    /*
     * jcparam.c
     *
     * Copyright (C) 1991-1998, 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 optional default-setting code for the JPEG compressor.
     * Applications do not have to use this file, but those that don't use it
     * must know a lot more about the innards of the JPEG code.
     */

    #define JPEG_INTERNALS
    #include "jinclude.h"
    #include "jpeglib.h"

    /*
     * Quantization table setup routines
     */

    GLOBAL(void)
    jpeg_add_quant_table (j_compress_ptr cinfo, int which_tbl,
    		      const unsigned int *basic_table,
    		      int scale_factor, int force_baseline)
    /* Define a quantization table equal to the basic_table times
     * a scale factor (given as a percentage).
     * If force_baseline is TRUE, the computed quantization table entries
     * are limited to 1..255 for JPEG baseline compatibility.
     */
    {
      JQUANT_TBL ** qtblptr;
      int i;
      long temp;

      /* Safety check to ensure start_compress not called yet. */
      if (cinfo->global_state != CSTATE_START)
        ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

      if (which_tbl < 0 || which_tbl >= NUM_QUANT_TBLS)
        ERREXIT1(cinfo, JERR_DQT_INDEX, which_tbl);

      qtblptr = & cinfo->quant_tbl_ptrs[which_tbl];

      if (*qtblptr == NULL)
        *qtblptr = jpeg_alloc_quant_table((j_common_ptr) cinfo);

      for (i = 0; i < DCTSIZE2; i++) {
        temp = ((long) basic_table[i] * scale_factor + 50L) / 100L;
        /* limit the values to the valid range */
        if (temp <= 0L) temp = 1L;
        if (temp > 32767L) temp = 32767L; /* max quantizer needed for 12 bits */
        if (force_baseline && temp > 255L)
          temp = 255L;		/* limit to baseline range if requested */
        (*qtblptr)->quantval[i] = (unsigned short) temp;
      }

      /* Initialize sent_table FALSE so table will be written to JPEG file. */
      (*qtblptr)->sent_table = FALSE;
    }

    GLOBAL(void)
    jpeg_set_linear_quality (j_compress_ptr cinfo, int scale_factor,
    			 int force_baseline)
    /* Set or change the 'quality' (quantization) setting, using default tables
     * and a straight percentage-scaling quality scale.  In most cases it's better
     * to use jpeg_set_quality (below); this entry point is provided for
     * applications that insist on a linear percentage scaling.
     */
    {
      /* These are the sample quantization tables given in JPEG spec section K.1.
       * The spec says that the values given produce "good" quality, and
       * when divided by 2, "very good" quality.
       */
      static const unsigned int std_luminance_quant_tbl[DCTSIZE2] = {
        16,  11,  10,  16,  24,  40,  51,  61,
        12,  12,  14,  19,  26,  58,  60,  55,
        14,  13,  16,  24,  40,  57,  69,  56,
        14,  17,  22,  29,  51,  87,  80,  62,
        18,  22,  37,  56,  68, 109, 103,  77,
        24,  35,  55,  64,  81, 104, 113,  92,
        49,  64,  78,  87, 103, 121, 120, 101,
        72,  92,  95,  98, 112, 100, 103,  99
      };
      static const unsigned int std_chrominance_quant_tbl[DCTSIZE2] = {
        17,  18,  24,  47,  99,  99,  99,  99,
        18,  21,  26,  66,  99,  99,  99,  99,
        24,  26,  56,  99,  99,  99,  99,  99,
        47,  66,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99
      };

      /* Set up two quantization tables using the specified scaling */
      jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl,
    		       scale_factor, force_baseline);
      jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl,
    		       scale_factor, force_baseline);
    }

    GLOBAL(int)
    jpeg_quality_scaling (int quality)
    /* Convert a user-specified quality rating to a percentage scaling factor
     * for an underlying quantization table, using our recommended scaling curve.
     * The input 'quality' factor should be 0 (terrible) to 100 (very good).
     */
    {
      /* Safety limit on quality factor.  Convert 0 to 1 to avoid zero divide. */
      if (quality <= 0) quality = 1;
      if (quality > 100) quality = 100;

      /* The basic table is used as-is (scaling 100) for a quality of 50.
       * Qualities 50..100 are converted to scaling percentage 200 - 2*Q;
       * note that at Q=100 the scaling is 0, which will cause jpeg_add_quant_table
       * to make all the table entries 1 (hence, minimum quantization loss).
       * Qualities 1..50 are converted to scaling percentage 5000/Q.
       */
      if (quality < 50)
        quality = 5000 / quality;
      else
        quality = 200 - quality*2;

      return quality;
    }

    GLOBAL(void)
    jpeg_set_quality (j_compress_ptr cinfo, int quality, int force_baseline)
    /* Set or change the 'quality' (quantization) setting, using default tables.
     * This is the standard quality-adjusting entry point for typical user
     * interfaces; only those who want detailed control over quantization tables
     * would use the preceding three routines directly.
     */
    {
      /* Convert user 0-100 rating to percentage scaling */
      quality = jpeg_quality_scaling(quality);

      /* Set up standard quality tables */
      jpeg_set_linear_quality(cinfo, quality, force_baseline);
    }

    /*
     * Huffman table setup routines
     */

    LOCAL(void)
    add_huff_table (j_compress_ptr cinfo,
    		JHUFF_TBL **htblptr, const unsigned char *bits, const unsigned char *val)
    /* Define a Huffman table */
    {
      int nsymbols, len;

      if (*htblptr == NULL)
        *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);

      /* Copy the number-of-symbols-of-each-code-length counts */
      MEMCOPY((*htblptr)->bits, bits, SIZEOF((*htblptr)->bits));

      /* Validate the counts.  We do this here mainly so we can copy the right
       * number of symbols from the val[] array, without risking marching off
       * the end of memory.  jchuff.c will do a more thorough test later.
       */
      nsymbols = 0;
      for (len = 1; len <= 16; len++)
        nsymbols += bits[len];
      if (nsymbols < 1 || nsymbols > 256)
        ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);

      MEMCOPY((*htblptr)->huffval, val, nsymbols * SIZEOF(unsigned char));

      /* Initialize sent_table FALSE so table will be written to JPEG file. */
      (*htblptr)->sent_table = FALSE;
    }

    LOCAL(void)
    std_huff_tables (j_compress_ptr cinfo)
    /* Set up the standard Huffman tables (cf. JPEG standard section K.3) */
    /* IMPORTANT: these are only valid for 8-bit data precision! */
    {
      static const unsigned char bits_dc_luminance[17] =
        { /* 0-base */ 0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0 };
      static const unsigned char val_dc_luminance[] =
        { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };

      static const unsigned char bits_dc_chrominance[17] =
        { /* 0-base */ 0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };
      static const unsigned char val_dc_chrominance[] =
        { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };

      static const unsigned char bits_ac_luminance[17] =
        { /* 0-base */ 0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d };
      static const unsigned char val_ac_luminance[] =
        { 0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
          0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
          0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
          0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
          0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
          0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
          0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
          0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
          0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
          0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
          0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
          0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
          0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
          0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
          0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
          0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,
          0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,
          0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,
          0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
          0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
          0xf9, 0xfa };

      static const unsigned char bits_ac_chrominance[17] =
        { /* 0-base */ 0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77 };
      static const unsigned char val_ac_chrominance[] =
        { 0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
          0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
          0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
          0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
          0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,
          0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,
          0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,
          0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
          0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
          0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
          0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
          0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
          0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
          0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
          0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,
          0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,
          0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,
          0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,
          0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
          0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
          0xf9, 0xfa };

      add_huff_table(cinfo, &cinfo->dc_huff_tbl_ptrs[0],
    		 bits_dc_luminance, val_dc_luminance);
      add_huff_table(cinfo, &cinfo->ac_huff_tbl_ptrs[0],
    		 bits_ac_luminance, val_ac_luminance);
      add_huff_table(cinfo, &cinfo->dc_huff_tbl_ptrs[1],
    		 bits_dc_chrominance, val_dc_chrominance);
      add_huff_table(cinfo, &cinfo->ac_huff_tbl_ptrs[1],
    		 bits_ac_chrominance, val_ac_chrominance);
    }

    /*
     * Default parameter setup for compression.
     *
     * Applications that don't choose to use this routine must do their
     * own setup of all these parameters.  Alternately, you can call this
     * to establish defaults and then alter parameters selectively.  This
     * is the recommended approach since, if we add any new parameters,
     * your code will still work (they'll be set to reasonable defaults).
     */

    GLOBAL(void)
    jpeg_set_defaults (j_compress_ptr cinfo)
    {
      int i;

      /* Safety check to ensure start_compress not called yet. */
      if (cinfo->global_state != CSTATE_START)
        ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

      /* Allocate comp_info array large enough for maximum component count.
       * Array is made permanent in case application wants to compress
       * multiple images at same param settings.
       */
      if (cinfo->comp_info == NULL)
        cinfo->comp_info = (jpeg_component_info *)
          (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
    				  MAX_COMPONENTS * SIZEOF(jpeg_component_info));

      /* Initialize everything not dependent on the color space */

      cinfo->data_precision = BITS_IN_JSAMPLE;
      /* Set up two quantization tables using default quality of 75 */
      jpeg_set_quality(cinfo, 75, TRUE);
      /* Set up two Huffman tables */
      std_huff_tables(cinfo);

      /* Initialize default arithmetic coding conditioning */
      for (i = 0; i < NUM_ARITH_TBLS; i++) {
        cinfo->arith_dc_L[i] = 0;
        cinfo->arith_dc_U[i] = 1;
        cinfo->arith_ac_K[i] = 5;
      }

      /* Default is no multiple-scan output */
      cinfo->scan_info = NULL;
      cinfo->num_scans = 0;

      /* Expect normal source image, not raw downsampled data */
      cinfo->raw_data_in = FALSE;

      /* Use Huffman coding, not arithmetic coding, by default */
      cinfo->arith_code = FALSE;

      /* By default, don't do extra passes to optimize entropy coding */
      cinfo->optimize_coding = FALSE;
      /* The standard Huffman tables are only valid for 8-bit data precision.
       * If the precision is higher, force optimization on so that usable
       * tables will be computed.  This test can be removed if default tables
       * are supplied that are valid for the desired precision.
       */
      if (cinfo->data_precision > 8)
        cinfo->optimize_coding = TRUE;

      /* By default, use the simpler non-cosited sampling alignment */
      cinfo->CCIR601_sampling = FALSE;

      /* No input smoothing */
      cinfo->smoothing_factor = 0;

      /* DCT algorithm preference */
      cinfo->dct_method = JDCT_DEFAULT;

      /* No restart markers */
      cinfo->restart_interval = 0;
      cinfo->restart_in_rows = 0;

      /* Fill in default JFIF marker parameters.  Note that whether the marker
       * will actually be written is determined by jpeg_set_colorspace.
       *
       * By default, the library emits JFIF version code 1.01.
       * An application that wants to emit JFIF 1.02 extension markers should set
       * JFIF_minor_version to 2.  We could probably get away with just defaulting
       * to 1.02, but there may still be some decoders in use that will complain
       * about that; saying 1.01 should minimize compatibility problems.
       */
      cinfo->JFIF_major_version = 1; /* Default JFIF version = 1.01 */
      cinfo->JFIF_minor_version = 1;
      cinfo->density_unit = 0;	/* Pixel size is unknown by default */
      cinfo->X_density = 1;		/* Pixel aspect ratio is square by default */
      cinfo->Y_density = 1;

      /* Choose JPEG colorspace based on input space, set defaults accordingly */

      jpeg_default_colorspace(cinfo);
    }

    /*
     * Select an appropriate JPEG colorspace for in_color_space.
     */

    GLOBAL(void)
    jpeg_default_colorspace (j_compress_ptr cinfo)
    {
      switch (cinfo->in_color_space) {
      case JCS_GRAYSCALE:
        jpeg_set_colorspace(cinfo, JCS_GRAYSCALE);
        break;
      case JCS_RGB:
        jpeg_set_colorspace(cinfo, JCS_YCbCr);
        break;
      case JCS_YCbCr:
        jpeg_set_colorspace(cinfo, JCS_YCbCr);
        break;
      case JCS_CMYK:
        jpeg_set_colorspace(cinfo, JCS_CMYK); /* By default, no translation */
        break;
      case JCS_YCCK:
        jpeg_set_colorspace(cinfo, JCS_YCCK);
        break;
      case JCS_UNKNOWN:
        jpeg_set_colorspace(cinfo, JCS_UNKNOWN);
        break;
      default:
        ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
      }
    }

    /*
     * Set the JPEG colorspace, and choose colorspace-dependent default values.
     */

    GLOBAL(void)
    jpeg_set_colorspace (j_compress_ptr cinfo, J_COLOR_SPACE colorspace)
    {
      jpeg_component_info * compptr;
      int ci;

    #define SET_COMP(index,id,hsamp,vsamp,quant,dctbl,actbl)  \
      (compptr = &cinfo->comp_info[index], \
       compptr->component_id = (id), \
       compptr->h_samp_factor = (hsamp), \
       compptr->v_samp_factor = (vsamp), \
       compptr->quant_tbl_no = (quant), \
       compptr->dc_tbl_no = (dctbl), \
       compptr->ac_tbl_no = (actbl) )

      /* Safety check to ensure start_compress not called yet. */
      if (cinfo->global_state != CSTATE_START)
        ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

      /* For all colorspaces, we use Q and Huff tables 0 for luminance components,
       * tables 1 for chrominance components.
       */

      cinfo->jpeg_color_space = colorspace;

      cinfo->write_JFIF_header = FALSE; /* No marker for non-JFIF colorspaces */
      cinfo->write_Adobe_marker = FALSE; /* write no Adobe marker by default */

      switch (colorspace) {
      case JCS_GRAYSCALE:
        cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
        cinfo->num_components = 1;
        /* JFIF specifies component ID 1 */
        SET_COMP(0, 1, 1,1, 0, 0,0);
        break;
      case JCS_RGB:
        cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag RGB */
        cinfo->num_components = 3;
        SET_COMP(0, 0x52 /* 'R' */, 1,1, 0, 0,0);
        SET_COMP(1, 0x47 /* 'G' */, 1,1, 0, 0,0);
        SET_COMP(2, 0x42 /* 'B' */, 1,1, 0, 0,0);
        break;
      case JCS_YCbCr:
        cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
        cinfo->num_components = 3;
        /* JFIF specifies component IDs 1,2,3 */
        /* We default to 2x2 subsamples of chrominance */
        SET_COMP(0, 1, 2,2, 0, 0,0);
        SET_COMP(1, 2, 1,1, 1, 1,1);
        SET_COMP(2, 3, 1,1, 1, 1,1);
        break;
      case JCS_CMYK:
        cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag CMYK */
        cinfo->num_components = 4;
        SET_COMP(0, 0x43 /* 'C' */, 1,1, 0, 0,0);
        SET_COMP(1, 0x4D /* 'M' */, 1,1, 0, 0,0);
        SET_COMP(2, 0x59 /* 'Y' */, 1,1, 0, 0,0);
        SET_COMP(3, 0x4B /* 'K' */, 1,1, 0, 0,0);
        break;
      case JCS_YCCK:
        cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag YCCK */
        cinfo->num_components = 4;
        SET_COMP(0, 1, 2,2, 0, 0,0);
        SET_COMP(1, 2, 1,1, 1, 1,1);
        SET_COMP(2, 3, 1,1, 1, 1,1);
        SET_COMP(3, 4, 2,2, 0, 0,0);
        break;
      case JCS_UNKNOWN:
        cinfo->num_components = cinfo->input_components;
        if (cinfo->num_components < 1 || cinfo->num_components > MAX_COMPONENTS)
          ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
    	       MAX_COMPONENTS);
        for (ci = 0; ci < cinfo->num_components; ci++) {
          SET_COMP(ci, ci, 1,1, 0, 0,0);
        }
        break;
      default:
        ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
      }
    }

    #ifdef C_PROGRESSIVE_SUPPORTED

    LOCAL(jpeg_scan_info *)
    fill_a_scan (jpeg_scan_info * scanptr, int ci,
    	     int Ss, int Se, int Ah, int Al)
    /* Support routine: generate one scan for specified component */
    {
      scanptr->comps_in_scan = 1;
      scanptr->component_index[0] = ci;
      scanptr->Ss = Ss;
      scanptr->Se = Se;
      scanptr->Ah = Ah;
      scanptr->Al = Al;
      scanptr++;
      return scanptr;
    }

    LOCAL(jpeg_scan_info *)
    fill_scans (jpeg_scan_info * scanptr, int ncomps,
    	    int Ss, int Se, int Ah, int Al)
    /* Support routine: generate one scan for each component */
    {
      int ci;

      for (ci = 0; ci < ncomps; ci++) {
        scanptr->comps_in_scan = 1;
        scanptr->component_index[0] = ci;
        scanptr->Ss = Ss;
        scanptr->Se = Se;
        scanptr->Ah = Ah;
        scanptr->Al = Al;
        scanptr++;
      }
      return scanptr;
    }

    LOCAL(jpeg_scan_info *)
    fill_dc_scans (jpeg_scan_info * scanptr, int ncomps, int Ah, int Al)
    /* Support routine: generate interleaved DC scan if possible, else N scans */
    {
      int ci;

      if (ncomps <= MAX_COMPS_IN_SCAN) {
        /* Single interleaved DC scan */
        scanptr->comps_in_scan = ncomps;
        for (ci = 0; ci < ncomps; ci++)
          scanptr->component_index[ci] = ci;
        scanptr->Ss = scanptr->Se = 0;
        scanptr->Ah = Ah;
        scanptr->Al = Al;
        scanptr++;
      } else {
        /* Noninterleaved DC scan for each component */
        scanptr = fill_scans(scanptr, ncomps, 0, 0, Ah, Al);
      }
      return scanptr;
    }

    /*
     * Create a recommended progressive-JPEG script.
     * cinfo->num_components and cinfo->jpeg_color_space must be correct.
     */

    GLOBAL(void)
    jpeg_simple_progression (j_compress_ptr cinfo)
    {
      int ncomps = cinfo->num_components;
      int nscans;
      jpeg_scan_info * scanptr;

      /* Safety check to ensure start_compress not called yet. */
      if (cinfo->global_state != CSTATE_START)
        ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

      /* Figure space needed for script.  Calculation must match code below! */
      if (ncomps == 3 && cinfo->jpeg_color_space == JCS_YCbCr) {
        /* Custom script for YCbCr color images. */
        nscans = 10;
      } else {
        /* All-purpose script for other color spaces. */
        if (ncomps > MAX_COMPS_IN_SCAN)
          nscans = 6 * ncomps;	/* 2 DC + 4 AC scans per component */
        else
          nscans = 2 + 4 * ncomps;	/* 2 DC scans; 4 AC scans per component */
      }

      /* Allocate space for script.
       * We need to put it in the permanent pool in case the application performs
       * multiple compressions without changing the settings.  To avoid a memory
       * leak if jpeg_simple_progression is called repeatedly for the same JPEG
       * object, we try to re-use previously allocated space, and we allocate
       * enough space to handle YCbCr even if initially asked for grayscale.
       */
      if (cinfo->script_space == NULL || cinfo->script_space_size < nscans) {
        cinfo->script_space_size = MAX(nscans, 10);
        cinfo->script_space = (jpeg_scan_info *)
          (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
    			cinfo->script_space_size * SIZEOF(jpeg_scan_info));
      }
      scanptr = cinfo->script_space;
      cinfo->scan_info = scanptr;
      cinfo->num_scans = nscans;

      if (ncomps == 3 && cinfo->jpeg_color_space == JCS_YCbCr) {
        /* Custom script for YCbCr color images. */
        /* Initial DC scan */
        scanptr = fill_dc_scans(scanptr, ncomps, 0, 1);
        /* Initial AC scan: get some luma data out in a hurry */
        scanptr = fill_a_scan(scanptr, 0, 1, 5, 0, 2);
        /* Chroma data is too small to be worth expending many scans on */
        scanptr = fill_a_scan(scanptr, 2, 1, 63, 0, 1);
        scanptr = fill_a_scan(scanptr, 1, 1, 63, 0, 1);
        /* Complete spectral selection for luma AC */
        scanptr = fill_a_scan(scanptr, 0, 6, 63, 0, 2);
        /* Refine next bit of luma AC */
        scanptr = fill_a_scan(scanptr, 0, 1, 63, 2, 1);
        /* Finish DC successive approximation */
        scanptr = fill_dc_scans(scanptr, ncomps, 1, 0);
        /* Finish AC successive approximation */
        scanptr = fill_a_scan(scanptr, 2, 1, 63, 1, 0);
        scanptr = fill_a_scan(scanptr, 1, 1, 63, 1, 0);
        /* Luma bottom bit comes last since it's usually largest scan */
        scanptr = fill_a_scan(scanptr, 0, 1, 63, 1, 0);
      } else {
        /* All-purpose script for other color spaces. */
        /* Successive approximation first pass */
        scanptr = fill_dc_scans(scanptr, ncomps, 0, 1);
        scanptr = fill_scans(scanptr, ncomps, 1, 5, 0, 2);
        scanptr = fill_scans(scanptr, ncomps, 6, 63, 0, 2);
        /* Successive approximation second pass */
        scanptr = fill_scans(scanptr, ncomps, 1, 63, 2, 1);
        /* Successive approximation final pass */
        scanptr = fill_dc_scans(scanptr, ncomps, 1, 0);
        scanptr = fill_scans(scanptr, ncomps, 1, 63, 1, 0);
      }
    }

    #endif /* C_PROGRESSIVE_SUPPORTED */