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/* This file is based on VFGS, available on

 * https://github.com/InterDigitalInc/VersatileFilmGrain

 *

 * VFGS implements film grain synthesis as a hardware model: it simulates the

 * output of a cost-effective hardware implementation in a video display

 * pipeline. Also, the C code is split into "fw" (firmware) and "hw" (hardware)

 * parts, and as self-explanatory as possible. See VFGS github repository for

 * more details.

 *

 * The VFGS github repository also contains other tools to experiment with film

 * grain synthesis (e.g. a graphical display and tuning tool for FGC SEI

 * message).

 */

#pragma once

#include <cstdint>

#define VFGS_MAX_PATTERNS 8

#define PATTERN_INTERPOLATION 0

namespace vvdec

{

/** Pseudo-random number generator (32-bit)

 * Note: loops on the 31 MSBs, so seed should be MSB-aligned in the register

 * (the register LSB has basically no effect since it is never fed back)

 */

static inline uint32_t prng( uint32_t x )

{

#if 1   // same as HW (bit-reversed RDD-5)

  uint32_t s = ( ( x << 30 ) ^ ( x << 2 ) ) & 0x80000000;

  x          = s | ( x >> 1 );

#else   // RDD-5

  uint32_t s = ( ( x >> 30 ) ^ ( x >> 2 ) ) & 1;

  x          = ( x << 1 ) | s;

#endif

  return x;

}

Unexecuted instantiation: vvdecimpl.cpp:vvdec::prng(unsigned int)

Unexecuted instantiation: FilmGrain.cpp:vvdec::prng(unsigned int)

Unexecuted instantiation: FilmGrainImpl.cpp:vvdec::prng(unsigned int)

Unexecuted instantiation: FilmGrainImpl_sse41.cpp:vvdec::prng(unsigned int)

Unexecuted instantiation: FilmGrainImpl_avx2.cpp:vvdec::prng(unsigned int)

template<class T>

constexpr inline auto round( T a, uint8_t s )

{

  return ( a + ( 1 << ( s - 1 ) ) ) >> s;

}

Unexecuted instantiation: auto vvdec::round<int>(int, unsigned char)

Unexecuted instantiation: auto vvdec::round<signed char>(signed char, unsigned char)

class FilmGrainImpl

{

protected:

  // Note: declarations optimized for code readability; e.g. pattern storage in

  //       actual hardware implementation would differ significantly

  int8_t  pattern[2][VFGS_MAX_PATTERNS + 1][64][64];   // +1 to simplify interpolation code

  uint8_t sLUT[3][256];

  uint8_t pLUT[3][256];

  uint8_t scale_shift = 5 + 6;

  uint8_t bs          = 0;   // bitshift = bitdepth - 8

  int     csubx       = 2;

  int     csuby       = 2;

  bool    allZero[3]  = { 0, 0, 0 };

  constexpr static uint8_t Y_min = 0;

  constexpr static uint8_t Y_max = 255;

  constexpr static uint8_t C_min = 0;

  constexpr static uint8_t C_max = 255;

  static void get_offset_y( uint32_t val, int* s, uint8_t* x, uint8_t* y );

         void get_offset_u( uint32_t val, int* s, uint8_t* x, uint8_t* y ) const;

         void get_offset_v( uint32_t val, int* s, uint8_t* x, uint8_t* y ) const;

public:

  FilmGrainImpl();

  virtual ~FilmGrainImpl() = default;

  void add_grain_block( void* I, int c, int x, int y, int width, uint32_t rnd, uint32_t rnd_up, int16_t grain[3][32], uint8_t scale[3][32] ) const;

  void set_luma_pattern( int index, int8_t* P );

  void set_chroma_pattern( int index, int8_t* P );

  void set_scale_lut( int c, uint8_t lut[] );

  void set_pattern_lut( int c, uint8_t lut[], bool all0 );

  void set_scale_shift( int shift );

  void set_depth( int depth );

  void set_chroma_subsampling( int subx, int suby );

private:

  virtual void make_grain_pattern( const void* I,

                                   int         c,

                                   int         x,

                                   int         subx,

                                   uint8_t     oc1,

                                   uint8_t     oc2,

                                   uint8_t     ox,

                                   uint8_t     ox_up,

                                   uint8_t     oy,

                                   uint8_t     oy_up,

                                   int         s,

                                   int         s_up,

                                   int16_t     grain[3][32],

                                   uint8_t     scale[3][32] ) const;

  virtual void scale_and_output( void*   I,   //

                                 int     c,

                                 int     x,

                                 int     subx,

                                 int     width,

                                 int16_t grain[3][32],

                                 uint8_t scale[3][32] ) const;

};

}   // namespace vvdec