1. Just copy all the files into the IJG source directory.
   The changes in detail:


'jcinit.c', function 'jinit_compress_master()':
'jctrans.c', function 'transencode_master_selection()':

  if (cinfo->arith_code)
    jinit_arith_encoder(cinfo);

  instead of ERREXIT(cinfo, JERR_ARITH_NOTIMPL).

  Note that the ERREXIT will be executed in the corresponding
  placeholder file.
  Thus, actual library support for arithmetic coding is solely
  enabled/disabled by selecting the appropriate source file,
  NOT by the support macros in 'jmorecfg.h' (which would be
  duplicated effort).
  The support macros in 'jmorecfg.h' enable/disable the support
  on application level, however.


'jdmaster.c'
'jdtrans.c'

  Similar patch for the decoder.


'jcmarker.c', function 'write_frame_header()'

  /* Emit the proper SOF marker */
  if (cinfo->arith_code) {
    if (cinfo->progressive_mode)
      emit_sof(cinfo, M_SOF10);	/* SOF code for progressive arithmetic */
    else
      emit_sof(cinfo, M_SOF9);	/* SOF code for sequential arithmetic */
  }

  Select proper progressive/sequential marker also for arithmetic coding!


'jcmaster.c', function 'jinit_c_master_control()'

  if (cinfo->progressive_mode && cinfo->arith_code == 0)
  /* TEMPORARY HACK ??? */
  /* GV: indeed ;-) */
    cinfo->optimize_coding = TRUE;
    /* assume default tables no good for progressive mode */
    /* GV: but only in Huffman case! */

  function 'prepare_for_pass()'

    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;
    }

    Removed cinfo->arith_code check here.


'jerror.h'

  JMESSAGE(JERR_NO_ARITH_TABLE, "Arithmetic table 0x%02x was not defined")
  JMESSAGE(JWRN_ARITH_BAD_CODE, "Corrupt JPEG data: bad arithmetic code")

  added.


'jpegint.h'

  Prototypes for jinit_arith_encoder() and jinit_arith_decoder() added.


2. A new 'makefile.cfg' is included for automatic update of your makefile
   by using './configure' before 'make'.
   If you are not using a configure-generated makefile, apply the
   corresponding changes to your specific Makefile/Projectfile
   for the inclusion of the 3 new placeholder files:

In 'LIBSOURCES' add 'jaricom.c', 'jcarith.c', and 'jdarith.c'.
In 'COMOBJECTS' add 'jaricom.$(O)'.
In 'CLIBOBJECTS' add 'jcarith.$(O)'.
In 'DLIBOBJECTS' add 'jdarith.$(O)'.
In the dependencies section add
jcarith.$(O): jcarith.c jinclude.h jconfig.h jpeglib.h jmorecfg.h jpegint.h jerror.h
jdarith.$(O): jdarith.c jinclude.h jconfig.h jpeglib.h jmorecfg.h jpegint.h jerror.h
jaricom.$(O): jaricom.c jinclude.h jconfig.h jpeglib.h jmorecfg.h jpegint.h jerror.h
