diff options
Diffstat (limited to 'pl/math/sv_erfcf_1u7.c')
-rw-r--r-- | pl/math/sv_erfcf_1u7.c | 111 |
1 files changed, 0 insertions, 111 deletions
diff --git a/pl/math/sv_erfcf_1u7.c b/pl/math/sv_erfcf_1u7.c deleted file mode 100644 index cda8f0b3752e..000000000000 --- a/pl/math/sv_erfcf_1u7.c +++ /dev/null @@ -1,111 +0,0 @@ -/* - * Single-precision vector erfc(x) function. - * - * Copyright (c) 2023, Arm Limited. - * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception - */ - -#include "sv_math.h" -#include "pl_sig.h" -#include "pl_test.h" - -static const struct data -{ - uint32_t off_idx, off_arr; - float max, shift; - float third, two_thirds, two_over_fifteen, two_over_five, tenth; -} data = { - /* Set an offset so the range of the index used for lookup is 644, and it can - be clamped using a saturated add. */ - .off_idx = 0xb7fffd7b, /* 0xffffffff - asuint(shift) - 644. */ - .off_arr = 0xfffffd7b, /* 0xffffffff - 644. */ - .max = 10.0625f, /* 644/64. */ - .shift = 0x1p17f, - .third = 0x1.555556p-2f, - .two_thirds = 0x1.555556p-1f, - .two_over_fifteen = 0x1.111112p-3f, - .two_over_five = -0x1.99999ap-2f, - .tenth = -0x1.99999ap-4f, -}; - -#define SignMask 0x80000000 -#define TableScale 0x28000000 /* 0x1p-47. */ - -/* Optimized single-precision vector erfcf(x). - Approximation based on series expansion near x rounded to - nearest multiple of 1/64. - Let d = x - r, and scale = 2 / sqrt(pi) * exp(-r^2). For x near r, - - erfc(x) ~ erfc(r) - scale * d * poly(r, d), with - - poly(r, d) = 1 - r d + (2/3 r^2 - 1/3) d^2 - r (1/3 r^2 - 1/2) d^3 - + (2/15 r^4 - 2/5 r^2 + 1/10) d^4 - - Values of erfc(r) and scale are read from lookup tables. Stored values - are scaled to avoid hitting the subnormal range. - - Note that for x < 0, erfc(x) = 2.0 - erfc(-x). - - Maximum error: 1.63 ULP (~1.0 ULP for x < 0.0). - _ZGVsMxv_erfcf(0x1.1dbf7ap+3) got 0x1.f51212p-120 - want 0x1.f51216p-120. */ -svfloat32_t SV_NAME_F1 (erfc) (svfloat32_t x, const svbool_t pg) -{ - const struct data *dat = ptr_barrier (&data); - - svfloat32_t a = svabs_x (pg, x); - - /* Clamp input at |x| <= 10.0 + 4/64. */ - a = svmin_x (pg, a, dat->max); - - /* Reduce x to the nearest multiple of 1/64. */ - svfloat32_t shift = sv_f32 (dat->shift); - svfloat32_t z = svadd_x (pg, a, shift); - - /* Saturate index for the NaN case. */ - svuint32_t i = svqadd (svreinterpret_u32 (z), dat->off_idx); - - /* Lookup erfc(r) and 2/sqrt(pi)*exp(-r^2) in tables. */ - i = svmul_x (pg, i, 2); - const float32_t *p = &__erfcf_data.tab[0].erfc - 2 * dat->off_arr; - svfloat32_t erfcr = svld1_gather_index (pg, p, i); - svfloat32_t scale = svld1_gather_index (pg, p + 1, i); - - /* erfc(x) ~ erfc(r) - scale * d * poly(r, d). */ - svfloat32_t r = svsub_x (pg, z, shift); - svfloat32_t d = svsub_x (pg, a, r); - svfloat32_t d2 = svmul_x (pg, d, d); - svfloat32_t r2 = svmul_x (pg, r, r); - - svfloat32_t coeffs = svld1rq (svptrue_b32 (), &dat->third); - svfloat32_t third = svdup_lane (coeffs, 0); - - svfloat32_t p1 = r; - svfloat32_t p2 = svmls_lane (third, r2, coeffs, 1); - svfloat32_t p3 = svmul_x (pg, r, svmla_lane (sv_f32 (-0.5), r2, coeffs, 0)); - svfloat32_t p4 = svmla_lane (sv_f32 (dat->two_over_five), r2, coeffs, 2); - p4 = svmls_x (pg, sv_f32 (dat->tenth), r2, p4); - - svfloat32_t y = svmla_x (pg, p3, d, p4); - y = svmla_x (pg, p2, d, y); - y = svmla_x (pg, p1, d, y); - - /* Solves the |x| = inf/nan case. */ - y = svmls_x (pg, erfcr, scale, svmls_x (pg, d, d2, y)); - - /* Offset equals 2.0f if sign, else 0.0f. */ - svuint32_t sign = svand_x (pg, svreinterpret_u32 (x), SignMask); - svfloat32_t off = svreinterpret_f32 (svlsr_x (pg, sign, 1)); - /* Handle sign and scale back in a single fma. */ - svfloat32_t fac = svreinterpret_f32 (svorr_x (pg, sign, TableScale)); - - return svmla_x (pg, off, fac, y); -} - -PL_SIG (SV, F, 1, erfc, -4.0, 10.0) -PL_TEST_ULP (SV_NAME_F1 (erfc), 1.14) -PL_TEST_SYM_INTERVAL (SV_NAME_F1 (erfc), 0.0, 0x1p-26, 40000) -PL_TEST_INTERVAL (SV_NAME_F1 (erfc), 0x1p-26, 10.0625, 40000) -PL_TEST_INTERVAL (SV_NAME_F1 (erfc), -0x1p-26, -4.0, 40000) -PL_TEST_INTERVAL (SV_NAME_F1 (erfc), 10.0625, inf, 40000) -PL_TEST_INTERVAL (SV_NAME_F1 (erfc), -4.0, -inf, 40000) |