text: /*
   * jcicc.c
   *
   * Copyright (C) 1997-1998, Thomas G. Lane, Todd Newman.
   * Copyright (C) 2017, D. R. Commander.
   * For conditions of distribution and use, see the accompanying README.ijg
   * file.
   *
   * This file provides code to write International Color Consortium (ICC) device
   * profiles embedded in JFIF JPEG image files.  The ICC has defined a standard
   * for including such data in JPEG "APP2" markers.  The code given here does
   * not know anything about the internal structure of the ICC profile data; it
   * just knows how to embed the profile data in a JPEG file while writing it.
   */
  
  #define JPEG_INTERNALS
  #include "jinclude.h"
  #include "jpeglib.h"
  #include "jerror.h"
  
  
  /*
   * Since an ICC profile can be larger than the maximum size of a JPEG marker
   * (64K), we need provisions to split it into multiple markers.  The format
   * defined by the ICC specifies one or more APP2 markers containing the
   * following data:
   *      Identifying string      ASCII "ICC_PROFILE\0"  (12 bytes)
   *      Marker sequence number  1 for first APP2, 2 for next, etc (1 byte)
   *      Number of markers       Total number of APP2's used (1 byte)
   *      Profile data            (remainder of APP2 data)
   * Decoders should use the marker sequence numbers to reassemble the profile,
   * rather than assuming that the APP2 markers appear in the correct sequence.
   */
  
  #define ICC_MARKER  (JPEG_APP0 + 2)     /* JPEG marker code for ICC */
  #define ICC_OVERHEAD_LEN  14            /* size of non-profile data in APP2 */
  #define MAX_BYTES_IN_MARKER  65533      /* maximum data len of a JPEG marker */
  #define MAX_DATA_BYTES_IN_MARKER  (MAX_BYTES_IN_MARKER - ICC_OVERHEAD_LEN)
  
  
  /*
   * This routine writes the given ICC profile data into a JPEG file.  It *must*
   * be called AFTER calling jpeg_start_compress() and BEFORE the first call to
   * jpeg_write_scanlines().  (This ordering ensures that the APP2 marker(s) will
   * appear after the SOI and JFIF or Adobe markers, but before all else.)
   */
  
  GLOBAL(void)
  jpeg_write_icc_profile (j_compress_ptr cinfo, const JOCTET *icc_data_ptr,
                          unsigned int icc_data_len)
  {
    unsigned int num_markers;     /* total number of markers we'll write */
    int cur_marker = 1;           /* per spec, counting starts at 1 */
    unsigned int length;          /* number of bytes to write in this marker */
  
    if (icc_data_ptr == NULL || icc_data_len == 0)
      ERREXIT(cinfo, JERR_BUFFER_SIZE);
    if (cinfo->global_state < CSTATE_SCANNING)
      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  
    /* Calculate the number of markers we'll need, rounding up of course */
    num_markers = icc_data_len / MAX_DATA_BYTES_IN_MARKER;
    if (num_markers * MAX_DATA_BYTES_IN_MARKER != icc_data_len)
      num_markers++;
  
    while (icc_data_len > 0) {
      /* length of profile to put in this marker */
      length = icc_data_len;
      if (length > MAX_DATA_BYTES_IN_MARKER)
        length = MAX_DATA_BYTES_IN_MARKER;
      icc_data_len -= length;
  
      /* Write the JPEG marker header (APP2 code and marker length) */
      jpeg_write_m_header(cinfo, ICC_MARKER,
                          (unsigned int) (length + ICC_OVERHEAD_LEN));
  
      /* Write the marker identifying string "ICC_PROFILE" (null-terminated).  We
       * code it in this less-than-transparent way so that the code works even if
       * the local character set is not ASCII.
       */
      jpeg_write_m_byte(cinfo, 0x49);
      jpeg_write_m_byte(cinfo, 0x43);
      jpeg_write_m_byte(cinfo, 0x43);
      jpeg_write_m_byte(cinfo, 0x5F);
      jpeg_write_m_byte(cinfo, 0x50);
      jpeg_write_m_byte(cinfo, 0x52);
      jpeg_write_m_byte(cinfo, 0x4F);
      jpeg_write_m_byte(cinfo, 0x46);
      jpeg_write_m_byte(cinfo, 0x49);
      jpeg_write_m_byte(cinfo, 0x4C);
      jpeg_write_m_byte(cinfo, 0x45);
      jpeg_write_m_byte(cinfo, 0x0);
  
      /* Add the sequencing info */
      jpeg_write_m_byte(cinfo, cur_marker);
      jpeg_write_m_byte(cinfo, (int) num_markers);
  
      /* Add the profile data */
      while (length--) {
        jpeg_write_m_byte(cinfo, *icc_data_ptr);
        icc_data_ptr++;
      }
      cur_marker++;
    }
  }
  