// Copyright 2015 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 methods for lossless encoder

//

// Author: Skal (pascal.massimino@gmail.com)

#include "src/dsp/dsp.h"

#if defined(WEBP_USE_NEON)

#include <arm_neon.h>

#include "src/dsp/lossless.h"

#include "src/dsp/neon.h"

//------------------------------------------------------------------------------

// Subtract-Green Transform

// vtbl?_u8 are marked unavailable for iOS arm64 with Xcode < 6.3, use

// non-standard versions there.

#if defined(__APPLE__) && defined(__aarch64__) && \

    defined(__apple_build_version__) && (__apple_build_version__< 6020037)

#define USE_VTBLQ

#endif

#ifdef USE_VTBLQ

// 255 = byte will be zeroed

static const uint8_t kGreenShuffle[16] = {

  1, 255, 1, 255, 5, 255, 5, 255, 9, 255, 9, 255, 13, 255, 13, 255

};

static WEBP_INLINE uint8x16_t DoGreenShuffle_NEON(const uint8x16_t argb,

                                                  const uint8x16_t shuffle) {

  return vcombine_u8(vtbl1q_u8(argb, vget_low_u8(shuffle)),

                     vtbl1q_u8(argb, vget_high_u8(shuffle)));

}

#else  // !USE_VTBLQ

// 255 = byte will be zeroed

static const uint8_t kGreenShuffle[8] = { 1, 255, 1, 255, 5, 255, 5, 255  };

static WEBP_INLINE uint8x16_t DoGreenShuffle_NEON(const uint8x16_t argb,

                                                  const uint8x8_t shuffle) {

  return vcombine_u8(vtbl1_u8(vget_low_u8(argb), shuffle),

                     vtbl1_u8(vget_high_u8(argb), shuffle));

}

#endif  // USE_VTBLQ

static void SubtractGreenFromBlueAndRed_NEON(uint32_t* argb_data,

                                             int num_pixels) {

  const uint32_t* const end = argb_data + (num_pixels & ~3);

#ifdef USE_VTBLQ

  const uint8x16_t shuffle = vld1q_u8(kGreenShuffle);

#else

  const uint8x8_t shuffle = vld1_u8(kGreenShuffle);

#endif

  for (; argb_data < end; argb_data += 4) {

    const uint8x16_t argb = vld1q_u8((uint8_t*)argb_data);

    const uint8x16_t greens = DoGreenShuffle_NEON(argb, shuffle);

    vst1q_u8((uint8_t*)argb_data, vsubq_u8(argb, greens));

  }

  // fallthrough and finish off with plain-C

  VP8LSubtractGreenFromBlueAndRed_C(argb_data, num_pixels & 3);

}

//------------------------------------------------------------------------------

// Color Transform

static void TransformColor_NEON(const VP8LMultipliers* const m,

                                uint32_t* argb_data, int num_pixels) {

  // sign-extended multiplying constants, pre-shifted by 6.

#define CST(X)  (((int16_t)(m->X << 8)) >> 6)

  const int16_t rb[8] = {

    CST(green_to_blue_), CST(green_to_red_),

    CST(green_to_blue_), CST(green_to_red_),

    CST(green_to_blue_), CST(green_to_red_),

    CST(green_to_blue_), CST(green_to_red_)

  };

  const int16x8_t mults_rb = vld1q_s16(rb);

  const int16_t b2[8] = {

    0, CST(red_to_blue_), 0, CST(red_to_blue_),

    0, CST(red_to_blue_), 0, CST(red_to_blue_),

  };

  const int16x8_t mults_b2 = vld1q_s16(b2);

#undef CST

#ifdef USE_VTBLQ

  static const uint8_t kg0g0[16] = {

    255, 1, 255, 1, 255, 5, 255, 5, 255, 9, 255, 9, 255, 13, 255, 13

  };

  const uint8x16_t shuffle = vld1q_u8(kg0g0);

#else

  static const uint8_t k0g0g[8] = { 255, 1, 255, 1, 255, 5, 255, 5 };

  const uint8x8_t shuffle = vld1_u8(k0g0g);

#endif

  const uint32x4_t mask_rb = vdupq_n_u32(0x00ff00ffu);  // red-blue masks

  int i;

  for (i = 0; i + 4 <= num_pixels; i += 4) {

    const uint8x16_t in = vld1q_u8((uint8_t*)(argb_data + i));

    // 0 g 0 g

    const uint8x16_t greens = DoGreenShuffle_NEON(in, shuffle);

    // x dr  x db1

    const int16x8_t A = vqdmulhq_s16(vreinterpretq_s16_u8(greens), mults_rb);

    // r 0   b   0

    const int16x8_t B = vshlq_n_s16(vreinterpretq_s16_u8(in), 8);

    // x db2 0   0

    const int16x8_t C = vqdmulhq_s16(B, mults_b2);

    // 0 0   x db2

    const uint32x4_t D = vshrq_n_u32(vreinterpretq_u32_s16(C), 16);

    // x dr  x  db

    const int8x16_t E = vaddq_s8(vreinterpretq_s8_u32(D),

                                 vreinterpretq_s8_s16(A));

    // 0 dr  0  db

    const uint32x4_t F = vandq_u32(vreinterpretq_u32_s8(E), mask_rb);

    const int8x16_t out = vsubq_s8(vreinterpretq_s8_u8(in),

                                   vreinterpretq_s8_u32(F));

    vst1q_s8((int8_t*)(argb_data + i), out);

  }

  // fallthrough and finish off with plain-C

  VP8LTransformColor_C(m, argb_data + i, num_pixels - i);

}

#undef USE_VTBLQ

//------------------------------------------------------------------------------

// Entry point

extern void VP8LEncDspInitNEON(void);

WEBP_TSAN_IGNORE_FUNCTION void VP8LEncDspInitNEON(void) {

  VP8LSubtractGreenFromBlueAndRed = SubtractGreenFromBlueAndRed_NEON;

  VP8LTransformColor = TransformColor_NEON;

}

#else  // !WEBP_USE_NEON

WEBP_DSP_INIT_STUB(VP8LEncDspInitNEON)

#endif  // WEBP_USE_NEON