src/jpeg/jdmerge.c

/*
 * 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 */
  JPEG_INT32 * Cr_g_tab;		/* => table for Cr to G conversion */
  JPEG_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;
  wxjpeg_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	((JPEG_INT32) 1 << (SCALEBITS-1))
#define FIX(x)		((JPEG_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;
  JPEG_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 = (JPEG_INT32 *)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
				(MAXJSAMPLE+1) * SIZEOF(JPEG_INT32));
  upsample->Cb_g_tab = (JPEG_INT32 *)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
				(MAXJSAMPLE+1) * SIZEOF(JPEG_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;
  JPEG_INT32 * Crgtab = upsample->Cr_g_tab;
  JPEG_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;
  JPEG_INT32 * Crgtab = upsample->Cr_g_tab;
  JPEG_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 */
Commit	Line	Data
	1	/*
	2	* jdmerge.c
	3	*
	4	* Copyright (C) 1994-1996, Thomas G. Lane.
	5	* This file is part of the Independent JPEG Group's software.
	6	* For conditions of distribution and use, see the accompanying README file.
	7	*
	8	* This file contains code for merged upsampling/color conversion.
	9	*
	10	* This file combines functions from jdsample.c and jdcolor.c;
	11	* read those files first to understand what's going on.
	12	*
	13	* When the chroma components are to be upsampled by simple replication
	14	* (ie, box filtering), we can save some work in color conversion by
	15	* calculating all the output pixels corresponding to a pair of chroma
	16	* samples at one time. In the conversion equations
	17	* R = Y + K1 * Cr
	18	* G = Y + K2 * Cb + K3 * Cr
	19	* B = Y + K4 * Cb
	20	* only the Y term varies among the group of pixels corresponding to a pair
	21	* of chroma samples, so the rest of the terms can be calculated just once.
	22	* At typical sampling ratios, this eliminates half or three-quarters of the
	23	* multiplications needed for color conversion.
	24	*
	25	* This file currently provides implementations for the following cases:
	26	* YCbCr => RGB color conversion only.
	27	* Sampling ratios of 2h1v or 2h2v.
	28	* No scaling needed at upsample time.
	29	* Corner-aligned (non-CCIR601) sampling alignment.
	30	* Other special cases could be added, but in most applications these are
	31	* the only common cases. (For uncommon cases we fall back on the more
	32	* general code in jdsample.c and jdcolor.c.)
	33	*/
	34
	35	#define JPEG_INTERNALS
	36	#include "jinclude.h"
	37	#include "jpeglib.h"
	38
	39	#ifdef UPSAMPLE_MERGING_SUPPORTED
	40
	41
	42	/* Private subobject */
	43
	44	typedef struct {
	45	struct jpeg_upsampler pub; /* public fields */
	46
	47	/* Pointer to routine to do actual upsampling/conversion of one row group */
	48	JMETHOD(void, upmethod, (j_decompress_ptr cinfo,
	49	JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
	50	JSAMPARRAY output_buf));
	51
	52	/* Private state for YCC->RGB conversion */
	53	int * Cr_r_tab; /* => table for Cr to R conversion */
	54	int * Cb_b_tab; /* => table for Cb to B conversion */
	55	JPEG_INT32 * Cr_g_tab; /* => table for Cr to G conversion */
	56	JPEG_INT32 * Cb_g_tab; /* => table for Cb to G conversion */
	57
	58	/* For 2:1 vertical sampling, we produce two output rows at a time.
	59	* We need a "spare" row buffer to hold the second output row if the
	60	* application provides just a one-row buffer; we also use the spare
	61	* to discard the dummy last row if the image height is odd.
	62	*/
	63	JSAMPROW spare_row;
	64	wxjpeg_boolean spare_full; /* T if spare buffer is occupied */
	65
	66	JDIMENSION out_row_width; /* samples per output row */
	67	JDIMENSION rows_to_go; /* counts rows remaining in image */
	68	} my_upsampler;
	69
	70	typedef my_upsampler * my_upsample_ptr;
	71
	72	#define SCALEBITS 16 /* speediest right-shift on some machines */
	73	#define ONE_HALF ((JPEG_INT32) 1 << (SCALEBITS-1))
	74	#define FIX(x) ((JPEG_INT32) ((x) * (1L<<SCALEBITS) + 0.5))
	75
	76
	77	/*
	78	* Initialize tables for YCC->RGB colorspace conversion.
	79	* This is taken directly from jdcolor.c; see that file for more info.
	80	*/
	81
	82	LOCAL(void)
	83	build_ycc_rgb_table (j_decompress_ptr cinfo)
	84	{
	85	my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
	86	int i;
	87	JPEG_INT32 x;
	88	SHIFT_TEMPS
	89
	90	upsample->Cr_r_tab = (int *)
	91	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	92	(MAXJSAMPLE+1) * SIZEOF(int));
	93	upsample->Cb_b_tab = (int *)
	94	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	95	(MAXJSAMPLE+1) * SIZEOF(int));
	96	upsample->Cr_g_tab = (JPEG_INT32 *)
	97	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	98	(MAXJSAMPLE+1) * SIZEOF(JPEG_INT32));
	99	upsample->Cb_g_tab = (JPEG_INT32 *)
	100	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	101	(MAXJSAMPLE+1) * SIZEOF(JPEG_INT32));
	102
	103	for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
	104	/* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
	105	/* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
	106	/* Cr=>R value is nearest int to 1.40200 * x */
	107	upsample->Cr_r_tab[i] = (int)
	108	RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS);
	109	/* Cb=>B value is nearest int to 1.77200 * x */
	110	upsample->Cb_b_tab[i] = (int)
	111	RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS);
	112	/* Cr=>G value is scaled-up -0.71414 * x */
	113	upsample->Cr_g_tab[i] = (- FIX(0.71414)) * x;
	114	/* Cb=>G value is scaled-up -0.34414 * x */
	115	/* We also add in ONE_HALF so that need not do it in inner loop */
	116	upsample->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF;
	117	}
	118	}
	119
	120
	121	/*
	122	* Initialize for an upsampling pass.
	123	*/
	124
	125	METHODDEF(void)
	126	start_pass_merged_upsample (j_decompress_ptr cinfo)
	127	{
	128	my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
	129
	130	/* Mark the spare buffer empty */
	131	upsample->spare_full = FALSE;
	132	/* Initialize total-height counter for detecting bottom of image */
	133	upsample->rows_to_go = cinfo->output_height;
	134	}
	135
	136
	137	/*
	138	* Control routine to do upsampling (and color conversion).
	139	*
	140	* The control routine just handles the row buffering considerations.
	141	*/
	142
	143	METHODDEF(void)
	144	merged_2v_upsample (j_decompress_ptr cinfo,
	145	JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	146	JDIMENSION in_row_groups_avail,
	147	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	148	JDIMENSION out_rows_avail)
	149	/* 2:1 vertical sampling case: may need a spare row. */
	150	{
	151	my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
	152	JSAMPROW work_ptrs[2];
	153	JDIMENSION num_rows; /* number of rows returned to caller */
	154
	155	if (upsample->spare_full) {
	156	/* If we have a spare row saved from a previous cycle, just return it. */
	157	jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0,
	158	1, upsample->out_row_width);
	159	num_rows = 1;
	160	upsample->spare_full = FALSE;
	161	} else {
	162	/* Figure number of rows to return to caller. */
	163	num_rows = 2;
	164	/* Not more than the distance to the end of the image. */
	165	if (num_rows > upsample->rows_to_go)
	166	num_rows = upsample->rows_to_go;
	167	/* And not more than what the client can accept: */
	168	out_rows_avail -= *out_row_ctr;
	169	if (num_rows > out_rows_avail)
	170	num_rows = out_rows_avail;
	171	/* Create output pointer array for upsampler. */
	172	work_ptrs[0] = output_buf[*out_row_ctr];
	173	if (num_rows > 1) {
	174	work_ptrs[1] = output_buf[*out_row_ctr + 1];
	175	} else {
	176	work_ptrs[1] = upsample->spare_row;
	177	upsample->spare_full = TRUE;
	178	}
	179	/* Now do the upsampling. */
	180	(upsample->upmethod) (cinfo, input_buf, in_row_group_ctr, work_ptrs);
	181	}
	182
	183	/* Adjust counts */
	184	*out_row_ctr += num_rows;
	185	upsample->rows_to_go -= num_rows;
	186	/* When the buffer is emptied, declare this input row group consumed */
	187	if (! upsample->spare_full)
	188	(*in_row_group_ctr)++;
	189	}
	190
	191
	192	METHODDEF(void)
	193	merged_1v_upsample (j_decompress_ptr cinfo,
	194	JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
	195	JDIMENSION in_row_groups_avail,
	196	JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
	197	JDIMENSION out_rows_avail)
	198	/* 1:1 vertical sampling case: much easier, never need a spare row. */
	199	{
	200	my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
	201
	202	/* Just do the upsampling. */
	203	(upsample->upmethod) (cinfo, input_buf, in_row_group_ctr,
	204	output_buf + *out_row_ctr);
	205	/* Adjust counts */
	206	(*out_row_ctr)++;
	207	(*in_row_group_ctr)++;
	208	}
	209
	210
	211	/*
	212	* These are the routines invoked by the control routines to do
	213	* the actual upsampling/conversion. One row group is processed per call.
	214	*
	215	* Note: since we may be writing directly into application-supplied buffers,
	216	* we have to be honest about the output width; we can't assume the buffer
	217	* has been rounded up to an even width.
	218	*/
	219
	220
	221	/*
	222	* Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical.
	223	*/
	224
	225	METHODDEF(void)
	226	h2v1_merged_upsample (j_decompress_ptr cinfo,
	227	JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
	228	JSAMPARRAY output_buf)
	229	{
	230	my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
	231	register int y, cred, cgreen, cblue;
	232	int cb, cr;
	233	register JSAMPROW outptr;
	234	JSAMPROW inptr0, inptr1, inptr2;
	235	JDIMENSION col;
	236	/* copy these pointers into registers if possible */
	237	register JSAMPLE * range_limit = cinfo->sample_range_limit;
	238	int * Crrtab = upsample->Cr_r_tab;
	239	int * Cbbtab = upsample->Cb_b_tab;
	240	JPEG_INT32 * Crgtab = upsample->Cr_g_tab;
	241	JPEG_INT32 * Cbgtab = upsample->Cb_g_tab;
	242	SHIFT_TEMPS
	243
	244	inptr0 = input_buf[0][in_row_group_ctr];
	245	inptr1 = input_buf[1][in_row_group_ctr];
	246	inptr2 = input_buf[2][in_row_group_ctr];
	247	outptr = output_buf[0];
	248	/* Loop for each pair of output pixels */
	249	for (col = cinfo->output_width >> 1; col > 0; col--) {
	250	/* Do the chroma part of the calculation */
	251	cb = GETJSAMPLE(*inptr1++);
	252	cr = GETJSAMPLE(*inptr2++);
	253	cred = Crrtab[cr];
	254	cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
	255	cblue = Cbbtab[cb];
	256	/* Fetch 2 Y values and emit 2 pixels */
	257	y = GETJSAMPLE(*inptr0++);
	258	outptr[RGB_RED] = range_limit[y + cred];
	259	outptr[RGB_GREEN] = range_limit[y + cgreen];
	260	outptr[RGB_BLUE] = range_limit[y + cblue];
	261	outptr += RGB_PIXELSIZE;
	262	y = GETJSAMPLE(*inptr0++);
	263	outptr[RGB_RED] = range_limit[y + cred];
	264	outptr[RGB_GREEN] = range_limit[y + cgreen];
	265	outptr[RGB_BLUE] = range_limit[y + cblue];
	266	outptr += RGB_PIXELSIZE;
	267	}
	268	/* If image width is odd, do the last output column separately */
	269	if (cinfo->output_width & 1) {
	270	cb = GETJSAMPLE(*inptr1);
	271	cr = GETJSAMPLE(*inptr2);
	272	cred = Crrtab[cr];
	273	cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
	274	cblue = Cbbtab[cb];
	275	y = GETJSAMPLE(*inptr0);
	276	outptr[RGB_RED] = range_limit[y + cred];
	277	outptr[RGB_GREEN] = range_limit[y + cgreen];
	278	outptr[RGB_BLUE] = range_limit[y + cblue];
	279	}
	280	}
	281
	282	/*
	283	* Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.
	284	*/
	285
	286	METHODDEF(void)
	287	h2v2_merged_upsample (j_decompress_ptr cinfo,
	288	JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
	289	JSAMPARRAY output_buf)
	290	{
	291	my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
	292	register int y, cred, cgreen, cblue;
	293	int cb, cr;
	294	register JSAMPROW outptr0, outptr1;
	295	JSAMPROW inptr00, inptr01, inptr1, inptr2;
	296	JDIMENSION col;
	297	/* copy these pointers into registers if possible */
	298	register JSAMPLE * range_limit = cinfo->sample_range_limit;
	299	int * Crrtab = upsample->Cr_r_tab;
	300	int * Cbbtab = upsample->Cb_b_tab;
	301	JPEG_INT32 * Crgtab = upsample->Cr_g_tab;
	302	JPEG_INT32 * Cbgtab = upsample->Cb_g_tab;
	303	SHIFT_TEMPS
	304
	305	inptr00 = input_buf[0][in_row_group_ctr*2];
	306	inptr01 = input_buf[0][in_row_group_ctr*2 + 1];
	307	inptr1 = input_buf[1][in_row_group_ctr];
	308	inptr2 = input_buf[2][in_row_group_ctr];
	309	outptr0 = output_buf[0];
	310	outptr1 = output_buf[1];
	311	/* Loop for each group of output pixels */
	312	for (col = cinfo->output_width >> 1; col > 0; col--) {
	313	/* Do the chroma part of the calculation */
	314	cb = GETJSAMPLE(*inptr1++);
	315	cr = GETJSAMPLE(*inptr2++);
	316	cred = Crrtab[cr];
	317	cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
	318	cblue = Cbbtab[cb];
	319	/* Fetch 4 Y values and emit 4 pixels */
	320	y = GETJSAMPLE(*inptr00++);
	321	outptr0[RGB_RED] = range_limit[y + cred];
	322	outptr0[RGB_GREEN] = range_limit[y + cgreen];
	323	outptr0[RGB_BLUE] = range_limit[y + cblue];
	324	outptr0 += RGB_PIXELSIZE;
	325	y = GETJSAMPLE(*inptr00++);
	326	outptr0[RGB_RED] = range_limit[y + cred];
	327	outptr0[RGB_GREEN] = range_limit[y + cgreen];
	328	outptr0[RGB_BLUE] = range_limit[y + cblue];
	329	outptr0 += RGB_PIXELSIZE;
	330	y = GETJSAMPLE(*inptr01++);
	331	outptr1[RGB_RED] = range_limit[y + cred];
	332	outptr1[RGB_GREEN] = range_limit[y + cgreen];
	333	outptr1[RGB_BLUE] = range_limit[y + cblue];
	334	outptr1 += RGB_PIXELSIZE;
	335	y = GETJSAMPLE(*inptr01++);
	336	outptr1[RGB_RED] = range_limit[y + cred];
	337	outptr1[RGB_GREEN] = range_limit[y + cgreen];
	338	outptr1[RGB_BLUE] = range_limit[y + cblue];
	339	outptr1 += RGB_PIXELSIZE;
	340	}
	341	/* If image width is odd, do the last output column separately */
	342	if (cinfo->output_width & 1) {
	343	cb = GETJSAMPLE(*inptr1);
	344	cr = GETJSAMPLE(*inptr2);
	345	cred = Crrtab[cr];
	346	cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
	347	cblue = Cbbtab[cb];
	348	y = GETJSAMPLE(*inptr00);
	349	outptr0[RGB_RED] = range_limit[y + cred];
	350	outptr0[RGB_GREEN] = range_limit[y + cgreen];
	351	outptr0[RGB_BLUE] = range_limit[y + cblue];
	352	y = GETJSAMPLE(*inptr01);
	353	outptr1[RGB_RED] = range_limit[y + cred];
	354	outptr1[RGB_GREEN] = range_limit[y + cgreen];
	355	outptr1[RGB_BLUE] = range_limit[y + cblue];
	356	}
	357	}
	358
	359
	360	/*
	361	* Module initialization routine for merged upsampling/color conversion.
	362	*
	363	* NB: this is called under the conditions determined by use_merged_upsample()
	364	* in jdmaster.c. That routine MUST correspond to the actual capabilities
	365	* of this module; no safety checks are made here.
	366	*/
	367
	368	GLOBAL(void)
	369	jinit_merged_upsampler (j_decompress_ptr cinfo)
	370	{
	371	my_upsample_ptr upsample;
	372
	373	upsample = (my_upsample_ptr)
	374	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	375	SIZEOF(my_upsampler));
	376	cinfo->upsample = (struct jpeg_upsampler *) upsample;
	377	upsample->pub.start_pass = start_pass_merged_upsample;
	378	upsample->pub.need_context_rows = FALSE;
	379
	380	upsample->out_row_width = cinfo->output_width * cinfo->out_color_components;
	381
	382	if (cinfo->max_v_samp_factor == 2) {
	383	upsample->pub.upsample = merged_2v_upsample;
	384	upsample->upmethod = h2v2_merged_upsample;
	385	/* Allocate a spare row buffer */
	386	upsample->spare_row = (JSAMPROW)
	387	(*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
	388	(size_t) (upsample->out_row_width * SIZEOF(JSAMPLE)));
	389	} else {
	390	upsample->pub.upsample = merged_1v_upsample;
	391	upsample->upmethod = h2v1_merged_upsample;
	392	/* No spare row needed */
	393	upsample->spare_row = NULL;
	394	}
	395
	396	build_ycc_rgb_table(cinfo);
	397	}
	398
	399	#endif /* UPSAMPLE_MERGING_SUPPORTED */