The Tor Browser: comparison gfx/2d/convolver.cpp

--1:000000000000
+:e25bdc2befdd
+// Copyright (c) 2006-2011 The Chromium Authors. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//  * Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+//  * Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in
+//    the documentation and/or other materials provided with the
+//    distribution.
+//  * Neither the name of Google, Inc. nor the names of its contributors
+//    may be used to endorse or promote products derived from this
+//    software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+// OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+// AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+// SUCH DAMAGE.
+#include "convolver.h"
+#include <algorithm>
+#include "skia/SkTypes.h"
+// note: SIMD_SSE2 is not enabled because of bugs, apparently
+#if defined(SIMD_SSE2)
+#include <emmintrin.h>  // ARCH_CPU_X86_FAMILY was defined in build/config.h
+#endif
+#if defined(SK_CPU_LENDIAN)
+#define R_OFFSET_IDX 0
+#define G_OFFSET_IDX 1
+#define B_OFFSET_IDX 2
+#define A_OFFSET_IDX 3
+#else
+#define R_OFFSET_IDX 3
+#define G_OFFSET_IDX 2
+#define B_OFFSET_IDX 1
+#define A_OFFSET_IDX 0
+#endif
+namespace skia {
+namespace {
+// Converts the argument to an 8-bit unsigned value by clamping to the range
+// 0-255.
+inline unsigned char ClampTo8(int a) {
+if (static_cast<unsigned>(a) < 256)
+return a;  // Avoid the extra check in the common case.
+if (a < 0)
+return 0;
+return 255;
+}
+// Stores a list of rows in a circular buffer. The usage is you write into it
+// by calling AdvanceRow. It will keep track of which row in the buffer it
+// should use next, and the total number of rows added.
+class CircularRowBuffer {
+public:
+// The number of pixels in each row is given in |source_row_pixel_width|.
+// The maximum number of rows needed in the buffer is |max_y_filter_size|
+// (we only need to store enough rows for the biggest filter).
+//
+// We use the |first_input_row| to compute the coordinates of all of the
+// following rows returned by Advance().
+CircularRowBuffer(int dest_row_pixel_width, int max_y_filter_size,
+int first_input_row)
+: row_byte_width_(dest_row_pixel_width * 4),
+num_rows_(max_y_filter_size),
+next_row_(0),
+next_row_coordinate_(first_input_row) {
+buffer_.resize(row_byte_width_ * max_y_filter_size);
+row_addresses_.resize(num_rows_);
+}
+// Moves to the next row in the buffer, returning a pointer to the beginning
+// of it.
+unsigned char* AdvanceRow() {
+unsigned char* row = &buffer_[next_row_ * row_byte_width_];
+next_row_coordinate_++;
+// Set the pointer to the next row to use, wrapping around if necessary.
+next_row_++;
+if (next_row_ == num_rows_)
+next_row_ = 0;
+return row;
+}
+// Returns a pointer to an "unrolled" array of rows. These rows will start
+// at the y coordinate placed into |*first_row_index| and will continue in
+// order for the maximum number of rows in this circular buffer.
+//
+// The |first_row_index_| may be negative. This means the circular buffer
+// starts before the top of the image (it hasn't been filled yet).
+unsigned char* const* GetRowAddresses(int* first_row_index) {
+// Example for a 4-element circular buffer holding coords 6-9.
+//   Row 0   Coord 8
+//   Row 1   Coord 9
+//   Row 2   Coord 6  <- next_row_ = 2, next_row_coordinate_ = 10.
+//   Row 3   Coord 7
+//
+// The "next" row is also the first (lowest) coordinate. This computation
+// may yield a negative value, but that's OK, the math will work out
+// since the user of this buffer will compute the offset relative
+// to the first_row_index and the negative rows will never be used.
+*first_row_index = next_row_coordinate_ - num_rows_;
+int cur_row = next_row_;
+for (int i = 0; i < num_rows_; i++) {
+row_addresses_[i] = &buffer_[cur_row * row_byte_width_];
+// Advance to the next row, wrapping if necessary.
+cur_row++;
+if (cur_row == num_rows_)
+cur_row = 0;
+}
+return &row_addresses_[0];
+}
+private:
+// The buffer storing the rows. They are packed, each one row_byte_width_.
+std::vector<unsigned char> buffer_;
+// Number of bytes per row in the |buffer_|.
+int row_byte_width_;
+// The number of rows available in the buffer.
+int num_rows_;
+// The next row index we should write into. This wraps around as the
+// circular buffer is used.
+int next_row_;
+// The y coordinate of the |next_row_|. This is incremented each time a
+// new row is appended and does not wrap.
+int next_row_coordinate_;
+// Buffer used by GetRowAddresses().
+std::vector<unsigned char*> row_addresses_;
+};
+// Convolves horizontally along a single row. The row data is given in
+// |src_data| and continues for the num_values() of the filter.
+template<bool has_alpha>
+// This function is miscompiled with gcc 4.5 with pgo. See bug 827946.
+#if defined(__GNUC__) && defined(MOZ_GCC_VERSION_AT_LEAST)
+#if MOZ_GCC_VERSION_AT_LEAST(4, 5, 0) && !MOZ_GCC_VERSION_AT_LEAST(4, 6, 0)
+__attribute__((optimize("-O1")))
+#endif
+#endif
+void ConvolveHorizontally(const unsigned char* src_data,
+const ConvolutionFilter1D& filter,
+unsigned char* out_row) {
+// Loop over each pixel on this row in the output image.
+int num_values = filter.num_values();
+for (int out_x = 0; out_x < num_values; out_x++) {
+// Get the filter that determines the current output pixel.
+int filter_offset, filter_length;
+const ConvolutionFilter1D::Fixed* filter_values =
+filter.FilterForValue(out_x, &filter_offset, &filter_length);
+// Compute the first pixel in this row that the filter affects. It will
+// touch |filter_length| pixels (4 bytes each) after this.
+const unsigned char* row_to_filter = &src_data[filter_offset * 4];
+// Apply the filter to the row to get the destination pixel in |accum|.
+int accum[4] = {0};
+for (int filter_x = 0; filter_x < filter_length; filter_x++) {
+ConvolutionFilter1D::Fixed cur_filter = filter_values[filter_x];
+accum[0] += cur_filter * row_to_filter[filter_x * 4 + R_OFFSET_IDX];
+accum[1] += cur_filter * row_to_filter[filter_x * 4 + G_OFFSET_IDX];
+accum[2] += cur_filter * row_to_filter[filter_x * 4 + B_OFFSET_IDX];
+if (has_alpha)
+accum[3] += cur_filter * row_to_filter[filter_x * 4 + A_OFFSET_IDX];
+}
+// Bring this value back in range. All of the filter scaling factors
+// are in fixed point with kShiftBits bits of fractional part.
+accum[0] >>= ConvolutionFilter1D::kShiftBits;
+accum[1] >>= ConvolutionFilter1D::kShiftBits;
+accum[2] >>= ConvolutionFilter1D::kShiftBits;
+if (has_alpha)
+accum[3] >>= ConvolutionFilter1D::kShiftBits;
+// Store the new pixel.
+out_row[out_x * 4 + R_OFFSET_IDX] = ClampTo8(accum[0]);
+out_row[out_x * 4 + G_OFFSET_IDX] = ClampTo8(accum[1]);
+out_row[out_x * 4 + B_OFFSET_IDX] = ClampTo8(accum[2]);
+if (has_alpha)
+out_row[out_x * 4 + A_OFFSET_IDX] = ClampTo8(accum[3]);
+}
+}
+// Does vertical convolution to produce one output row. The filter values and
+// length are given in the first two parameters. These are applied to each
+// of the rows pointed to in the |source_data_rows| array, with each row
+// being |pixel_width| wide.
+//
+// The output must have room for |pixel_width * 4| bytes.
+template<bool has_alpha>
+void ConvolveVertically(const ConvolutionFilter1D::Fixed* filter_values,
+int filter_length,
+unsigned char* const* source_data_rows,
+int pixel_width,
+unsigned char* out_row) {
+// We go through each column in the output and do a vertical convolution,
+// generating one output pixel each time.
+for (int out_x = 0; out_x < pixel_width; out_x++) {
+// Compute the number of bytes over in each row that the current column
+// we're convolving starts at. The pixel will cover the next 4 bytes.
+int byte_offset = out_x * 4;
+// Apply the filter to one column of pixels.
+int accum[4] = {0};
+for (int filter_y = 0; filter_y < filter_length; filter_y++) {
+ConvolutionFilter1D::Fixed cur_filter = filter_values[filter_y];
+accum[0] += cur_filter
+	* source_data_rows[filter_y][byte_offset + R_OFFSET_IDX];
+accum[1] += cur_filter
+	* source_data_rows[filter_y][byte_offset + G_OFFSET_IDX];
+accum[2] += cur_filter
+	* source_data_rows[filter_y][byte_offset + B_OFFSET_IDX];
+if (has_alpha)
+accum[3] += cur_filter
+	  * source_data_rows[filter_y][byte_offset + A_OFFSET_IDX];
+}
+// Bring this value back in range. All of the filter scaling factors
+// are in fixed point with kShiftBits bits of precision.
+accum[0] >>= ConvolutionFilter1D::kShiftBits;
+accum[1] >>= ConvolutionFilter1D::kShiftBits;
+accum[2] >>= ConvolutionFilter1D::kShiftBits;
+if (has_alpha)
+accum[3] >>= ConvolutionFilter1D::kShiftBits;
+// Store the new pixel.
+out_row[byte_offset + R_OFFSET_IDX] = ClampTo8(accum[0]);
+out_row[byte_offset + G_OFFSET_IDX] = ClampTo8(accum[1]);
+out_row[byte_offset + B_OFFSET_IDX] = ClampTo8(accum[2]);
+if (has_alpha) {
+unsigned char alpha = ClampTo8(accum[3]);
+// Make sure the alpha channel doesn't come out smaller than any of the
+// color channels. We use premultipled alpha channels, so this should
+// never happen, but rounding errors will cause this from time to time.
+// These "impossible" colors will cause overflows (and hence random pixel
+// values) when the resulting bitmap is drawn to the screen.
+//
+// We only need to do this when generating the final output row (here).
+int max_color_channel = std::max(out_row[byte_offset + R_OFFSET_IDX],
+std::max(out_row[byte_offset + G_OFFSET_IDX], out_row[byte_offset + B_OFFSET_IDX]));
+if (alpha < max_color_channel)
+out_row[byte_offset + A_OFFSET_IDX] = max_color_channel;
+else
+out_row[byte_offset + A_OFFSET_IDX] = alpha;
+} else {
+// No alpha channel, the image is opaque.
+out_row[byte_offset + A_OFFSET_IDX] = 0xff;
+}
+}
+}
+// Convolves horizontally along a single row. The row data is given in
+// |src_data| and continues for the num_values() of the filter.
+void ConvolveHorizontally_SSE2(const unsigned char* src_data,
+const ConvolutionFilter1D& filter,
+unsigned char* out_row) {
+#if defined(SIMD_SSE2)
+int num_values = filter.num_values();
+int filter_offset, filter_length;
+__m128i zero = _mm_setzero_si128();
+__m128i mask[4];
+// |mask| will be used to decimate all extra filter coefficients that are
+// loaded by SIMD when |filter_length| is not divisible by 4.
+// mask[0] is not used in following algorithm.
+mask[1] = _mm_set_epi16(0, 0, 0, 0, 0, 0, 0, -1);
+mask[2] = _mm_set_epi16(0, 0, 0, 0, 0, 0, -1, -1);
+mask[3] = _mm_set_epi16(0, 0, 0, 0, 0, -1, -1, -1);
+// Output one pixel each iteration, calculating all channels (RGBA) together.
+for (int out_x = 0; out_x < num_values; out_x++) {
+const ConvolutionFilter1D::Fixed* filter_values =
+filter.FilterForValue(out_x, &filter_offset, &filter_length);
+__m128i accum = _mm_setzero_si128();
+// Compute the first pixel in this row that the filter affects. It will
+// touch |filter_length| pixels (4 bytes each) after this.
+const __m128i* row_to_filter =
+reinterpret_cast<const __m128i*>(&src_data[filter_offset << 2]);
+// We will load and accumulate with four coefficients per iteration.
+for (int filter_x = 0; filter_x < filter_length >> 2; filter_x++) {
+// Load 4 coefficients => duplicate 1st and 2nd of them for all channels.
+__m128i coeff, coeff16;
+// [16] xx xx xx xx c3 c2 c1 c0
+coeff = _mm_loadl_epi64(reinterpret_cast<const __m128i*>(filter_values));
+// [16] xx xx xx xx c1 c1 c0 c0
+coeff16 = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(1, 1, 0, 0));
+// [16] c1 c1 c1 c1 c0 c0 c0 c0
+coeff16 = _mm_unpacklo_epi16(coeff16, coeff16);
+// Load four pixels => unpack the first two pixels to 16 bits =>
+// multiply with coefficients => accumulate the convolution result.
+// [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
+__m128i src8 = _mm_loadu_si128(row_to_filter);
+// [16] a1 b1 g1 r1 a0 b0 g0 r0
+__m128i src16 = _mm_unpacklo_epi8(src8, zero);
+__m128i mul_hi = _mm_mulhi_epi16(src16, coeff16);
+__m128i mul_lo = _mm_mullo_epi16(src16, coeff16);
+// [32]  a0*c0 b0*c0 g0*c0 r0*c0
+__m128i t = _mm_unpacklo_epi16(mul_lo, mul_hi);
+accum = _mm_add_epi32(accum, t);
+// [32]  a1*c1 b1*c1 g1*c1 r1*c1
+t = _mm_unpackhi_epi16(mul_lo, mul_hi);
+accum = _mm_add_epi32(accum, t);
+// Duplicate 3rd and 4th coefficients for all channels =>
+// unpack the 3rd and 4th pixels to 16 bits => multiply with coefficients
+// => accumulate the convolution results.
+// [16] xx xx xx xx c3 c3 c2 c2
+coeff16 = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(3, 3, 2, 2));
+// [16] c3 c3 c3 c3 c2 c2 c2 c2
+coeff16 = _mm_unpacklo_epi16(coeff16, coeff16);
+// [16] a3 g3 b3 r3 a2 g2 b2 r2
+src16 = _mm_unpackhi_epi8(src8, zero);
+mul_hi = _mm_mulhi_epi16(src16, coeff16);
+mul_lo = _mm_mullo_epi16(src16, coeff16);
+// [32]  a2*c2 b2*c2 g2*c2 r2*c2
+t = _mm_unpacklo_epi16(mul_lo, mul_hi);
+accum = _mm_add_epi32(accum, t);
+// [32]  a3*c3 b3*c3 g3*c3 r3*c3
+t = _mm_unpackhi_epi16(mul_lo, mul_hi);
+accum = _mm_add_epi32(accum, t);
+// Advance the pixel and coefficients pointers.
+row_to_filter += 1;
+filter_values += 4;
+}
+// When |filter_length| is not divisible by 4, we need to decimate some of
+// the filter coefficient that was loaded incorrectly to zero; Other than
+// that the algorithm is same with above, exceot that the 4th pixel will be
+// always absent.
+int r = filter_length&3;
+if (r) {
+// Note: filter_values must be padded to align_up(filter_offset, 8).
+__m128i coeff, coeff16;
+coeff = _mm_loadl_epi64(reinterpret_cast<const __m128i*>(filter_values));
+// Mask out extra filter taps.
+coeff = _mm_and_si128(coeff, mask[r]);
+coeff16 = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(1, 1, 0, 0));
+coeff16 = _mm_unpacklo_epi16(coeff16, coeff16);
+// Note: line buffer must be padded to align_up(filter_offset, 16).
+// We resolve this by use C-version for the last horizontal line.
+__m128i src8 = _mm_loadu_si128(row_to_filter);
+__m128i src16 = _mm_unpacklo_epi8(src8, zero);
+__m128i mul_hi = _mm_mulhi_epi16(src16, coeff16);
+__m128i mul_lo = _mm_mullo_epi16(src16, coeff16);
+__m128i t = _mm_unpacklo_epi16(mul_lo, mul_hi);
+accum = _mm_add_epi32(accum, t);
+t = _mm_unpackhi_epi16(mul_lo, mul_hi);
+accum = _mm_add_epi32(accum, t);
+src16 = _mm_unpackhi_epi8(src8, zero);
+coeff16 = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(3, 3, 2, 2));
+coeff16 = _mm_unpacklo_epi16(coeff16, coeff16);
+mul_hi = _mm_mulhi_epi16(src16, coeff16);
+mul_lo = _mm_mullo_epi16(src16, coeff16);
+t = _mm_unpacklo_epi16(mul_lo, mul_hi);
+accum = _mm_add_epi32(accum, t);
+}
+// Shift right for fixed point implementation.
+accum = _mm_srai_epi32(accum, ConvolutionFilter1D::kShiftBits);
+// Packing 32 bits |accum| to 16 bits per channel (signed saturation).
+accum = _mm_packs_epi32(accum, zero);
+// Packing 16 bits |accum| to 8 bits per channel (unsigned saturation).
+accum = _mm_packus_epi16(accum, zero);
+// Store the pixel value of 32 bits.
+*(reinterpret_cast<int*>(out_row)) = _mm_cvtsi128_si32(accum);
+out_row += 4;
+}
+#endif
+}
+// Convolves horizontally along four rows. The row data is given in
+// |src_data| and continues for the num_values() of the filter.
+// The algorithm is almost same as |ConvolveHorizontally_SSE2|. Please
+// refer to that function for detailed comments.
+void ConvolveHorizontally4_SSE2(const unsigned char* src_data[4],
+const ConvolutionFilter1D& filter,
+unsigned char* out_row[4]) {
+#if defined(SIMD_SSE2)
+int num_values = filter.num_values();
+int filter_offset, filter_length;
+__m128i zero = _mm_setzero_si128();
+__m128i mask[4];
+// |mask| will be used to decimate all extra filter coefficients that are
+// loaded by SIMD when |filter_length| is not divisible by 4.
+// mask[0] is not used in following algorithm.
+mask[1] = _mm_set_epi16(0, 0, 0, 0, 0, 0, 0, -1);
+mask[2] = _mm_set_epi16(0, 0, 0, 0, 0, 0, -1, -1);
+mask[3] = _mm_set_epi16(0, 0, 0, 0, 0, -1, -1, -1);
+// Output one pixel each iteration, calculating all channels (RGBA) together.
+for (int out_x = 0; out_x < num_values; out_x++) {
+const ConvolutionFilter1D::Fixed* filter_values =
+filter.FilterForValue(out_x, &filter_offset, &filter_length);
+// four pixels in a column per iteration.
+__m128i accum0 = _mm_setzero_si128();
+__m128i accum1 = _mm_setzero_si128();
+__m128i accum2 = _mm_setzero_si128();
+__m128i accum3 = _mm_setzero_si128();
+int start = (filter_offset<<2);
+// We will load and accumulate with four coefficients per iteration.
+for (int filter_x = 0; filter_x < (filter_length >> 2); filter_x++) {
+__m128i coeff, coeff16lo, coeff16hi;
+// [16] xx xx xx xx c3 c2 c1 c0
+coeff = _mm_loadl_epi64(reinterpret_cast<const __m128i*>(filter_values));
+// [16] xx xx xx xx c1 c1 c0 c0
+coeff16lo = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(1, 1, 0, 0));
+// [16] c1 c1 c1 c1 c0 c0 c0 c0
+coeff16lo = _mm_unpacklo_epi16(coeff16lo, coeff16lo);
+// [16] xx xx xx xx c3 c3 c2 c2
+coeff16hi = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(3, 3, 2, 2));
+// [16] c3 c3 c3 c3 c2 c2 c2 c2
+coeff16hi = _mm_unpacklo_epi16(coeff16hi, coeff16hi);
+__m128i src8, src16, mul_hi, mul_lo, t;
+#define ITERATION(src, accum)                                          \
+src8 = _mm_loadu_si128(reinterpret_cast<const __m128i*>(src));   \
+src16 = _mm_unpacklo_epi8(src8, zero);                           \
+mul_hi = _mm_mulhi_epi16(src16, coeff16lo);                      \
+mul_lo = _mm_mullo_epi16(src16, coeff16lo);                      \
+t = _mm_unpacklo_epi16(mul_lo, mul_hi);                          \
+accum = _mm_add_epi32(accum, t);                                 \
+t = _mm_unpackhi_epi16(mul_lo, mul_hi);                          \
+accum = _mm_add_epi32(accum, t);                                 \
+src16 = _mm_unpackhi_epi8(src8, zero);                           \
+mul_hi = _mm_mulhi_epi16(src16, coeff16hi);                      \
+mul_lo = _mm_mullo_epi16(src16, coeff16hi);                      \
+t = _mm_unpacklo_epi16(mul_lo, mul_hi);                          \
+accum = _mm_add_epi32(accum, t);                                 \
+t = _mm_unpackhi_epi16(mul_lo, mul_hi);                          \
+accum = _mm_add_epi32(accum, t)
+ITERATION(src_data[0] + start, accum0);
+ITERATION(src_data[1] + start, accum1);
+ITERATION(src_data[2] + start, accum2);
+ITERATION(src_data[3] + start, accum3);
+start += 16;
+filter_values += 4;
+}
+int r = filter_length & 3;
+if (r) {
+// Note: filter_values must be padded to align_up(filter_offset, 8);
+__m128i coeff;
+coeff = _mm_loadl_epi64(reinterpret_cast<const __m128i*>(filter_values));
+// Mask out extra filter taps.
+coeff = _mm_and_si128(coeff, mask[r]);
+__m128i coeff16lo = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(1, 1, 0, 0));
+/* c1 c1 c1 c1 c0 c0 c0 c0 */
+coeff16lo = _mm_unpacklo_epi16(coeff16lo, coeff16lo);
+__m128i coeff16hi = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(3, 3, 2, 2));
+coeff16hi = _mm_unpacklo_epi16(coeff16hi, coeff16hi);
+__m128i src8, src16, mul_hi, mul_lo, t;
+ITERATION(src_data[0] + start, accum0);
+ITERATION(src_data[1] + start, accum1);
+ITERATION(src_data[2] + start, accum2);
+ITERATION(src_data[3] + start, accum3);
+}
+accum0 = _mm_srai_epi32(accum0, ConvolutionFilter1D::kShiftBits);
+accum0 = _mm_packs_epi32(accum0, zero);
+accum0 = _mm_packus_epi16(accum0, zero);
+accum1 = _mm_srai_epi32(accum1, ConvolutionFilter1D::kShiftBits);
+accum1 = _mm_packs_epi32(accum1, zero);
+accum1 = _mm_packus_epi16(accum1, zero);
+accum2 = _mm_srai_epi32(accum2, ConvolutionFilter1D::kShiftBits);
+accum2 = _mm_packs_epi32(accum2, zero);
+accum2 = _mm_packus_epi16(accum2, zero);
+accum3 = _mm_srai_epi32(accum3, ConvolutionFilter1D::kShiftBits);
+accum3 = _mm_packs_epi32(accum3, zero);
+accum3 = _mm_packus_epi16(accum3, zero);
+*(reinterpret_cast<int*>(out_row[0])) = _mm_cvtsi128_si32(accum0);
+*(reinterpret_cast<int*>(out_row[1])) = _mm_cvtsi128_si32(accum1);
+*(reinterpret_cast<int*>(out_row[2])) = _mm_cvtsi128_si32(accum2);
+*(reinterpret_cast<int*>(out_row[3])) = _mm_cvtsi128_si32(accum3);
+out_row[0] += 4;
+out_row[1] += 4;
+out_row[2] += 4;
+out_row[3] += 4;
+}
+#endif
+}
+// Does vertical convolution to produce one output row. The filter values and
+// length are given in the first two parameters. These are applied to each
+// of the rows pointed to in the |source_data_rows| array, with each row
+// being |pixel_width| wide.
+//
+// The output must have room for |pixel_width * 4| bytes.
+template<bool has_alpha>
+void ConvolveVertically_SSE2(const ConvolutionFilter1D::Fixed* filter_values,
+int filter_length,
+unsigned char* const* source_data_rows,
+int pixel_width,
+unsigned char* out_row) {
+#if defined(SIMD_SSE2)
+int width = pixel_width & ~3;
+__m128i zero = _mm_setzero_si128();
+__m128i accum0, accum1, accum2, accum3, coeff16;
+const __m128i* src;
+// Output four pixels per iteration (16 bytes).
+for (int out_x = 0; out_x < width; out_x += 4) {
+// Accumulated result for each pixel. 32 bits per RGBA channel.
+accum0 = _mm_setzero_si128();
+accum1 = _mm_setzero_si128();
+accum2 = _mm_setzero_si128();
+accum3 = _mm_setzero_si128();
+// Convolve with one filter coefficient per iteration.
+for (int filter_y = 0; filter_y < filter_length; filter_y++) {
+// Duplicate the filter coefficient 8 times.
+// [16] cj cj cj cj cj cj cj cj
+coeff16 = _mm_set1_epi16(filter_values[filter_y]);
+// Load four pixels (16 bytes) together.
+// [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
+src = reinterpret_cast<const __m128i*>(
+&source_data_rows[filter_y][out_x << 2]);
+__m128i src8 = _mm_loadu_si128(src);
+// Unpack 1st and 2nd pixels from 8 bits to 16 bits for each channels =>
+// multiply with current coefficient => accumulate the result.
+// [16] a1 b1 g1 r1 a0 b0 g0 r0
+__m128i src16 = _mm_unpacklo_epi8(src8, zero);
+__m128i mul_hi = _mm_mulhi_epi16(src16, coeff16);
+__m128i mul_lo = _mm_mullo_epi16(src16, coeff16);
+// [32] a0 b0 g0 r0
+__m128i t = _mm_unpacklo_epi16(mul_lo, mul_hi);
+accum0 = _mm_add_epi32(accum0, t);
+// [32] a1 b1 g1 r1
+t = _mm_unpackhi_epi16(mul_lo, mul_hi);
+accum1 = _mm_add_epi32(accum1, t);
+// Unpack 3rd and 4th pixels from 8 bits to 16 bits for each channels =>
+// multiply with current coefficient => accumulate the result.
+// [16] a3 b3 g3 r3 a2 b2 g2 r2
+src16 = _mm_unpackhi_epi8(src8, zero);
+mul_hi = _mm_mulhi_epi16(src16, coeff16);
+mul_lo = _mm_mullo_epi16(src16, coeff16);
+// [32] a2 b2 g2 r2
+t = _mm_unpacklo_epi16(mul_lo, mul_hi);
+accum2 = _mm_add_epi32(accum2, t);
+// [32] a3 b3 g3 r3
+t = _mm_unpackhi_epi16(mul_lo, mul_hi);
+accum3 = _mm_add_epi32(accum3, t);
+}
+// Shift right for fixed point implementation.
+accum0 = _mm_srai_epi32(accum0, ConvolutionFilter1D::kShiftBits);
+accum1 = _mm_srai_epi32(accum1, ConvolutionFilter1D::kShiftBits);
+accum2 = _mm_srai_epi32(accum2, ConvolutionFilter1D::kShiftBits);
+accum3 = _mm_srai_epi32(accum3, ConvolutionFilter1D::kShiftBits);
+// Packing 32 bits |accum| to 16 bits per channel (signed saturation).
+// [16] a1 b1 g1 r1 a0 b0 g0 r0
+accum0 = _mm_packs_epi32(accum0, accum1);
+// [16] a3 b3 g3 r3 a2 b2 g2 r2
+accum2 = _mm_packs_epi32(accum2, accum3);
+// Packing 16 bits |accum| to 8 bits per channel (unsigned saturation).
+// [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
+accum0 = _mm_packus_epi16(accum0, accum2);
+if (has_alpha) {
+// Compute the max(ri, gi, bi) for each pixel.
+// [8] xx a3 b3 g3 xx a2 b2 g2 xx a1 b1 g1 xx a0 b0 g0
+__m128i a = _mm_srli_epi32(accum0, 8);
+// [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
+__m128i b = _mm_max_epu8(a, accum0);  // Max of r and g.
+// [8] xx xx a3 b3 xx xx a2 b2 xx xx a1 b1 xx xx a0 b0
+a = _mm_srli_epi32(accum0, 16);
+// [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
+b = _mm_max_epu8(a, b);  // Max of r and g and b.
+// [8] max3 00 00 00 max2 00 00 00 max1 00 00 00 max0 00 00 00
+b = _mm_slli_epi32(b, 24);
+// Make sure the value of alpha channel is always larger than maximum
+// value of color channels.
+accum0 = _mm_max_epu8(b, accum0);
+} else {
+// Set value of alpha channels to 0xFF.
+__m128i mask = _mm_set1_epi32(0xff000000);
+accum0 = _mm_or_si128(accum0, mask);
+}
+// Store the convolution result (16 bytes) and advance the pixel pointers.
+_mm_storeu_si128(reinterpret_cast<__m128i*>(out_row), accum0);
+out_row += 16;
+}
+// When the width of the output is not divisible by 4, We need to save one
+// pixel (4 bytes) each time. And also the fourth pixel is always absent.
+if (pixel_width & 3) {
+accum0 = _mm_setzero_si128();
+accum1 = _mm_setzero_si128();
+accum2 = _mm_setzero_si128();
+for (int filter_y = 0; filter_y < filter_length; ++filter_y) {
+coeff16 = _mm_set1_epi16(filter_values[filter_y]);
+// [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
+src = reinterpret_cast<const __m128i*>(
+&source_data_rows[filter_y][width<<2]);
+__m128i src8 = _mm_loadu_si128(src);
+// [16] a1 b1 g1 r1 a0 b0 g0 r0
+__m128i src16 = _mm_unpacklo_epi8(src8, zero);
+__m128i mul_hi = _mm_mulhi_epi16(src16, coeff16);
+__m128i mul_lo = _mm_mullo_epi16(src16, coeff16);
+// [32] a0 b0 g0 r0
+__m128i t = _mm_unpacklo_epi16(mul_lo, mul_hi);
+accum0 = _mm_add_epi32(accum0, t);
+// [32] a1 b1 g1 r1
+t = _mm_unpackhi_epi16(mul_lo, mul_hi);
+accum1 = _mm_add_epi32(accum1, t);
+// [16] a3 b3 g3 r3 a2 b2 g2 r2
+src16 = _mm_unpackhi_epi8(src8, zero);
+mul_hi = _mm_mulhi_epi16(src16, coeff16);
+mul_lo = _mm_mullo_epi16(src16, coeff16);
+// [32] a2 b2 g2 r2
+t = _mm_unpacklo_epi16(mul_lo, mul_hi);
+accum2 = _mm_add_epi32(accum2, t);
+}
+accum0 = _mm_srai_epi32(accum0, ConvolutionFilter1D::kShiftBits);
+accum1 = _mm_srai_epi32(accum1, ConvolutionFilter1D::kShiftBits);
+accum2 = _mm_srai_epi32(accum2, ConvolutionFilter1D::kShiftBits);
+// [16] a1 b1 g1 r1 a0 b0 g0 r0
+accum0 = _mm_packs_epi32(accum0, accum1);
+// [16] a3 b3 g3 r3 a2 b2 g2 r2
+accum2 = _mm_packs_epi32(accum2, zero);
+// [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
+accum0 = _mm_packus_epi16(accum0, accum2);
+if (has_alpha) {
+// [8] xx a3 b3 g3 xx a2 b2 g2 xx a1 b1 g1 xx a0 b0 g0
+__m128i a = _mm_srli_epi32(accum0, 8);
+// [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
+__m128i b = _mm_max_epu8(a, accum0);  // Max of r and g.
+// [8] xx xx a3 b3 xx xx a2 b2 xx xx a1 b1 xx xx a0 b0
+a = _mm_srli_epi32(accum0, 16);
+// [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
+b = _mm_max_epu8(a, b);  // Max of r and g and b.
+// [8] max3 00 00 00 max2 00 00 00 max1 00 00 00 max0 00 00 00
+b = _mm_slli_epi32(b, 24);
+accum0 = _mm_max_epu8(b, accum0);
+} else {
+__m128i mask = _mm_set1_epi32(0xff000000);
+accum0 = _mm_or_si128(accum0, mask);
+}
+for (int out_x = width; out_x < pixel_width; out_x++) {
+*(reinterpret_cast<int*>(out_row)) = _mm_cvtsi128_si32(accum0);
+accum0 = _mm_srli_si128(accum0, 4);
+out_row += 4;
+}
+}
+#endif
+}
+}  // namespace
+// ConvolutionFilter1D ---------------------------------------------------------
+ConvolutionFilter1D::ConvolutionFilter1D()
+: max_filter_(0) {
+}
+ConvolutionFilter1D::~ConvolutionFilter1D() {
+}
+void ConvolutionFilter1D::AddFilter(int filter_offset,
+const float* filter_values,
+int filter_length) {
+SkASSERT(filter_length > 0);
+std::vector<Fixed> fixed_values;
+fixed_values.reserve(filter_length);
+for (int i = 0; i < filter_length; ++i)
+fixed_values.push_back(FloatToFixed(filter_values[i]));
+AddFilter(filter_offset, &fixed_values[0], filter_length);
+}
+void ConvolutionFilter1D::AddFilter(int filter_offset,
+const Fixed* filter_values,
+int filter_length) {
+// It is common for leading/trailing filter values to be zeros. In such
+// cases it is beneficial to only store the central factors.
+// For a scaling to 1/4th in each dimension using a Lanczos-2 filter on
+// a 1080p image this optimization gives a ~10% speed improvement.
+int first_non_zero = 0;
+while (first_non_zero < filter_length && filter_values[first_non_zero] == 0)
+first_non_zero++;
+if (first_non_zero < filter_length) {
+// Here we have at least one non-zero factor.
+int last_non_zero = filter_length - 1;
+while (last_non_zero >= 0 && filter_values[last_non_zero] == 0)
+last_non_zero--;
+filter_offset += first_non_zero;
+filter_length = last_non_zero + 1 - first_non_zero;
+SkASSERT(filter_length > 0);
+for (int i = first_non_zero; i <= last_non_zero; i++)
+filter_values_.push_back(filter_values[i]);
+} else {
+// Here all the factors were zeroes.
+filter_length = 0;
+}
+FilterInstance instance;
+// We pushed filter_length elements onto filter_values_
+instance.data_location = (static_cast<int>(filter_values_.size()) -
+filter_length);
+instance.offset = filter_offset;
+instance.length = filter_length;
+filters_.push_back(instance);
+max_filter_ = std::max(max_filter_, filter_length);
+}
+void BGRAConvolve2D(const unsigned char* source_data,
+int source_byte_row_stride,
+bool source_has_alpha,
+const ConvolutionFilter1D& filter_x,
+const ConvolutionFilter1D& filter_y,
+int output_byte_row_stride,
+unsigned char* output,
+bool use_sse2) {
+#if !defined(SIMD_SSE2)
+// Even we have runtime support for SSE2 instructions, since the binary
+// was not built with SSE2 support, we had to fallback to C version.
+use_sse2 = false;
+#endif
+int max_y_filter_size = filter_y.max_filter();
+// The next row in the input that we will generate a horizontally
+// convolved row for. If the filter doesn't start at the beginning of the
+// image (this is the case when we are only resizing a subset), then we
+// don't want to generate any output rows before that. Compute the starting
+// row for convolution as the first pixel for the first vertical filter.
+int filter_offset, filter_length;
+const ConvolutionFilter1D::Fixed* filter_values =
+filter_y.FilterForValue(0, &filter_offset, &filter_length);
+int next_x_row = filter_offset;
+// We loop over each row in the input doing a horizontal convolution. This
+// will result in a horizontally convolved image. We write the results into
+// a circular buffer of convolved rows and do vertical convolution as rows
+// are available. This prevents us from having to store the entire
+// intermediate image and helps cache coherency.
+// We will need four extra rows to allow horizontal convolution could be done
+// simultaneously. We also padding each row in row buffer to be aligned-up to
+// 16 bytes.
+// TODO(jiesun): We do not use aligned load from row buffer in vertical
+// convolution pass yet. Somehow Windows does not like it.
+int row_buffer_width = (filter_x.num_values() + 15) & ~0xF;
+int row_buffer_height = max_y_filter_size + (use_sse2 ? 4 : 0);
+CircularRowBuffer row_buffer(row_buffer_width,
+row_buffer_height,
+filter_offset);
+// Loop over every possible output row, processing just enough horizontal
+// convolutions to run each subsequent vertical convolution.
+SkASSERT(output_byte_row_stride >= filter_x.num_values() * 4);
+int num_output_rows = filter_y.num_values();
+// We need to check which is the last line to convolve before we advance 4
+// lines in one iteration.
+int last_filter_offset, last_filter_length;
+filter_y.FilterForValue(num_output_rows - 1, &last_filter_offset,
+&last_filter_length);
+for (int out_y = 0; out_y < num_output_rows; out_y++) {
+filter_values = filter_y.FilterForValue(out_y,
+&filter_offset, &filter_length);
+// Generate output rows until we have enough to run the current filter.
+if (use_sse2) {
+while (next_x_row < filter_offset + filter_length) {
+if (next_x_row + 3 < last_filter_offset + last_filter_length - 1) {
+const unsigned char* src[4];
+unsigned char* out_row[4];
+for (int i = 0; i < 4; ++i) {
+src[i] = &source_data[(next_x_row + i) * source_byte_row_stride];
+out_row[i] = row_buffer.AdvanceRow();
+}
+ConvolveHorizontally4_SSE2(src, filter_x, out_row);
+next_x_row += 4;
+} else {
+// For the last row, SSE2 load possibly to access data beyond the
+// image area. therefore we use C version here.
+if (next_x_row == last_filter_offset + last_filter_length - 1) {
+if (source_has_alpha) {
+ConvolveHorizontally<true>(
+&source_data[next_x_row * source_byte_row_stride],
+filter_x, row_buffer.AdvanceRow());
+} else {
+ConvolveHorizontally<false>(
+&source_data[next_x_row * source_byte_row_stride],
+filter_x, row_buffer.AdvanceRow());
+}
+} else {
+ConvolveHorizontally_SSE2(
+&source_data[next_x_row * source_byte_row_stride],
+filter_x, row_buffer.AdvanceRow());
+}
+next_x_row++;
+}
+}
+} else {
+while (next_x_row < filter_offset + filter_length) {
+if (source_has_alpha) {
+ConvolveHorizontally<true>(
+&source_data[next_x_row * source_byte_row_stride],
+filter_x, row_buffer.AdvanceRow());
+} else {
+ConvolveHorizontally<false>(
+&source_data[next_x_row * source_byte_row_stride],
+filter_x, row_buffer.AdvanceRow());
+}
+next_x_row++;
+}
+}
+// Compute where in the output image this row of final data will go.
+unsigned char* cur_output_row = &output[out_y * output_byte_row_stride];
+// Get the list of rows that the circular buffer has, in order.
+int first_row_in_circular_buffer;
+unsigned char* const* rows_to_convolve =
+row_buffer.GetRowAddresses(&first_row_in_circular_buffer);
+// Now compute the start of the subset of those rows that the filter
+// needs.
+unsigned char* const* first_row_for_filter =
+&rows_to_convolve[filter_offset - first_row_in_circular_buffer];
+if (source_has_alpha) {
+if (use_sse2) {
+ConvolveVertically_SSE2<true>(filter_values, filter_length,
+first_row_for_filter,
+filter_x.num_values(), cur_output_row);
+} else {
+ConvolveVertically<true>(filter_values, filter_length,
+first_row_for_filter,
+filter_x.num_values(), cur_output_row);
+}
+} else {
+if (use_sse2) {
+ConvolveVertically_SSE2<false>(filter_values, filter_length,
+first_row_for_filter,
+filter_x.num_values(), cur_output_row);
+} else {
+ConvolveVertically<false>(filter_values, filter_length,
+first_row_for_filter,
+filter_x.num_values(), cur_output_row);
+}
+}
+}
+}
+}  // namespace skia

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comparison: gfx/2d/convolver.cpp

gfx/2d/convolver.cpp