diff options
Diffstat (limited to 'arm_compute')
-rw-r--r-- | arm_compute/core/NEON/NEMath.inl | 35 |
1 files changed, 5 insertions, 30 deletions
diff --git a/arm_compute/core/NEON/NEMath.inl b/arm_compute/core/NEON/NEMath.inl index 2bc1ab7964..4de80509f0 100644 --- a/arm_compute/core/NEON/NEMath.inl +++ b/arm_compute/core/NEON/NEMath.inl @@ -245,37 +245,12 @@ inline float16x8_t vtaylor_polyq_f16(float16x8_t x, const std::array<float16x8_t inline float16x8_t vexpq_f16(float16x8_t x) { - static const std::array<float16x8_t, 8> exp_tab_f16 = - { - { - vdupq_n_f16(1.f), - vdupq_n_f16(0.0416598916054f), - vdupq_n_f16(0.500000596046f), - vdupq_n_f16(0.0014122662833f), - vdupq_n_f16(1.00000011921f), - vdupq_n_f16(0.00833693705499f), - vdupq_n_f16(0.166665703058f), - vdupq_n_f16(0.000195780929062f), - } - }; - - static const float16x8_t CONST_LN2 = vdupq_n_f16(0.6931471805f); // ln(2) - static const float16x8_t CONST_INV_LN2 = vdupq_n_f16(1.4426950408f); // 1/ln(2) - static const float16x8_t CONST_0 = vdupq_n_f16(0.f); - static const int16x8_t CONST_NEGATIVE_126 = vdupq_n_s16(-126); - - // Perform range reduction [-log(2),log(2)] - const int16x8_t m = vcvtq_s16_f16(vmulq_f16(x, CONST_INV_LN2)); - const float16x8_t val = vsubq_f16(x, vmulq_f16(vcvtq_f16_s16(m), CONST_LN2)); + // TODO (COMPMID-1535) : Revisit FP16 approximations + const float32x4_t x_high = vcvt_f32_f16(vget_high_f16(x)); + const float32x4_t x_low = vcvt_f32_f16(vget_low_f16(x)); - // Polynomial Approximation - float16x8_t poly = vtaylor_polyq_f16(val, exp_tab_f16); - - // Reconstruct - poly = vreinterpretq_f16_s16(vqaddq_s16(vreinterpretq_s16_f16(poly), vqshlq_n_s16(m, 9))); - poly = vbslq_f16(vcltq_s16(m, CONST_NEGATIVE_126), CONST_0, poly); - - return poly; + const float16x8_t res = vcvt_high_f16_f32(vcvt_f16_f32(vexpq_f32(x_low)), vexpq_f32(x_high)); + return res; } inline float16x8_t vlogq_f16(float16x8_t x) |