// Copyright 2009 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include "Common/ColorUtil.h"
#include "Common/Swap.h"

namespace Common
{
static const int s_lut5to8[] = {0x00, 0x08, 0x10, 0x18, 0x20, 0x29, 0x31, 0x39, 0x41, 0x4A, 0x52,
                                0x5A, 0x62, 0x6A, 0x73, 0x7B, 0x83, 0x8B, 0x94, 0x9C, 0xA4, 0xAC,
                                0xB4, 0xBD, 0xC5, 0xCD, 0xD5, 0xDE, 0xE6, 0xEE, 0xF6, 0xFF};

static const int s_lut4to8[] = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
                                0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF};

static const int s_lut3to8[] = {0x00, 0x24, 0x48, 0x6D, 0x91, 0xB6, 0xDA, 0xFF};

static u32 Decode5A3(u16 val)
{
  const u32 bg_color = 0x00000000;

  int r, g, b, a;

  if (val & 0x8000)
  {
    r = s_lut5to8[(val >> 10) & 0x1f];
    g = s_lut5to8[(val >> 5) & 0x1f];
    b = s_lut5to8[(val)&0x1f];
    a = 0xFF;
  }
  else
  {
    a = s_lut3to8[(val >> 12) & 0x7];
    r = (s_lut4to8[(val >> 8) & 0xf] * a + (bg_color & 0xFF) * (255 - a)) / 255;
    g = (s_lut4to8[(val >> 4) & 0xf] * a + ((bg_color >> 8) & 0xFF) * (255 - a)) / 255;
    b = (s_lut4to8[(val)&0xf] * a + ((bg_color >> 16) & 0xFF) * (255 - a)) / 255;
    a = 0xFF;
  }
  return (a << 24) | (r << 16) | (g << 8) | b;
}

void Decode5A3Image(u32* dst, const u16* src, int width, int height)
{
  for (int y = 0; y < height; y += 4)
  {
    for (int x = 0; x < width; x += 4)
    {
      for (int iy = 0; iy < 4; iy++, src += 4)
      {
        for (int ix = 0; ix < 4; ix++)
        {
          u32 RGBA = Decode5A3(Common::swap16(src[ix]));
          dst[(y + iy) * width + (x + ix)] = RGBA;
        }
      }
    }
  }
}

void DecodeCI8Image(u32* dst, const u8* src, const u16* pal, int width, int height)
{
  for (int y = 0; y < height; y += 4)
  {
    for (int x = 0; x < width; x += 8)
    {
      for (int iy = 0; iy < 4; iy++, src += 8)
      {
        u32* tdst = dst + (y + iy) * width + x;
        for (int ix = 0; ix < 8; ix++)
        {
          // huh, this seems wrong. CI8, not 5A3, no?
          tdst[ix] = Decode5A3(Common::swap16(pal[src[ix]]));
        }
      }
    }
  }
}
}  // namespace Common
