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authorElliott Hughes <enh@google.com>2023-01-25 16:31:42 +0000
committerElliott Hughes <enh@google.com>2023-01-25 18:11:56 +0000
commit62662f115a17a5548402fcd02f3b7e1b9b38e087 (patch)
tree945eb1832687ad5eb97c433013617dbe107718e5 /pl/math/v_log1pf_inline.h
parent04d0bc466ce39c702459d77a15754a19533eaec9 (diff)
parent56e3bf05c19c4e28e1f5edd9093c712f16c5c32a (diff)
downloadarm-optimized-routines-62662f115a17a5548402fcd02f3b7e1b9b38e087.tar.gz
Upgrade ARM-software/optimized-routines to v23.01
This project was upgraded with external_updater. Usage: tools/external_updater/updater.sh update arm-optimized-routines For more info, check https://cs.android.com/android/platform/superproject/+/master:tools/external_updater/README.md Test: TreeHugger Change-Id: I03de0ecb0ea89c2a77b1c411685af09fd480b63e
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+/*
+ * Helper for single-precision routines which calculate log(1 + x) and do not
+ * need special-case handling
+ *
+ * Copyright (c) 2022-2023, Arm Limited.
+ * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
+ */
+
+#ifndef PL_MATH_V_LOG1PF_INLINE_H
+#define PL_MATH_V_LOG1PF_INLINE_H
+
+#include "v_math.h"
+#include "math_config.h"
+
+#define Four 0x40800000
+#define Ln2 v_f32 (0x1.62e43p-1f)
+
+#define C(i) v_f32 (__log1pf_data.coeffs[i])
+
+static inline v_f32_t
+eval_poly (v_f32_t m)
+{
+ /* Approximate log(1+m) on [-0.25, 0.5] using Estrin scheme. */
+ v_f32_t p_12 = v_fma_f32 (m, C (1), C (0));
+ v_f32_t p_34 = v_fma_f32 (m, C (3), C (2));
+ v_f32_t p_56 = v_fma_f32 (m, C (5), C (4));
+ v_f32_t p_78 = v_fma_f32 (m, C (7), C (6));
+
+ v_f32_t m2 = m * m;
+ v_f32_t p_02 = v_fma_f32 (m2, p_12, m);
+ v_f32_t p_36 = v_fma_f32 (m2, p_56, p_34);
+ v_f32_t p_79 = v_fma_f32 (m2, C (8), p_78);
+
+ v_f32_t m4 = m2 * m2;
+ v_f32_t p_06 = v_fma_f32 (m4, p_36, p_02);
+
+ return v_fma_f32 (m4, m4 * p_79, p_06);
+}
+
+static inline v_f32_t
+log1pf_inline (v_f32_t x)
+{
+ /* Helper for calculating log(x + 1). Copied from log1pf_2u1.c, with no
+ special-case handling. See that file for details of the algorithm. */
+ v_f32_t m = x + 1.0f;
+ v_u32_t k = (v_as_u32_f32 (m) - 0x3f400000) & 0xff800000;
+ v_f32_t s = v_as_f32_u32 (v_u32 (Four) - k);
+ v_f32_t m_scale = v_as_f32_u32 (v_as_u32_f32 (x) - k)
+ + v_fma_f32 (v_f32 (0.25f), s, v_f32 (-1.0f));
+ v_f32_t p = eval_poly (m_scale);
+ v_f32_t scale_back = v_to_f32_u32 (k) * 0x1.0p-23f;
+ return v_fma_f32 (scale_back, Ln2, p);
+}
+
+#endif // PL_MATH_V_LOG1PF_INLINE_H