add scalar stubs for neon functions to give arm guys a place to work
BUG=
R=djsollen@google.com, reed@google.com
Author: humper@google.com
Review URL: https://chromiumcodereview.appspot.com/20749003
git-svn-id: http://skia.googlecode.com/svn/trunk@10431 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/opts/SkBitmapProcState_opts_arm.cpp b/src/opts/SkBitmapProcState_opts_arm.cpp
index 997843d..2b0b6a2 100644
--- a/src/opts/SkBitmapProcState_opts_arm.cpp
+++ b/src/opts/SkBitmapProcState_opts_arm.cpp
@@ -11,6 +11,9 @@
#include "SkPaint.h"
#include "SkTypes.h"
#include "SkUtils.h"
+#include "SkUtilsArm.h"
+
+#include "SkConvolver.h"
#if SK_ARM_ARCH >= 6 && !defined(SK_CPU_BENDIAN)
void SI8_D16_nofilter_DX_arm(
@@ -219,6 +222,201 @@
}
}
+/////////////////////////////////////
+
+/* FUNCTIONS BELOW ARE SCALAR STUBS INTENDED FOR ARM DEVELOPERS TO REPLACE */
+
+/////////////////////////////////////
+
+
+static 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;
+}
+
+// Convolves horizontally along a single row. The row data is given in
+// |srcData| and continues for the numValues() of the filter.
+void convolveHorizontally_arm(const unsigned char* srcData,
+ const SkConvolutionFilter1D& filter,
+ unsigned char* outRow,
+ bool hasAlpha) {
+ // Loop over each pixel on this row in the output image.
+ int numValues = filter.numValues();
+ for (int outX = 0; outX < numValues; outX++) {
+ // Get the filter that determines the current output pixel.
+ int filterOffset, filterLength;
+ const SkConvolutionFilter1D::ConvolutionFixed* filterValues =
+ filter.FilterForValue(outX, &filterOffset, &filterLength);
+
+ // Compute the first pixel in this row that the filter affects. It will
+ // touch |filterLength| pixels (4 bytes each) after this.
+ const unsigned char* rowToFilter = &srcData[filterOffset * 4];
+
+ // Apply the filter to the row to get the destination pixel in |accum|.
+ int accum[4] = {0};
+ for (int filterX = 0; filterX < filterLength; filterX++) {
+ SkConvolutionFilter1D::ConvolutionFixed curFilter = filterValues[filterX];
+ accum[0] += curFilter * rowToFilter[filterX * 4 + 0];
+ accum[1] += curFilter * rowToFilter[filterX * 4 + 1];
+ accum[2] += curFilter * rowToFilter[filterX * 4 + 2];
+ if (hasAlpha) {
+ accum[3] += curFilter * rowToFilter[filterX * 4 + 3];
+ }
+ }
+
+ // Bring this value back in range. All of the filter scaling factors
+ // are in fixed point with kShiftBits bits of fractional part.
+ accum[0] >>= SkConvolutionFilter1D::kShiftBits;
+ accum[1] >>= SkConvolutionFilter1D::kShiftBits;
+ accum[2] >>= SkConvolutionFilter1D::kShiftBits;
+ if (hasAlpha) {
+ accum[3] >>= SkConvolutionFilter1D::kShiftBits;
+ }
+
+ // Store the new pixel.
+ outRow[outX * 4 + 0] = ClampTo8(accum[0]);
+ outRow[outX * 4 + 1] = ClampTo8(accum[1]);
+ outRow[outX * 4 + 2] = ClampTo8(accum[2]);
+ if (hasAlpha) {
+ outRow[outX * 4 + 3] = 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 |sourceDataRows| array, with each row
+// being |pixelWidth| wide.
+//
+// The output must have room for |pixelWidth * 4| bytes.
+template<bool hasAlpha>
+ void convolveVertically_arm(const SkConvolutionFilter1D::ConvolutionFixed* filterValues,
+ int filterLength,
+ unsigned char* const* sourceDataRows,
+ int pixelWidth,
+ unsigned char* outRow) {
+ // We go through each column in the output and do a vertical convolution,
+ // generating one output pixel each time.
+ for (int outX = 0; outX < pixelWidth; outX++) {
+ // 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 byteOffset = outX * 4;
+
+ // Apply the filter to one column of pixels.
+ int accum[4] = {0};
+ for (int filterY = 0; filterY < filterLength; filterY++) {
+ SkConvolutionFilter1D::ConvolutionFixed curFilter = filterValues[filterY];
+ accum[0] += curFilter * sourceDataRows[filterY][byteOffset + 0];
+ accum[1] += curFilter * sourceDataRows[filterY][byteOffset + 1];
+ accum[2] += curFilter * sourceDataRows[filterY][byteOffset + 2];
+ if (hasAlpha) {
+ accum[3] += curFilter * sourceDataRows[filterY][byteOffset + 3];
+ }
+ }
+
+ // Bring this value back in range. All of the filter scaling factors
+ // are in fixed point with kShiftBits bits of precision.
+ accum[0] >>= SkConvolutionFilter1D::kShiftBits;
+ accum[1] >>= SkConvolutionFilter1D::kShiftBits;
+ accum[2] >>= SkConvolutionFilter1D::kShiftBits;
+ if (hasAlpha) {
+ accum[3] >>= SkConvolutionFilter1D::kShiftBits;
+ }
+
+ // Store the new pixel.
+ outRow[byteOffset + 0] = ClampTo8(accum[0]);
+ outRow[byteOffset + 1] = ClampTo8(accum[1]);
+ outRow[byteOffset + 2] = ClampTo8(accum[2]);
+ if (hasAlpha) {
+ 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 maxColorChannel = SkTMax(outRow[byteOffset + 0],
+ SkTMax(outRow[byteOffset + 1],
+ outRow[byteOffset + 2]));
+ if (alpha < maxColorChannel) {
+ outRow[byteOffset + 3] = maxColorChannel;
+ } else {
+ outRow[byteOffset + 3] = alpha;
+ }
+ } else {
+ // No alpha channel, the image is opaque.
+ outRow[byteOffset + 3] = 0xff;
+ }
+ }
+ }
+
+void convolveVertically_arm(const SkConvolutionFilter1D::ConvolutionFixed* filterValues,
+ int filterLength,
+ unsigned char* const* sourceDataRows,
+ int pixelWidth,
+ unsigned char* outRow,
+ bool sourceHasAlpha) {
+ if (sourceHasAlpha) {
+ convolveVertically_arm<true>(filterValues, filterLength,
+ sourceDataRows, pixelWidth,
+ outRow);
+ } else {
+ convolveVertically_arm<false>(filterValues, filterLength,
+ sourceDataRows, pixelWidth,
+ outRow);
+ }
+}
+
+// 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 convolve4RowsHorizontally_arm(const unsigned char* src_data[4],
+ const SkConvolutionFilter1D& filter,
+ unsigned char* out_row[4]) {
+}
+
+///////////////////////////
+
+/* STOP REWRITING FUNCTIONS HERE, BUT DON'T FORGET TO EDIT THE
+ PLATFORM CONVOLUTION PROCS BELOW */
+
+///////////////////////////
+
+void applySIMDPadding_arm(SkConvolutionFilter1D *filter) {
+ // Padding |paddingCount| of more dummy coefficients after the coefficients
+ // of last filter to prevent SIMD instructions which load 8 or 16 bytes
+ // together to access invalid memory areas. We are not trying to align the
+ // coefficients right now due to the opaqueness of <vector> implementation.
+ // This has to be done after all |AddFilter| calls.
+ for (int i = 0; i < 8; ++i) {
+ filter->addFilterValue(static_cast<SkConvolutionFilter1D::ConvolutionFixed>(0));
+ }
+}
+
void SkBitmapProcState::platformConvolutionProcs() {
- // no specialization for ARM here yet.
+ if (sk_cpu_arm_has_neon()) {
+ fConvolutionProcs->fExtraHorizontalReads = 3;
+ fConvolutionProcs->fConvolveVertically = &convolveVertically_arm;
+
+ // next line is commented out because the four-row convolution function above is
+ // just a no-op. Please see the comment above its definition, and the SSE implementation
+ // in SkBitmapProcState_opts_SSE2.cpp for guidance on its semantics.
+ // leaving it as NULL will just cause the convolution system to not attempt
+ // to operate on four rows at once, which is correct but not performance-optimal.
+
+ // fConvolutionProcs->fConvolve4RowsHorizontally = &convolve4RowsHorizontally_arm;
+
+ fConvolutionProcs->fConvolve4RowsHorizontally = NULL;
+
+ fConvolutionProcs->fConvolveHorizontally = &convolveHorizontally_arm;
+ fConvolutionProcs->fApplySIMDPadding = &applySIMDPadding_arm;
+ }
}