diff options
Diffstat (limited to 'pl/math/v_expm1f_inline.h')
| -rw-r--r-- | pl/math/v_expm1f_inline.h | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/pl/math/v_expm1f_inline.h b/pl/math/v_expm1f_inline.h index 5a706f5..6ae94c4 100644 --- a/pl/math/v_expm1f_inline.h +++ b/pl/math/v_expm1f_inline.h @@ -16,20 +16,19 @@ struct v_expm1f_data { float32x4_t poly[5]; - float32x4_t invln2, ln2_lo, ln2_hi, shift; + float32x4_t invln2_and_ln2, shift; int32x4_t exponent_bias; }; /* Coefficients generated using fpminimax with degree=5 in [-log(2)/2, - * log(2)/2]. Exponent bias is asuint(1.0f). */ + log(2)/2]. Exponent bias is asuint(1.0f). + invln2_and_ln2 Stores constants: invln2, ln2_lo, ln2_hi, 0. */ #define V_EXPM1F_DATA \ { \ .poly = { V4 (0x1.fffffep-2), V4 (0x1.5554aep-3), V4 (0x1.555736p-5), \ V4 (0x1.12287cp-7), V4 (0x1.6b55a2p-10) }, \ - \ - .invln2 = V4 (0x1.715476p+0f), .ln2_hi = V4 (0x1.62e4p-1f), \ - .ln2_lo = V4 (0x1.7f7d1cp-20f), .shift = V4 (0x1.8p23f), \ - .exponent_bias = V4 (0x3f800000), \ + .shift = V4 (0x1.8p23f), .exponent_bias = V4 (0x3f800000), \ + .invln2_and_ln2 = { 0x1.715476p+0f, 0x1.62e4p-1f, 0x1.7f7d1cp-20f, 0 }, \ } static inline float32x4_t @@ -40,10 +39,11 @@ expm1f_inline (float32x4_t x, const struct v_expm1f_data *d) calling routine should handle special values if required. */ /* Reduce argument: f in [-ln2/2, ln2/2], i is exact. */ - float32x4_t j = vsubq_f32 (vfmaq_f32 (d->shift, d->invln2, x), d->shift); + float32x4_t j = vsubq_f32 ( + vfmaq_laneq_f32 (d->shift, x, d->invln2_and_ln2, 0), d->shift); int32x4_t i = vcvtq_s32_f32 (j); - float32x4_t f = vfmsq_f32 (x, j, d->ln2_hi); - f = vfmsq_f32 (f, j, d->ln2_lo); + float32x4_t f = vfmsq_laneq_f32 (x, j, d->invln2_and_ln2, 1); + f = vfmsq_laneq_f32 (f, j, d->invln2_and_ln2, 2); /* Approximate expm1(f) with polynomial P, expm1(f) ~= f + f^2 * P(f). Uses Estrin scheme, where the main _ZGVnN4v_expm1f routine uses |