openkylin
/
qemu
mirror of https://gitee.com/openkylin/qemu.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

target-arm: fix support for VRECPE. 

Now use the same algorithm as described in the ARM ARM.

Signed-off-by: Christophe Lyon <christophe.lyon@st.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Christophe Lyon 2011-02-21 17:38:47 +01:00 committed by Aurelien Jarno
parent 56bf4fe297
commit fe0e4872e4
1 changed files with 71 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

83
target-arm/helper.c
View File

@ -2692,13 +2692,67 @@ float32 HELPER(rsqrts_f32)(float32 a, float32 b, CPUState *env)
#define float64_256 make_float64(0x4070000000000000LL)
#define float64_512 make_float64(0x4080000000000000LL)
/* TODO: The architecture specifies the value that the estimate functions
should return. We return the exact reciprocal/root instead. */
/* The algorithm that must be used to calculate the estimate
* is specified by the ARM ARM.
*/
static float64 recip_estimate(float64 a, CPUState *env)
{
float_status *s = &env->vfp.standard_fp_status;
/* q = (int)(a * 512.0) */
float64 q = float64_mul(float64_512, a, s);
int64_t q_int = float64_to_int64_round_to_zero(q, s);
/* r = 1.0 / (((double)q + 0.5) / 512.0) */
q = int64_to_float64(q_int, s);
q = float64_add(q, float64_half, s);
q = float64_div(q, float64_512, s);
q = float64_div(float64_one, q, s);
/* s = (int)(256.0 * r + 0.5) */
q = float64_mul(q, float64_256, s);
q = float64_add(q, float64_half, s);
q_int = float64_to_int64_round_to_zero(q, s);
/* return (double)s / 256.0 */
return float64_div(int64_to_float64(q_int, s), float64_256, s);
}
float32 HELPER(recpe_f32)(float32 a, CPUState *env)
{
float_status *s = &env->vfp.fp_status;
float32 one = int32_to_float32(1, s);
return float32_div(one, a, s);
float_status *s = &env->vfp.standard_fp_status;
float64 f64;
uint32_t val32 = float32_val(a);
int result_exp;
int a_exp = (val32 & 0x7f800000) >> 23;
int sign = val32 & 0x80000000;
if (float32_is_any_nan(a)) {
if (float32_is_signaling_nan(a)) {
float_raise(float_flag_invalid, s);
}
return float32_default_nan;
} else if (float32_is_infinity(a)) {
return float32_set_sign(float32_zero, float32_is_neg(a));
} else if (float32_is_zero_or_denormal(a)) {
float_raise(float_flag_divbyzero, s);
return float32_set_sign(float32_infinity, float32_is_neg(a));
} else if (a_exp >= 253) {
float_raise(float_flag_underflow, s);
return float32_set_sign(float32_zero, float32_is_neg(a));
}
f64 = make_float64((0x3feULL << 52)
| ((int64_t)(val32 & 0x7fffff) << 29));
result_exp = 253 - a_exp;
f64 = recip_estimate(f64, env);
val32 = sign
| ((result_exp & 0xff) << 23)
| ((float64_val(f64) >> 29) & 0x7fffff);
return make_float32(val32);
}
float32 HELPER(rsqrte_f32)(float32 a, CPUState *env)
@ -2710,13 +2764,18 @@ float32 HELPER(rsqrte_f32)(float32 a, CPUState *env)
uint32_t HELPER(recpe_u32)(uint32_t a, CPUState *env)
{
float_status *s = &env->vfp.fp_status;
float32 tmp;
tmp = int32_to_float32(a, s);
tmp = float32_scalbn(tmp, -32, s);
tmp = helper_recpe_f32(tmp, env);
tmp = float32_scalbn(tmp, 31, s);
return float32_to_int32(tmp, s);
float64 f64;
if ((a & 0x80000000) == 0) {
return 0xffffffff;
}
f64 = make_float64((0x3feULL << 52)
| ((int64_t)(a & 0x7fffffff) << 21));
f64 = recip_estimate (f64, env);
return 0x80000000 | ((float64_val(f64) >> 21) & 0x7fffffff);
}
uint32_t HELPER(rsqrte_u32)(uint32_t a, CPUState *env)