// Copyright 2017 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// NEON variant of alpha filters
//
// Author: Skal (pascal.massimino@gmail.com)
#include "src/dsp/dsp.h"
#if defined(WEBP_USE_NEON)
#include <assert.h>
#include "src/dsp/neon.h"
//------------------------------------------------------------------------------
// Helpful macros.
# define SANITY_CHECK(in, out) \
assert(in != NULL); \
assert(out != NULL); \
assert(width > 0); \
assert(height > 0); \
assert(stride >= width); \
assert(row >= 0 && num_rows > 0 && row + num_rows <= height); \
(void)height; // Silence unused warning.
// load eight u8 and widen to s16
#define U8_TO_S16(A) vreinterpretq_s16_u16(vmovl_u8(A))
#define LOAD_U8_TO_S16(A) U8_TO_S16(vld1_u8(A))
// shift left or right by N byte, inserting zeros
#define SHIFT_RIGHT_N_Q(A, N) vextq_u8((A), zero, (N))
#define SHIFT_LEFT_N_Q(A, N) vextq_u8(zero, (A), (16 - (N)) % 16)
// rotate left by N bytes
#define ROTATE_LEFT_N(A, N) vext_u8((A), (A), (N))
// rotate right by N bytes
#define ROTATE_RIGHT_N(A, N) vext_u8((A), (A), (8 - (N)) % 8)
static void PredictLine_NEON(const uint8_t* src, const uint8_t* pred,
uint8_t* dst, int length) {
int i;
assert(length >= 0);
for (i = 0; i + 16 <= length; i += 16) {
const uint8x16_t A = vld1q_u8(&src[i]);
const uint8x16_t B = vld1q_u8(&pred[i]);
const uint8x16_t C = vsubq_u8(A, B);
vst1q_u8(&dst[i], C);
}
for (; i < length; ++i) dst[i] = src[i] - pred[i];
}
// Special case for left-based prediction (when preds==dst-1 or preds==src-1).
static void PredictLineLeft_NEON(const uint8_t* src, uint8_t* dst, int length) {
PredictLine_NEON(src, src - 1, dst, length);
}
//------------------------------------------------------------------------------
// Horizontal filter.
static WEBP_INLINE void DoHorizontalFilter_NEON(const uint8_t* in,
int width, int height,
int stride,
int row, int num_rows,
uint8_t* out) {
const size_t start_offset = row * stride;
const int last_row = row + num_rows;
SANITY_CHECK(in, out);
in += start_offset;
out += start_offset;
if (row == 0) {
// Leftmost pixel is the same as input for topmost scanline.
out[0] = in[0];
PredictLineLeft_NEON(in + 1, out + 1, width - 1);
row = 1;
in += stride;
out += stride;
}
// Filter line-by-line.
while (row < last_row) {
// Leftmost pixel is predicted from above.
out[0] = in[0] - in[-stride];
PredictLineLeft_NEON(in + 1, out + 1, width - 1);
++row;
in += stride;
out += stride;
}
}
static void HorizontalFilter_NEON(const uint8_t* data, int width, int height,
int stride, uint8_t* filtered_data) {
DoHorizontalFilter_NEON(data, width, height, stride, 0, height,
filtered_data);
}
//------------------------------------------------------------------------------
// Vertical filter.
static WEBP_INLINE void DoVerticalFilter_NEON(const uint8_t* in,
int width, int height, int stride,
int row, int num_rows,
uint8_t* out) {
const size_t start_offset = row * stride;
const int last_row = row + num_rows;
SANITY_CHECK(in, out);
in += start_offset;
out += start_offset;
if (row == 0) {
// Very first top-left pixel is copied.
out[0] = in[0];
// Rest of top scan-line is left-predicted.
PredictLineLeft_NEON(in + 1, out + 1, width - 1);
row = 1;
in += stride;
out += stride;
}
// Filter line-by-line.
while (row < last_row) {
PredictLine_NEON(in, in - stride, out, width);
++row;
in += stride;
out += stride;
}
}
static void VerticalFilter_NEON(const uint8_t* data, int width, int height,
int stride, uint8_t* filtered_data) {
DoVerticalFilter_NEON(data, width, height, stride, 0, height,
filtered_data);
}
//------------------------------------------------------------------------------
// Gradient filter.
static WEBP_INLINE int GradientPredictor_C(uint8_t a, uint8_t b, uint8_t c) {
const int g = a + b - c;
return ((g & ~0xff) == 0) ? g : (g < 0) ? 0 : 255; // clip to 8bit
}
static void GradientPredictDirect_NEON(const uint8_t* const row,
const uint8_t* const top,
uint8_t* const out, int length) {
int i;
for (i = 0; i + 8 <= length; i += 8) {
const uint8x8_t A = vld1_u8(&row[i - 1]);
const uint8x8_t B = vld1_u8(&top[i + 0]);
const int16x8_t C = vreinterpretq_s16_u16(vaddl_u8(A, B));
const int16x8_t D = LOAD_U8_TO_S16(&top[i - 1]);
const uint8x8_t E = vqmovun_s16(vsubq_s16(C, D));
const uint8x8_t F = vld1_u8(&row[i + 0]);
vst1_u8(&out[i], vsub_u8(F, E));
}
for (; i < length; ++i) {
out[i] = row[i] - GradientPredictor_C(row[i - 1], top[i], top[i - 1]);
}
}
static WEBP_INLINE void DoGradientFilter_NEON(const uint8_t* in,
int width, int height,
int stride,
int row, int num_rows,
uint8_t* out) {
const size_t start_offset = row * stride;
const int last_row = row + num_rows;
SANITY_CHECK(in, out);
in += start_offset;
out += start_offset;
// left prediction for top scan-line
if (row == 0) {
out[0] = in[0];
PredictLineLeft_NEON(in + 1, out + 1, width - 1);
row = 1;
in += stride;
out += stride;
}
// Filter line-by-line.
while (row < last_row) {
out[0] = in[0] - in[-stride];
GradientPredictDirect_NEON(in + 1, in + 1 - stride, out + 1, width - 1);
++row;
in += stride;
out += stride;
}
}
static void GradientFilter_NEON(const uint8_t* data, int width, int height,
int stride, uint8_t* filtered_data) {
DoGradientFilter_NEON(data, width, height, stride, 0, height,
filtered_data);
}
#undef SANITY_CHECK
//------------------------------------------------------------------------------
// Inverse transforms
static void HorizontalUnfilter_NEON(const uint8_t* prev, const uint8_t* in,
uint8_t* out, int width) {
int i;
const uint8x16_t zero = vdupq_n_u8(0);
uint8x16_t last;
out[0] = in[0] + (prev == NULL ? 0 : prev[0]);
if (width <= 1) return;
last = vsetq_lane_u8(out[0], zero, 0);
for (i = 1; i + 16 <= width; i += 16) {
const uint8x16_t A0 = vld1q_u8(&in[i]);
const uint8x16_t A1 = vaddq_u8(A0, last);
const uint8x16_t A2 = SHIFT_LEFT_N_Q(A1, 1);
const uint8x16_t A3 = vaddq_u8(A1, A2);
const uint8x16_t A4 = SHIFT_LEFT_N_Q(A3, 2);
const uint8x16_t A5 = vaddq_u8(A3, A4);
const uint8x16_t A6 = SHIFT_LEFT_N_Q(A5, 4);
const uint8x16_t A7 = vaddq_u8(A5, A6);
const uint8x16_t A8 = SHIFT_LEFT_N_Q(A7, 8);
const uint8x16_t A9 = vaddq_u8(A7, A8);
vst1q_u8(&out[i], A9);
last = SHIFT_RIGHT_N_Q(A9, 15);
}
for (; i < width; ++i) out[i] = in[i] + out[i - 1];
}
static void VerticalUnfilter_NEON(const uint8_t* prev, const uint8_t* in,
uint8_t* out, int width) {
if (prev == NULL) {
HorizontalUnfilter_NEON(NULL, in, out, width);
} else {
int i;
assert(width >= 0);
for (i = 0; i + 16 <= width; i += 16) {
const uint8x16_t A = vld1q_u8(&in[i]);
const uint8x16_t B = vld1q_u8(&prev[i]);
const uint8x16_t C = vaddq_u8(A, B);
vst1q_u8(&out[i], C);
}
for (; i < width; ++i) out[i] = in[i] + prev[i];
}
}
// GradientUnfilter_NEON is correct but slower than the C-version,
// at least on ARM64. For armv7, it's a wash.
// So best is to disable it for now, but keep the idea around...
#if !defined(USE_GRADIENT_UNFILTER)
#define USE_GRADIENT_UNFILTER 0 // ALTERNATE_CODE
#endif
#if (USE_GRADIENT_UNFILTER == 1)
#define GRAD_PROCESS_LANE(L) do { \
const uint8x8_t tmp1 = ROTATE_RIGHT_N(pred, 1); /* rotate predictor in */ \
const int16x8_t tmp2 = vaddq_s16(BC, U8_TO_S16(tmp1)); \
const uint8x8_t delta = vqmovun_s16(tmp2); \
pred = vadd_u8(D, delta); \
out = vext_u8(out, ROTATE_LEFT_N(pred, (L)), 1); \
} while (0)
static void GradientPredictInverse_NEON(const uint8_t* const in,
const uint8_t* const top,
uint8_t* const row, int length) {
if (length > 0) {
int i;
uint8x8_t pred = vdup_n_u8(row[-1]); // left sample
uint8x8_t out = vdup_n_u8(0);
for (i = 0; i + 8 <= length; i += 8) {
const int16x8_t B = LOAD_U8_TO_S16(&top[i + 0]);
const int16x8_t C = LOAD_U8_TO_S16(&top[i - 1]);
const int16x8_t BC = vsubq_s16(B, C); // unclipped gradient basis B - C
const uint8x8_t D = vld1_u8(&in[i]); // base input
GRAD_PROCESS_LANE(0);
GRAD_PROCESS_LANE(1);
GRAD_PROCESS_LANE(2);
GRAD_PROCESS_LANE(3);
GRAD_PROCESS_LANE(4);
GRAD_PROCESS_LANE(5);
GRAD_PROCESS_LANE(6);
GRAD_PROCESS_LANE(7);
vst1_u8(&row[i], out);
}
for (; i < length; ++i) {
row[i] = in[i] + GradientPredictor_C(row[i - 1], top[i], top[i - 1]);
}
}
}
#undef GRAD_PROCESS_LANE
static void GradientUnfilter_NEON(const uint8_t* prev, const uint8_t* in,
uint8_t* out, int width) {
if (prev == NULL) {
HorizontalUnfilter_NEON(NULL, in, out, width);
} else {
out[0] = in[0] + prev[0]; // predict from above
GradientPredictInverse_NEON(in + 1, prev + 1, out + 1, width - 1);
}
}
#endif // USE_GRADIENT_UNFILTER
//------------------------------------------------------------------------------
// Entry point
extern void VP8FiltersInitNEON(void);
WEBP_TSAN_IGNORE_FUNCTION void VP8FiltersInitNEON(void) {
WebPUnfilters[WEBP_FILTER_HORIZONTAL] = HorizontalUnfilter_NEON;
WebPUnfilters[WEBP_FILTER_VERTICAL] = VerticalUnfilter_NEON;
#if (USE_GRADIENT_UNFILTER == 1)
WebPUnfilters[WEBP_FILTER_GRADIENT] = GradientUnfilter_NEON;
#endif
WebPFilters[WEBP_FILTER_HORIZONTAL] = HorizontalFilter_NEON;
WebPFilters[WEBP_FILTER_VERTICAL] = VerticalFilter_NEON;
WebPFilters[WEBP_FILTER_GRADIENT] = GradientFilter_NEON;
}
#else // !WEBP_USE_NEON
WEBP_DSP_INIT_STUB(VP8FiltersInitNEON)
#endif // WEBP_USE_NEON