Implement SIMD in two passes.
In a first pass, we put the pixels values and the coefficients in two separate buffers. In a second pass, we computer the interpolation.master
Fabien Freling
parent
2491796107
commit
d28caec8cc
2
Makefile
2
Makefile
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@ -1,7 +1,7 @@
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include Makefile.rules
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CXXFLAGS = -std=c++11 -W -Wall -O3 -ffast-math -g $(CXXFLAGS_PLATFORM)
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DEFINES = #-DSIMD
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DEFINES = -DSIMD
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BUILD_DIR = .
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SRC = rotation.cpp \
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image.cpp \
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109
rotation.cpp
109
rotation.cpp
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@ -325,6 +325,61 @@ uint16_t* generate_border_table_back(uint16_t const* front_padding,
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// Image rotation
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//
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inline
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void fill_row(Image const& src,
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Point const& src_rotated_point,
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uint8_t* row_buffer, unsigned int row_index,
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uint8_t* row_coefs,
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int q_pow)
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{
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// Quantize on a 8x8 grid
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int const q_inter_pow = 3;
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int const q_inter = 8; // 1 << q_inter_pow;
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int const mask = 0x07;
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int const src_x = src_rotated_point.x >> q_pow;
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int const src_y = src_rotated_point.y >> q_pow;
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// Bilinear interpolation
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unsigned int const src_index_1 = src_y * src.width + src_x;
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unsigned int const src_index_3 = src_index_1 + src.width;
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row_buffer[4 * row_index] = src.buffer[src_index_1];
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row_buffer[4 * row_index + 1] = src.buffer[src_index_1 + 1];
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row_buffer[4 * row_index + 2] = src.buffer[src_index_3];
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row_buffer[4 * row_index + 3] = src.buffer[src_index_3 + 1];
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unsigned int const x_delta = (src_rotated_point.x >> (q_pow - q_inter_pow)) & mask;
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unsigned int const y_delta = (src_rotated_point.y >> (q_pow - q_inter_pow)) & mask;
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unsigned int const inv_x = q_inter - x_delta;
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unsigned int const inv_y = q_inter - y_delta;
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row_coefs[4 * row_index] = inv_x * inv_y;
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row_coefs[4 * row_index + 1] = x_delta * inv_y;
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row_coefs[4 * row_index + 2] = inv_x * y_delta;
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row_coefs[4 * row_index + 3] = x_delta * y_delta;
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}
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inline
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void interpolate_row(uint8_t* row_buffer, uint8_t* row_coefs,
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unsigned int row_index,
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pvalue_t* rotate_buffer, unsigned int rot_index)
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{
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__m128i pixels = _mm_loadu_si128((__m128i*) &row_buffer[row_index]);
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__m128i coefs = _mm_loadu_si128((__m128i*) &row_coefs[row_index]);
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pixels = _mm_maddubs_epi16(pixels, coefs); // 2 bins per pixel, 4 pixels
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__m128i const zero = _mm_set1_epi16(0);
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pixels = _mm_hadd_epi16(pixels, zero); // 1 bin per pixel, 4 pixels
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pixels = _mm_srli_epi16(pixels, 6);
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rotate_buffer[rot_index] = _mm_extract_epi16(pixels, 0);
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rotate_buffer[rot_index + 1] = _mm_extract_epi16(pixels, 1);
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rotate_buffer[rot_index + 2] = _mm_extract_epi16(pixels, 2);
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rotate_buffer[rot_index + 3] = _mm_extract_epi16(pixels, 3);
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}
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inline
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void rotate_pixel(Image const& src,
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Point const& src_rotated_point,
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@ -333,7 +388,7 @@ void rotate_pixel(Image const& src,
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{
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// Quantize on a 8x8 grid
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int const q_inter_pow = 3;
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int const q_inter = 1 << q_inter_pow;
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int const q_inter = 8; // 1 << q_inter_pow;
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int const mask = 0x07;
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int const src_x = src_rotated_point.x >> q_pow;
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@ -353,33 +408,9 @@ void rotate_pixel(Image const& src,
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unsigned int const inv_x = q_inter - x_delta;
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unsigned int const inv_y = q_inter - y_delta;
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#ifndef SIMD
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pvalue_t interpolated = ((src_tl * inv_x + src_tr * x_delta) * inv_y
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+ (src_bl * inv_x + src_br * x_delta) * y_delta) >> (q_inter_pow << 1);
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+ (src_bl * inv_x + src_br * x_delta) * y_delta) >> 6;
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rotate_buffer[rot_index] = interpolated;
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#else
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// X-axis
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__m128i top = _mm_loadu_si128((__m128i*) &src.buffer[src_index_1]);
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__m128i bottom = _mm_loadu_si128((__m128i*) &src.buffer[src_index_3]);
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__m128i coef = _mm_set_epi16(x_delta, x_delta, x_delta, x_delta, inv_x, inv_x, inv_x, inv_x);
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top = _mm_mullo_epi16(top, coef);
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bottom = _mm_mullo_epi16(bottom, coef);
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// Y-axis
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coef = _mm_set1_epi16(inv_y);
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top = _mm_mullo_epi16(top, coef);
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coef = _mm_set1_epi16(y_delta);
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bottom = _mm_mullo_epi16(bottom, coef);
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top = _mm_add_epi16(top, bottom);
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top = _mm_srli_epi16(top, 2 * q_pow);
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rotate_buffer[rot_index] = _mm_extract_epi16(top, 0) + _mm_extract_epi16(top, 4);
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#endif // ! SIMD
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}
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Image* rotate(Image const& src, double angle)
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@ -428,6 +459,11 @@ Image* rotate(Image const& src, double angle)
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int previous_right_padding = 0;
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// Row buffer
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unique_ptr<uint8_t[]> row_buffer(new uint8_t[width * 4]);
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unique_ptr<uint8_t[]> row_coefs(new uint8_t[width * 4]);
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for (int y = 0; y < height; ++y)
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{
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@ -453,12 +489,33 @@ Image* rotate(Image const& src, double angle)
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src_rotated_origin.y + left_padding * qdx.y);
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// Body
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#ifndef SIMD
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for (int x = 0; x < core_pixels; ++x, ++buffer_index)
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{
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rotate_pixel(src, src_rotated_point, buffer, buffer_index, q_pos_pow);
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src_rotated_point += qdx;
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}
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#else
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for (int x = 0; x < core_pixels; ++x)
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{
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fill_row(src, src_rotated_point, row_buffer.get(), x, row_coefs.get(), q_pos_pow);
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src_rotated_point += qdx;
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}
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// We process 4 pixels at a time
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for (int x = 0; x < core_pixels / 4; ++x)
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{
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interpolate_row(row_buffer.get(), row_coefs.get(), x * 16, buffer, buffer_index);
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buffer_index += 4;
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}
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buffer_index += core_pixels % 4;
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#endif // ! SIMD
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// // Border
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// for (int x = 0; x < right_border; ++x, ++buffer_index)
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// {
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