/* * jdcoefct.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 decompression. * This controller is the top level of the JPEG decompressor proper. * The coefficient buffer lies between entropy decoding and inverse-DCT steps. * * In buffered-image mode, this controller is the interface between * input-oriented processing and output-oriented processing. * Also, the input side (only) is used when reading a file for transcoding. */#define JPEG_INTERNALS#include "jinclude.h"#include "jpeglib.h"/* Block smoothing is only applicable for progressive JPEG, so: */#ifndef D_PROGRESSIVE_SUPPORTED#undef BLOCK_SMOOTHING_SUPPORTED#endif/* Private buffer controller object */typedef struct {  struct jpeg_d_coef_controller pub; /* public fields */  /* These variables keep track of the current location of the input side. */  /* cinfo->input_iMCU_row is also used for this. */  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 */  /* The output side's location is represented by cinfo->output_iMCU_row. */  /* In single-pass modes, it's sufficient to buffer just one MCU.   * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks,   * and let the entropy decoder write into that workspace each time.   * (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; it is used only by the input side.   */  JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];#ifdef D_MULTISCAN_FILES_SUPPORTED  /* In multi-pass modes, we need a virtual block array for each component. */  jvirt_barray_ptr whole_image[MAX_COMPONENTS];#endif#ifdef BLOCK_SMOOTHING_SUPPORTED  /* When doing block smoothing, we latch coefficient Al values here */  int * coef_bits_latch;#define SAVED_COEFS  6		/* we save coef_bits[0..5] */#endif} my_coef_controller;typedef my_coef_controller * my_coef_ptr;/* Forward declarations */METHODDEF(int) decompress_onepass	JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));#ifdef D_MULTISCAN_FILES_SUPPORTEDMETHODDEF(int) decompress_data	JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));#endif#ifdef BLOCK_SMOOTHING_SUPPORTEDLOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo));METHODDEF(int) decompress_smooth_data	JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));#endifLOCAL(void)start_iMCU_row (j_decompress_ptr cinfo)/* Reset within-iMCU-row counters for a new row (input side) */{  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 (cinfo->input_iMCU_row < (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 an input processing pass. */METHODDEF(void)start_input_pass (j_decompress_ptr cinfo){  cinfo->input_iMCU_row = 0;  start_iMCU_row(cinfo);}/* * Initialize for an output processing pass. */METHODDEF(void)start_output_pass (j_decompress_ptr cinfo){#ifdef BLOCK_SMOOTHING_SUPPORTED  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;  /* If multipass, check to see whether to use block smoothing on this pass */  if (coef->pub.coef_arrays != NULL) {    if (cinfo->do_block_smoothing && smoothing_ok(cinfo))      coef->pub.decompress_data = decompress_smooth_data;    else      coef->pub.decompress_data = decompress_data;  }#endif  cinfo->output_iMCU_row = 0;}/* * Decompress and return some data in the single-pass case. * Always attempts to emit one fully interleaved MCU row ("iMCU" row). * Input and output must run in lockstep since we have only a one-MCU buffer. * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. * * NB: output_buf contains a plane for each component in image, * which we index according to the component's SOF position. */METHODDEF(int)decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_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, ci, xindex, yindex, yoffset, useful_width;  JSAMPARRAY output_ptr;  JDIMENSION start_col, output_col;  jpeg_component_info *compptr;  inverse_DCT_method_ptr inverse_DCT;  /* Loop to process 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++) {      /* Try to fetch an MCU.  Entropy decoder expects buffer to be zeroed. */      jzero_far((void FAR *) coef->MCU_buffer[0],		(size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK)));      if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {	/* Suspension forced; update state counters and exit */	coef->MCU_vert_offset = yoffset;	coef->MCU_ctr = MCU_col_num;	return JPEG_SUSPENDED;      }      /* Determine where data should go in output_buf and do the IDCT thing.       * We skip dummy blocks at the right and bottom edges (but blkn gets       * incremented past them!).  Note the inner loop relies on having       * allocated the MCU_buffer[] blocks sequentially.       */      blkn = 0;			/* index of current DCT block within MCU */      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {	compptr = cinfo->cur_comp_info[ci];	/* Don't bother to IDCT an uninteresting component. */	if (! compptr->component_needed) {	  blkn += compptr->MCU_blocks;	  continue;	}	inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];	useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width						    : compptr->last_col_width;	output_ptr = output_buf[compptr->component_index] +	  yoffset * compptr->DCT_scaled_size;	start_col = MCU_col_num * compptr->MCU_sample_width;	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {	  if (cinfo->input_iMCU_row < last_iMCU_row ||	      yoffset+yindex < compptr->last_row_height) {	    output_col = start_col;	    for (xindex = 0; xindex < useful_width; xindex++) {	      (*inverse_DCT) (cinfo, compptr,			      (JCOEFPTR) coef->MCU_buffer[blkn+xindex],			      output_ptr, output_col);	      output_col += compptr->DCT_scaled_size;	    }	  }	  blkn += compptr->MCU_width;	  output_ptr += compptr->DCT_scaled_size;	}      }    }    /* Completed an MCU row, but perhaps not an iMCU row */    coef->MCU_ctr = 0;  }  /* Completed the iMCU row, advance counters for next one */  cinfo->output_iMCU_row++;  if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {    start_iMCU_row(cinfo);    return JPEG_ROW_COMPLETED;  }  /* Completed the scan */  (*cinfo->inputctl->finish_input_pass) (cinfo);  return JPEG_SCAN_COMPLETED;}/* * Dummy consume-input routine for single-pass operation. */METHODDEF(int)dummy_consume_data (j_decompress_ptr cinfo){  return JPEG_SUSPENDED;	/* Always indicate nothing was done */}#ifdef D_MULTISCAN_FILES_SUPPORTED/* * Consume input data and store it in the full-image coefficient buffer. * We read as much as one fully interleaved MCU row ("iMCU" row) per call, * ie, v_samp_factor block rows for each component in the scan. * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. */METHODDEF(int)consume_data (j_decompress_ptr cinfo){  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. */  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],       cinfo->input_iMCU_row * compptr->v_samp_factor,       (JDIMENSION) compptr->v_samp_factor, TRUE);    /* Note: entropy decoder expects buffer to be zeroed,     * but this is handled automatically by the memory manager     * because we requested a pre-zeroed array.     */  }  /* 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 fetch the MCU. */      if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {	/* Suspension forced; update state counters and exit */	coef->MCU_vert_offset = yoffset;	coef->MCU_ctr = MCU_col_num;	return JPEG_SUSPENDED;      }    }    /* Completed an MCU row, but perhaps not an iMCU row */    coef->MCU_ctr = 0;  }  /* Completed the iMCU row, advance counters for next one */  if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {    start_iMCU_row(cinfo);    return JPEG_ROW_COMPLETED;  }  /* Completed the scan */  (*cinfo->inputctl->finish_input_pass) (cinfo);  return JPEG_SCAN_COMPLETED;}/* * Decompress and return some data in the multi-pass case. * Always attempts to emit one fully interleaved MCU row ("iMCU" row). * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. * * NB: output_buf contains a plane for each component in image. */METHODDEF(int)decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf){  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;  JDIMENSION block_num;  int ci, block_row, block_rows;  JBLOCKARRAY buffer;  JBLOCKROW buffer_ptr;  JSAMPARRAY output_ptr;  JDIMENSION output_col;  jpeg_component_info *compptr;  inverse_DCT_method_ptr inverse_DCT;  /* Force some input to be done if we are getting ahead of the input. */  while (cinfo->input_scan_number < cinfo->output_scan_number ||	 (cinfo->input_scan_number == cinfo->output_scan_number &&	  cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {    if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)      return JPEG_SUSPENDED;  }  /* OK, output from the virtual arrays. */  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;       ci++, compptr++) {    /* Don't bother to IDCT an uninteresting component. */    if (! compptr->component_needed)      continue;    /* Align the virtual buffer for this component. */    buffer = (*cinfo->mem->access_virt_barray)      ((j_common_ptr) cinfo, coef->whole_image[ci],       cinfo->output_iMCU_row * compptr->v_samp_factor,       (JDIMENSION) compptr->v_samp_factor, FALSE);    /* Count non-dummy DCT block rows in this iMCU row. */    if (cinfo->output_iMCU_row < last_iMCU_row)      block_rows = compptr->v_samp_factor;    else {      /* NB: can't use last_row_height here; it is input-side-dependent! */      block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);      if (block_rows == 0) block_rows = compptr->v_samp_factor;    }    inverse_DCT = cinfo->idct->inverse_DCT[ci];    output_ptr = output_buf[ci];    /* Loop over all DCT blocks to be processed. */    for (block_row = 0; block_row < block_rows; block_row++) {      buffer_ptr = buffer[block_row];      output_col = 0;      for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) {	(*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,			output_ptr, output_col);	buffer_ptr++;	output_col += compptr->DCT_scaled_size;      }      output_ptr += compptr->DCT_scaled_size;    }  }