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target-arm: Add set_neon_rmode helper

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This helper sets the rounding mode in the standard_fp_status word to
allow NEON instructions to modify the rounding mode whilst using the
standard FPSCR values for everything else.

Signed-off-by: Will Newton <will.newton@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Will Newton 2014-01-31 14:47:35 +00:00 committed by Peter Maydell
parent 2ce7062501
commit 43630e5853
2 changed files with 18 additions and 0 deletions
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17
target-arm/helper.c
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@ -4048,6 +4048,23 @@ uint32_t HELPER(set_rmode)(uint32_t rmode, CPUARMState *env)
return prev_rmode;
}
/* Set the current fp rounding mode in the standard fp status and return
* the old one. This is for NEON instructions that need to change the
* rounding mode but wish to use the standard FPSCR values for everything
* else. Always set the rounding mode back to the correct value after
* modifying it.
* The argument is a softfloat float_round_ value.
*/
uint32_t HELPER(set_neon_rmode)(uint32_t rmode, CPUARMState *env)
{
float_status *fp_status = &env->vfp.standard_fp_status;
uint32_t prev_rmode = get_float_rounding_mode(fp_status);
set_float_rounding_mode(rmode, fp_status);
return prev_rmode;
}
/* Half precision conversions. */
static float32 do_fcvt_f16_to_f32(uint32_t a, CPUARMState *env, float_status *s)
{

1
target-arm/helper.h
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@ -149,6 +149,7 @@ DEF_HELPER_3(vfp_ultod, f64, i64, i32, ptr)
DEF_HELPER_3(vfp_uqtod, f64, i64, i32, ptr)
DEF_HELPER_FLAGS_2(set_rmode, TCG_CALL_NO_RWG, i32, i32, env)
DEF_HELPER_FLAGS_2(set_neon_rmode, TCG_CALL_NO_RWG, i32, i32, env)
DEF_HELPER_2(vfp_fcvt_f16_to_f32, f32, i32, env)
DEF_HELPER_2(vfp_fcvt_f32_to_f16, i32, f32, env)