__status = fpsr, .__control = fpcr };
*envp = env;
// Clear all exceptions.
fpsr &= ~FE_ALL_EXCEPT;
__set_fpsr(fpsr);
fegetenv(envp);
feclearexcept(FE_ALL_EXCEPT);
return 0;
}
int feupdateenv(const fenv_t* envp) {
fpu_status_t fpsr;
fpu_control_t fpcr;
// Set FPU Control register.
__get_fpcr(fpcr);
if (envp->__control != fpcr) {
__set_fpcr(envp->__control);
}
// Set FPU Status register to status | currently raised exceptions.
__get_fpsr(fpsr);
fpsr = envp->__status | (fpsr & FE_ALL_EXCEPT);
__set_fpsr(fpsr);
int excepts = fetestexcept(FE_ALL_EXCEPT);
fesetenv(envp);
feraiseexcept(excepts);
return 0;
}