tinyjpeg.c

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  p = priv->plane[1];
  s = priv->Cb;
  for (i=0; i<8; i+=2)
   {
     for (j=0; j<8; j+=2, s+=2)
       *p++ = *s;
     s += 8; /* Skip one line */
     p += priv->width/2 - 4;
   }

  p = priv->plane[2];
  s = priv->Cr;
  for (i=0; i<8; i+=2)
   {
     for (j=0; j<8; j+=2, s+=2)
       *p++ = *s;
     s += 8; /* Skip one line */
     p += priv->width/2 - 4;
   }
}

/**
 *  YCrCb -> YUV420P (2x1)
 *  .-------.
 *  | 1 | 2 |
 *  `-------'
 */
static void YCrCB_to_YUV420P_2x1(struct jdec_private *priv)
{
  unsigned char *p;
  const unsigned char *s, *y1;
  unsigned int i;

  p = priv->plane[0];
  y1 = priv->Y;
  for (i=0; i<8; i++)
   {
     memcpy(p, y1, 16);
     p += priv->width;
     y1 += 16;
   }

  p = priv->plane[1];
  s = priv->Cb;
  for (i=0; i<8; i+=2)
   {
     memcpy(p, s, 8);
     s += 16; /* Skip one line */
     p += priv->width/2;
   }

  p = priv->plane[2];
  s = priv->Cr;
  for (i=0; i<8; i+=2)
   {
     memcpy(p, s, 8);
     s += 16; /* Skip one line */
     p += priv->width/2;
   }
}


/**
 *  YCrCb -> YUV420P (1x2)
 *  .---.
 *  | 1 |
 *  |---|
 *  | 2 |
 *  `---'
 */
static void YCrCB_to_YUV420P_1x2(struct jdec_private *priv)
{
  const unsigned char *s, *y;
  unsigned char *p;
  int i,j;

  p = priv->plane[0];
  y = priv->Y;
  for (i=0; i<16; i++)
   {
     memcpy(p, y, 8);
     p+=priv->width;
     y+=8;
   }

  p = priv->plane[1];
  s = priv->Cb;
  for (i=0; i<8; i++)
   {
     for (j=0; j<8; j+=2, s+=2)
       *p++ = *s;
     p += priv->width/2 - 4;
   }

  p = priv->plane[2];
  s = priv->Cr;
  for (i=0; i<8; i++)
   {
     for (j=0; j<8; j+=2, s+=2)
       *p++ = *s;
     p += priv->width/2 - 4;
   }
}

/**
 *  YCrCb -> YUV420P (2x2)
 *  .-------.
 *  | 1 | 2 |
 *  |---+---|
 *  | 3 | 4 |
 *  `-------'
 */
static void YCrCB_to_YUV420P_2x2(struct jdec_private *priv)
{
  unsigned char *p;
  const unsigned char *s, *y1;
  unsigned int i;

  p = priv->plane[0];
  y1 = priv->Y;
  for (i=0; i<16; i++)
   {
     memcpy(p, y1, 16);
     p += priv->width;
     y1 += 16;
   }

  p = priv->plane[1];
  s = priv->Cb;
  for (i=0; i<8; i++)
   {
     memcpy(p, s, 8);
     s += 8;
     p += priv->width/2;
   }

  p = priv->plane[2];
  s = priv->Cr;
  for (i=0; i<8; i++)
   {
     memcpy(p, s, 8);
     s += 8;
     p += priv->width/2;
   }
}

/**
 *  YCrCb -> RGB24 (1x1)
 *  .---.
 *  | 1 |
 *  `---'
 */
static void YCrCB_to_RGB24_1x1(struct jdec_private *priv)
{
  const unsigned char *Y, *Cb, *Cr;
  unsigned char *p;
  int i,j;
  int offset_to_next_row;

#define SCALEBITS       10
#define ONE_HALF        (1UL << (SCALEBITS-1))
#define FIX(x)          ((int)((x) * (1UL<<SCALEBITS) + 0.5))

  p = priv->plane[0];
  Y = priv->Y;
  Cb = priv->Cb;
  Cr = priv->Cr;
  offset_to_next_row = priv->width*3 - 8*3;
  for (i=0; i<8; i++) {

    for (j=0; j<8; j++) {

       int y, cb, cr;
       int add_r, add_g, add_b;
       int r, g , b;

       y  = (*Y++) << SCALEBITS;
       cb = *Cb++ - 128;
       cr = *Cr++ - 128;
       add_r = FIX(1.40200) * cr + ONE_HALF;
       add_g = - FIX(0.34414) * cb - FIX(0.71414) * cr + ONE_HALF;
       add_b = FIX(1.77200) * cb + ONE_HALF;

       r = (y + add_r) >> SCALEBITS;
       *p++ = clamp(r);
       g = (y + add_g) >> SCALEBITS;
       *p++ = clamp(g);
       b = (y + add_b) >> SCALEBITS;
       *p++ = clamp(b);

    }

    p += offset_to_next_row;
  }

#undef SCALEBITS
#undef ONE_HALF
#undef FIX

}

/**
 *  YCrCb -> BGR24 (1x1)
 *  .---.
 *  | 1 |
 *  `---'
 */
static void YCrCB_to_BGR24_1x1(struct jdec_private *priv)
{
  const unsigned char *Y, *Cb, *Cr;
  unsigned char *p;
  int i,j;
  int offset_to_next_row;

#define SCALEBITS       10
#define ONE_HALF        (1UL << (SCALEBITS-1))
#define FIX(x)          ((int)((x) * (1UL<<SCALEBITS) + 0.5))

  p = priv->plane[0];
  Y = priv->Y;
  Cb = priv->Cb;
  Cr = priv->Cr;
  offset_to_next_row = priv->width*3 - 8*3;
  for (i=0; i<8; i++) {

    for (j=0; j<8; j++) {

       int y, cb, cr;
       int add_r, add_g, add_b;
       int r, g , b;

       y  = (*Y++) << SCALEBITS;
       cb = *Cb++ - 128;
       cr = *Cr++ - 128;
       add_r = FIX(1.40200) * cr + ONE_HALF;
       add_g = - FIX(0.34414) * cb - FIX(0.71414) * cr + ONE_HALF;
       add_b = FIX(1.77200) * cb + ONE_HALF;

       b = (y + add_b) >> SCALEBITS;
       *p++ = clamp(b);
       g = (y + add_g) >> SCALEBITS;
       *p++ = clamp(g);
       r = (y + add_r) >> SCALEBITS;
       *p++ = clamp(r);

    }

    p += offset_to_next_row;
  }

#undef SCALEBITS
#undef ONE_HALF
#undef FIX

}


/**
 *  YCrCb -> RGB24 (2x1)
 *  .-------.
 *  | 1 | 2 |
 *  `-------'
 */
static void YCrCB_to_RGB24_2x1(struct jdec_private *priv)
{
  const unsigned char *Y, *Cb, *Cr;
  unsigned char *p;
  int i,j;
  int offset_to_next_row;

#define SCALEBITS       10
#define ONE_HALF        (1UL << (SCALEBITS-1))
#define FIX(x)          ((int)((x) * (1UL<<SCALEBITS) + 0.5))

  p = priv->plane[0];
  Y = priv->Y;
  Cb = priv->Cb;
  Cr = priv->Cr;
  offset_to_next_row = priv->width*3 - 16*3;
  for (i=0; i<8; i++) {

    for (j=0; j<8; j++) {

       int y, cb, cr;
       int add_r, add_g, add_b;
       int r, g , b;

       y  = (*Y++) << SCALEBITS;
       cb = *Cb++ - 128;
       cr = *Cr++ - 128;
       add_r = FIX(1.40200) * cr + ONE_HALF;
       add_g = - FIX(0.34414) * cb - FIX(0.71414) * cr + ONE_HALF;
       add_b = FIX(1.77200) * cb + ONE_HALF;

       r = (y + add_r) >> SCALEBITS;
       *p++ = clamp(r);
       g = (y + add_g) >> SCALEBITS;
       *p++ = clamp(g);
       b = (y + add_b) >> SCALEBITS;
       *p++ = clamp(b);

       y  = (*Y++) << SCALEBITS;
       r = (y + add_r) >> SCALEBITS;
       *p++ = clamp(r);
       g = (y + add_g) >> SCALEBITS;
       *p++ = clamp(g);
       b = (y + add_b) >> SCALEBITS;
       *p++ = clamp(b);

    }

    p += offset_to_next_row;
  }

#undef SCALEBITS
#undef ONE_HALF
#undef FIX

}

/*
 *  YCrCb -> BGR24 (2x1)
 *  .-------.
 *  | 1 | 2 |
 *  `-------'
 */
static void YCrCB_to_BGR24_2x1(struct jdec_private *priv)
{
  const unsigned char *Y, *Cb, *Cr;
  unsigned char *p;
  int i,j;
  int offset_to_next_row;

#define SCALEBITS       10
#define ONE_HALF        (1UL << (SCALEBITS-1))
#define FIX(x)          ((int)((x) * (1UL<<SCALEBITS) + 0.5))

  p = priv->plane[0];
  Y = priv->Y;
  Cb = priv->Cb;
  Cr = priv->Cr;
  offset_to_next_row = priv->width*3 - 16*3;
  for (i=0; i<8; i++) {

    for (j=0; j<8; j++) {

       int y, cb, cr;
       int add_r, add_g, add_b;
       int r, g , b;

       cb = *Cb++ - 128;
       cr = *Cr++ - 128;
       add_r = FIX(1.40200) * cr + ONE_HALF;
       add_g = - FIX(0.34414) * cb - FIX(0.71414) * cr + ONE_HALF;
       add_b = FIX(1.77200) * cb + ONE_HALF;

       y  = (*Y++) << SCALEBITS;
       b = (y + add_b) >> SCALEBITS;
       *p++ = clamp(b);
       g = (y + add_g) >> SCALEBITS;
       *p++ = clamp(g);
       r = (y + add_r) >> SCALEBITS;
       *p++ = clamp(r);

       y  = (*Y++) << SCALEBITS;
       b = (y + add_b) >> SCALEBITS;
       *p++ = clamp(b);
       g = (y + add_g) >> SCALEBITS;
       *p++ = clamp(g);
       r = (y + add_r) >> SCALEBITS;
       *p++ = clamp(r);

    }

    p += offset_to_next_row;
  }

#undef SCALEBITS
#undef ONE_HALF
#undef FIX

}

/**
 *  YCrCb -> RGB24 (1x2)
 *  .---.
 *  | 1 |
 *  |---|
 *  | 2 |
 *  `---'
 */
static void YCrCB_to_RGB24_1x2(struct jdec_private *priv)
{
  const unsigned char *Y, *Cb, *Cr;
  unsigned char *p, *p2;
  int i,j;
  int offset_to_next_row;

#define SCALEBITS       10
#define ONE_HALF        (1UL << (SCALEBITS-1))
#define FIX(x)          ((int)((x) * (1UL<<SCALEBITS) + 0.5))

  p = priv->plane[0];
  p2 = priv->plane[0] + priv->width*3;
  Y = priv->Y;
  Cb = priv->Cb;
  Cr = priv->Cr;
  offset_to_next_row = 2*priv->width*3 - 8*3;
  for (i=0; i<8; i++) {

    for (j=0; j<8; j++) {

       int y, cb, cr;
       int add_r, add_g, add_b;
       int r, g , b;

       cb = *Cb++ - 128;
       cr = *Cr++ - 128;
       add_r = FIX(1.40200) * cr + ONE_HALF;
       add_g = - FIX(0.34414) * cb - FIX(0.71414) * cr + ONE_HALF;
       add_b = FIX(1.77200) * cb + ONE_HALF;

       y  = (*Y++) << SCALEBITS;
       r = (y + add_r) >> SCALEBITS;
       *p++ = clamp(r);
       g = (y + add_g) >> SCALEBITS;
       *p++ = clamp(g);
       b = (y + add_b) >> SCALEBITS;
       *p++ = clamp(b);

       y  = (Y[8-1]) << SCALEBITS;
       r = (y + add_r) >> SCALEBITS;
       *p2++ = clamp(r);
       g = (y + add_g) >> SCALEBITS;
       *p2++ = clamp(g);
       b = (y + add_b) >> SCALEBITS;
       *p2++ = clamp(b);

    }
    Y += 8;
    p += offset_to_next_row;
    p2 += offset_to_next_row;
  }

#undef SCALEBITS
#undef ONE_HALF
#undef FIX

}

/*
 *  YCrCb -> BGR24 (1x2)
 *  .---.
 *  | 1 |
 *  |---|
 *  | 2 |
 *  `---'
 */
static void YCrCB_to_BGR24_1x2(struct jdec_private *priv)
{
  const unsigned char *Y, *Cb, *Cr;
  unsigned char *p, *p2;
  int i,j;
  int offset_to_next_row;

#define SCALEBITS       10
#define ONE_HALF        (1UL << (SCALEBITS-1))
#define FIX(x)          ((int)((x) * (1UL<<SCALEBITS) + 0.5))

  p = priv->plane[0];
  p2 = priv->plane[0] + priv->width*3;
  Y = priv->Y;
  Cb = priv->Cb;
  Cr = priv->Cr;
  offset_to_next_row = 2*priv->width*3 - 8*3;
  for (i=0; i<8; i++) {

    for (j=0; j<8; j++) {

       int y, cb, cr;
       int add_r, add_g, add_b;
       int r, g , b;

       cb = *Cb++ - 128;
       cr = *Cr++ - 128;
       add_r = FIX(1.40200) * cr + ONE_HALF;
       add_g = - FIX(0.34414) * cb - FIX(0.71414) * cr + ONE_HALF;
       add_b = FIX(1.77200) * cb + ONE_HALF;

       y  = (*Y++) << SCALEBITS;
       b = (y + add_b) >> SCALEBITS;
       *p++ = clamp(b);
       g = (y + add_g) >> SCALEBITS;
       *p++ = clamp(g);
       r = (y + add_r) >> SCALEBITS;
       *p++ = clamp(r);

       y  = (Y[8-1]) << SCALEBITS;
       b = (y + add_b) >> SCALEBITS;
       *p2++ = clamp(b);
       g = (y + add_g) >> SCALEBITS;
       *p2++ = clamp(g);
       r = (y + add_r) >> SCALEBITS;
       *p2++ = clamp(r);

    }
    Y += 8;
    p += offset_to_next_row;
    p2 += offset_to_next_row;
  }

#undef SCALEBITS
#undef ONE_HALF
#undef FIX

}


/**
 *  YCrCb -> RGB24 (2x2)
 *  .-------.
 *  | 1 | 2 |
 *  |---+---|
 *  | 3 | 4 |
 *  `-------'
 */
static void YCrCB_to_RGB24_2x2(struct jdec_private *priv)
{
  const unsigned char *Y, *Cb, *Cr;
  unsigned char *p, *p2;
  int i,j;
  int offset_to_next_row;

#define SCALEBITS       10
#define ONE_HALF        (1UL << (SCALEBITS-1))
#define FIX(x)          ((int)((x) * (1UL<<SCALEBITS) + 0.5))

  p = priv->plane[0];
  p2 = priv->plane[0] + priv->width*3;
  Y = priv->Y;