3rdparty/libjpeg/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 */
  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 */
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	INT32 * Cr_g_tab; /* => table for Cr to G conversion */
56	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	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 ((INT32) 1 << (SCALEBITS-1))
74	#define FIX(x) ((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	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 = (INT32 *)
97	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
98	(MAXJSAMPLE+1) * SIZEOF(INT32));
99	upsample->Cb_g_tab = (INT32 *)
100	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
101	(MAXJSAMPLE+1) * SIZEOF(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	INT32 * Crgtab = upsample->Cr_g_tab;
241	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	/*
284	* Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.
285	*/
286
287	METHODDEF(void)
288	h2v2_merged_upsample (j_decompress_ptr cinfo,
289	JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
290	JSAMPARRAY output_buf)
291	{
292	my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
293	register int y, cred, cgreen, cblue;
294	int cb, cr;
295	register JSAMPROW outptr0, outptr1;
296	JSAMPROW inptr00, inptr01, inptr1, inptr2;
297	JDIMENSION col;
298	/* copy these pointers into registers if possible */
299	register JSAMPLE * range_limit = cinfo->sample_range_limit;
300	int * Crrtab = upsample->Cr_r_tab;
301	int * Cbbtab = upsample->Cb_b_tab;
302	INT32 * Crgtab = upsample->Cr_g_tab;
303	INT32 * Cbgtab = upsample->Cb_g_tab;
304	SHIFT_TEMPS
305
306	inptr00 = input_buf[0][in_row_group_ctr*2];
307	inptr01 = input_buf[0][in_row_group_ctr*2 + 1];
308	inptr1 = input_buf[1][in_row_group_ctr];
309	inptr2 = input_buf[2][in_row_group_ctr];
310	outptr0 = output_buf[0];
311	outptr1 = output_buf[1];
312	/* Loop for each group of output pixels */
313	for (col = cinfo->output_width >> 1; col > 0; col--) {
314	/* Do the chroma part of the calculation */
315	cb = GETJSAMPLE(*inptr1++);
316	cr = GETJSAMPLE(*inptr2++);
317	cred = Crrtab[cr];
318	cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
319	cblue = Cbbtab[cb];
320	/* Fetch 4 Y values and emit 4 pixels */
321	y = GETJSAMPLE(*inptr00++);
322	outptr0[RGB_RED] = range_limit[y + cred];
323	outptr0[RGB_GREEN] = range_limit[y + cgreen];
324	outptr0[RGB_BLUE] = range_limit[y + cblue];
325	outptr0 += RGB_PIXELSIZE;
326	y = GETJSAMPLE(*inptr00++);
327	outptr0[RGB_RED] = range_limit[y + cred];
328	outptr0[RGB_GREEN] = range_limit[y + cgreen];
329	outptr0[RGB_BLUE] = range_limit[y + cblue];
330	outptr0 += RGB_PIXELSIZE;
331	y = GETJSAMPLE(*inptr01++);
332	outptr1[RGB_RED] = range_limit[y + cred];
333	outptr1[RGB_GREEN] = range_limit[y + cgreen];
334	outptr1[RGB_BLUE] = range_limit[y + cblue];
335	outptr1 += RGB_PIXELSIZE;
336	y = GETJSAMPLE(*inptr01++);
337	outptr1[RGB_RED] = range_limit[y + cred];
338	outptr1[RGB_GREEN] = range_limit[y + cgreen];
339	outptr1[RGB_BLUE] = range_limit[y + cblue];
340	outptr1 += RGB_PIXELSIZE;
341	}
342	/* If image width is odd, do the last output column separately */
343	if (cinfo->output_width & 1) {
344	cb = GETJSAMPLE(*inptr1);
345	cr = GETJSAMPLE(*inptr2);
346	cred = Crrtab[cr];
347	cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
348	cblue = Cbbtab[cb];
349	y = GETJSAMPLE(*inptr00);
350	outptr0[RGB_RED] = range_limit[y + cred];
351	outptr0[RGB_GREEN] = range_limit[y + cgreen];
352	outptr0[RGB_BLUE] = range_limit[y + cblue];
353	y = GETJSAMPLE(*inptr01);
354	outptr1[RGB_RED] = range_limit[y + cred];
355	outptr1[RGB_GREEN] = range_limit[y + cgreen];
356	outptr1[RGB_BLUE] = range_limit[y + cblue];
357	}
358	}
359
360
361	/*
362	* Module initialization routine for merged upsampling/color conversion.
363	*
364	* NB: this is called under the conditions determined by use_merged_upsample()
365	* in jdmaster.c. That routine MUST correspond to the actual capabilities
366	* of this module; no safety checks are made here.
367	*/
368
369	GLOBAL(void)
370	jinit_merged_upsampler (j_decompress_ptr cinfo)
371	{
372	my_upsample_ptr upsample;
373
374	upsample = (my_upsample_ptr)
375	(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
376	SIZEOF(my_upsampler));
377	cinfo->upsample = (struct jpeg_upsampler *) upsample;
378	upsample->pub.start_pass = start_pass_merged_upsample;
379	upsample->pub.need_context_rows = FALSE;
380
381	upsample->out_row_width = cinfo->output_width * cinfo->out_color_components;
382
383	if (cinfo->max_v_samp_factor == 2) {
384	upsample->pub.upsample = merged_2v_upsample;
385	upsample->upmethod = h2v2_merged_upsample;
386	/* Allocate a spare row buffer */
387	upsample->spare_row = (JSAMPROW)
388	(*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
389	(size_t) (upsample->out_row_width * SIZEOF(JSAMPLE)));
390	} else {
391	upsample->pub.upsample = merged_1v_upsample;
392	upsample->upmethod = h2v1_merged_upsample;
393	/* No spare row needed */
394	upsample->spare_row = NULL;
395	}
396
397	build_ycc_rgb_table(cinfo);
398	}
399
400	#endif /* UPSAMPLE_MERGING_SUPPORTED */