// 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.
// -----------------------------------------------------------------------------
//
// WebAssembly (WASM) version of some decoding functions.
//
// Based on dec_sse2.c

#include "./dsp.h"
#include "../dec/vp8i_dec.h"

#if defined(WEBP_USE_WASM)

typedef int32_t int32x4 __attribute__((__vector_size__(16)));
typedef uint32_t uint32x4 __attribute__((__vector_size__(16)));
typedef int16_t int16x8 __attribute__((__vector_size__(16)));
typedef uint16_t uint16x8 __attribute__((__vector_size__(16)));
typedef int8_t  int8x16 __attribute__((__vector_size__(16)));
typedef uint8_t  uint8x16 __attribute__((__vector_size__(16)));

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

static WEBP_INLINE uint8x16 get_16_bytes(uint8_t* dst) {
  uint8x16 a;
  memcpy(&a, dst, 16);
  return a;
}

static WEBP_INLINE uint8x16 splat_uint8(uint32_t val) {
  uint8x16 a;
  a[0] = val;
  a = (uint8x16)__builtin_shufflevector(
      a, a, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
  return a;
}

//------------------------------------------------------------------------------
// Luma 16x16

static WEBP_INLINE void Put16(uint8_t v, uint8_t* dst) {
  int j;
  const uint8x16 values = splat_uint8(v);
  for (j = 0; j < 16; ++j) {
    memcpy(dst, &values, 16);
    dst += BPS;
  }
}

static void VE16(uint8_t* dst) {
  const uint8x16 top = get_16_bytes(dst - BPS);
  int j;
  for (j = 0; j < 16; ++j) {
    memcpy(dst + j * BPS, &top, 16);
  }
}

static void HE16(uint8_t* dst) {     // horizontal
  int j;
  for (j = 16; j > 0; --j) {
    const uint8x16 values = splat_uint8(dst[-1]);
    memcpy(dst, &values, 16);
    dst += BPS;
  }
}

static WEBP_INLINE uint32_t add_horizontal_16(uint8_t* dst) {
  const uint8x16 zero = (uint8x16){0};
  const uint8x16 a = get_16_bytes(dst);
  const uint16x8 _a_lbw = (uint16x8)__builtin_shufflevector(
      a, zero, 0, 16, 1, 16, 2, 16, 3, 16, 4, 16, 5, 16, 6, 16, 7, 16);
  const uint16x8 _a_hbw = (uint16x8)__builtin_shufflevector(
      a, zero, 8, 16, 9, 16, 10, 16, 11, 16, 12, 16, 13, 16, 14, 16, 15, 16);
  const uint16x8 sum_a = _a_lbw + _a_hbw;
  const uint16x8 sum_b = (uint16x8)__builtin_shufflevector(
      sum_a, sum_a, 4, 5, 6, 7, 4, 5, 6, 7);
  const uint16x8 sum_c = sum_a + sum_b;
  const uint16x8 sum_d = (uint16x8)__builtin_shufflevector(
      sum_c, sum_c, 2, 3, 2, 3, 2, 3, 2, 3);
  const uint16x8 sum_e = sum_c + sum_d;
  const uint16x8 sum_f = (uint16x8)__builtin_shufflevector(
      sum_e, sum_e, 1, 1, 1, 1, 1, 1, 1, 1);
  const uint16x8 sum_g = sum_e + sum_f;
  return sum_g[0] & 0xffff;
}

static void DC16(uint8_t* dst) {    // DC
  const uint32_t sum = add_horizontal_16(dst - BPS);
  int left = 0;
  int j;
  for (j = 0; j < 16; ++j) {
    left += dst[-1 + j * BPS];
  }
  {
    const int DC = sum + left + 16;
    Put16(DC >> 5, dst);
  }
}

static void DC16NoTop(uint8_t* dst) {   // DC with top samples not available
  int DC = 8;
  int j;
  for (j = 0; j < 16; ++j) {
    DC += dst[-1 + j * BPS];
  }
  Put16(DC >> 4, dst);
}

static void DC16NoLeft(uint8_t* dst) {  // DC with left samples not available
  const int DC = 8 + add_horizontal_16(dst - BPS);
  Put16(DC >> 4, dst);
}

static void DC16NoTopLeft(uint8_t* dst) {  // DC with no top and left samples
  Put16(0x80, dst);
}

//------------------------------------------------------------------------------
// Entry point

extern void VP8DspInitWASM(void);

WEBP_TSAN_IGNORE_FUNCTION void VP8DspInitWASM(void) {
  VP8PredLuma16[0] = DC16;
  VP8PredLuma16[2] = VE16;
  VP8PredLuma16[3] = HE16;
  VP8PredLuma16[4] = DC16NoTop;
  VP8PredLuma16[5] = DC16NoLeft;
  VP8PredLuma16[6] = DC16NoTopLeft;
}

#else  // !WEBP_USE_WASM

WEBP_DSP_INIT_STUB(VP8DspInitWASM)

#endif  // WEBP_USE_WASM