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/*

 * jdmerge.c

 *

 * Copyright (C) 1994-1996, Thomas G. Lane.

 * This file is part of the Independent JPEG Group's software.

 * For conditions of distribution and use, see the accompanying README file.

 *

 * This file contains code for merged upsampling/color conversion.

 *

 * This file combines functions from jdsample.c and jdcolor.c;

 * read those files first to understand what's going on.

 *

 * When the chroma components are to be upsampled by simple replication

 * (ie, box filtering), we can save some work in color conversion by

 * calculating all the output pixels corresponding to a pair of chroma

 * samples at one time.  In the conversion equations

 *      R = Y           + K1 * Cr

 *      G = Y + K2 * Cb + K3 * Cr

 *      B = Y + K4 * Cb

 * only the Y term varies among the group of pixels corresponding to a pair

 * of chroma samples, so the rest of the terms can be calculated just once.

 * At typical sampling ratios, this eliminates half or three-quarters of the

 * multiplications needed for color conversion.

 *

 * This file currently provides implementations for the following cases:

 *      YCbCr => RGB color conversion only.

 *      Sampling ratios of 2h1v or 2h2v.

 *      No scaling needed at upsample time.

 *      Corner-aligned (non-CCIR601) sampling alignment.

 * Other special cases could be added, but in most applications these are

 * the only common cases.  (For uncommon cases we fall back on the more

 * general code in jdsample.c and jdcolor.c.)

 */

#define JPEG_INTERNALS

#include "jinclude.h"

#include "jpeglib.h"

#ifdef UPSAMPLE_MERGING_SUPPORTED

/* Private subobject */

typedef struct {

  struct jpeg_upsampler pub;    /* public fields */

  /* Pointer to routine to do actual upsampling/conversion of one row group */

  JMETHOD(void, upmethod, (j_decompress_ptr cinfo,

                           JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,

                           JSAMPARRAY output_buf));

  /* Private state for YCC->RGB conversion */

  int * Cr_r_tab;               /* => table for Cr to R conversion */

  int * Cb_b_tab;               /* => table for Cb to B conversion */

  INT32 * Cr_g_tab;             /* => table for Cr to G conversion */

  INT32 * Cb_g_tab;             /* => table for Cb to G conversion */

  /* For 2:1 vertical sampling, we produce two output rows at a time.

   * We need a "spare" row buffer to hold the second output row if the

   * application provides just a one-row buffer; we also use the spare

   * to discard the dummy last row if the image height is odd.

   */

  JSAMPROW spare_row;

  boolean spare_full;           /* T if spare buffer is occupied */

  JDIMENSION out_row_width;     /* samples per output row */

  JDIMENSION rows_to_go;        /* counts rows remaining in image */

} my_upsampler;

typedef my_upsampler * my_upsample_ptr;

#define SCALEBITS       16      /* speediest right-shift on some machines */

#define ONE_HALF        ((INT32) 1 << (SCALEBITS-1))

#define FIX(x)          ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))

/*

 * Initialize tables for YCC->RGB colorspace conversion.

 * This is taken directly from jdcolor.c; see that file for more info.

 */

LOCAL(void)

build_ycc_rgb_table (j_decompress_ptr cinfo)

{

  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

  int i;

  INT32 x;

  SHIFT_TEMPS

  upsample->Cr_r_tab = (int *)

    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

                                (MAXJSAMPLE+1) * SIZEOF(int));

  upsample->Cb_b_tab = (int *)

    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

                                (MAXJSAMPLE+1) * SIZEOF(int));

  upsample->Cr_g_tab = (INT32 *)

    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

                                (MAXJSAMPLE+1) * SIZEOF(INT32));

  upsample->Cb_g_tab = (INT32 *)

    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

                                (MAXJSAMPLE+1) * SIZEOF(INT32));

  for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {

    /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */

    /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */

    /* Cr=>R value is nearest int to 1.40200 * x */

    upsample->Cr_r_tab[i] = (int)

                    RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS);

    /* Cb=>B value is nearest int to 1.77200 * x */

    upsample->Cb_b_tab[i] = (int)

                    RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS);

    /* Cr=>G value is scaled-up -0.71414 * x */

    upsample->Cr_g_tab[i] = (- FIX(0.71414)) * x;

    /* Cb=>G value is scaled-up -0.34414 * x */

    /* We also add in ONE_HALF so that need not do it in inner loop */

    upsample->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF;

  }

}

/*

 * Initialize for an upsampling pass.

 */

METHODDEF(void)

start_pass_merged_upsample (j_decompress_ptr cinfo)

{

  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

  /* Mark the spare buffer empty */

  upsample->spare_full = FALSE;

  /* Initialize total-height counter for detecting bottom of image */

  upsample->rows_to_go = cinfo->output_height;

}

/*

 * Control routine to do upsampling (and color conversion).

 *

 * The control routine just handles the row buffering considerations.

 */

METHODDEF(void)

merged_2v_upsample (j_decompress_ptr cinfo,

                    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,

                    JDIMENSION in_row_groups_avail,

                    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,

                    JDIMENSION out_rows_avail)

/* 2:1 vertical sampling case: may need a spare row. */

{

  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

  JSAMPROW work_ptrs[2];

  JDIMENSION num_rows;          /* number of rows returned to caller */

  if (upsample->spare_full) {

    /* If we have a spare row saved from a previous cycle, just return it. */

    jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0,

                      1, upsample->out_row_width);

    num_rows = 1;

    upsample->spare_full = FALSE;

  } else {

    /* Figure number of rows to return to caller. */

    num_rows = 2;

    /* Not more than the distance to the end of the image. */

    if (num_rows > upsample->rows_to_go)

      num_rows = upsample->rows_to_go;

    /* And not more than what the client can accept: */

    out_rows_avail -= *out_row_ctr;

    if (num_rows > out_rows_avail)

      num_rows = out_rows_avail;

    /* Create output pointer array for upsampler. */

    work_ptrs[0] = output_buf[*out_row_ctr];

    if (num_rows > 1) {

      work_ptrs[1] = output_buf[*out_row_ctr + 1];

    } else {

      work_ptrs[1] = upsample->spare_row;

      upsample->spare_full = TRUE;

    }

    /* Now do the upsampling. */

    (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs);

  }

  /* Adjust counts */

  *out_row_ctr += num_rows;

  upsample->rows_to_go -= num_rows;

  /* When the buffer is emptied, declare this input row group consumed */

  if (! upsample->spare_full)

    (*in_row_group_ctr)++;

}

METHODDEF(void)

merged_1v_upsample (j_decompress_ptr cinfo,

                    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,

                    JDIMENSION in_row_groups_avail,

                    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,

                    JDIMENSION out_rows_avail)

/* 1:1 vertical sampling case: much easier, never need a spare row. */

{

  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

  /* Just do the upsampling. */

  (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr,

                         output_buf + *out_row_ctr);

  /* Adjust counts */

  (*out_row_ctr)++;

  (*in_row_group_ctr)++;

}

/*

 * These are the routines invoked by the control routines to do

 * the actual upsampling/conversion.  One row group is processed per call.

 *

 * Note: since we may be writing directly into application-supplied buffers,

 * we have to be honest about the output width; we can't assume the buffer

 * has been rounded up to an even width.

 */

/*

 * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical.

 */

METHODDEF(void)

h2v1_merged_upsample (j_decompress_ptr cinfo,

                      JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,

                      JSAMPARRAY output_buf)

{

  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

  register int y, cred, cgreen, cblue;

  int cb, cr;

  register JSAMPROW outptr;

  JSAMPROW inptr0, inptr1, inptr2;

  JDIMENSION col;

  /* copy these pointers into registers if possible */

  register JSAMPLE * range_limit = cinfo->sample_range_limit;

  int * Crrtab = upsample->Cr_r_tab;

  int * Cbbtab = upsample->Cb_b_tab;

  INT32 * Crgtab = upsample->Cr_g_tab;

  INT32 * Cbgtab = upsample->Cb_g_tab;

  SHIFT_TEMPS

  inptr0 = input_buf[0][in_row_group_ctr];

  inptr1 = input_buf[1][in_row_group_ctr];

  inptr2 = input_buf[2][in_row_group_ctr];

  outptr = output_buf[0];

  /* Loop for each pair of output pixels */

  for (col = cinfo->output_width >> 1; col > 0; col--) {

    /* Do the chroma part of the calculation */

    cb = GETJSAMPLE(*inptr1++);

    cr = GETJSAMPLE(*inptr2++);

    cred = Crrtab[cr];

    cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);

    cblue = Cbbtab[cb];

    /* Fetch 2 Y values and emit 2 pixels */

    y  = GETJSAMPLE(*inptr0++);

    outptr[RGB_RED] =   range_limit[y + cred];

    outptr[RGB_GREEN] = range_limit[y + cgreen];

    outptr[RGB_BLUE] =  range_limit[y + cblue];

    outptr += RGB_PIXELSIZE;

    y  = GETJSAMPLE(*inptr0++);

    outptr[RGB_RED] =   range_limit[y + cred];

    outptr[RGB_GREEN] = range_limit[y + cgreen];

    outptr[RGB_BLUE] =  range_limit[y + cblue];

    outptr += RGB_PIXELSIZE;

  }

  /* If image width is odd, do the last output column separately */

  if (cinfo->output_width & 1) {

    cb = GETJSAMPLE(*inptr1);

    cr = GETJSAMPLE(*inptr2);

    cred = Crrtab[cr];

    cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);

    cblue = Cbbtab[cb];

    y  = GETJSAMPLE(*inptr0);

    outptr[RGB_RED] =   range_limit[y + cred];

    outptr[RGB_GREEN] = range_limit[y + cgreen];

    outptr[RGB_BLUE] =  range_limit[y + cblue];

  }

}

/*

 * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.

 */

METHODDEF(void)

h2v2_merged_upsample (j_decompress_ptr cinfo,

                      JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,

                      JSAMPARRAY output_buf)

{

  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

  register int y, cred, cgreen, cblue;

  int cb, cr;

  register JSAMPROW outptr0, outptr1;

  JSAMPROW inptr00, inptr01, inptr1, inptr2;

  JDIMENSION col;

  /* copy these pointers into registers if possible */

  register JSAMPLE * range_limit = cinfo->sample_range_limit;

  int * Crrtab = upsample->Cr_r_tab;

  int * Cbbtab = upsample->Cb_b_tab;

  INT32 * Crgtab = upsample->Cr_g_tab;

  INT32 * Cbgtab = upsample->Cb_g_tab;

  SHIFT_TEMPS

  inptr00 = input_buf[0][in_row_group_ctr*2];

  inptr01 = input_buf[0][in_row_group_ctr*2 + 1];

  inptr1 = input_buf[1][in_row_group_ctr];

  inptr2 = input_buf[2][in_row_group_ctr];

  outptr0 = output_buf[0];

  outptr1 = output_buf[1];

  /* Loop for each group of output pixels */

  for (col = cinfo->output_width >> 1; col > 0; col--) {

    /* Do the chroma part of the calculation */

    cb = GETJSAMPLE(*inptr1++);

    cr = GETJSAMPLE(*inptr2++);

    cred = Crrtab[cr];

    cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);

    cblue = Cbbtab[cb];

    /* Fetch 4 Y values and emit 4 pixels */

    y  = GETJSAMPLE(*inptr00++);

    outptr0[RGB_RED] =   range_limit[y + cred];

    outptr0[RGB_GREEN] = range_limit[y + cgreen];

    outptr0[RGB_BLUE] =  range_limit[y + cblue];

    outptr0 += RGB_PIXELSIZE;

    y  = GETJSAMPLE(*inptr00++);

    outptr0[RGB_RED] =   range_limit[y + cred];

    outptr0[RGB_GREEN] = range_limit[y + cgreen];

    outptr0[RGB_BLUE] =  range_limit[y + cblue];

    outptr0 += RGB_PIXELSIZE;

    y  = GETJSAMPLE(*inptr01++);

    outptr1[RGB_RED] =   range_limit[y + cred];

    outptr1[RGB_GREEN] = range_limit[y + cgreen];

    outptr1[RGB_BLUE] =  range_limit[y + cblue];

    outptr1 += RGB_PIXELSIZE;

    y  = GETJSAMPLE(*inptr01++);

    outptr1[RGB_RED] =   range_limit[y + cred];

    outptr1[RGB_GREEN] = range_limit[y + cgreen];

    outptr1[RGB_BLUE] =  range_limit[y + cblue];

    outptr1 += RGB_PIXELSIZE;

  }

  /* If image width is odd, do the last output column separately */

  if (cinfo->output_width & 1) {

    cb = GETJSAMPLE(*inptr1);

    cr = GETJSAMPLE(*inptr2);

    cred = Crrtab[cr];

    cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);

    cblue = Cbbtab[cb];

    y  = GETJSAMPLE(*inptr00);

    outptr0[RGB_RED] =   range_limit[y + cred];

    outptr0[RGB_GREEN] = range_limit[y + cgreen];

    outptr0[RGB_BLUE] =  range_limit[y + cblue];

    y  = GETJSAMPLE(*inptr01);

    outptr1[RGB_RED] =   range_limit[y + cred];

    outptr1[RGB_GREEN] = range_limit[y + cgreen];

    outptr1[RGB_BLUE] =  range_limit[y + cblue];

  }

}

/*

 * Module initialization routine for merged upsampling/color conversion.

 *

 * NB: this is called under the conditions determined by use_merged_upsample()

 * in jdmaster.c.  That routine MUST correspond to the actual capabilities

 * of this module; no safety checks are made here.

 */

GLOBAL(void)

jinit_merged_upsampler (j_decompress_ptr cinfo)

{

  my_upsample_ptr upsample;

  upsample = (my_upsample_ptr)

    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

                                SIZEOF(my_upsampler));

  cinfo->upsample = (struct jpeg_upsampler *) upsample;

  upsample->pub.start_pass = start_pass_merged_upsample;

  upsample->pub.need_context_rows = FALSE;

  upsample->out_row_width = cinfo->output_width * cinfo->out_color_components;

  if (cinfo->max_v_samp_factor == 2) {

    upsample->pub.upsample = merged_2v_upsample;

    upsample->upmethod = h2v2_merged_upsample;

    /* Allocate a spare row buffer */

    upsample->spare_row = (JSAMPROW)

      (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,

                (size_t) (upsample->out_row_width * SIZEOF(JSAMPLE)));

  } else {

    upsample->pub.upsample = merged_1v_upsample;

    upsample->upmethod = h2v1_merged_upsample;

    /* No spare row needed */

    upsample->spare_row = NULL;

  }

  build_ycc_rgb_table(cinfo);

}

#endif /* UPSAMPLE_MERGING_SUPPORTED */