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 /*

  * 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 */

   }

 }