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add scalar stubs for neon functions to give arm guys a place to work

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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
This commit is contained in:
commit-bot@chromium.org 2013-07-30 13:16:18 +00:00
parent 05256f6811
commit 5abacf6720
1 changed files with 200 additions and 2 deletions
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202
src/opts/SkBitmapProcState_opts_arm.cpp
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@ -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 @@ void SkBitmapProcState::platformProcs() {
}
}
void SkBitmapProcState::platformConvolutionProcs() {
// no specialization for ARM here yet.
/////////////////////////////////////
/* 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() {
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;
}
}