diff options
Diffstat (limited to 'math/aarch64/experimental/advsimd/v_logf_inline.h')
| -rw-r--r-- | math/aarch64/experimental/advsimd/v_logf_inline.h | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/math/aarch64/experimental/advsimd/v_logf_inline.h b/math/aarch64/experimental/advsimd/v_logf_inline.h new file mode 100644 index 000000000000..3f4534173289 --- /dev/null +++ b/math/aarch64/experimental/advsimd/v_logf_inline.h @@ -0,0 +1,59 @@ +/* + * Single-precision vector log function - inline version + * + * Copyright (c) 2019-2024, Arm Limited. + * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception + */ + +#include "v_math.h" + +struct v_logf_data +{ + float32x4_t poly[7]; + float32x4_t ln2; + uint32x4_t off, mantissa_mask; +}; + +#define V_LOGF_CONSTANTS \ + { \ + .poly \ + = { V4 (-0x1.3e737cp-3f), V4 (0x1.5a9aa2p-3f), V4 (-0x1.4f9934p-3f), \ + V4 (0x1.961348p-3f), V4 (-0x1.00187cp-2f), V4 (0x1.555d7cp-2f), \ + V4 (-0x1.ffffc8p-2f) }, \ + .ln2 = V4 (0x1.62e43p-1f), .off = V4 (0x3f2aaaab), \ + .mantissa_mask = V4 (0x007fffff) \ + } + +#define P(i) d->poly[7 - i] + +static inline float32x4_t +v_logf_inline (float32x4_t x, const struct v_logf_data *d) +{ + float32x4_t n, p, q, r, r2, y; + uint32x4_t u; + + u = vreinterpretq_u32_f32 (x); + + /* x = 2^n * (1+r), where 2/3 < 1+r < 4/3. */ + u = vsubq_u32 (u, d->off); + n = vcvtq_f32_s32 ( + vshrq_n_s32 (vreinterpretq_s32_u32 (u), 23)); /* signextend. */ + u = vandq_u32 (u, d->mantissa_mask); + u = vaddq_u32 (u, d->off); + r = vsubq_f32 (vreinterpretq_f32_u32 (u), v_f32 (1.0f)); + + /* y = log(1+r) + n*ln2. */ + r2 = vmulq_f32 (r, r); + /* n*ln2 + r + r2*(P1 + r*P2 + r2*(P3 + r*P4 + r2*(P5 + r*P6 + r2*P7))). */ + p = vfmaq_f32 (P (5), P (6), r); + q = vfmaq_f32 (P (3), P (4), r); + y = vfmaq_f32 (P (1), P (2), r); + p = vfmaq_f32 (p, P (7), r2); + q = vfmaq_f32 (q, p, r2); + y = vfmaq_f32 (y, q, r2); + p = vfmaq_f32 (r, d->ln2, n); + + return vfmaq_f32 (p, y, r2); +} + +#undef P |