jdmarker.pas

用pascal寫的jpeg codec, 測試過的

  { Unload the local copies --- do this only at a restart boundary }
  datasrc^.next_input_byte := next_input_byte;
  datasrc^.bytes_in_buffer := bytes_in_buffer;

  if (length > 0) then          { skip any remaining data -- could be lots }
    cinfo^.src^.skip_input_data(cinfo, long(length));

  get_app0 := TRUE;
end;  { get_app0 }


{METHODDEF}
function get_app14 (cinfo : j_decompress_ptr) : boolean; far;
{ Process an APP14 marker }
const
  ADOBE_LEN = 12;
var
  length : INT32;
  b : Array[0..ADOBE_LEN-1] of UINT8;
  buffp : int;
  version, flags0, flags1, transform : uint;
var
  datasrc : jpeg_source_mgr_ptr;
  next_input_byte : JOCTETptr;
  bytes_in_buffer : size_t;
begin
  datasrc := cinfo^.src;
  next_input_byte := datasrc^.next_input_byte;
  bytes_in_buffer := datasrc^.bytes_in_buffer;

{ Read two bytes interpreted as an unsigned 16-bit integer.
  length should be declared unsigned int or perhaps INT32. }

{ make a byte available.
  Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
  but we must reload the local copies after a successful fill. }
  if (bytes_in_buffer = 0) then
  begin
    if (not datasrc^.fill_input_buffer(cinfo)) then
    begin
      get_app14 := FALSE;
      exit;
    end;
    { Reload the local copies }
    next_input_byte := datasrc^.next_input_byte;
    bytes_in_buffer := datasrc^.bytes_in_buffer;
  end;
  Dec( bytes_in_buffer );

  length := (uint( GETJOCTET(next_input_byte^)) shl 8);
  Inc( next_input_byte );
  { make a byte available.
    Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
    but we must reload the local copies after a successful fill. }
  if (bytes_in_buffer = 0) then
  begin
    if (not datasrc^.fill_input_buffer(cinfo)) then
    begin
      get_app14 := FALSE;
      exit;
    end;
    { Reload the local copies }
    next_input_byte := datasrc^.next_input_byte;
    bytes_in_buffer := datasrc^.bytes_in_buffer;
  end;
  Dec( bytes_in_buffer );

  Inc( length, GETJOCTET( next_input_byte^));
  Inc( next_input_byte );

  Dec(length, 2);

  { See if an Adobe APP14 marker is present }

  if (length >= ADOBE_LEN) then
  begin
    for buffp := 0 to Pred(ADOBE_LEN) do
    begin
      { Read a byte into variable b[buffp]. If must suspend, return FALSE. }
      { make a byte available.
        Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
        but we must reload the local copies after a successful fill. }
      if (bytes_in_buffer = 0) then
      begin
        if (not datasrc^.fill_input_buffer(cinfo)) then
        begin
          get_app14 := FALSE;
          exit;
        end;
        { Reload the local copies }
        next_input_byte := datasrc^.next_input_byte;
        bytes_in_buffer := datasrc^.bytes_in_buffer;
      end;
      Dec( bytes_in_buffer );

      b[buffp] := GETJOCTET(next_input_byte^);
      Inc(next_input_byte);
    end;
    length := length - ADOBE_LEN;

    if (b[0]=$41) and (b[1]=$64) and (b[2]=$6F) and (b[3]=$62) and (b[4]=$65) then
    begin
      { Found Adobe APP14 marker }
      version := (b[5] shl 8) + b[6];
      flags0 := (b[7] shl 8) + b[8];
      flags1 := (b[9] shl 8) + b[10];
      transform := b[11];
      TRACEMS4(j_common_ptr(cinfo), 1, JTRC_ADOBE,
         version, flags0, flags1, transform);
      cinfo^.saw_Adobe_marker := TRUE;
      cinfo^.Adobe_transform := UINT8(transform);
    end
    else
    begin
      { Start of APP14 does not match "Adobe" }
      TRACEMS1(j_common_ptr(cinfo), 1, JTRC_APP14, int(length) + ADOBE_LEN);
    end;
  end
  else
  begin
    { Too short to be Adobe marker }
    TRACEMS1(j_common_ptr(cinfo), 1, JTRC_APP14, int(length));
  end;

  { Unload the local copies --- do this only at a restart boundary }
  datasrc^.next_input_byte := next_input_byte;
  datasrc^.bytes_in_buffer := bytes_in_buffer;

  if (length > 0) then          { skip any remaining data -- could be lots }
    cinfo^.src^.skip_input_data (cinfo, long(length));

  get_app14 := TRUE;
end; { get_app14 }


{LOCAL}
function get_dac (cinfo : j_decompress_ptr) : boolean;
{ Process a DAC marker }
var
  length : INT32;
  index, val : int;
var
  datasrc : jpeg_source_mgr_ptr;
  next_input_byte : JOCTETptr;
  bytes_in_buffer : size_t;
begin
  datasrc := cinfo^.src;
  next_input_byte := datasrc^.next_input_byte;
  bytes_in_buffer := datasrc^.bytes_in_buffer;

{ Read two bytes interpreted as an unsigned 16-bit integer.
  length should be declared unsigned int or perhaps INT32. }

{ make a byte available.
  Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
  but we must reload the local copies after a successful fill. }
  if (bytes_in_buffer = 0) then
  begin
    if (not datasrc^.fill_input_buffer(cinfo)) then
    begin
      get_dac := FALSE;
      exit;
    end;
    { Reload the local copies }
    next_input_byte := datasrc^.next_input_byte;
    bytes_in_buffer := datasrc^.bytes_in_buffer;
  end;
  Dec( bytes_in_buffer );

  length := (uint( GETJOCTET(next_input_byte^)) shl 8);
  Inc( next_input_byte );
  { make a byte available.
    Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
    but we must reload the local copies after a successful fill. }
    if (bytes_in_buffer = 0) then
    begin
      if (not datasrc^.fill_input_buffer(cinfo)) then
      begin
        get_dac := FALSE;
        exit;
      end;
      { Reload the local copies }
      next_input_byte := datasrc^.next_input_byte;
      bytes_in_buffer := datasrc^.bytes_in_buffer;
    end;
    Dec( bytes_in_buffer );

  Inc( length, GETJOCTET( next_input_byte^));
  Inc( next_input_byte );

  Dec(length,  2);

  while (length > 0) do
  begin
    { Read a byte into variable index. If must suspend, return FALSE. }
    { make a byte available.
      Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
      but we must reload the local copies after a successful fill. }
    if (bytes_in_buffer = 0) then
    begin
      if (not datasrc^.fill_input_buffer(cinfo)) then
      begin
        get_dac := FALSE;
        exit;
      end;
      { Reload the local copies }
      next_input_byte := datasrc^.next_input_byte;
      bytes_in_buffer := datasrc^.bytes_in_buffer;
    end;
    Dec( bytes_in_buffer );

    index := GETJOCTET(next_input_byte^);
    Inc(next_input_byte);

    { Read a byte into variable val. If must suspend, return FALSE. }
    { make a byte available.
      Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
      but we must reload the local copies after a successful fill. }
    if (bytes_in_buffer = 0) then
    begin
      if (not datasrc^.fill_input_buffer(cinfo)) then
      begin
        get_dac := FALSE;
        exit;
      end;
      { Reload the local copies }
      next_input_byte := datasrc^.next_input_byte;
      bytes_in_buffer := datasrc^.bytes_in_buffer;
    end;
    Dec( bytes_in_buffer );

    val := GETJOCTET(next_input_byte^);
    Inc(next_input_byte);

    Dec( length, 2);

    TRACEMS2(j_common_ptr(cinfo), 1, JTRC_DAC, index, val);

    if (index < 0) or (index >= (2*NUM_ARITH_TBLS)) then
      ERREXIT1(j_common_ptr(cinfo) , JERR_DAC_INDEX, index);

    if (index >= NUM_ARITH_TBLS) then
    begin { define AC table }
      cinfo^.arith_ac_K[index-NUM_ARITH_TBLS] := UINT8(val);
    end
    else
    begin { define DC table }
      cinfo^.arith_dc_L[index] := UINT8(val and $0F);
      cinfo^.arith_dc_U[index] := UINT8(val shr 4);
      if (cinfo^.arith_dc_L[index] > cinfo^.arith_dc_U[index]) then
	ERREXIT1(j_common_ptr(cinfo) , JERR_DAC_VALUE, val);
    end;
  end;

  { Unload the local copies --- do this only at a restart boundary }
  datasrc^.next_input_byte := next_input_byte;
  datasrc^.bytes_in_buffer := bytes_in_buffer;

  get_dac := TRUE;
end;  { get_dac }


{LOCAL}
function get_dht (cinfo : j_decompress_ptr) : boolean;
{ Process a DHT marker }
var
  length : INT32;
  bits : Array[0..17-1] of UINT8;
  huffval : Array[0..256-1] of UINT8;
  i, index, count : int;
  htblptr : ^JHUFF_TBL_PTR;
var
  datasrc : jpeg_source_mgr_ptr;
  next_input_byte : JOCTETptr;
  bytes_in_buffer : size_t;
begin
  datasrc := cinfo^.src;
  next_input_byte := datasrc^.next_input_byte;
  bytes_in_buffer := datasrc^.bytes_in_buffer;

{ Read two bytes interpreted as an unsigned 16-bit integer.
  length should be declared unsigned int or perhaps INT32. }

{ make a byte available.
  Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
  but we must reload the local copies after a successful fill. }
  if (bytes_in_buffer = 0) then
  begin
    if (not datasrc^.fill_input_buffer(cinfo)) then
    begin
      get_dht := FALSE;
      exit;
    end;
    { Reload the local copies }
    next_input_byte := datasrc^.next_input_byte;
    bytes_in_buffer := datasrc^.bytes_in_buffer;
  end;
  Dec( bytes_in_buffer );

  length := (uint( GETJOCTET(next_input_byte^)) shl 8);
  Inc( next_input_byte );
  { make a byte available.
    Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
    but we must reload the local copies after a successful fill. }
    if (bytes_in_buffer = 0) then
    begin
      if (not datasrc^.fill_input_buffer(cinfo)) then
      begin
        get_dht := FALSE;
        exit;
      end;
      { Reload the local copies }
      next_input_byte := datasrc^.next_input_byte;
      bytes_in_buffer := datasrc^.bytes_in_buffer;
    end;
    Dec( bytes_in_buffer );

  Inc( length, GETJOCTET( next_input_byte^));
  Inc( next_input_byte );

  Dec(length,  2);

  while (length > 0) do
  begin
    { Read a byte into variable index. If must suspend, return FALSE. }
    { make a byte available.
      Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
      but we must reload the local copies after a successful fill. }
    if (bytes_in_buffer = 0) then
    begin
      if (not datasrc^.fill_input_buffer(cinfo)) then
      begin
        get_dht := FALSE;
        exit;
      end;
      { Reload the local copies }
      next_input_byte := datasrc^.next_input_byte;
      bytes_in_buffer := datasrc^.bytes_in_buffer;
    end;
    Dec( bytes_in_buffer );

    index := GETJOCTET(next_input_byte^);
    Inc(next_input_byte);


    TRACEMS1(j_common_ptr(cinfo), 1, JTRC_DHT, index);
      
    bits[0] := 0;
    count := 0;
    for i := 1 to 16 do
    begin
      { Read a byte into variable bits[i]. If must suspend, return FALSE. }
      { make a byte available.
        Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
        but we must reload the local copies after a successful fill. }
      if (bytes_in_buffer = 0) then
      begin
        if (not datasrc^.fill_input_buffer(cinfo)) then
        begin
          get_dht := FALSE;
          exit;
        end;
        { Reload the local copies }
        next_input_byte := datasrc^.next_input_byte;
        bytes_in_buffer := datasrc^.bytes_in_buffer;
      end;
      Dec( bytes_in_buffer );

      bits[i] := GETJOCTET(next_input_byte^);
      Inc(next_input_byte);

      Inc( count, bits[i] );
    end;

    Dec( length, (1 + 16) );

    TRACEMS8(j_common_ptr(cinfo), 2, JTRC_HUFFBITS,
	     bits[1], bits[2], bits[3], bits[4],
	     bits[5], bits[6], bits[7], bits[8]);
    TRACEMS8(j_common_ptr(cinfo), 2, JTRC_HUFFBITS,
	     bits[9], bits[10], bits[11], bits[12],
	     bits[13], bits[14], bits[15], bits[16]);

    if (count > 256) or (INT32(count) > length) then
      ERREXIT(j_common_ptr(cinfo), JERR_DHT_COUNTS);

    for i := 0 to Pred(count) do
    begin
    { Read a byte into variable huffval[i]. If must suspend, return FALSE. }
    { make a byte available.
      Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
      but we must reload the local copies after a successful fill. }
      if (bytes_in_buffer = 0) then
      begin
        if (not datasrc^.fill_input_buffer(cinfo)) then
        begin
          get_dht := FALSE;
          exit;
        end;
        { Reload the local copies }
        next_input_byte := datasrc^.next_input_byte;
        bytes_in_buffer := datasrc^.bytes_in_buffer;
      end;
      Dec( bytes_in_buffer );

      huffval[i] := GETJOCTET(next_input_byte^);
      Inc(next_input_byte);
    end;

    Dec( length, count );

    if (index and $10)<>0 then
    begin  { AC table definition }
      Dec( index, $10 );
      htblptr := @cinfo^.ac_huff_tbl_ptrs[index];
    end
    else
    begin { DC table definition }
      htblptr := @cinfo^.dc_huff_tbl_ptrs[index];
    end;

    if (index < 0) or (index >= NUM_HUFF_TBLS) then
      ERREXIT1(j_common_ptr(cinfo), JERR_DHT_INDEX, index);

    if (htblptr^ = NIL) then
      htblptr^ := jpeg_alloc_huff_table(j_common_ptr(cinfo));