mod_ijl_jpg.bas

打印预览程序

Rem

Public Type FRAME_COMPONENT
  ident     As Long
  hsampling As Long
  vsampling As Long
  quant_sel As Long
End Type


Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem  Name:        FRAME
Rem
Rem  Purpose:     Stores frame-specific data.
Rem
Rem  Context:     One Frame structure per image.
Rem
Rem  Fields:
Rem    precision       Sample precision in bits.
Rem    width           Width of the source image in pixels.
Rem    height          Height of the source image in pixels.
Rem    MCUheight       Height of a frame MCU.
Rem    MCUwidth        Width of a frame MCU.
Rem    max_hsampling   Max horiz sampling ratio of any component in the frame.
Rem    max_vsampling   Max vert sampling ratio of any component in the frame.
Rem    ncomps          Number of components/channels in the frame.
Rem    horMCU          Number of horizontal MCUs in the frame.
Rem    totalMCU        Total number of MCUs in the frame.
Rem    comps           Array of 'ncomps' component descriptors.
Rem    restart_interv  Indicates number of MCUs after which to restart the
Rem                    entropy parameters.
Rem    SeenAllDCScans  Used when decoding Multiscan images to determine if
Rem                    all channels of an image have been decoded.
Rem    SeenAllACScans  (See SeenAllDCScans)
Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem

Public Type FRAME
  precision      As Long
  width          As Long
  Height         As Long
  MCUheight      As Long
  MCUwidth       As Long
  max_hsampling  As Long
  max_vsampling  As Long
  ncomps         As Long
  horMCU         As Long
  totalMCU       As Long
  comps          As Long
  restart_interv As Long
  SeenAllDCScans As Long
  SeenAllACScans As Long
End Type


Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem  Name:        SCAN_COMPONENT
Rem
Rem  Purpose:     One scan-component structure is allocated per component
Rem               of each scan in a frame.
Rem
Rem  Context:     Used by Huffman decoder to manage components within scans.
Rem
Rem  Fields:
Rem    comp        Component number, index to the comps member of FRAME.
Rem    hsampling   Horizontal sampling factor.
Rem    vsampling   Vertical sampling factor.
Rem    dc_table    DC Huffman table pointer for this scan.
Rem    ac_table    AC Huffman table pointer for this scan.
Rem    quant_table Quantization table pointer for this scan.
Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem

Public Type SCAN_COMPONENT
  comp       As Long
  hsampling  As Long
  vsampling  As Long
  dc_table   As Long
  ac_table   As Long
  quantTable As Long
End Type


Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem  Name:        SCAN
Rem
Rem  Purpose:     One SCAN structure is allocated per scan in a frame.
Rem
Rem  Context:     Used by Huffman decoder to manage scans.
Rem
Rem  Fields:
Rem    ncomps          Number of image components in a scan, 1-4 legal.
Rem    gray_scale      If TRUE, decode only the Y channel.
Rem    start_spec      Start coefficient of spectral or predictor selector.
Rem    end_spec        End coefficient of spectral selector.
Rem    approx_high     High bit position in successive approximation
Rem                    Progressive coding.
Rem    approx_low      Low bit position in successive approximation
Rem                    Progressive coding.
Rem    restart_interv  Restart interval, 0 if disabled.
Rem    curxMCU         Next horizontal MCU index to be processed after
Rem                    an interrupted SCAN.
Rem    curyMCU         Next vertical MCU index to be processed after
Rem                    an interrupted SCAN.
Rem    dc_diff         Array of DC predictor values for DPCM modes.
Rem    comps           Array of ncomps SCAN_COMPONENT component identifiers.
Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem

Public Type SCAN
  ncomps          As Long
  gray_scale      As Long
  start_spec      As Long
  end_spec        As Long
  approx_high     As Long
  approx_low      As Long
  restart_interv  As Long
  curxMCU         As Long
  curyMCU         As Long
  dc_diff(0 To 3) As Long
  comps           As Long
End Type


Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem  Name:        DCTTYPE
Rem
Rem  Purpose:     Possible algorithms to be used to perform the discrete
Rem               cosine transform (DCT).
Rem
Rem  Fields:
Rem    IJL_AAN     The AAN (Arai, Agui, and Nakajima) algorithm from
Rem                Trans. IEICE, vol. E 71(11), 1095-1097, Nov. 1988.
Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem

Public Enum DCTTYPE
  IJL_AAN = 0
  IJL_IPP = 1
End Enum


Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem Name:        UPSAMPLING_TYPE
Rem
Rem Purpose:            -  Possible algorithms to be used to perform upsampling
Rem
Rem Fields:
Rem  IJL_BOX_FILTER      - the algorithm is simple replication of the input pixel
Rem                        onto the corresponding output pixels (box filter);
Rem  IJL_TRIANGLE_FILTER - 3/4 * nearer pixel + 1/4 * further pixel in each
Rem                        dimension
Rem//////////////////////////////////////////////////////////////////////////
Rem

Public Enum upsampling_type
  IJL_BOX_FILTER = 0
  IJL_TRIANGLE_FILTER = 1
End Enum


Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem Name:        SAMPLING_STATE
Rem
Rem Purpose:     Stores current conditions of sampling. Only for upsampling
Rem              with triangle filter is used now.
Rem
Rem Fields:
Rem  top_row        - pointer to buffer with MCUs, that are located above than
Rem                   current row of MCUs;
Rem  cur_row        - pointer to buffer with current row of MCUs;
Rem  bottom_row     - pointer to buffer with MCUs, that are located below than
Rem                   current row of MCUs;
Rem  last_row       - pointer to bottom boundary of last row of MCUs
Rem  cur_row_number - number of row of MCUs, that is decoding;
Rem  user_interrupt - field to store jprops->interrupt, because of we prohibit
Rem                   interrupts while top row of MCUs is upsampling.
Rem//////////////////////////////////////////////////////////////////////////
Rem

Public Type SAMPLING_STATE
  top_row        As Long
  cur_row        As Long
  bottom_row     As Long
  last_row       As Long
  cur_row_number As Long
End Type


Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem  Name:        PROCESSOR_TYPE
Rem
Rem  Purpose:     Possible types of processors.
Rem               Note that the enums are defined in ascending order
Rem               depending upon their various IA32 instruction support.
Rem
Rem  Fields:
Rem
Rem    IJL_OTHER_PROC
Rem      Does not support the CPUID instruction and
Rem      assumes no Pentium(R) processor instructions.
Rem
Rem    IJL_PENTIUM_PROC
Rem      Corresponds to an Intel(R) Pentium(R) processor
Rem      (or a 100% compatible) that supports the
Rem      Pentium(R) processor instructions.
Rem
Rem    IJL_PENTIUM_PRO_PROC
Rem      Corresponds to an Intel(R) Pentium(R) Pro processor
Rem      (or a 100% compatible) that supports the
Rem      Pentium(R) Pro processor instructions.
Rem
Rem    IJL_PENTIUM_PROC_MMX_TECH
Rem      Corresponds to an Intel(R) Pentium(R) processor
Rem      with MMX(TM) technology (or a 100% compatible)
Rem      that supports the MMX(TM) instructions.
Rem
Rem    IJL_PENTIUM_II_PROC
Rem      Corresponds to an Intel(R) Pentium(R) II processor
Rem      (or a 100% compatible) that supports both the
Rem      Pentium(R) Pro processor instructions and the
Rem      MMX(TM) instructions.
Rem
Rem    IJL_PENTIUM_III_PROC
Rem      Corresponds to an Intel(R) Pentium(R) III processor
Rem
Rem  Any additional processor types that support a superset
Rem  of both the Pentium(R) Pro processor instructions and the
Rem  MMX(TM) instructions should be given an enum value greater
Rem  than IJL_PENTIUM_III_PROC.
Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem

Public Enum PROCESSOR_TYPE
  IJL_OTHER_PROC = 0
  IJL_PENTIUM_PROC = 1
  IJL_PENTIUM_PRO_PROC = 2
  IJL_PENTIUM_PROC_MMX_TECH = 3
  IJL_PENTIUM_II_PROC = 4
  IJL_PENTIUM_III_PROC = 5
End Enum


Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem  Name:        ENTROPYSTRUCT
Rem
Rem  Purpose:     Stores the decoder state information necessary to "jump"
Rem               to a particular MCU row in a compressed entropy stream.
Rem
Rem  Context:     Used to persist the decoder state within Decode_Scan when
Rem               decoding using ROIs.
Rem
Rem  Fields:
Rem    offset              Offset (in bytes) into the entropy stream
Rem                        from the beginning.
Rem    dcval1              DC val at the beginning of the MCU row
Rem                        for component 1.
Rem    dcval2              DC val at the beginning of the MCU row
Rem                        for component 2.
Rem    dcval3              DC val at the beginning of the MCU row
Rem                        for component 3.
Rem    dcval4              DC val at the beginning of the MCU row
Rem                        for component 4.
Rem    bit_buffer_64       64-bit Huffman bit buffer.  Stores current
Rem                        bit buffer at the start of a MCU row.
Rem                        Also used as a 32-bit buffer on 32-bit
Rem                        architectures.
Rem    bitbuf_bits_valid   Number of valid bits in the above bit buffer.
Rem    unread_marker       Have any markers been decoded but not
Rem                        processed at the beginning of a MCU row?
Rem                        This entry holds the unprocessed marker, or
Rem                        0 if none.
Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem

Public Type ENTROPYSTRUCT
  offset               As Long
  dcval1               As Long
  dcval2               As Long
  dcval3               As Long
  dcval4               As Long
  ' IJL use 8 byte pack structures
  pad0                 As Byte
  pad1                 As Byte
  pad2                 As Byte
  pad3                 As Byte
  bit_buffer_64        As Long
  bit_buffer_64_part_2 As Long
  bitbuf_bits_valid    As Long
  unread_marker        As Byte
  ' IJL use 8 byte pack structures
  pad4                 As Byte
  pad5                 As Byte
  pad6                 As Byte
End Type


Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem  Name:        STATE
Rem
Rem  Purpose:     Stores the active state of the IJL.
Rem
Rem  Context:     Used by all low-level routines to store pseudo-global or
Rem               state variables.
Rem
Rem  Fields:
Rem    bit_buffer_64           64-bit bitbuffer utilized by Huffman
Rem                            encoder/decoder algorithms utilizing routines
Rem                            designed for MMX(TM) technology.
Rem    bit_buffer_32           32-bit bitbuffer for all other Huffman
Rem                            encoder/decoder algorithms.
Rem    bitbuf_bits_valid       Number of bits in the above two fields that
Rem                            are valid.
Rem
Rem    cur_entropy_ptr         Current position (absolute address) in
Rem                            the entropy buffer.
Rem    start_entropy_ptr       Starting position (absolute address) of
Rem                            the entropy buffer.
Rem    end_entropy_ptr         Ending position (absolute address) of
Rem                            the entropy buffer.
Rem    entropy_bytes_processed Number of bytes actually processed
Rem                            (passed over) in the entropy buffer.
Rem    entropy_buf_maxsize     Max size of the entropy buffer.
Rem    entropy_bytes_left      Number of bytes left in the entropy buffer.
Rem    Prog_EndOfBlock_Run     Progressive block run counter.
Rem
Rem    DIB_ptr                 Temporary offset into the input/output DIB.
Rem
Rem    unread_marker           If a marker has been read but not processed,
Rem                            stick it in this field.
Rem    processor_type          (0, 1, or 2) == current processor does not
Rem                            support MMX(TM) instructions.
Rem                           (3 or 4) == current processor does
Rem                            support MMX(TM) instructions.
Rem    cur_scan_comp           On which component of the scan are we working?
Rem    file                    Process file handle, or
Rem                            0x00000000 if no file is defined.
Rem    JPGBuffer               Entropy buffer (~4K).
Rem
Rem
Rem//////////////////////////////////////////////////////////////////////////
Rem

Public Type STATE
  bit_buffer_64                As Long
  bit_buffer_64_part_2         As Long
  bit_buffer_32                As Long
  bitbuf_bits_valid            As Long
  cur_entropy_ptr              As Long
  start_entropy_ptr            As Long
  end_entropy_ptr              As Long
  entropy_bytes_processed      As Long
  entropy_buf_maxsize          As Long
  entropy_bytes_left           As Long
  Prog_EndOfBlock_Run          As Long
  DIB_ptr                      As Long
  unread_marker                As Byte
  ' IJL use 8 byte pack structures