diff options
Diffstat (limited to 'src/dsp/arm/intrapred_directional_neon.cc')
| -rw-r--r-- | src/dsp/arm/intrapred_directional_neon.cc | 926 |
1 files changed, 926 insertions, 0 deletions
diff --git a/src/dsp/arm/intrapred_directional_neon.cc b/src/dsp/arm/intrapred_directional_neon.cc new file mode 100644 index 0000000..805ba81 --- /dev/null +++ b/src/dsp/arm/intrapred_directional_neon.cc @@ -0,0 +1,926 @@ +// Copyright 2019 The libgav1 Authors +// +// 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 "src/dsp/intrapred.h" +#include "src/utils/cpu.h" + +#if LIBGAV1_ENABLE_NEON + +#include <arm_neon.h> + +#include <algorithm> // std::min +#include <cassert> +#include <cstddef> +#include <cstdint> +#include <cstring> // memset + +#include "src/dsp/arm/common_neon.h" +#include "src/dsp/constants.h" +#include "src/dsp/dsp.h" +#include "src/utils/common.h" + +namespace libgav1 { +namespace dsp { +namespace low_bitdepth { +namespace { + +// Blend two values based on a 32 bit weight. +inline uint8x8_t WeightedBlend(const uint8x8_t a, const uint8x8_t b, + const uint8x8_t a_weight, + const uint8x8_t b_weight) { + const uint16x8_t a_product = vmull_u8(a, a_weight); + const uint16x8_t b_product = vmull_u8(b, b_weight); + + return vrshrn_n_u16(vaddq_u16(a_product, b_product), 5); +} + +// For vertical operations the weights are one constant value. +inline uint8x8_t WeightedBlend(const uint8x8_t a, const uint8x8_t b, + const uint8_t weight) { + return WeightedBlend(a, b, vdup_n_u8(32 - weight), vdup_n_u8(weight)); +} + +// Fill |left| and |right| with the appropriate values for a given |base_step|. +inline void LoadStepwise(const uint8_t* const source, const uint8x8_t left_step, + const uint8x8_t right_step, uint8x8_t* left, + uint8x8_t* right) { + const uint8x16_t mixed = vld1q_u8(source); + *left = VQTbl1U8(mixed, left_step); + *right = VQTbl1U8(mixed, right_step); +} + +// Handle signed step arguments by ignoring the sign. Negative values are +// considered out of range and overwritten later. +inline void LoadStepwise(const uint8_t* const source, const int8x8_t left_step, + const int8x8_t right_step, uint8x8_t* left, + uint8x8_t* right) { + LoadStepwise(source, vreinterpret_u8_s8(left_step), + vreinterpret_u8_s8(right_step), left, right); +} + +// Process 4 or 8 |width| by any |height|. +template <int width> +inline void DirectionalZone1_WxH(uint8_t* dst, const ptrdiff_t stride, + const int height, const uint8_t* const top, + const int xstep, const bool upsampled) { + assert(width == 4 || width == 8); + + const int upsample_shift = static_cast<int>(upsampled); + const int scale_bits = 6 - upsample_shift; + + const int max_base_x = (width + height - 1) << upsample_shift; + const int8x8_t max_base = vdup_n_s8(max_base_x); + const uint8x8_t top_max_base = vdup_n_u8(top[max_base_x]); + + const int8x8_t all = vcreate_s8(0x0706050403020100); + const int8x8_t even = vcreate_s8(0x0e0c0a0806040200); + const int8x8_t base_step = upsampled ? even : all; + const int8x8_t right_step = vadd_s8(base_step, vdup_n_s8(1)); + + int top_x = xstep; + int y = 0; + do { + const int top_base_x = top_x >> scale_bits; + + if (top_base_x >= max_base_x) { + for (int i = y; i < height; ++i) { + memset(dst, top[max_base_x], 4 /* width */); + dst += stride; + } + return; + } + + const uint8_t shift = ((top_x << upsample_shift) & 0x3F) >> 1; + + // Zone2 uses negative values for xstep. Use signed values to compare + // |top_base_x| to |max_base_x|. + const int8x8_t base_v = vadd_s8(vdup_n_s8(top_base_x), base_step); + + const uint8x8_t max_base_mask = vclt_s8(base_v, max_base); + + // 4 wide subsamples the output. 8 wide subsamples the input. + if (width == 4) { + const uint8x8_t left_values = vld1_u8(top + top_base_x); + const uint8x8_t right_values = RightShift<8>(left_values); + const uint8x8_t value = WeightedBlend(left_values, right_values, shift); + + // If |upsampled| is true then extract every other value for output. + const uint8x8_t value_stepped = + vtbl1_u8(value, vreinterpret_u8_s8(base_step)); + const uint8x8_t masked_value = + vbsl_u8(max_base_mask, value_stepped, top_max_base); + + StoreLo4(dst, masked_value); + } else /* width == 8 */ { + uint8x8_t left_values, right_values; + // WeightedBlend() steps up to Q registers. Downsample the input to avoid + // doing extra calculations. + LoadStepwise(top + top_base_x, base_step, right_step, &left_values, + &right_values); + + const uint8x8_t value = WeightedBlend(left_values, right_values, shift); + const uint8x8_t masked_value = + vbsl_u8(max_base_mask, value, top_max_base); + + vst1_u8(dst, masked_value); + } + dst += stride; + top_x += xstep; + } while (++y < height); +} + +// Process a multiple of 8 |width| by any |height|. Processes horizontally +// before vertically in the hopes of being a little more cache friendly. +inline void DirectionalZone1_WxH(uint8_t* dst, const ptrdiff_t stride, + const int width, const int height, + const uint8_t* const top, const int xstep, + const bool upsampled) { + assert(width % 8 == 0); + const int upsample_shift = static_cast<int>(upsampled); + const int scale_bits = 6 - upsample_shift; + + const int max_base_x = (width + height - 1) << upsample_shift; + const int8x8_t max_base = vdup_n_s8(max_base_x); + const uint8x8_t top_max_base = vdup_n_u8(top[max_base_x]); + + const int8x8_t all = vcreate_s8(0x0706050403020100); + const int8x8_t even = vcreate_s8(0x0e0c0a0806040200); + const int8x8_t base_step = upsampled ? even : all; + const int8x8_t right_step = vadd_s8(base_step, vdup_n_s8(1)); + const int8x8_t block_step = vdup_n_s8(8 << upsample_shift); + + int top_x = xstep; + int y = 0; + do { + const int top_base_x = top_x >> scale_bits; + + if (top_base_x >= max_base_x) { + for (int i = y; i < height; ++i) { + memset(dst, top[max_base_x], 4 /* width */); + dst += stride; + } + return; + } + + const uint8_t shift = ((top_x << upsample_shift) & 0x3F) >> 1; + + // Zone2 uses negative values for xstep. Use signed values to compare + // |top_base_x| to |max_base_x|. + int8x8_t base_v = vadd_s8(vdup_n_s8(top_base_x), base_step); + + int x = 0; + do { + const uint8x8_t max_base_mask = vclt_s8(base_v, max_base); + + // Extract the input values based on |upsampled| here to avoid doing twice + // as many calculations. + uint8x8_t left_values, right_values; + LoadStepwise(top + top_base_x + x, base_step, right_step, &left_values, + &right_values); + + const uint8x8_t value = WeightedBlend(left_values, right_values, shift); + const uint8x8_t masked_value = + vbsl_u8(max_base_mask, value, top_max_base); + + vst1_u8(dst + x, masked_value); + + base_v = vadd_s8(base_v, block_step); + x += 8; + } while (x < width); + top_x += xstep; + dst += stride; + } while (++y < height); +} + +void DirectionalIntraPredictorZone1_NEON(void* const dest, + const ptrdiff_t stride, + const void* const top_row, + const int width, const int height, + const int xstep, + const bool upsampled_top) { + const uint8_t* const top = static_cast<const uint8_t*>(top_row); + uint8_t* dst = static_cast<uint8_t*>(dest); + + assert(xstep > 0); + + const int upsample_shift = static_cast<int>(upsampled_top); + + const uint8x8_t all = vcreate_u8(0x0706050403020100); + + if (xstep == 64) { + assert(!upsampled_top); + const uint8_t* top_ptr = top + 1; + int y = 0; + do { + memcpy(dst, top_ptr, width); + memcpy(dst + stride, top_ptr + 1, width); + memcpy(dst + 2 * stride, top_ptr + 2, width); + memcpy(dst + 3 * stride, top_ptr + 3, width); + dst += 4 * stride; + top_ptr += 4; + y += 4; + } while (y < height); + } else if (width == 4) { + DirectionalZone1_WxH<4>(dst, stride, height, top, xstep, upsampled_top); + } else if (xstep > 51) { + // 7.11.2.10. Intra edge upsample selection process + // if ( d <= 0 || d >= 40 ) useUpsample = 0 + // For |upsample_top| the delta is from vertical so |prediction_angle - 90|. + // In |kDirectionalIntraPredictorDerivative[]| angles less than 51 will meet + // this criteria. The |xstep| value for angle 51 happens to be 51 as well. + // Shallower angles have greater xstep values. + assert(!upsampled_top); + const int max_base_x = ((width + height) - 1); + const uint8x8_t max_base = vdup_n_u8(max_base_x); + const uint8x8_t top_max_base = vdup_n_u8(top[max_base_x]); + const uint8x8_t block_step = vdup_n_u8(8); + + int top_x = xstep; + int y = 0; + do { + const int top_base_x = top_x >> 6; + const uint8_t shift = ((top_x << upsample_shift) & 0x3F) >> 1; + uint8x8_t base_v = vadd_u8(vdup_n_u8(top_base_x), all); + int x = 0; + // Only calculate a block of 8 when at least one of the output values is + // within range. Otherwise it can read off the end of |top|. + const int must_calculate_width = + std::min(width, max_base_x - top_base_x + 7) & ~7; + for (; x < must_calculate_width; x += 8) { + const uint8x8_t max_base_mask = vclt_u8(base_v, max_base); + + // Since these |xstep| values can not be upsampled the load is + // simplified. + const uint8x8_t left_values = vld1_u8(top + top_base_x + x); + const uint8x8_t right_values = vld1_u8(top + top_base_x + x + 1); + const uint8x8_t value = WeightedBlend(left_values, right_values, shift); + const uint8x8_t masked_value = + vbsl_u8(max_base_mask, value, top_max_base); + + vst1_u8(dst + x, masked_value); + base_v = vadd_u8(base_v, block_step); + } + memset(dst + x, top[max_base_x], width - x); + dst += stride; + top_x += xstep; + } while (++y < height); + } else { + DirectionalZone1_WxH(dst, stride, width, height, top, xstep, upsampled_top); + } +} + +// Process 4 or 8 |width| by 4 or 8 |height|. +template <int width> +inline void DirectionalZone3_WxH(uint8_t* dest, const ptrdiff_t stride, + const int height, + const uint8_t* const left_column, + const int base_left_y, const int ystep, + const int upsample_shift) { + assert(width == 4 || width == 8); + assert(height == 4 || height == 8); + const int scale_bits = 6 - upsample_shift; + + // Zone3 never runs out of left_column values. + assert((width + height - 1) << upsample_shift > // max_base_y + ((ystep * width) >> scale_bits) + + (/* base_step */ 1 << upsample_shift) * + (height - 1)); // left_base_y + + // Limited improvement for 8x8. ~20% faster for 64x64. + const uint8x8_t all = vcreate_u8(0x0706050403020100); + const uint8x8_t even = vcreate_u8(0x0e0c0a0806040200); + const uint8x8_t base_step = upsample_shift ? even : all; + const uint8x8_t right_step = vadd_u8(base_step, vdup_n_u8(1)); + + uint8_t* dst = dest; + uint8x8_t left_v[8], right_v[8], value_v[8]; + const uint8_t* const left = left_column; + + const int index_0 = base_left_y; + LoadStepwise(left + (index_0 >> scale_bits), base_step, right_step, + &left_v[0], &right_v[0]); + value_v[0] = WeightedBlend(left_v[0], right_v[0], + ((index_0 << upsample_shift) & 0x3F) >> 1); + + const int index_1 = base_left_y + ystep; + LoadStepwise(left + (index_1 >> scale_bits), base_step, right_step, + &left_v[1], &right_v[1]); + value_v[1] = WeightedBlend(left_v[1], right_v[1], + ((index_1 << upsample_shift) & 0x3F) >> 1); + + const int index_2 = base_left_y + ystep * 2; + LoadStepwise(left + (index_2 >> scale_bits), base_step, right_step, + &left_v[2], &right_v[2]); + value_v[2] = WeightedBlend(left_v[2], right_v[2], + ((index_2 << upsample_shift) & 0x3F) >> 1); + + const int index_3 = base_left_y + ystep * 3; + LoadStepwise(left + (index_3 >> scale_bits), base_step, right_step, + &left_v[3], &right_v[3]); + value_v[3] = WeightedBlend(left_v[3], right_v[3], + ((index_3 << upsample_shift) & 0x3F) >> 1); + + const int index_4 = base_left_y + ystep * 4; + LoadStepwise(left + (index_4 >> scale_bits), base_step, right_step, + &left_v[4], &right_v[4]); + value_v[4] = WeightedBlend(left_v[4], right_v[4], + ((index_4 << upsample_shift) & 0x3F) >> 1); + + const int index_5 = base_left_y + ystep * 5; + LoadStepwise(left + (index_5 >> scale_bits), base_step, right_step, + &left_v[5], &right_v[5]); + value_v[5] = WeightedBlend(left_v[5], right_v[5], + ((index_5 << upsample_shift) & 0x3F) >> 1); + + const int index_6 = base_left_y + ystep * 6; + LoadStepwise(left + (index_6 >> scale_bits), base_step, right_step, + &left_v[6], &right_v[6]); + value_v[6] = WeightedBlend(left_v[6], right_v[6], + ((index_6 << upsample_shift) & 0x3F) >> 1); + + const int index_7 = base_left_y + ystep * 7; + LoadStepwise(left + (index_7 >> scale_bits), base_step, right_step, + &left_v[7], &right_v[7]); + value_v[7] = WeightedBlend(left_v[7], right_v[7], + ((index_7 << upsample_shift) & 0x3F) >> 1); + + // 8x8 transpose. + const uint8x16x2_t b0 = vtrnq_u8(vcombine_u8(value_v[0], value_v[4]), + vcombine_u8(value_v[1], value_v[5])); + const uint8x16x2_t b1 = vtrnq_u8(vcombine_u8(value_v[2], value_v[6]), + vcombine_u8(value_v[3], value_v[7])); + + const uint16x8x2_t c0 = vtrnq_u16(vreinterpretq_u16_u8(b0.val[0]), + vreinterpretq_u16_u8(b1.val[0])); + const uint16x8x2_t c1 = vtrnq_u16(vreinterpretq_u16_u8(b0.val[1]), + vreinterpretq_u16_u8(b1.val[1])); + + const uint32x4x2_t d0 = vuzpq_u32(vreinterpretq_u32_u16(c0.val[0]), + vreinterpretq_u32_u16(c1.val[0])); + const uint32x4x2_t d1 = vuzpq_u32(vreinterpretq_u32_u16(c0.val[1]), + vreinterpretq_u32_u16(c1.val[1])); + + if (width == 4) { + StoreLo4(dst, vreinterpret_u8_u32(vget_low_u32(d0.val[0]))); + dst += stride; + StoreLo4(dst, vreinterpret_u8_u32(vget_high_u32(d0.val[0]))); + dst += stride; + StoreLo4(dst, vreinterpret_u8_u32(vget_low_u32(d1.val[0]))); + dst += stride; + StoreLo4(dst, vreinterpret_u8_u32(vget_high_u32(d1.val[0]))); + if (height == 4) return; + dst += stride; + StoreLo4(dst, vreinterpret_u8_u32(vget_low_u32(d0.val[1]))); + dst += stride; + StoreLo4(dst, vreinterpret_u8_u32(vget_high_u32(d0.val[1]))); + dst += stride; + StoreLo4(dst, vreinterpret_u8_u32(vget_low_u32(d1.val[1]))); + dst += stride; + StoreLo4(dst, vreinterpret_u8_u32(vget_high_u32(d1.val[1]))); + } else { + vst1_u8(dst, vreinterpret_u8_u32(vget_low_u32(d0.val[0]))); + dst += stride; + vst1_u8(dst, vreinterpret_u8_u32(vget_high_u32(d0.val[0]))); + dst += stride; + vst1_u8(dst, vreinterpret_u8_u32(vget_low_u32(d1.val[0]))); + dst += stride; + vst1_u8(dst, vreinterpret_u8_u32(vget_high_u32(d1.val[0]))); + if (height == 4) return; + dst += stride; + vst1_u8(dst, vreinterpret_u8_u32(vget_low_u32(d0.val[1]))); + dst += stride; + vst1_u8(dst, vreinterpret_u8_u32(vget_high_u32(d0.val[1]))); + dst += stride; + vst1_u8(dst, vreinterpret_u8_u32(vget_low_u32(d1.val[1]))); + dst += stride; + vst1_u8(dst, vreinterpret_u8_u32(vget_high_u32(d1.val[1]))); + } +} + +// Because the source values "move backwards" as the row index increases, the +// indices derived from ystep are generally negative. This is accommodated by +// making sure the relative indices are within [-15, 0] when the function is +// called, and sliding them into the inclusive range [0, 15], relative to a +// lower base address. +constexpr int kPositiveIndexOffset = 15; + +// Process 4 or 8 |width| by any |height|. +template <int width> +inline void DirectionalZone2FromLeftCol_WxH(uint8_t* dst, + const ptrdiff_t stride, + const int height, + const uint8_t* const left_column, + const int16x8_t left_y, + const int upsample_shift) { + assert(width == 4 || width == 8); + + // The shift argument must be a constant. + int16x8_t offset_y, shift_upsampled = left_y; + if (upsample_shift) { + offset_y = vshrq_n_s16(left_y, 5); + shift_upsampled = vshlq_n_s16(shift_upsampled, 1); + } else { + offset_y = vshrq_n_s16(left_y, 6); + } + + // Select values to the left of the starting point. + // The 15th element (and 16th) will be all the way at the end, to the right. + // With a negative ystep everything else will be "left" of them. + // This supports cumulative steps up to 15. We could support up to 16 by doing + // separate loads for |left_values| and |right_values|. vtbl supports 2 Q + // registers as input which would allow for cumulative offsets of 32. + const int16x8_t sampler = + vaddq_s16(offset_y, vdupq_n_s16(kPositiveIndexOffset)); + const uint8x8_t left_values = vqmovun_s16(sampler); + const uint8x8_t right_values = vadd_u8(left_values, vdup_n_u8(1)); + + const int16x8_t shift_masked = vandq_s16(shift_upsampled, vdupq_n_s16(0x3f)); + const uint8x8_t shift_mul = vreinterpret_u8_s8(vshrn_n_s16(shift_masked, 1)); + const uint8x8_t inv_shift_mul = vsub_u8(vdup_n_u8(32), shift_mul); + + int y = 0; + do { + uint8x8_t src_left, src_right; + LoadStepwise(left_column - kPositiveIndexOffset + (y << upsample_shift), + left_values, right_values, &src_left, &src_right); + const uint8x8_t val = + WeightedBlend(src_left, src_right, inv_shift_mul, shift_mul); + + if (width == 4) { + StoreLo4(dst, val); + } else { + vst1_u8(dst, val); + } + dst += stride; + } while (++y < height); +} + +// Process 4 or 8 |width| by any |height|. +template <int width> +inline void DirectionalZone1Blend_WxH(uint8_t* dest, const ptrdiff_t stride, + const int height, + const uint8_t* const top_row, + int zone_bounds, int top_x, + const int xstep, + const int upsample_shift) { + assert(width == 4 || width == 8); + + const int scale_bits_x = 6 - upsample_shift; + + const uint8x8_t all = vcreate_u8(0x0706050403020100); + const uint8x8_t even = vcreate_u8(0x0e0c0a0806040200); + const uint8x8_t base_step = upsample_shift ? even : all; + const uint8x8_t right_step = vadd_u8(base_step, vdup_n_u8(1)); + + int y = 0; + do { + const uint8_t* const src = top_row + (top_x >> scale_bits_x); + uint8x8_t left, right; + LoadStepwise(src, base_step, right_step, &left, &right); + + const uint8_t shift = ((top_x << upsample_shift) & 0x3f) >> 1; + const uint8x8_t val = WeightedBlend(left, right, shift); + + uint8x8_t dst_blend = vld1_u8(dest); + // |zone_bounds| values can be negative. + uint8x8_t blend = + vcge_s8(vreinterpret_s8_u8(all), vdup_n_s8((zone_bounds >> 6))); + uint8x8_t output = vbsl_u8(blend, val, dst_blend); + + if (width == 4) { + StoreLo4(dest, output); + } else { + vst1_u8(dest, output); + } + dest += stride; + zone_bounds += xstep; + top_x -= xstep; + } while (++y < height); +} + +// The height at which a load of 16 bytes will not contain enough source pixels +// from |left_column| to supply an accurate row when computing 8 pixels at a +// time. The values are found by inspection. By coincidence, all angles that +// satisfy (ystep >> 6) == 2 map to the same value, so it is enough to look up +// by ystep >> 6. The largest index for this lookup is 1023 >> 6 == 15. +constexpr int kDirectionalZone2ShuffleInvalidHeight[16] = { + 1024, 1024, 16, 16, 16, 16, 0, 0, 18, 0, 0, 0, 0, 0, 0, 40}; + +// 7.11.2.4 (8) 90 < angle > 180 +// The strategy for these functions (4xH and 8+xH) is to know how many blocks +// can be processed with just pixels from |top_ptr|, then handle mixed blocks, +// then handle only blocks that take from |left_ptr|. Additionally, a fast +// index-shuffle approach is used for pred values from |left_column| in sections +// that permit it. +inline void DirectionalZone2_4xH(uint8_t* dst, const ptrdiff_t stride, + const uint8_t* const top_row, + const uint8_t* const left_column, + const int height, const int xstep, + const int ystep, const bool upsampled_top, + const bool upsampled_left) { + const int upsample_left_shift = static_cast<int>(upsampled_left); + const int upsample_top_shift = static_cast<int>(upsampled_top); + + // Helper vector. + const int16x8_t zero_to_seven = {0, 1, 2, 3, 4, 5, 6, 7}; + + // Loop incrementers for moving by block (4xN). Vertical still steps by 8. If + // it's only 4, it will be finished in the first iteration. + const ptrdiff_t stride8 = stride << 3; + const int xstep8 = xstep << 3; + + const int min_height = (height == 4) ? 4 : 8; + + // All columns from |min_top_only_x| to the right will only need |top_row| to + // compute and can therefore call the Zone1 functions. This assumes |xstep| is + // at least 3. + assert(xstep >= 3); + const int min_top_only_x = std::min((height * xstep) >> 6, /* width */ 4); + + // For steep angles, the source pixels from |left_column| may not fit in a + // 16-byte load for shuffling. + // TODO(petersonab): Find a more precise formula for this subject to x. + // TODO(johannkoenig): Revisit this for |width| == 4. + const int max_shuffle_height = + std::min(kDirectionalZone2ShuffleInvalidHeight[ystep >> 6], height); + + // Offsets the original zone bound value to simplify x < (y+1)*xstep/64 -1 + int xstep_bounds_base = (xstep == 64) ? 0 : xstep - 1; + + const int left_base_increment = ystep >> 6; + const int ystep_remainder = ystep & 0x3F; + + // If the 64 scaling is regarded as a decimal point, the first value of the + // left_y vector omits the portion which is covered under the left_column + // offset. The following values need the full ystep as a relative offset. + int16x8_t left_y = vmulq_n_s16(zero_to_seven, -ystep); + left_y = vaddq_s16(left_y, vdupq_n_s16(-ystep_remainder)); + + // This loop treats each set of 4 columns in 3 stages with y-value boundaries. + // The first stage, before the first y-loop, covers blocks that are only + // computed from the top row. The second stage, comprising two y-loops, covers + // blocks that have a mixture of values computed from top or left. The final + // stage covers blocks that are only computed from the left. + if (min_top_only_x > 0) { + // Round down to the nearest multiple of 8. + // TODO(johannkoenig): This never hits for Wx4 blocks but maybe it should. + const int max_top_only_y = std::min((1 << 6) / xstep, height) & ~7; + DirectionalZone1_WxH<4>(dst, stride, max_top_only_y, top_row, -xstep, + upsampled_top); + + if (max_top_only_y == height) return; + + int y = max_top_only_y; + dst += stride * y; + const int xstep_y = xstep * y; + + // All rows from |min_left_only_y| down for this set of columns only need + // |left_column| to compute. + const int min_left_only_y = std::min((4 << 6) / xstep, height); + // At high angles such that min_left_only_y < 8, ystep is low and xstep is + // high. This means that max_shuffle_height is unbounded and xstep_bounds + // will overflow in 16 bits. This is prevented by stopping the first + // blending loop at min_left_only_y for such cases, which means we skip over + // the second blending loop as well. + const int left_shuffle_stop_y = + std::min(max_shuffle_height, min_left_only_y); + int xstep_bounds = xstep_bounds_base + xstep_y; + int top_x = -xstep - xstep_y; + + // +8 increment is OK because if height is 4 this only goes once. + for (; y < left_shuffle_stop_y; + y += 8, dst += stride8, xstep_bounds += xstep8, top_x -= xstep8) { + DirectionalZone2FromLeftCol_WxH<4>( + dst, stride, min_height, + left_column + ((y - left_base_increment) << upsample_left_shift), + left_y, upsample_left_shift); + + DirectionalZone1Blend_WxH<4>(dst, stride, min_height, top_row, + xstep_bounds, top_x, xstep, + upsample_top_shift); + } + + // Pick up from the last y-value, using the slower but secure method for + // left prediction. + const int16_t base_left_y = vgetq_lane_s16(left_y, 0); + for (; y < min_left_only_y; + y += 8, dst += stride8, xstep_bounds += xstep8, top_x -= xstep8) { + DirectionalZone3_WxH<4>( + dst, stride, min_height, + left_column + ((y - left_base_increment) << upsample_left_shift), + base_left_y, -ystep, upsample_left_shift); + + DirectionalZone1Blend_WxH<4>(dst, stride, min_height, top_row, + xstep_bounds, top_x, xstep, + upsample_top_shift); + } + // Loop over y for left_only rows. + for (; y < height; y += 8, dst += stride8) { + DirectionalZone3_WxH<4>( + dst, stride, min_height, + left_column + ((y - left_base_increment) << upsample_left_shift), + base_left_y, -ystep, upsample_left_shift); + } + } else { + DirectionalZone1_WxH<4>(dst, stride, height, top_row, -xstep, + upsampled_top); + } +} + +// Process a multiple of 8 |width|. +inline void DirectionalZone2_8(uint8_t* const dst, const ptrdiff_t stride, + const uint8_t* const top_row, + const uint8_t* const left_column, + const int width, const int height, + const int xstep, const int ystep, + const bool upsampled_top, + const bool upsampled_left) { + const int upsample_left_shift = static_cast<int>(upsampled_left); + const int upsample_top_shift = static_cast<int>(upsampled_top); + + // Helper vector. + const int16x8_t zero_to_seven = {0, 1, 2, 3, 4, 5, 6, 7}; + + // Loop incrementers for moving by block (8x8). This function handles blocks + // with height 4 as well. They are calculated in one pass so these variables + // do not get used. + const ptrdiff_t stride8 = stride << 3; + const int xstep8 = xstep << 3; + const int ystep8 = ystep << 3; + + // Process Wx4 blocks. + const int min_height = (height == 4) ? 4 : 8; + + // All columns from |min_top_only_x| to the right will only need |top_row| to + // compute and can therefore call the Zone1 functions. This assumes |xstep| is + // at least 3. + assert(xstep >= 3); + const int min_top_only_x = std::min((height * xstep) >> 6, width); + + // For steep angles, the source pixels from |left_column| may not fit in a + // 16-byte load for shuffling. + // TODO(petersonab): Find a more precise formula for this subject to x. + const int max_shuffle_height = + std::min(kDirectionalZone2ShuffleInvalidHeight[ystep >> 6], height); + + // Offsets the original zone bound value to simplify x < (y+1)*xstep/64 -1 + int xstep_bounds_base = (xstep == 64) ? 0 : xstep - 1; + + const int left_base_increment = ystep >> 6; + const int ystep_remainder = ystep & 0x3F; + + const int left_base_increment8 = ystep8 >> 6; + const int ystep_remainder8 = ystep8 & 0x3F; + const int16x8_t increment_left8 = vdupq_n_s16(ystep_remainder8); + + // If the 64 scaling is regarded as a decimal point, the first value of the + // left_y vector omits the portion which is covered under the left_column + // offset. Following values need the full ystep as a relative offset. + int16x8_t left_y = vmulq_n_s16(zero_to_seven, -ystep); + left_y = vaddq_s16(left_y, vdupq_n_s16(-ystep_remainder)); + + // This loop treats each set of 4 columns in 3 stages with y-value boundaries. + // The first stage, before the first y-loop, covers blocks that are only + // computed from the top row. The second stage, comprising two y-loops, covers + // blocks that have a mixture of values computed from top or left. The final + // stage covers blocks that are only computed from the left. + int x = 0; + for (int left_offset = -left_base_increment; x < min_top_only_x; x += 8, + xstep_bounds_base -= (8 << 6), + left_y = vsubq_s16(left_y, increment_left8), + left_offset -= left_base_increment8) { + uint8_t* dst_x = dst + x; + + // Round down to the nearest multiple of 8. + const int max_top_only_y = std::min(((x + 1) << 6) / xstep, height) & ~7; + DirectionalZone1_WxH<8>(dst_x, stride, max_top_only_y, + top_row + (x << upsample_top_shift), -xstep, + upsampled_top); + + if (max_top_only_y == height) continue; + + int y = max_top_only_y; + dst_x += stride * y; + const int xstep_y = xstep * y; + + // All rows from |min_left_only_y| down for this set of columns only need + // |left_column| to compute. + const int min_left_only_y = std::min(((x + 8) << 6) / xstep, height); + // At high angles such that min_left_only_y < 8, ystep is low and xstep is + // high. This means that max_shuffle_height is unbounded and xstep_bounds + // will overflow in 16 bits. This is prevented by stopping the first + // blending loop at min_left_only_y for such cases, which means we skip over + // the second blending loop as well. + const int left_shuffle_stop_y = + std::min(max_shuffle_height, min_left_only_y); + int xstep_bounds = xstep_bounds_base + xstep_y; + int top_x = -xstep - xstep_y; + + for (; y < left_shuffle_stop_y; + y += 8, dst_x += stride8, xstep_bounds += xstep8, top_x -= xstep8) { + DirectionalZone2FromLeftCol_WxH<8>( + dst_x, stride, min_height, + left_column + ((left_offset + y) << upsample_left_shift), left_y, + upsample_left_shift); + + DirectionalZone1Blend_WxH<8>( + dst_x, stride, min_height, top_row + (x << upsample_top_shift), + xstep_bounds, top_x, xstep, upsample_top_shift); + } + + // Pick up from the last y-value, using the slower but secure method for + // left prediction. + const int16_t base_left_y = vgetq_lane_s16(left_y, 0); + for (; y < min_left_only_y; + y += 8, dst_x += stride8, xstep_bounds += xstep8, top_x -= xstep8) { + DirectionalZone3_WxH<8>( + dst_x, stride, min_height, + left_column + ((left_offset + y) << upsample_left_shift), base_left_y, + -ystep, upsample_left_shift); + + DirectionalZone1Blend_WxH<8>( + dst_x, stride, min_height, top_row + (x << upsample_top_shift), + xstep_bounds, top_x, xstep, upsample_top_shift); + } + // Loop over y for left_only rows. + for (; y < height; y += 8, dst_x += stride8) { + DirectionalZone3_WxH<8>( + dst_x, stride, min_height, + left_column + ((left_offset + y) << upsample_left_shift), base_left_y, + -ystep, upsample_left_shift); + } + } + // TODO(johannkoenig): May be able to remove this branch. + if (x < width) { + DirectionalZone1_WxH(dst + x, stride, width - x, height, + top_row + (x << upsample_top_shift), -xstep, + upsampled_top); + } +} + +void DirectionalIntraPredictorZone2_NEON( + void* const dest, const ptrdiff_t stride, const void* const top_row, + const void* const left_column, const int width, const int height, + const int xstep, const int ystep, const bool upsampled_top, + const bool upsampled_left) { + // Increasing the negative buffer for this function allows more rows to be + // processed at a time without branching in an inner loop to check the base. + uint8_t top_buffer[288]; + uint8_t left_buffer[288]; + memcpy(top_buffer + 128, static_cast<const uint8_t*>(top_row) - 16, 160); + memcpy(left_buffer + 128, static_cast<const uint8_t*>(left_column) - 16, 160); + const uint8_t* top_ptr = top_buffer + 144; + const uint8_t* left_ptr = left_buffer + 144; + auto* dst = static_cast<uint8_t*>(dest); + + if (width == 4) { + DirectionalZone2_4xH(dst, stride, top_ptr, left_ptr, height, xstep, ystep, + upsampled_top, upsampled_left); + } else { + DirectionalZone2_8(dst, stride, top_ptr, left_ptr, width, height, xstep, + ystep, upsampled_top, upsampled_left); + } +} + +void DirectionalIntraPredictorZone3_NEON(void* const dest, + const ptrdiff_t stride, + const void* const left_column, + const int width, const int height, + const int ystep, + const bool upsampled_left) { + const auto* const left = static_cast<const uint8_t*>(left_column); + + assert(ystep > 0); + + const int upsample_shift = static_cast<int>(upsampled_left); + const int scale_bits = 6 - upsample_shift; + const int base_step = 1 << upsample_shift; + + if (width == 4 || height == 4) { + // This block can handle all sizes but the specializations for other sizes + // are faster. + const uint8x8_t all = vcreate_u8(0x0706050403020100); + const uint8x8_t even = vcreate_u8(0x0e0c0a0806040200); + const uint8x8_t base_step_v = upsampled_left ? even : all; + const uint8x8_t right_step = vadd_u8(base_step_v, vdup_n_u8(1)); + + int y = 0; + do { + int x = 0; + do { + uint8_t* dst = static_cast<uint8_t*>(dest); + dst += y * stride + x; + uint8x8_t left_v[4], right_v[4], value_v[4]; + const int ystep_base = ystep * x; + const int offset = y * base_step; + + const int index_0 = ystep_base + ystep * 1; + LoadStepwise(left + offset + (index_0 >> scale_bits), base_step_v, + right_step, &left_v[0], &right_v[0]); + value_v[0] = WeightedBlend(left_v[0], right_v[0], + ((index_0 << upsample_shift) & 0x3F) >> 1); + + const int index_1 = ystep_base + ystep * 2; + LoadStepwise(left + offset + (index_1 >> scale_bits), base_step_v, + right_step, &left_v[1], &right_v[1]); + value_v[1] = WeightedBlend(left_v[1], right_v[1], + ((index_1 << upsample_shift) & 0x3F) >> 1); + + const int index_2 = ystep_base + ystep * 3; + LoadStepwise(left + offset + (index_2 >> scale_bits), base_step_v, + right_step, &left_v[2], &right_v[2]); + value_v[2] = WeightedBlend(left_v[2], right_v[2], + ((index_2 << upsample_shift) & 0x3F) >> 1); + + const int index_3 = ystep_base + ystep * 4; + LoadStepwise(left + offset + (index_3 >> scale_bits), base_step_v, + right_step, &left_v[3], &right_v[3]); + value_v[3] = WeightedBlend(left_v[3], right_v[3], + ((index_3 << upsample_shift) & 0x3F) >> 1); + + // 8x4 transpose. + const uint8x8x2_t b0 = vtrn_u8(value_v[0], value_v[1]); + const uint8x8x2_t b1 = vtrn_u8(value_v[2], value_v[3]); + + const uint16x4x2_t c0 = vtrn_u16(vreinterpret_u16_u8(b0.val[0]), + vreinterpret_u16_u8(b1.val[0])); + const uint16x4x2_t c1 = vtrn_u16(vreinterpret_u16_u8(b0.val[1]), + vreinterpret_u16_u8(b1.val[1])); + + StoreLo4(dst, vreinterpret_u8_u16(c0.val[0])); + dst += stride; + StoreLo4(dst, vreinterpret_u8_u16(c1.val[0])); + dst += stride; + StoreLo4(dst, vreinterpret_u8_u16(c0.val[1])); + dst += stride; + StoreLo4(dst, vreinterpret_u8_u16(c1.val[1])); + + if (height > 4) { + dst += stride; + StoreHi4(dst, vreinterpret_u8_u16(c0.val[0])); + dst += stride; + StoreHi4(dst, vreinterpret_u8_u16(c1.val[0])); + dst += stride; + StoreHi4(dst, vreinterpret_u8_u16(c0.val[1])); + dst += stride; + StoreHi4(dst, vreinterpret_u8_u16(c1.val[1])); + } + x += 4; + } while (x < width); + y += 8; + } while (y < height); + } else { // 8x8 at a time. + // Limited improvement for 8x8. ~20% faster for 64x64. + int y = 0; + do { + int x = 0; + do { + uint8_t* dst = static_cast<uint8_t*>(dest); + dst += y * stride + x; + const int ystep_base = ystep * (x + 1); + + DirectionalZone3_WxH<8>(dst, stride, 8, left + (y << upsample_shift), + ystep_base, ystep, upsample_shift); + x += 8; + } while (x < width); + y += 8; + } while (y < height); + } +} + +void Init8bpp() { + Dsp* const dsp = dsp_internal::GetWritableDspTable(kBitdepth8); + assert(dsp != nullptr); + dsp->directional_intra_predictor_zone1 = DirectionalIntraPredictorZone1_NEON; + dsp->directional_intra_predictor_zone2 = DirectionalIntraPredictorZone2_NEON; + dsp->directional_intra_predictor_zone3 = DirectionalIntraPredictorZone3_NEON; +} + +} // namespace +} // namespace low_bitdepth + +void IntraPredDirectionalInit_NEON() { low_bitdepth::Init8bpp(); } + +} // namespace dsp +} // namespace libgav1 + +#else // !LIBGAV1_ENABLE_NEON +namespace libgav1 { +namespace dsp { + +void IntraPredDirectionalInit_NEON() {} + +} // namespace dsp +} // namespace libgav1 +#endif // LIBGAV1_ENABLE_NEON |