1 files changed, 113 insertions, 0 deletions
diff --git a/lib/src/dsp/arm/gainmapmath_neon.cpp b/lib/src/dsp/arm/gainmapmath_neon.cpp
new file mode 100644
index 0000000..6536045
--- /dev/null
+++ b/lib/src/dsp/arm/gainmapmath_neon.cpp
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+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ultrahdr/gainmapmath.h"
+
+#include <arm_neon.h>
+
+namespace ultrahdr {
+
+// Scale all coefficients by 2^14 to avoid needing floating-point arithmetic. This can cause an off
+// by one error compared to the scalar floating-point implementation.
+
+// Removing conversion coefficients 1 and 0 from the group for each standard leaves 6 coefficients.
+// Pack them into a single 128-bit vector as follows, zeroing the remaining elements:
+// {Y1, Y2, U1, U2, V1, V2, 0, 0}
+
+// Yuv Bt709 -> Yuv Bt601
+// Y' = (1.0f * Y) + ( 0.101579f * U) + ( 0.196076f * V)
+// U' = (0.0f * Y) + ( 0.989854f * U) + (-0.110653f * V)
+// V' = (0.0f * Y) + (-0.072453f * U) + ( 0.983398f * V)
+__attribute__((aligned(16)))
+const int16_t kYuv709To601_coeffs_neon[8] = {1664, 3213, 16218, -1813, -1187, 16112, 0, 0};
+
+// Yuv Bt709 -> Yuv Bt2100
+// Y' = (1.0f * Y) + (-0.016969f * U) + ( 0.096312f * V)
+// U' = (0.0f * Y) + ( 0.995306f * U) + (-0.051192f * V)
+// V' = (0.0f * Y) + ( 0.011507f * U) + ( 1.002637f * V)
+__attribute__((aligned(16)))
+const int16_t kYuv709To2100_coeffs_neon[8] = {-278, 1578, 16307, -839, 189, 16427, 0, 0};
+
+// Yuv Bt601 -> Yuv Bt709
+// Y' = (1.0f * Y) + (-0.118188f * U) + (-0.212685f * V),
+// U' = (0.0f * Y) + ( 1.018640f * U) + ( 0.114618f * V),
+// V' = (0.0f * Y) + ( 0.075049f * U) + ( 1.025327f * V);
+__attribute__((aligned(16)))
+const int16_t kYuv601To709_coeffs_neon[8] = {-1936, -3485, 16689, 1878, 1230, 16799, 0, 0};
+
+// Yuv Bt601 -> Yuv Bt2100
+// Y' = (1.0f * Y) + (-0.128245f * U) + (-0.115879f * V)
+// U' = (0.0f * Y) + ( 1.010016f * U) + ( 0.061592f * V)
+// V' = (0.0f * Y) + ( 0.086969f * U) + ( 1.029350f * V)
+__attribute__((aligned(16)))
+const int16_t kYuv601To2100_coeffs_neon[8] = {-2101, -1899, 16548, 1009, 1425, 16865, 0, 0};
+
+// Yuv Bt2100 -> Yuv Bt709
+// Y' = (1.0f * Y) + ( 0.018149f * U) + (-0.095132f * V)
+// U' = (0.0f * Y) + ( 1.004123f * U) + ( 0.051267f * V)
+// V' = (0.0f * Y) + (-0.011524f * U) + ( 0.996782f * V)
+__attribute__((aligned(16)))
+const int16_t kYuv2100To709_coeffs_neon[8] = {297, -1559, 16452, 840, -189, 16331, 0, 0};
+
+// Yuv Bt2100 -> Yuv Bt601
+// Y' = (1.0f * Y) + ( 0.117887f * U) + ( 0.105521f * V)
+// U' = (0.0f * Y) + ( 0.995211f * U) + (-0.059549f * V)
+// V' = (0.0f * Y) + (-0.084085f * U) + ( 0.976518f * V)
+__attribute__((aligned(16)))
+const int16_t kYuv2100To601_coeffs_neon[8] = {1931, 1729, 16306, -976, -1378, 15999, 0, 0};
+
+static inline int16x8_t yConversion_neon(uint8x8_t y, int16x8_t u, int16x8_t v, int16x8_t coeffs) {
+  int32x4_t lo = vmull_laneq_s16(vget_low_s16(u), coeffs, 0);
+  int32x4_t hi = vmull_laneq_s16(vget_high_s16(u), coeffs, 0);
+  lo = vmlal_laneq_s16(lo, vget_low_s16(v), coeffs, 1);
+  hi = vmlal_laneq_s16(hi, vget_high_s16(v), coeffs, 1);
+
+  // Descale result to account for coefficients being scaled by 2^14.
+  uint16x8_t y_output =
+      vreinterpretq_u16_s16(vcombine_s16(vqrshrn_n_s32(lo, 14), vqrshrn_n_s32(hi, 14)));
+  return vreinterpretq_s16_u16(vaddw_u8(y_output, y));
+}
+
+static inline int16x8_t uConversion_neon(int16x8_t u, int16x8_t v, int16x8_t coeffs) {
+  int32x4_t u_lo = vmull_laneq_s16(vget_low_s16(u), coeffs, 2);
+  int32x4_t u_hi = vmull_laneq_s16(vget_high_s16(u), coeffs, 2);
+  u_lo = vmlal_laneq_s16(u_lo, vget_low_s16(v), coeffs, 3);
+  u_hi = vmlal_laneq_s16(u_hi, vget_high_s16(v), coeffs, 3);
+
+  // Descale result to account for coefficients being scaled by 2^14.
+  const int16x8_t u_output = vcombine_s16(vqrshrn_n_s32(u_lo, 14), vqrshrn_n_s32(u_hi, 14));
+  return u_output;
+}
+
+static inline int16x8_t vConversion_neon(int16x8_t u, int16x8_t v, int16x8_t coeffs) {
+  int32x4_t v_lo = vmull_laneq_s16(vget_low_s16(u), coeffs, 4);
+  int32x4_t v_hi = vmull_laneq_s16(vget_high_s16(u), coeffs, 4);
+  v_lo = vmlal_laneq_s16(v_lo, vget_low_s16(v), coeffs, 5);
+  v_hi = vmlal_laneq_s16(v_hi, vget_high_s16(v), coeffs, 5);
+
+  // Descale result to account for coefficients being scaled by 2^14.
+  const int16x8_t v_output = vcombine_s16(vqrshrn_n_s32(v_lo, 14), vqrshrn_n_s32(v_hi, 14));
+  return v_output;
+}
+
+int16x8x3_t yuvConversion_neon(uint8x8_t y, int16x8_t u, int16x8_t v, int16x8_t coeffs) {
+  const int16x8_t y_output = yConversion_neon(y, u, v, coeffs);
+  const int16x8_t u_output = uConversion_neon(u, v, coeffs);
+  const int16x8_t v_output = vConversion_neon(u, v, coeffs);
+  return {y_output, u_output, v_output};
+}
+
+}  // namespace ultrahdr