static WEBP_INLINE void DoHorizontalFilter(const uint8_t* in,
int width, int height, int stride,
int row, int num_rows,
int inverse, uint8_t* out) {
const uint8_t* preds;
const size_t start_offset = row * stride;
const int last_row = row + num_rows;
SANITY_CHECK(in, out);
in += start_offset;
out += start_offset;
preds = inverse ? out : in;
if (row == 0) {
// Leftmost pixel is the same as input for topmost scanline.
out[0] = in[0];
PredictLine(in + 1, preds, out + 1, width - 1, inverse);
row = 1;
preds += stride;
in += stride;
out += stride;
}
// Filter line-by-line.
while (row < last_row) {
// Leftmost pixel is predicted from above.
PredictLine(in, preds - stride, out, 1, inverse);
PredictLine(in + 1, preds, out + 1, width - 1, inverse);
++row;
preds += stride;
in += stride;
out += stride;
}
}
static WEBP_INLINE void DoVerticalFilter(const uint8_t* in,
int width, int height, int stride,
int row, int num_rows,
int inverse, uint8_t* out) {
const uint8_t* preds;
const size_t start_offset = row * stride;
const int last_row = row + num_rows;
SANITY_CHECK(in, out);
in += start_offset;
out += start_offset;
preds = inverse ? out : in;
if (row == 0) {
// Very first top-left pixel is copied.
out[0] = in[0];
// Rest of top scan-line is left-predicted.
PredictLine(in + 1, preds, out + 1, width - 1, inverse);
row = 1;
in += stride;
out += stride;
} else {
// We are starting from in-between. Make sure 'preds' points to prev row.
preds -= stride;
}
// Filter line-by-line.
while (row < last_row) {
PredictLine(in, preds, out, width, inverse);
++row;
preds += stride;
in += stride;
out += stride;
}
}
static WEBP_INLINE
void DoGradientFilter(const uint8_t* in, int width, int height,
int stride, int inverse, uint8_t* out) {
const uint8_t* preds = (inverse ? out : in);
int h;
SANITY_CHECK(in, out);
// left prediction for top scan-line
out[0] = in[0];
PredictLine(in + 1, preds, out + 1, width - 1, inverse);
// Filter line-by-line.
for (h = 1; h < height; ++h) {
int w;
preds += stride;
in += stride;
out += stride;
// leftmost pixel: predict from above.
PredictLine(in, preds - stride, out, 1, inverse);
for (w = 1; w < width; ++w) {
const int pred = GradientPredictor(preds[w - 1],
preds[w - stride],
preds[w - stride - 1]);
out[w] = in[w] + (inverse ? pred : -pred);
}
}
}
static WEBP_INLINE void DoVerticalFilter(const uint8_t* in,
int width, int height, int stride,
int inverse, uint8_t* out) {
int h;
const uint8_t* preds = (inverse ? out : in);
SANITY_CHECK(in, out);
// Very first top-left pixel is copied.
out[0] = in[0];
// Rest of top scan-line is left-predicted.
PredictLine(in + 1, preds, out + 1, width - 1, inverse);
// Filter line-by-line.
for (h = 1; h < height; ++h) {
in += stride;
out += stride;
PredictLine(in, preds, out, width, inverse);
preds += stride;
}
}
static WEBP_INLINE void DoHorizontalFilter(const uint8_t* in,
int width, int height, int stride,
int inverse, uint8_t* out) {
int h;
const uint8_t* preds = (inverse ? out : in);
SANITY_CHECK(in, out);
// Filter line-by-line.
for (h = 0; h < height; ++h) {
// Leftmost pixel is predicted from above (except for topmost scanline).
if (h == 0) {
out[0] = in[0];
} else {
PredictLine(in, preds - stride, out, 1, inverse);
}
PredictLine(in + 1, preds, out + 1, width - 1, inverse);
preds += stride;
in += stride;
out += stride;
}
}
static WEBP_INLINE void DoGradientFilter(const uint8_t* in,
int width, int height, int stride,
int row, int num_rows,
int inverse, uint8_t* out) {
const uint8_t* preds;
const size_t start_offset = row * stride;
const int last_row = row + num_rows;
SANITY_CHECK(in, out);
in += start_offset;
out += start_offset;
preds = inverse ? out : in;
// left prediction for top scan-line
if (row == 0) {
out[0] = in[0];
PredictLine(in + 1, preds, out + 1, width - 1, inverse);
row = 1;
preds += stride;
in += stride;
out += stride;
}
// Filter line-by-line.
while (row < last_row) {
int w;
// leftmost pixel: predict from above.
PredictLine(in, preds - stride, out, 1, inverse);
for (w = 1; w < width; ++w) {
const int pred = GradientPredictor(preds[w - 1],
preds[w - stride],
preds[w - stride - 1]);
out[w] = in[w] + (inverse ? pred : -pred);
}
++row;
preds += stride;
in += stride;
out += stride;
}
}
