/*

 * jcmaster.c

 *

 * Copyright (C) 1991-1997, Thomas G. Lane.

 * Modified 2003-2020 by Guido Vollbeding.

 * 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 master control logic for the JPEG compressor.

 * These routines are concerned with parameter validation, initial setup,

 * and inter-pass control (determining the number of passes and the work 

 * to be done in each pass).

 */

#define JPEG_INTERNALS

#include "jinclude.h"

#include "jpeglib.h"

/* Private state */

typedef enum {

  main_pass,    /* input data, also do first output step */

  huff_opt_pass,    /* Huffman code optimization pass */

  output_pass   /* data output pass */

} c_pass_type;

typedef struct {

  struct jpeg_comp_master pub;  /* public fields */

  c_pass_type pass_type;  /* the type of the current pass */

  int pass_number;    /* # of passes completed */

  int total_passes;   /* total # of passes needed */

  int scan_number;    /* current index in scan_info[] */

} my_comp_master;

typedef my_comp_master * my_master_ptr;

/*

 * Support routines that do various essential calculations.

 */

LOCAL(void)

initial_setup (j_compress_ptr cinfo)

/* Do computations that are needed before master selection phase */

{

  int ci, ssize;

  jpeg_component_info *compptr;

  /* Sanity check on block_size */

  if (cinfo->block_size < 1 || cinfo->block_size > 16)

    ERREXIT2(cinfo, JERR_BAD_DCTSIZE, cinfo->block_size, cinfo->block_size);

  /* Derive natural_order from block_size */

  switch (cinfo->block_size) {

  case 2: cinfo->natural_order = jpeg_natural_order2; break;

  case 3: cinfo->natural_order = jpeg_natural_order3; break;

  case 4: cinfo->natural_order = jpeg_natural_order4; break;

  case 5: cinfo->natural_order = jpeg_natural_order5; break;

  case 6: cinfo->natural_order = jpeg_natural_order6; break;

  case 7: cinfo->natural_order = jpeg_natural_order7; break;

  default: cinfo->natural_order = jpeg_natural_order;

  }

  /* Derive lim_Se from block_size */

  cinfo->lim_Se = cinfo->block_size < DCTSIZE ?

    cinfo->block_size * cinfo->block_size - 1 : DCTSIZE2-1;

  /* Sanity check on image dimensions */

  if (cinfo->jpeg_height <= 0 || cinfo->jpeg_width <= 0 ||

      cinfo->num_components <= 0)

    ERREXIT(cinfo, JERR_EMPTY_IMAGE);

  /* Make sure image isn't bigger than I can handle */

  if ((long) cinfo->jpeg_height > (long) JPEG_MAX_DIMENSION ||

      (long) cinfo->jpeg_width > (long) JPEG_MAX_DIMENSION)

    ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);

  /* Only 8 to 12 bits data precision are supported for DCT based JPEG */

  if (cinfo->data_precision < 8 || cinfo->data_precision > 12)

    ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);

  /* Check that number of components won't exceed internal array sizes */

  if (cinfo->num_components > MAX_COMPONENTS)

    ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,

       MAX_COMPONENTS);

  /* Compute maximum sampling factors; check factor validity */

  cinfo->max_h_samp_factor = 1;

  cinfo->max_v_samp_factor = 1;

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

       ci++, compptr++) {

    if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||

  compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)

      ERREXIT(cinfo, JERR_BAD_SAMPLING);

    cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,

           compptr->h_samp_factor);

    cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,

           compptr->v_samp_factor);

  }

  /* Compute dimensions of components */

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

       ci++, compptr++) {

    /* Fill in the correct component_index value; don't rely on application */

    compptr->component_index = ci;

    /* In selecting the actual DCT scaling for each component, we try to

     * scale down the chroma components via DCT scaling rather than downsampling.

     * This saves time if the downsampler gets to use 1:1 scaling.

     * Note this code adapts subsampling ratios which are powers of 2.

     */

    ssize = 1;

#ifdef DCT_SCALING_SUPPORTED

    if (! cinfo->raw_data_in)

      while (cinfo->min_DCT_h_scaled_size * ssize <=

       (cinfo->do_fancy_downsampling ? DCTSIZE : DCTSIZE / 2) &&

       (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) ==

       0) {

  ssize = ssize * 2;

      }

#endif

    compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;

    ssize = 1;

#ifdef DCT_SCALING_SUPPORTED

    if (! cinfo->raw_data_in)

      while (cinfo->min_DCT_v_scaled_size * ssize <=

       (cinfo->do_fancy_downsampling ? DCTSIZE : DCTSIZE / 2) &&

       (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) ==

       0) {

  ssize = ssize * 2;

      }

#endif

    compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;

    /* We don't support DCT ratios larger than 2. */

    if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)

  compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;

    else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)

  compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;

    /* Size in DCT blocks */

    compptr->width_in_blocks = (JDIMENSION)

      jdiv_round_up((long) cinfo->jpeg_width * (long) compptr->h_samp_factor,

        (long) (cinfo->max_h_samp_factor * cinfo->block_size));

    compptr->height_in_blocks = (JDIMENSION)

      jdiv_round_up((long) cinfo->jpeg_height * (long) compptr->v_samp_factor,

        (long) (cinfo->max_v_samp_factor * cinfo->block_size));

    /* Size in samples */

    compptr->downsampled_width = (JDIMENSION)

      jdiv_round_up((long) cinfo->jpeg_width *

        (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size),

        (long) (cinfo->max_h_samp_factor * cinfo->block_size));

    compptr->downsampled_height = (JDIMENSION)

      jdiv_round_up((long) cinfo->jpeg_height *

        (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),

        (long) (cinfo->max_v_samp_factor * cinfo->block_size));

    /* Don't need quantization scale after DCT,

     * until color conversion says otherwise.

     */

    compptr->component_needed = FALSE;

  }

  /* Compute number of fully interleaved MCU rows (number of times that

   * main controller will call coefficient controller).

   */

  cinfo->total_iMCU_rows = (JDIMENSION)

    jdiv_round_up((long) cinfo->jpeg_height,

      (long) (cinfo->max_v_samp_factor * cinfo->block_size));

}

#ifdef C_MULTISCAN_FILES_SUPPORTED

LOCAL(void)

validate_script (j_compress_ptr cinfo)

/* Verify that the scan script in cinfo->scan_info[] is valid; also

 * determine whether it uses progressive JPEG, and set cinfo->progressive_mode.

 */

{

  const jpeg_scan_info * scanptr;

  int scanno, ncomps, ci, coefi, thisi;

  int Ss, Se, Ah, Al;

  boolean component_sent[MAX_COMPONENTS];

#ifdef C_PROGRESSIVE_SUPPORTED

  int * last_bitpos_ptr;

  int last_bitpos[MAX_COMPONENTS][DCTSIZE2];

  /* -1 until that coefficient has been seen; then last Al for it */

#endif

  if (cinfo->num_scans <= 0)

    ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, 0);

  /* For sequential JPEG, all scans must have Ss=0, Se=DCTSIZE2-1;

   * for progressive JPEG, no scan can have this.

   */

  scanptr = cinfo->scan_info;

  if (scanptr->Ss != 0 || scanptr->Se != DCTSIZE2-1) {

#ifdef C_PROGRESSIVE_SUPPORTED

    cinfo->progressive_mode = TRUE;

    last_bitpos_ptr = & last_bitpos[0][0];

    for (ci = 0; ci < cinfo->num_components; ci++) 

      for (coefi = 0; coefi < DCTSIZE2; coefi++)

  *last_bitpos_ptr++ = -1;

#else

    ERREXIT(cinfo, JERR_NOT_COMPILED);

#endif

  } else {

    cinfo->progressive_mode = FALSE;

    for (ci = 0; ci < cinfo->num_components; ci++) 

      component_sent[ci] = FALSE;

  }

  for (scanno = 1; scanno <= cinfo->num_scans; scanptr++, scanno++) {

    /* Validate component indexes */

    ncomps = scanptr->comps_in_scan;

    if (ncomps <= 0 || ncomps > MAX_COMPS_IN_SCAN)

      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, ncomps, MAX_COMPS_IN_SCAN);

    for (ci = 0; ci < ncomps; ci++) {

      thisi = scanptr->component_index[ci];

      if (thisi < 0 || thisi >= cinfo->num_components)

  ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);

      /* Components must appear in SOF order within each scan */

      if (ci > 0 && thisi <= scanptr->component_index[ci-1])

  ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);

    }

    /* Validate progression parameters */

    Ss = scanptr->Ss;

    Se = scanptr->Se;

    Ah = scanptr->Ah;

    Al = scanptr->Al;

    if (cinfo->progressive_mode) {

#ifdef C_PROGRESSIVE_SUPPORTED

      /* The JPEG spec simply gives the ranges 0..13 for Ah and Al, but that

       * seems wrong: the upper bound ought to depend on data precision.

       * Perhaps they really meant 0..N+1 for N-bit precision.

       * Here we allow 0..10 for 8-bit data; Al larger than 10 results in

       * out-of-range reconstructed DC values during the first DC scan,

       * which might cause problems for some decoders.

       */

      if (Ss < 0 || Ss >= DCTSIZE2 || Se < Ss || Se >= DCTSIZE2 ||

    Ah < 0 || Ah > (cinfo->data_precision > 8 ? 13 : 10) ||

    Al < 0 || Al > (cinfo->data_precision > 8 ? 13 : 10))

  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);

      if (Ss == 0) {

  if (Se != 0)    /* DC and AC together not OK */

    ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);

      } else {

  if (ncomps != 1)  /* AC scans must be for only one component */

    ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);

      }

      for (ci = 0; ci < ncomps; ci++) {

  last_bitpos_ptr = & last_bitpos[scanptr->component_index[ci]][0];

  if (Ss != 0 && last_bitpos_ptr[0] < 0) /* AC without prior DC scan */

    ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);

  for (coefi = Ss; coefi <= Se; coefi++) {

    if (last_bitpos_ptr[coefi] < 0) {

      /* first scan of this coefficient */

      if (Ah != 0)

        ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);

    } else {

      /* not first scan */

      if (Ah != last_bitpos_ptr[coefi] || Al != Ah-1)

        ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);

    }

    last_bitpos_ptr[coefi] = Al;

  }

      }

#endif

    } else {

      /* For sequential JPEG, all progression parameters must be these: */

      if (Ss != 0 || Se != DCTSIZE2-1 || Ah != 0 || Al != 0)

  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);

      /* Make sure components are not sent twice */

      for (ci = 0; ci < ncomps; ci++) {

  thisi = scanptr->component_index[ci];

  if (component_sent[thisi])

    ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);

  component_sent[thisi] = TRUE;

      }

    }

  }

  /* Now verify that everything got sent. */

  if (cinfo->progressive_mode) {

#ifdef C_PROGRESSIVE_SUPPORTED

    /* For progressive mode, we only check that at least some DC data

     * got sent for each component; the spec does not require that all bits

     * of all coefficients be transmitted.  Would it be wiser to enforce

     * transmission of all coefficient bits??

     */

    for (ci = 0; ci < cinfo->num_components; ci++) {

      if (last_bitpos[ci][0] < 0)

  ERREXIT(cinfo, JERR_MISSING_DATA);

    }

#endif

  } else {

    for (ci = 0; ci < cinfo->num_components; ci++) {

      if (! component_sent[ci])

  ERREXIT(cinfo, JERR_MISSING_DATA);

    }

  }

}

LOCAL(void)

reduce_script (j_compress_ptr cinfo)

/* Adapt scan script for use with reduced block size;

 * assume that script has been validated before.

 */

{

  jpeg_scan_info * scanptr;

  int idxout, idxin;

  /* Circumvent const declaration for this function */

  scanptr = (jpeg_scan_info *) cinfo->scan_info;

  idxout = 0;

  for (idxin = 0; idxin < cinfo->num_scans; idxin++) {

    /* After skipping, idxout becomes smaller than idxin */

    if (idxin != idxout)

      /* Copy rest of data;

       * note we stay in given chunk of allocated memory.

       */

      scanptr[idxout] = scanptr[idxin];

    if (scanptr[idxout].Ss > cinfo->lim_Se)

      /* Entire scan out of range - skip this entry */

      continue;

    if (scanptr[idxout].Se > cinfo->lim_Se)

      /* Limit scan to end of block */

      scanptr[idxout].Se = cinfo->lim_Se;

    idxout++;

  }

  cinfo->num_scans = idxout;

}

#endif /* C_MULTISCAN_FILES_SUPPORTED */

LOCAL(void)

select_scan_parameters (j_compress_ptr cinfo)

/* Set up the scan parameters for the current scan */

{

  int ci;

#ifdef C_MULTISCAN_FILES_SUPPORTED

  if (cinfo->scan_info != NULL) {

    /* Prepare for current scan --- the script is already validated */

    my_master_ptr master = (my_master_ptr) cinfo->master;

    const jpeg_scan_info * scanptr = cinfo->scan_info + master->scan_number;

    cinfo->comps_in_scan = scanptr->comps_in_scan;

    for (ci = 0; ci < scanptr->comps_in_scan; ci++) {

      cinfo->cur_comp_info[ci] =

  &cinfo->comp_info[scanptr->component_index[ci]];

    }

    if (cinfo->progressive_mode) {

      cinfo->Ss = scanptr->Ss;

      cinfo->Se = scanptr->Se;

      cinfo->Ah = scanptr->Ah;

      cinfo->Al = scanptr->Al;

      return;

    }

  }

  else

#endif

  {

    /* Prepare for single sequential-JPEG scan containing all components */

    if (cinfo->num_components > MAX_COMPS_IN_SCAN)

      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,

         MAX_COMPS_IN_SCAN);

    cinfo->comps_in_scan = cinfo->num_components;

    for (ci = 0; ci < cinfo->num_components; ci++) {

      cinfo->cur_comp_info[ci] = &cinfo->comp_info[ci];

    }

  }

  cinfo->Ss = 0;

  cinfo->Se = cinfo->block_size * cinfo->block_size - 1;

  cinfo->Ah = 0;

  cinfo->Al = 0;

}

LOCAL(void)

per_scan_setup (j_compress_ptr cinfo)

/* Do computations that are needed before processing a JPEG scan */

/* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */

{

  int ci, mcublks, tmp;

  jpeg_component_info *compptr;

  if (cinfo->comps_in_scan == 1) {

    /* Noninterleaved (single-component) scan */

    compptr = cinfo->cur_comp_info[0];

    /* Overall image size in MCUs */

    cinfo->MCUs_per_row = compptr->width_in_blocks;

    cinfo->MCU_rows_in_scan = compptr->height_in_blocks;

    /* For noninterleaved scan, always one block per MCU */

    compptr->MCU_width = 1;

    compptr->MCU_height = 1;

    compptr->MCU_blocks = 1;

    compptr->MCU_sample_width = compptr->DCT_h_scaled_size;

    compptr->last_col_width = 1;

    /* For noninterleaved scans, it is convenient to define last_row_height

     * as the number of block rows present in the last iMCU row.

     */

    tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);

    if (tmp == 0) tmp = compptr->v_samp_factor;

    compptr->last_row_height = tmp;

    /* Prepare array describing MCU composition */

    cinfo->blocks_in_MCU = 1;

    cinfo->MCU_membership[0] = 0;

  } else {

    /* Interleaved (multi-component) scan */

    if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)

      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,

         MAX_COMPS_IN_SCAN);

    /* Overall image size in MCUs */

    cinfo->MCUs_per_row = (JDIMENSION)

      jdiv_round_up((long) cinfo->jpeg_width,

        (long) (cinfo->max_h_samp_factor * cinfo->block_size));

    cinfo->MCU_rows_in_scan = cinfo->total_iMCU_rows;

    cinfo->blocks_in_MCU = 0;

    for (ci = 0; ci < cinfo->comps_in_scan; ci++) {

      compptr = cinfo->cur_comp_info[ci];

      /* Sampling factors give # of blocks of component in each MCU */

      compptr->MCU_width = compptr->h_samp_factor;

      compptr->MCU_height = compptr->v_samp_factor;

      compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;

      compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_h_scaled_size;

      /* Figure number of non-dummy blocks in last MCU column & row */

      tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);

      if (tmp == 0) tmp = compptr->MCU_width;

      compptr->last_col_width = tmp;

      tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);

      if (tmp == 0) tmp = compptr->MCU_height;

      compptr->last_row_height = tmp;

      /* Prepare array describing MCU composition */

      mcublks = compptr->MCU_blocks;

      if (cinfo->blocks_in_MCU + mcublks > C_MAX_BLOCKS_IN_MCU)

  ERREXIT(cinfo, JERR_BAD_MCU_SIZE);

      while (mcublks-- > 0) {

  cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;

      }

    }

  }

  /* Convert restart specified in rows to actual MCU count. */

  /* Note that count must fit in 16 bits, so we provide limiting. */

  if (cinfo->restart_in_rows > 0) {

    long nominal = (long) cinfo->restart_in_rows * (long) cinfo->MCUs_per_row;

    cinfo->restart_interval = (unsigned int) MIN(nominal, 65535L);

  }

}

/*

 * Per-pass setup.

 * This is called at the beginning of each pass.  We determine which modules

 * will be active during this pass and give them appropriate start_pass calls.

 * We also set is_last_pass to indicate whether any more passes will be

 * required.

 */

METHODDEF(void)

prepare_for_pass (j_compress_ptr cinfo)

{

  my_master_ptr master = (my_master_ptr) cinfo->master;

  switch (master->pass_type) {

  case main_pass:

    /* Initial pass: will collect input data, and do either Huffman

     * optimization or data output for the first scan.

     */

    select_scan_parameters(cinfo);

    per_scan_setup(cinfo);

    if (! cinfo->raw_data_in) {

      (*cinfo->cconvert->start_pass) (cinfo);

      (*cinfo->downsample->start_pass) (cinfo);

      (*cinfo->prep->start_pass) (cinfo, JBUF_PASS_THRU);

    }

    (*cinfo->fdct->start_pass) (cinfo);

    (*cinfo->entropy->start_pass) (cinfo, cinfo->optimize_coding);

    (*cinfo->coef->start_pass) (cinfo,

        (master->total_passes > 1 ?

         JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));

    (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);

    if (cinfo->optimize_coding) {

      /* No immediate data output; postpone writing frame/scan headers */

      master->pub.call_pass_startup = FALSE;

    } else {

      /* Will write frame/scan headers at first jpeg_write_scanlines call */

      master->pub.call_pass_startup = TRUE;

    }

    break;

#ifdef ENTROPY_OPT_SUPPORTED

  case huff_opt_pass:

    /* Do Huffman optimization for a scan after the first one. */

    select_scan_parameters(cinfo);

    per_scan_setup(cinfo);

    if (cinfo->Ss != 0 || cinfo->Ah == 0) {

      (*cinfo->entropy->start_pass) (cinfo, TRUE);

      (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);

      master->pub.call_pass_startup = FALSE;

      break;

    }

    /* Special case: Huffman DC refinement scans need no Huffman table

     * and therefore we can skip the optimization pass for them.

     */

    master->pass_type = output_pass;

    master->pass_number++;

    /*FALLTHROUGH*/

#endif

  case output_pass:

    /* Do a data-output pass. */

    /* We need not repeat per-scan setup if prior optimization pass did it. */

    if (! cinfo->optimize_coding) {

      select_scan_parameters(cinfo);

      per_scan_setup(cinfo);

    }

    (*cinfo->entropy->start_pass) (cinfo, FALSE);

    (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);

    /* We emit frame/scan headers now */

    if (master->scan_number == 0)

      (*cinfo->marker->write_frame_header) (cinfo);

    (*cinfo->marker->write_scan_header) (cinfo);

    master->pub.call_pass_startup = FALSE;

    break;

  default:

    ERREXIT(cinfo, JERR_NOT_COMPILED);

  }

  master->pub.is_last_pass = (master->pass_number == master->total_passes-1);

  /* Set up progress monitor's pass info if present */

  if (cinfo->progress != NULL) {

    cinfo->progress->completed_passes = master->pass_number;

    cinfo->progress->total_passes = master->total_passes;

  }

}

/*

 * Special start-of-pass hook.

 * This is called by jpeg_write_scanlines if call_pass_startup is TRUE.

 * In single-pass processing, we need this hook because we don't want to

 * write frame/scan headers during jpeg_start_compress; we want to let the

 * application write COM markers etc. between jpeg_start_compress and the

 * jpeg_write_scanlines loop.

 * In multi-pass processing, this routine is not used.

 */

METHODDEF(void)

pass_startup (j_compress_ptr cinfo)

{

  cinfo->master->call_pass_startup = FALSE; /* reset flag so call only once */

  (*cinfo->marker->write_frame_header) (cinfo);

  (*cinfo->marker->write_scan_header) (cinfo);

}

/*

 * Finish up at end of pass.

 */

METHODDEF(void)

finish_pass_master (j_compress_ptr cinfo)

{

  my_master_ptr master = (my_master_ptr) cinfo->master;

  /* The entropy coder always needs an end-of-pass call,

   * either to analyze statistics or to flush its output buffer.

   */

  (*cinfo->entropy->finish_pass) (cinfo);

  /* Update state for next pass */

  switch (master->pass_type) {

  case main_pass:

    /* next pass is either output of scan 0 (after optimization)

     * or output of scan 1 (if no optimization).

     */

    master->pass_type = output_pass;

    if (! cinfo->optimize_coding)

      master->scan_number++;

    break;

  case huff_opt_pass:

    /* next pass is always output of current scan */

    master->pass_type = output_pass;

    break;

  case output_pass:

    /* next pass is either optimization or output of next scan */

    if (cinfo->optimize_coding)

      master->pass_type = huff_opt_pass;

    master->scan_number++;

    break;

  }

  master->pass_number++;

}

/*

 * Initialize master compression control.

 */

GLOBAL(void)

jinit_c_master_control (j_compress_ptr cinfo, boolean transcode_only)

{

  my_master_ptr master;

  master = (my_master_ptr) (*cinfo->mem->alloc_small)

    ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_comp_master));

  cinfo->master = &master->pub;

  master->pub.prepare_for_pass = prepare_for_pass;

  master->pub.pass_startup = pass_startup;

  master->pub.finish_pass = finish_pass_master;

  master->pub.is_last_pass = FALSE;

  /* Validate parameters, determine derived values */

  initial_setup(cinfo);

  if (cinfo->scan_info != NULL) {

#ifdef C_MULTISCAN_FILES_SUPPORTED

    validate_script(cinfo);

    if (cinfo->block_size < DCTSIZE)

      reduce_script(cinfo);

#else

    ERREXIT(cinfo, JERR_NOT_COMPILED);

#endif

  } else {

    cinfo->progressive_mode = FALSE;

    cinfo->num_scans = 1;

  }

  if (cinfo->optimize_coding)

    cinfo->arith_code = FALSE; /* disable arithmetic coding */

  else if (! cinfo->arith_code &&

     (cinfo->progressive_mode ||

      (cinfo->block_size > 1 && cinfo->block_size < DCTSIZE)))

    /* TEMPORARY HACK ??? */

    /* assume default tables no good for progressive or reduced AC mode */

    cinfo->optimize_coding = TRUE; /* force Huffman optimization */

  /* Initialize my private state */

  if (transcode_only) {

    /* no main pass in transcoding */

    if (cinfo->optimize_coding)

      master->pass_type = huff_opt_pass;

    else

      master->pass_type = output_pass;

  } else {

    /* for normal compression, first pass is always this type: */

    master->pass_type = main_pass;

  }

  master->scan_number = 0;

  master->pass_number = 0;

  if (cinfo->optimize_coding)

    master->total_passes = cinfo->num_scans * 2;

  else

    master->total_passes = cinfo->num_scans;

}