/* 
 * jccoefct.c 
 * 
 * Copyright (C) 1994-1997, 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 the coefficient buffer controller for compression. 
 * This controller is the top level of the JPEG compressor proper. 
 * The coefficient buffer lies between forward-DCT and entropy encoding steps. 
 */ 
 
#define JPEG_INTERNALS 
#include "jinclude.h" 
#include "jpeglib.h" 
 
 
/* We use a full-image coefficient buffer when doing Huffman optimization, 
 * and also for writing multiple-scan JPEG files.  In all cases, the DCT 
 * step is run during the first pass, and subsequent passes need only read 
 * the buffered coefficients. 
 */ 
#ifdef ENTROPY_OPT_SUPPORTED 
#define FULL_COEF_BUFFER_SUPPORTED 
#else 
#ifdef C_MULTISCAN_FILES_SUPPORTED 
#define FULL_COEF_BUFFER_SUPPORTED 
#endif 
#endif 
 
 
/* Private buffer controller object */ 
 
typedef struct { 
  struct jpeg_c_coef_controller pub; /* public fields */ 
 
  JDIMENSION iMCU_row_num;	/* iMCU row # within image */ 
  JDIMENSION mcu_ctr;		/* counts MCUs processed in current row */ 
  int MCU_vert_offset;		/* counts MCU rows within iMCU row */ 
  int MCU_rows_per_iMCU_row;	/* number of such rows needed */ 
 
  /* For single-pass compression, it's sufficient to buffer just one MCU 
   * (although this may prove a bit slow in practice).  We allocate a 
   * workspace of C_MAX_BLOCKS_IN_MCU coefficient blocks, and reuse it for each 
   * MCU constructed and sent.  (On 80x86, the workspace is FAR even though 
   * it's not really very big; this is to keep the module interfaces unchanged 
   * when a large coefficient buffer is necessary.) 
   * In multi-pass modes, this array points to the current MCU's blocks 
   * within the virtual arrays. 
   */ 
  JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU]; 
 
  /* In multi-pass modes, we need a virtual block array for each component. */ 
  jvirt_barray_ptr whole_image[MAX_COMPONENTS]; 
} my_coef_controller; 
 
typedef my_coef_controller * my_coef_ptr; 
 
 
/* Forward declarations */ 
METHODDEF(boolean) compress_data 
    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf)); 
#ifdef FULL_COEF_BUFFER_SUPPORTED 
METHODDEF(boolean) compress_first_pass 
    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf)); 
METHODDEF(boolean) compress_output 
    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf)); 
#endif 
 
 
LOCAL(void) 
start_iMCU_row (j_compress_ptr cinfo) 
/* Reset within-iMCU-row counters for a new row */ 
{ 
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 
 
  /* In an interleaved scan, an MCU row is the same as an iMCU row. 
   * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows. 
   * But at the bottom of the image, process only what's left. 
   */ 
  if (cinfo->comps_in_scan > 1) { 
    coef->MCU_rows_per_iMCU_row = 1; 
  } else { 
    if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1)) 
      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor; 
    else 
      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height; 
  } 
 
  coef->mcu_ctr = 0; 
  coef->MCU_vert_offset = 0; 
} 
 
 
/* 
 * Initialize for a processing pass. 
 */ 
 
METHODDEF(void) 
start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode) 
{ 
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 
 
  coef->iMCU_row_num = 0; 
  start_iMCU_row(cinfo); 
 
  switch (pass_mode) { 
  case JBUF_PASS_THRU: 
    if (coef->whole_image[0] != NULL) 
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 
    coef->pub.compress_data = compress_data; 
    break; 
#ifdef FULL_COEF_BUFFER_SUPPORTED 
  case JBUF_SAVE_AND_PASS: 
    if (coef->whole_image[0] == NULL) 
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 
    coef->pub.compress_data = compress_first_pass; 
    break; 
  case JBUF_CRANK_DEST: 
    if (coef->whole_image[0] == NULL) 
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 
    coef->pub.compress_data = compress_output; 
    break; 
#endif 
  default: 
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 
    break; 
  } 
} 
 
 
/* 
 * Process some data in the single-pass case. 
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row) 
 * per call, ie, v_samp_factor block rows for each component in the image. 
 * Returns TRUE if the iMCU row is completed, FALSE if suspended. 
 * 
 * NB: input_buf contains a plane for each component in image, 
 * which we index according to the component's SOF position. 
 */ 
 
METHODDEF(boolean) 
compress_data (j_compress_ptr cinfo, JSAMPIMAGE input_buf) 
{ 
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 
  JDIMENSION MCU_col_num;	/* index of current MCU within row */ 
  JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1; 
  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 
  int blkn, bi, ci, yindex, yoffset, blockcnt; 
  JDIMENSION ypos, xpos; 
  jpeg_component_info *compptr; 
 
  /* Loop to write as much as one whole iMCU row */ 
  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 
       yoffset++) { 
    for (MCU_col_num = coef->mcu_ctr; MCU_col_num <= last_MCU_col; 
	 MCU_col_num++) { 
      /* Determine where data comes from in input_buf and do the DCT thing. 
       * Each call on forward_DCT processes a horizontal row of DCT blocks 
       * as wide as an MCU; we rely on having allocated the MCU_buffer[] blocks 
       * sequentially.  Dummy blocks at the right or bottom edge are filled in 
       * specially.  The data in them does not matter for image reconstruction, 
       * so we fill them with values that will encode to the smallest amount of 
       * data, viz: all zeroes in the AC entries, DC entries equal to previous 
       * block's DC value.  (Thanks to Thomas Kinsman for this idea.) 
       */ 
      blkn = 0; 
      for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 
	compptr = cinfo->cur_comp_info[ci]; 
	blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width 
						: compptr->last_col_width; 
	xpos = MCU_col_num * compptr->MCU_sample_width; 
	ypos = yoffset * DCTSIZE; /* ypos == (yoffset+yindex) * DCTSIZE */ 
	for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 
	  if (coef->iMCU_row_num < last_iMCU_row || 
	      yoffset+yindex < compptr->last_row_height) { 
	    (*cinfo->fdct->forward_DCT) (cinfo, compptr, 
					 input_buf[compptr->component_index], 
					 coef->MCU_buffer[blkn], 
					 ypos, xpos, (JDIMENSION) blockcnt); 
	    if (blockcnt < compptr->MCU_width) { 
	      /* Create some dummy blocks at the right edge of the image. */ 
	      jzero_far((void FAR *) coef->MCU_buffer[blkn + blockcnt], 
			(compptr->MCU_width - blockcnt) * SIZEOF(JBLOCK)); 
	      for (bi = blockcnt; bi < compptr->MCU_width; bi++) { 
		coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn+bi-1][0][0]; 
	      } 
	    } 
	  } else { 
	    /* Create a row of dummy blocks at the bottom of the image. */ 
	    jzero_far((void FAR *) coef->MCU_buffer[blkn], 
		      compptr->MCU_width * SIZEOF(JBLOCK)); 
	    for (bi = 0; bi < compptr->MCU_width; bi++) { 
	      coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn-1][0][0]; 
	    } 
	  } 
	  blkn += compptr->MCU_width; 
	  ypos += DCTSIZE; 
	} 
      } 
      /* Try to write the MCU.  In event of a suspension failure, we will 
       * re-DCT the MCU on restart (a bit inefficient, could be fixed...) 
       */ 
      if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) { 
	/* Suspension forced; update state counters and exit */ 
	coef->MCU_vert_offset = yoffset; 
	coef->mcu_ctr = MCU_col_num; 
	return FALSE; 
      } 
    } 
    /* Completed an MCU row, but perhaps not an iMCU row */ 
    coef->mcu_ctr = 0; 
  } 
  /* Completed the iMCU row, advance counters for next one */ 
  coef->iMCU_row_num++; 
  start_iMCU_row(cinfo); 
  return TRUE; 
} 
 
 
#ifdef FULL_COEF_BUFFER_SUPPORTED 
 
/* 
 * Process some data in the first pass of a multi-pass case. 
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row) 
 * per call, ie, v_samp_factor block rows for each component in the image. 
 * This amount of data is read from the source buffer, DCT'd and quantized, 
 * and saved into the virtual arrays.  We also generate suitable dummy blocks 
 * as needed at the right and lower edges.  (The dummy blocks are constructed 
 * in the virtual arrays, which have been padded appropriately.)  This makes 
 * it possible for subsequent passes not to worry about real vs. dummy blocks. 
 * 
 * We must also emit the data to the entropy encoder.  This is conveniently 
 * done by calling compress_output() after we've loaded the current strip 
 * of the virtual arrays. 
 * 
 * NB: input_buf contains a plane for each component in image.  All 
 * components are DCT'd and loaded into the virtual arrays in this pass. 
 * However, it may be that only a subset of the components are emitted to 
 * the entropy encoder during this first pass; be careful about looking 
 * at the scan-dependent variables (MCU dimensions, etc). 
 */ 
 
METHODDEF(boolean) 
compress_first_pass (j_compress_ptr cinfo, JSAMPIMAGE input_buf) 
{ 
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 
  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 
  JDIMENSION blocks_across, MCUs_across, MCUindex; 
  int bi, ci, h_samp_factor, block_row, block_rows, ndummy; 
  JCOEF lastDC; 
  jpeg_component_info *compptr; 
  JBLOCKARRAY buffer; 
  JBLOCKROW thisblockrow, lastblockrow; 
 
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 
       ci++, compptr++) { 
    /* Align the virtual buffer for this component. */ 
    buffer = (*cinfo->mem->access_virt_barray) 
      ((j_common_ptr) cinfo, coef->whole_image[ci], 
       coef->iMCU_row_num * compptr->v_samp_factor, 
       (JDIMENSION) compptr->v_samp_factor, TRUE); 
    /* Count non-dummy DCT block rows in this iMCU row. */ 
    if (coef->iMCU_row_num < last_iMCU_row) 
      block_rows = compptr->v_samp_factor; 
    else { 
      /* NB: can't use last_row_height here, since may not be set! */ 
      block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 
      if (block_rows == 0) block_rows = compptr->v_samp_factor; 
    } 
    blocks_across = compptr->width_in_blocks; 
    h_samp_factor = compptr->h_samp_factor; 
    /* Count number of dummy blocks to be added at the right margin. */ 
    ndummy = (int) (blocks_across % h_samp_factor); 
    if (ndummy > 0) 
      ndummy = h_samp_factor - ndummy; 
    /* Perform DCT for all non-dummy blocks in this iMCU row.  Each call 
     * on forward_DCT processes a complete horizontal row of DCT blocks. 
     */ 
    for (block_row = 0; block_row < block_rows; block_row++) { 
      thisblockrow = buffer[block_row]; 
      (*cinfo->fdct->forward_DCT) (cinfo, compptr, 
				   input_buf[ci], thisblockrow, 
				   (JDIMENSION) (block_row * DCTSIZE), 
				   (JDIMENSION) 0, blocks_across); 
      if (ndummy > 0) { 
	/* Create dummy blocks at the right edge of the image. */ 
	thisblockrow += blocks_across; /* => first dummy block */ 
	jzero_far((void FAR *) thisblockrow, ndummy * SIZEOF(JBLOCK)); 
	lastDC = thisblockrow[-1][0]; 
	for (bi = 0; bi < ndummy; bi++) { 
	  thisblockrow[bi][0] = lastDC; 
	} 
      } 
    } 
    /* If at end of image, create dummy block rows as needed. 
     * The tricky part here is that within each MCU, we want the DC values 
     * of the dummy blocks to match the last real block's DC value. 
     * This squeezes a few more bytes out of the resulting file... 
     */ 
    if (coef->iMCU_row_num == last_iMCU_row) { 
      blocks_across += ndummy;	/* include lower right corner */ 
      MCUs_across = blocks_across / h_samp_factor; 
      for (block_row = block_rows; block_row < compptr->v_samp_factor; 
	   block_row++) { 
	thisblockrow = buffer[block_row]; 
	lastblockrow = buffer[block_row-1]; 
	jzero_far((void FAR *) thisblockrow, 
		  (size_t) (blocks_across * SIZEOF(JBLOCK))); 
	for (MCUindex = 0; MCUindex < MCUs_across; MCUindex++) { 
	  lastDC = lastblockrow[h_samp_factor-1][0]; 
	  for (bi = 0; bi < h_samp_factor; bi++) { 
	    thisblockrow[bi][0] = lastDC; 
	  } 
	  thisblockrow += h_samp_factor; /* advance to next MCU in row */ 
	  lastblockrow += h_samp_factor; 
	} 
      } 
    } 
  } 
  /* NB: compress_output will increment iMCU_row_num if successful. 
   * A suspension return will result in redoing all the work above next time. 
   */ 
 
  /* Emit data to the entropy encoder, sharing code with subsequent passes */ 
  return compress_output(cinfo, input_buf); 
} 
 
 
/* 
 * Process some data in subsequent passes of a multi-pass case. 
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row) 
 * per call, ie, v_samp_factor block rows for each component in the scan. 
 * The data is obtained from the virtual arrays and fed to the entropy coder. 
 * Returns TRUE if the iMCU row is completed, FALSE if suspended. 
 * 
 * NB: input_buf is ignored; it is likely to be a NULL pointer. 
 */ 
 
METHODDEF(boolean) 
compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf) 
{ 
  my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 
  JDIMENSION MCU_col_num;	/* index of current MCU within row */ 
  int blkn, ci, xindex, yindex, yoffset; 
  JDIMENSION start_col; 
  JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN]; 
  JBLOCKROW buffer_ptr; 
  jpeg_component_info *compptr; 
 
  /* Align the virtual buffers for the components used in this scan. 
   * NB: during first pass, this is safe only because the buffers will 
   * already be aligned properly, so jmemmgr.c won't need to do any I/O. 
   */ 
  for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 
    compptr = cinfo->cur_comp_info[ci]; 
    buffer[ci] = (*cinfo->mem->access_virt_barray) 
      ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index], 
       coef->iMCU_row_num * compptr->v_samp_factor, 
       (JDIMENSION) compptr->v_samp_factor, FALSE); 
  } 
 
  /* Loop to process one whole iMCU row */ 
  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 
       yoffset++) { 
    for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row; 
	 MCU_col_num++) { 
      /* Construct list of pointers to DCT blocks belonging to this MCU */ 
      blkn = 0;			/* index of current DCT block within MCU */ 
      for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 
	compptr = cinfo->cur_comp_info[ci]; 
	start_col = MCU_col_num * compptr->MCU_width; 
	for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 
	  buffer_ptr = buffer[ci][yindex+yoffset] + start_col; 
	  for (xindex = 0; xindex < compptr->MCU_width; xindex++) { 
	    coef->MCU_buffer[blkn++] = buffer_ptr++; 
	  } 
	} 
      } 
      /* Try to write the MCU. */ 
      if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) { 
	/* Suspension forced; update state counters and exit */ 
	coef->MCU_vert_offset = yoffset; 
	coef->mcu_ctr = MCU_col_num; 
	return FALSE; 
      } 
    } 
    /* Completed an MCU row, but perhaps not an iMCU row */ 
    coef->mcu_ctr = 0; 
  } 
  /* Completed the iMCU row, advance counters for next one */ 
  coef->iMCU_row_num++; 
  start_iMCU_row(cinfo); 
  return TRUE; 
} 
 
#endif /* FULL_COEF_BUFFER_SUPPORTED */ 
 
 
/* 
 * Initialize coefficient buffer controller. 
 */ 
 
GLOBAL(void) 
jinit_c_coef_controller (j_compress_ptr cinfo, boolean need_full_buffer) 
{ 
  my_coef_ptr coef; 
 
  coef = (my_coef_ptr) 
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 
				SIZEOF(my_coef_controller)); 
  cinfo->coef = (struct jpeg_c_coef_controller *) coef; 
  coef->pub.start_pass = start_pass_coef; 
 
  /* Create the coefficient buffer. */ 
  if (need_full_buffer) { 
#ifdef FULL_COEF_BUFFER_SUPPORTED 
    /* Allocate a full-image virtual array for each component, */ 
    /* padded to a multiple of samp_factor DCT blocks in each direction. */ 
    int ci; 
    jpeg_component_info *compptr; 
 
    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 
	 ci++, compptr++) { 
      coef->whole_image[ci] = (*cinfo->mem->request_virt_barray) 
	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE, 
	 (JDIMENSION) jround_up((long) compptr->width_in_blocks, 
				(long) compptr->h_samp_factor), 
	 (JDIMENSION) jround_up((long) compptr->height_in_blocks, 
				(long) compptr->v_samp_factor), 
	 (JDIMENSION) compptr->v_samp_factor); 
    } 
#else 
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 
#endif 
  } else { 
    /* We only need a single-MCU buffer. */ 
    JBLOCKROW buffer; 
    int i; 
 
    buffer = (JBLOCKROW) 
      (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, 
				  C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)); 
    for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) { 
      coef->MCU_buffer[i] = buffer + i; 
    } 
    coef->whole_image[0] = NULL; /* flag for no virtual arrays */ 
  } 
} 
