/*

 * jpeglib.h

 *

 * This file was part of the Independent JPEG Group's software:

 * Copyright (C) 1991-1998, Thomas G. Lane.

 * Modified 2002-2009 by Guido Vollbeding.

 * libjpeg-turbo Modifications:

 * Copyright (C) 2009-2011, 2013-2014, 2016-2017, 2020, D. R. Commander.

 * Copyright (C) 2015, Google, Inc.

 * For conditions of distribution and use, see the accompanying README.ijg

 * file.

 *

 * This file defines the application interface for the JPEG library.

 * Most applications using the library need only include this file,

 * and perhaps jerror.h if they want to know the exact error codes.

 */

#ifndef JPEGLIB_H

#define JPEGLIB_H

/*

 * First we include the configuration files that record how this

 * installation of the JPEG library is set up.  jconfig.h can be

 * generated automatically for many systems.  jmorecfg.h contains

 * manual configuration options that most people need not worry about.

 */

#ifndef JCONFIG_INCLUDED        /* in case jinclude.h already did */

#include "jconfig.h"            /* widely used configuration options */

#endif

#include "jmorecfg.h"           /* seldom changed options */

#ifdef __cplusplus

#ifndef DONT_USE_EXTERN_C

extern "C" {

#endif

#endif

/* Various constants determining the sizes of things.

 * All of these are specified by the JPEG standard, so don't change them

 * if you want to be compatible.

 */

#define DCTSIZE             8   /* The basic DCT block is 8x8 samples */

#define DCTSIZE2            64  /* DCTSIZE squared; # of elements in a block */

#define NUM_QUANT_TBLS      4   /* Quantization tables are numbered 0..3 */

#define NUM_HUFF_TBLS       4   /* Huffman tables are numbered 0..3 */

#define NUM_ARITH_TBLS      16  /* Arith-coding tables are numbered 0..15 */

#define MAX_COMPS_IN_SCAN   4   /* JPEG limit on # of components in one scan */

#define MAX_SAMP_FACTOR     4   /* JPEG limit on sampling factors */

/* Unfortunately, some bozo at Adobe saw no reason to be bound by the standard;

 * the PostScript DCT filter can emit files with many more than 10 blocks/MCU.

 * If you happen to run across such a file, you can up D_MAX_BLOCKS_IN_MCU

 * to handle it.  We even let you do this from the jconfig.h file.  However,

 * we strongly discourage changing C_MAX_BLOCKS_IN_MCU; just because Adobe

 * sometimes emits noncompliant files doesn't mean you should too.

 */

#define C_MAX_BLOCKS_IN_MCU   10 /* compressor's limit on blocks per MCU */

#ifndef D_MAX_BLOCKS_IN_MCU

#define D_MAX_BLOCKS_IN_MCU   10 /* decompressor's limit on blocks per MCU */

#endif

/* Data structures for images (arrays of samples and of DCT coefficients).

 */

typedef JSAMPLE *JSAMPROW;      /* ptr to one image row of pixel samples. */

typedef JSAMPROW *JSAMPARRAY;   /* ptr to some rows (a 2-D sample array) */

typedef JSAMPARRAY *JSAMPIMAGE; /* a 3-D sample array: top index is color */

typedef JCOEF JBLOCK[DCTSIZE2]; /* one block of coefficients */

typedef JBLOCK *JBLOCKROW;      /* pointer to one row of coefficient blocks */

typedef JBLOCKROW *JBLOCKARRAY;         /* a 2-D array of coefficient blocks */

typedef JBLOCKARRAY *JBLOCKIMAGE;       /* a 3-D array of coefficient blocks */

typedef JCOEF *JCOEFPTR;        /* useful in a couple of places */

/* Types for JPEG compression parameters and working tables. */

/* DCT coefficient quantization tables. */

typedef struct {

  /* This array gives the coefficient quantizers in natural array order

   * (not the zigzag order in which they are stored in a JPEG DQT marker).

   * CAUTION: IJG versions prior to v6a kept this array in zigzag order.

   */

  UINT16 quantval[DCTSIZE2];    /* quantization step for each coefficient */

  /* This field is used only during compression.  It's initialized FALSE when

   * the table is created, and set TRUE when it's been output to the file.

   * You could suppress output of a table by setting this to TRUE.

   * (See jpeg_suppress_tables for an example.)

   */

  boolean sent_table;           /* TRUE when table has been output */

} JQUANT_TBL;

/* Huffman coding tables. */

typedef struct {

  /* These two fields directly represent the contents of a JPEG DHT marker */

  UINT8 bits[17];               /* bits[k] = # of symbols with codes of */

                                /* length k bits; bits[0] is unused */

  UINT8 huffval[256];           /* The symbols, in order of incr code length */

  /* This field is used only during compression.  It's initialized FALSE when

   * the table is created, and set TRUE when it's been output to the file.

   * You could suppress output of a table by setting this to TRUE.

   * (See jpeg_suppress_tables for an example.)

   */

  boolean sent_table;           /* TRUE when table has been output */

} JHUFF_TBL;

/* Basic info about one component (color channel). */

typedef struct {

  /* These values are fixed over the whole image. */

  /* For compression, they must be supplied by parameter setup; */

  /* for decompression, they are read from the SOF marker. */

  int component_id;             /* identifier for this component (0..255) */

  int component_index;          /* its index in SOF or cinfo->comp_info[] */

  int h_samp_factor;            /* horizontal sampling factor (1..4) */

  int v_samp_factor;            /* vertical sampling factor (1..4) */

  int quant_tbl_no;             /* quantization table selector (0..3) */

  /* These values may vary between scans. */

  /* For compression, they must be supplied by parameter setup; */

  /* for decompression, they are read from the SOS marker. */

  /* The decompressor output side may not use these variables. */

  int dc_tbl_no;                /* DC entropy table selector (0..3) */

  int ac_tbl_no;                /* AC entropy table selector (0..3) */

  /* Remaining fields should be treated as private by applications. */

  /* These values are computed during compression or decompression startup: */

  /* Component's size in DCT blocks.

   * Any dummy blocks added to complete an MCU are not counted; therefore

   * these values do not depend on whether a scan is interleaved or not.

   */

  JDIMENSION width_in_blocks;

  JDIMENSION height_in_blocks;

  /* Size of a DCT block in samples.  Always DCTSIZE for compression.

   * For decompression this is the size of the output from one DCT block,

   * reflecting any scaling we choose to apply during the IDCT step.

   * Values from 1 to 16 are supported.

   * Note that different components may receive different IDCT scalings.

   */

#if JPEG_LIB_VERSION >= 70

  int DCT_h_scaled_size;

  int DCT_v_scaled_size;

#else

  int DCT_scaled_size;

#endif

  /* The downsampled dimensions are the component's actual, unpadded number

   * of samples at the main buffer (preprocessing/compression interface), thus

   * downsampled_width = ceil(image_width * Hi/Hmax)

   * and similarly for height.  For decompression, IDCT scaling is included, so

   * downsampled_width = ceil(image_width * Hi/Hmax * DCT_[h_]scaled_size/DCTSIZE)

   */

  JDIMENSION downsampled_width;  /* actual width in samples */

  JDIMENSION downsampled_height; /* actual height in samples */

  /* This flag is used only for decompression.  In cases where some of the

   * components will be ignored (eg grayscale output from YCbCr image),

   * we can skip most computations for the unused components.

   */

  boolean component_needed;     /* do we need the value of this component? */

  /* These values are computed before starting a scan of the component. */

  /* The decompressor output side may not use these variables. */

  int MCU_width;                /* number of blocks per MCU, horizontally */

  int MCU_height;               /* number of blocks per MCU, vertically */

  int MCU_blocks;               /* MCU_width * MCU_height */

  int MCU_sample_width;         /* MCU width in samples, MCU_width*DCT_[h_]scaled_size */

  int last_col_width;           /* # of non-dummy blocks across in last MCU */

  int last_row_height;          /* # of non-dummy blocks down in last MCU */

  /* Saved quantization table for component; NULL if none yet saved.

   * See jdinput.c comments about the need for this information.

   * This field is currently used only for decompression.

   */

  JQUANT_TBL *quant_table;

  /* Private per-component storage for DCT or IDCT subsystem. */

  void *dct_table;

} jpeg_component_info;

/* The script for encoding a multiple-scan file is an array of these: */

typedef struct {

  int comps_in_scan;            /* number of components encoded in this scan */

  int component_index[MAX_COMPS_IN_SCAN]; /* their SOF/comp_info[] indexes */

  int Ss, Se;                   /* progressive JPEG spectral selection parms */

  int Ah, Al;                   /* progressive JPEG successive approx. parms */

} jpeg_scan_info;

/* The decompressor can save APPn and COM markers in a list of these: */

typedef struct jpeg_marker_struct *jpeg_saved_marker_ptr;

struct jpeg_marker_struct {

  jpeg_saved_marker_ptr next;   /* next in list, or NULL */

  UINT8 marker;                 /* marker code: JPEG_COM, or JPEG_APP0+n */

  unsigned int original_length; /* # bytes of data in the file */

  unsigned int data_length;     /* # bytes of data saved at data[] */

  JOCTET *data;                 /* the data contained in the marker */

  /* the marker length word is not counted in data_length or original_length */

};

/* Known color spaces. */

#define JCS_EXTENSIONS  1

#define JCS_ALPHA_EXTENSIONS  1

typedef enum {

  JCS_UNKNOWN,            /* error/unspecified */

  JCS_GRAYSCALE,          /* monochrome */

  JCS_RGB,                /* red/green/blue as specified by the RGB_RED,

                             RGB_GREEN, RGB_BLUE, and RGB_PIXELSIZE macros */

  JCS_YCbCr,              /* Y/Cb/Cr (also known as YUV) */

  JCS_CMYK,               /* C/M/Y/K */

  JCS_YCCK,               /* Y/Cb/Cr/K */

  JCS_EXT_RGB,            /* red/green/blue */

  JCS_EXT_RGBX,           /* red/green/blue/x */

  JCS_EXT_BGR,            /* blue/green/red */

  JCS_EXT_BGRX,           /* blue/green/red/x */

  JCS_EXT_XBGR,           /* x/blue/green/red */

  JCS_EXT_XRGB,           /* x/red/green/blue */

  /* When out_color_space it set to JCS_EXT_RGBX, JCS_EXT_BGRX, JCS_EXT_XBGR,

     or JCS_EXT_XRGB during decompression, the X byte is undefined, and in

     order to ensure the best performance, libjpeg-turbo can set that byte to

     whatever value it wishes.  Use the following colorspace constants to

     ensure that the X byte is set to 0xFF, so that it can be interpreted as an

     opaque alpha channel. */

  JCS_EXT_RGBA,           /* red/green/blue/alpha */

  JCS_EXT_BGRA,           /* blue/green/red/alpha */

  JCS_EXT_ABGR,           /* alpha/blue/green/red */

  JCS_EXT_ARGB,           /* alpha/red/green/blue */

  JCS_RGB565              /* 5-bit red/6-bit green/5-bit blue */

} J_COLOR_SPACE;

/* DCT/IDCT algorithm options. */

typedef enum {

  JDCT_ISLOW,             /* accurate integer method */

  JDCT_IFAST,             /* less accurate integer method [legacy feature] */

  JDCT_FLOAT              /* floating-point method [legacy feature] */

} J_DCT_METHOD;

#ifndef JDCT_DEFAULT            /* may be overridden in jconfig.h */

#define JDCT_DEFAULT  JDCT_ISLOW

#endif

#ifndef JDCT_FASTEST            /* may be overridden in jconfig.h */

#define JDCT_FASTEST  JDCT_IFAST

#endif

/* Dithering options for decompression. */

typedef enum {

  JDITHER_NONE,           /* no dithering */

  JDITHER_ORDERED,        /* simple ordered dither */

  JDITHER_FS              /* Floyd-Steinberg error diffusion dither */

} J_DITHER_MODE;

/* Common fields between JPEG compression and decompression master structs. */

#define jpeg_common_fields \

  struct jpeg_error_mgr *err;   /* Error handler module */ \

  struct jpeg_memory_mgr *mem;  /* Memory manager module */ \

  struct jpeg_progress_mgr *progress; /* Progress monitor, or NULL if none */ \

  void *client_data;            /* Available for use by application */ \

  boolean is_decompressor;      /* So common code can tell which is which */ \

  int global_state              /* For checking call sequence validity */

/* Routines that are to be used by both halves of the library are declared

 * to receive a pointer to this structure.  There are no actual instances of

 * jpeg_common_struct, only of jpeg_compress_struct and jpeg_decompress_struct.

 */

struct jpeg_common_struct {

  jpeg_common_fields;           /* Fields common to both master struct types */

  /* Additional fields follow in an actual jpeg_compress_struct or

   * jpeg_decompress_struct.  All three structs must agree on these

   * initial fields!  (This would be a lot cleaner in C++.)

   */

};

typedef struct jpeg_common_struct *j_common_ptr;

typedef struct jpeg_compress_struct *j_compress_ptr;

typedef struct jpeg_decompress_struct *j_decompress_ptr;

/* Master record for a compression instance */

struct jpeg_compress_struct {

  jpeg_common_fields;           /* Fields shared with jpeg_decompress_struct */

  /* Destination for compressed data */

  struct jpeg_destination_mgr *dest;

  /* Description of source image --- these fields must be filled in by

   * outer application before starting compression.  in_color_space must

   * be correct before you can even call jpeg_set_defaults().

   */

  JDIMENSION image_width;       /* input image width */

  JDIMENSION image_height;      /* input image height */

  int input_components;         /* # of color components in input image */

  J_COLOR_SPACE in_color_space; /* colorspace of input image */

  double input_gamma;           /* image gamma of input image */

  /* Compression parameters --- these fields must be set before calling

   * jpeg_start_compress().  We recommend calling jpeg_set_defaults() to

   * initialize everything to reasonable defaults, then changing anything

   * the application specifically wants to change.  That way you won't get

   * burnt when new parameters are added.  Also note that there are several

   * helper routines to simplify changing parameters.

   */

#if JPEG_LIB_VERSION >= 70

  unsigned int scale_num, scale_denom; /* fraction by which to scale image */

  JDIMENSION jpeg_width;        /* scaled JPEG image width */

  JDIMENSION jpeg_height;       /* scaled JPEG image height */

  /* Dimensions of actual JPEG image that will be written to file,

   * derived from input dimensions by scaling factors above.

   * These fields are computed by jpeg_start_compress().

   * You can also use jpeg_calc_jpeg_dimensions() to determine these values

   * in advance of calling jpeg_start_compress().

   */

#endif

  int data_precision;           /* bits of precision in image data */

  int num_components;           /* # of color components in JPEG image */

  J_COLOR_SPACE jpeg_color_space; /* colorspace of JPEG image */

  jpeg_component_info *comp_info;

  /* comp_info[i] describes component that appears i'th in SOF */

  JQUANT_TBL *quant_tbl_ptrs[NUM_QUANT_TBLS];

#if JPEG_LIB_VERSION >= 70

  int q_scale_factor[NUM_QUANT_TBLS];

#endif

  /* ptrs to coefficient quantization tables, or NULL if not defined,

   * and corresponding scale factors (percentage, initialized 100).

   */

  JHUFF_TBL *dc_huff_tbl_ptrs[NUM_HUFF_TBLS];

  JHUFF_TBL *ac_huff_tbl_ptrs[NUM_HUFF_TBLS];

  /* ptrs to Huffman coding tables, or NULL if not defined */

  UINT8 arith_dc_L[NUM_ARITH_TBLS]; /* L values for DC arith-coding tables */

  UINT8 arith_dc_U[NUM_ARITH_TBLS]; /* U values for DC arith-coding tables */

  UINT8 arith_ac_K[NUM_ARITH_TBLS]; /* Kx values for AC arith-coding tables */

  int num_scans;                /* # of entries in scan_info array */

  const jpeg_scan_info *scan_info; /* script for multi-scan file, or NULL */

  /* The default value of scan_info is NULL, which causes a single-scan

   * sequential JPEG file to be emitted.  To create a multi-scan file,

   * set num_scans and scan_info to point to an array of scan definitions.

   */

  boolean raw_data_in;          /* TRUE=caller supplies downsampled data */

  boolean arith_code;           /* TRUE=arithmetic coding, FALSE=Huffman */

  boolean optimize_coding;      /* TRUE=optimize entropy encoding parms */

  boolean CCIR601_sampling;     /* TRUE=first samples are cosited */

#if JPEG_LIB_VERSION >= 70

  boolean do_fancy_downsampling; /* TRUE=apply fancy downsampling */

#endif

  int smoothing_factor;         /* 1..100, or 0 for no input smoothing */

  J_DCT_METHOD dct_method;      /* DCT algorithm selector */

  /* The restart interval can be specified in absolute MCUs by setting

   * restart_interval, or in MCU rows by setting restart_in_rows

   * (in which case the correct restart_interval will be figured

   * for each scan).

   */

  unsigned int restart_interval; /* MCUs per restart, or 0 for no restart */

  int restart_in_rows;          /* if > 0, MCU rows per restart interval */

  /* Parameters controlling emission of special markers. */

  boolean write_JFIF_header;    /* should a JFIF marker be written? */

  UINT8 JFIF_major_version;     /* What to write for the JFIF version number */

  UINT8 JFIF_minor_version;

  /* These three values are not used by the JPEG code, merely copied */

  /* into the JFIF APP0 marker.  density_unit can be 0 for unknown, */

  /* 1 for dots/inch, or 2 for dots/cm.  Note that the pixel aspect */

  /* ratio is defined by X_density/Y_density even when density_unit=0. */

  UINT8 density_unit;           /* JFIF code for pixel size units */

  UINT16 X_density;             /* Horizontal pixel density */

  UINT16 Y_density;             /* Vertical pixel density */

  boolean write_Adobe_marker;   /* should an Adobe marker be written? */

  /* State variable: index of next scanline to be written to

   * jpeg_write_scanlines().  Application may use this to control its

   * processing loop, e.g., "while (next_scanline < image_height)".

   */

  JDIMENSION next_scanline;     /* 0 .. image_height-1  */

  /* Remaining fields are known throughout compressor, but generally

   * should not be touched by a surrounding application.

   */

  /*

   * These fields are computed during compression startup

   */

  boolean progressive_mode;     /* TRUE if scan script uses progressive mode */

  int max_h_samp_factor;        /* largest h_samp_factor */

  int max_v_samp_factor;        /* largest v_samp_factor */

#if JPEG_LIB_VERSION >= 70

  int min_DCT_h_scaled_size;    /* smallest DCT_h_scaled_size of any component */

  int min_DCT_v_scaled_size;    /* smallest DCT_v_scaled_size of any component */

#endif

  JDIMENSION total_iMCU_rows;   /* # of iMCU rows to be input to coef ctlr */

  /* The coefficient controller receives data in units of MCU rows as defined

   * for fully interleaved scans (whether the JPEG file is interleaved or not).

   * There are v_samp_factor * DCTSIZE sample rows of each component in an

   * "iMCU" (interleaved MCU) row.

   */

  /*

   * These fields are valid during any one scan.

   * They describe the components and MCUs actually appearing in the scan.

   */

  int comps_in_scan;            /* # of JPEG components in this scan */

  jpeg_component_info *cur_comp_info[MAX_COMPS_IN_SCAN];

  /* *cur_comp_info[i] describes component that appears i'th in SOS */

  JDIMENSION MCUs_per_row;      /* # of MCUs across the image */

  JDIMENSION MCU_rows_in_scan;  /* # of MCU rows in the image */

  int blocks_in_MCU;            /* # of DCT blocks per MCU */

  int MCU_membership[C_MAX_BLOCKS_IN_MCU];

  /* MCU_membership[i] is index in cur_comp_info of component owning */

  /* i'th block in an MCU */

  int Ss, Se, Ah, Al;           /* progressive JPEG parameters for scan */

#if JPEG_LIB_VERSION >= 80

  int block_size;               /* the basic DCT block size: 1..16 */

  const int *natural_order;     /* natural-order position array */

  int lim_Se;                   /* min( Se, DCTSIZE2-1 ) */

#endif

  /*

   * Links to compression subobjects (methods and private variables of modules)

   */

  struct jpeg_comp_master *master;

  struct jpeg_c_main_controller *main;

  struct jpeg_c_prep_controller *prep;

  struct jpeg_c_coef_controller *coef;

  struct jpeg_marker_writer *marker;

  struct jpeg_color_converter *cconvert;

  struct jpeg_downsampler *downsample;

  struct jpeg_forward_dct *fdct;

  struct jpeg_entropy_encoder *entropy;

  jpeg_scan_info *script_space; /* workspace for jpeg_simple_progression */

  int script_space_size;

};

/* Master record for a decompression instance */

struct jpeg_decompress_struct {

  jpeg_common_fields;           /* Fields shared with jpeg_compress_struct */

  /* Source of compressed data */

  struct jpeg_source_mgr *src;

  /* Basic description of image --- filled in by jpeg_read_header(). */

  /* Application may inspect these values to decide how to process image. */

  JDIMENSION image_width;       /* nominal image width (from SOF marker) */

  JDIMENSION image_height;      /* nominal image height */

  int num_components;           /* # of color components in JPEG image */

  J_COLOR_SPACE jpeg_color_space; /* colorspace of JPEG image */

  /* Decompression processing parameters --- these fields must be set before

   * calling jpeg_start_decompress().  Note that jpeg_read_header() initializes

   * them to default values.

   */

  J_COLOR_SPACE out_color_space; /* colorspace for output */

  unsigned int scale_num, scale_denom; /* fraction by which to scale image */

  double output_gamma;          /* image gamma wanted in output */

  boolean buffered_image;       /* TRUE=multiple output passes */

  boolean raw_data_out;         /* TRUE=downsampled data wanted */

  J_DCT_METHOD dct_method;      /* IDCT algorithm selector */

  boolean do_fancy_upsampling;  /* TRUE=apply fancy upsampling */

  boolean do_block_smoothing;   /* TRUE=apply interblock smoothing */

  boolean quantize_colors;      /* TRUE=colormapped output wanted */

  /* the following are ignored if not quantize_colors: */

  J_DITHER_MODE dither_mode;    /* type of color dithering to use */

  boolean two_pass_quantize;    /* TRUE=use two-pass color quantization */

  int desired_number_of_colors; /* max # colors to use in created colormap */

  /* these are significant only in buffered-image mode: */

  boolean enable_1pass_quant;   /* enable future use of 1-pass quantizer */

  boolean enable_external_quant;/* enable future use of external colormap */

  boolean enable_2pass_quant;   /* enable future use of 2-pass quantizer */

  /* Description of actual output image that will be returned to application.

   * These fields are computed by jpeg_start_decompress().

   * You can also use jpeg_calc_output_dimensions() to determine these values

   * in advance of calling jpeg_start_decompress().

   */

  JDIMENSION output_width;      /* scaled image width */

  JDIMENSION output_height;     /* scaled image height */

  int out_color_components;     /* # of color components in out_color_space */

  int output_components;        /* # of color components returned */

  /* output_components is 1 (a colormap index) when quantizing colors;

   * otherwise it equals out_color_components.

   */

  int rec_outbuf_height;        /* min recommended height of scanline buffer */

  /* If the buffer passed to jpeg_read_scanlines() is less than this many rows

   * high, space and time will be wasted due to unnecessary data copying.

   * Usually rec_outbuf_height will be 1 or 2, at most 4.

   */

  /* When quantizing colors, the output colormap is described by these fields.

   * The application can supply a colormap by setting colormap non-NULL before

   * calling jpeg_start_decompress; otherwise a colormap is created during

   * jpeg_start_decompress or jpeg_start_output.

   * The map has out_color_components rows and actual_number_of_colors columns.

   */

  int actual_number_of_colors;  /* number of entries in use */

  JSAMPARRAY colormap;          /* The color map as a 2-D pixel array */

  /* State variables: these variables indicate the progress of decompression.

   * The application may examine these but must not modify them.

   */

  /* Row index of next scanline to be read from jpeg_read_scanlines().

   * Application may use this to control its processing loop, e.g.,

   * "while (output_scanline < output_height)".

   */

  JDIMENSION output_scanline;   /* 0 .. output_height-1  */

  /* Current input scan number and number of iMCU rows completed in scan.

   * These indicate the progress of the decompressor input side.

   */

  int input_scan_number;        /* Number of SOS markers seen so far */

  JDIMENSION input_iMCU_row;    /* Number of iMCU rows completed */

  /* The "output scan number" is the notional scan being displayed by the

   * output side.  The decompressor will not allow output scan/row number

   * to get ahead of input scan/row, but it can fall arbitrarily far behind.

   */

  int output_scan_number;       /* Nominal scan number being displayed */

  JDIMENSION output_iMCU_row;   /* Number of iMCU rows read */

  /* Current progression status.  coef_bits[c][i] indicates the precision

   * with which component c's DCT coefficient i (in zigzag order) is known.

   * It is -1 when no data has yet been received, otherwise it is the point

   * transform (shift) value for the most recent scan of the coefficient

   * (thus, 0 at completion of the progression).

   * This pointer is NULL when reading a non-progressive file.

   */

  int (*coef_bits)[DCTSIZE2];   /* -1 or current Al value for each coef */

  /* Internal JPEG parameters --- the application usually need not look at

   * these fields.  Note that the decompressor output side may not use

   * any parameters that can change between scans.

   */

  /* Quantization and Huffman tables are carried forward across input

   * datastreams when processing abbreviated JPEG datastreams.

   */

  JQUANT_TBL *quant_tbl_ptrs[NUM_QUANT_TBLS];

  /* ptrs to coefficient quantization tables, or NULL if not defined */

  JHUFF_TBL *dc_huff_tbl_ptrs[NUM_HUFF_TBLS];

  JHUFF_TBL *ac_huff_tbl_ptrs[NUM_HUFF_TBLS];

  /* ptrs to Huffman coding tables, or NULL if not defined */

  /* These parameters are never carried across datastreams, since they

   * are given in SOF/SOS markers or defined to be reset by SOI.

   */

  int data_precision;           /* bits of precision in image data */

  jpeg_component_info *comp_info;

  /* comp_info[i] describes component that appears i'th in SOF */

#if JPEG_LIB_VERSION >= 80

  boolean is_baseline;          /* TRUE if Baseline SOF0 encountered */

#endif

  boolean progressive_mode;     /* TRUE if SOFn specifies progressive mode */

  boolean arith_code;           /* TRUE=arithmetic coding, FALSE=Huffman */

  UINT8 arith_dc_L[NUM_ARITH_TBLS]; /* L values for DC arith-coding tables */

  UINT8 arith_dc_U[NUM_ARITH_TBLS]; /* U values for DC arith-coding tables */

  UINT8 arith_ac_K[NUM_ARITH_TBLS]; /* Kx values for AC arith-coding tables */

  unsigned int restart_interval; /* MCUs per restart interval, or 0 for no restart */

  /* These fields record data obtained from optional markers recognized by

   * the JPEG library.

   */

  boolean saw_JFIF_marker;      /* TRUE iff a JFIF APP0 marker was found */

  /* Data copied from JFIF marker; only valid if saw_JFIF_marker is TRUE: */

  UINT8 JFIF_major_version;     /* JFIF version number */

  UINT8 JFIF_minor_version;

  UINT8 density_unit;           /* JFIF code for pixel size units */

  UINT16 X_density;             /* Horizontal pixel density */

  UINT16 Y_density;             /* Vertical pixel density */

  boolean saw_Adobe_marker;     /* TRUE iff an Adobe APP14 marker was found */

  UINT8 Adobe_transform;        /* Color transform code from Adobe marker */

  boolean CCIR601_sampling;     /* TRUE=first samples are cosited */

  /* Aside from the specific data retained from APPn markers known to the

   * library, the uninterpreted contents of any or all APPn and COM markers

   * can be saved in a list for examination by the application.

   */

  jpeg_saved_marker_ptr marker_list; /* Head of list of saved markers */

  /* Remaining fields are known throughout decompressor, but generally

   * should not be touched by a surrounding application.

   */

  /*

   * These fields are computed during decompression startup

   */

  int max_h_samp_factor;        /* largest h_samp_factor */

  int max_v_samp_factor;        /* largest v_samp_factor */

#if JPEG_LIB_VERSION >= 70

  int min_DCT_h_scaled_size;    /* smallest DCT_h_scaled_size of any component */

  int min_DCT_v_scaled_size;    /* smallest DCT_v_scaled_size of any component */

#else

  int min_DCT_scaled_size;      /* smallest DCT_scaled_size of any component */

#endif

  JDIMENSION total_iMCU_rows;   /* # of iMCU rows in image */

  /* The coefficient controller's input and output progress is measured in

   * units of "iMCU" (interleaved MCU) rows.  These are the same as MCU rows

   * in fully interleaved JPEG scans, but are used whether the scan is

   * interleaved or not.  We define an iMCU row as v_samp_factor DCT block

   * rows of each component.  Therefore, the IDCT output contains

   * v_samp_factor*DCT_[v_]scaled_size sample rows of a component per iMCU row.

   */

  JSAMPLE *sample_range_limit;  /* table for fast range-limiting */

  /*

   * These fields are valid during any one scan.

   * They describe the components and MCUs actually appearing in the scan.

   * Note that the decompressor output side must not use these fields.

   */

  int comps_in_scan;            /* # of JPEG components in this scan */

  jpeg_component_info *cur_comp_info[MAX_COMPS_IN_SCAN];

  /* *cur_comp_info[i] describes component that appears i'th in SOS */

  JDIMENSION MCUs_per_row;      /* # of MCUs across the image */

  JDIMENSION MCU_rows_in_scan;  /* # of MCU rows in the image */

  int blocks_in_MCU;            /* # of DCT blocks per MCU */

  int MCU_membership[D_MAX_BLOCKS_IN_MCU];

  /* MCU_membership[i] is index in cur_comp_info of component owning */

  /* i'th block in an MCU */

  int Ss, Se, Ah, Al;           /* progressive JPEG parameters for scan */

#if JPEG_LIB_VERSION >= 80

  /* These fields are derived from Se of first SOS marker.

   */

  int block_size;               /* the basic DCT block size: 1..16 */

  const int *natural_order; /* natural-order position array for entropy decode */

  int lim_Se;                   /* min( Se, DCTSIZE2-1 ) for entropy decode */

#endif

  /* This field is shared between entropy decoder and marker parser.

   * It is either zero or the code of a JPEG marker that has been

   * read from the data source, but has not yet been processed.

   */

  int unread_marker;

  /*

   * Links to decompression subobjects (methods, private variables of modules)

   */

  struct jpeg_decomp_master *master;

  struct jpeg_d_main_controller *main;

  struct jpeg_d_coef_controller *coef;

  struct jpeg_d_post_controller *post;

  struct jpeg_input_controller *inputctl;

  struct jpeg_marker_reader *marker;

  struct jpeg_entropy_decoder *entropy;

  struct jpeg_inverse_dct *idct;

  struct jpeg_upsampler *upsample;

  struct jpeg_color_deconverter *cconvert;

  struct jpeg_color_quantizer *cquantize;

};

/* "Object" declarations for JPEG modules that may be supplied or called

 * directly by the surrounding application.

 * As with all objects in the JPEG library, these structs only define the

 * publicly visible methods and state variables of a module.  Additional

 * private fields may exist after the public ones.

 */

/* Error handler object */

struct jpeg_error_mgr {

  /* Error exit handler: does not return to caller */

  void (*error_exit) (j_common_ptr cinfo);

  /* Conditionally emit a trace or warning message */

  void (*emit_message) (j_common_ptr cinfo, int msg_level);

  /* Routine that actually outputs a trace or error message */

  void (*output_message) (j_common_ptr cinfo);

  /* Format a message string for the most recent JPEG error or message */

  void (*format_message) (j_common_ptr cinfo, char *buffer);

#define JMSG_LENGTH_MAX  200    /* recommended size of format_message buffer */

  /* Reset error state variables at start of a new image */

  void (*reset_error_mgr) (j_common_ptr cinfo);

  /* The message ID code and any parameters are saved here.

   * A message can have one string parameter or up to 8 int parameters.

   */

  int msg_code;

#define JMSG_STR_PARM_MAX  80

  union {

    int i[8];

    char s[JMSG_STR_PARM_MAX];

  } msg_parm;

  /* Standard state variables for error facility */

  int trace_level;              /* max msg_level that will be displayed */

  /* For recoverable corrupt-data errors, we emit a warning message,

   * but keep going unless emit_message chooses to abort.  emit_message

   * should count warnings in num_warnings.  The surrounding application

   * can check for bad data by seeing if num_warnings is nonzero at the

   * end of processing.

   */

  long num_warnings;            /* number of corrupt-data warnings */

  /* These fields point to the table(s) of error message strings.

   * An application can change the table pointer to switch to a different

   * message list (typically, to change the language in which errors are

   * reported).  Some applications may wish to add additional error codes

   * that will be handled by the JPEG library error mechanism; the second

   * table pointer is used for this purpose.

   *

   * First table includes all errors generated by JPEG library itself.

   * Error code 0 is reserved for a "no such error string" message.

   */

  const char * const *jpeg_message_table; /* Library errors */

  int last_jpeg_message;    /* Table contains strings 0..last_jpeg_message */

  /* Second table can be added by application (see cjpeg/djpeg for example).

   * It contains strings numbered first_addon_message..last_addon_message.

   */

  const char * const *addon_message_table; /* Non-library errors */

  int first_addon_message;      /* code for first string in addon table */

  int last_addon_message;       /* code for last string in addon table */

};

/* Progress monitor object */

struct jpeg_progress_mgr {

  void (*progress_monitor) (j_common_ptr cinfo);

  long pass_counter;            /* work units completed in this pass */

  long pass_limit;              /* total number of work units in this pass */

  int completed_passes;         /* passes completed so far */

  int total_passes;             /* total number of passes expected */

};

/* Data destination object for compression */

struct jpeg_destination_mgr {

  JOCTET *next_output_byte;     /* => next byte to write in buffer */

  size_t free_in_buffer;        /* # of byte spaces remaining in buffer */

  void (*init_destination) (j_compress_ptr cinfo);

  boolean (*empty_output_buffer) (j_compress_ptr cinfo);

  void (*term_destination) (j_compress_ptr cinfo);

};

/* Data source object for decompression */

struct jpeg_source_mgr {

  const JOCTET *next_input_byte; /* => next byte to read from buffer */

  size_t bytes_in_buffer;       /* # of bytes remaining in buffer */

  void (*init_source) (j_decompress_ptr cinfo);

  boolean (*fill_input_buffer) (j_decompress_ptr cinfo);

  void (*skip_input_data) (j_decompress_ptr cinfo, long num_bytes);

  boolean (*resync_to_restart) (j_decompress_ptr cinfo, int desired);

  void (*term_source) (j_decompress_ptr cinfo);

};

/* Memory manager object.

 * Allocates "small" objects (a few K total), "large" objects (tens of K),

 * and "really big" objects (virtual arrays with backing store if needed).

 * The memory manager does not allow individual objects to be freed; rather,

 * each created object is assigned to a pool, and whole pools can be freed

 * at once.  This is faster and more convenient than remembering exactly what

 * to free, especially where malloc()/free() are not too speedy.

 * NB: alloc routines never return NULL.  They exit to error_exit if not

 * successful.

 */

#define JPOOL_PERMANENT  0      /* lasts until master record is destroyed */

#define JPOOL_IMAGE      1      /* lasts until done with image/datastream */

#define JPOOL_NUMPOOLS   2

typedef struct jvirt_sarray_control *jvirt_sarray_ptr;

typedef struct jvirt_barray_control *jvirt_barray_ptr;

struct jpeg_memory_mgr {

  /* Method pointers */

  void *(*alloc_small) (j_common_ptr cinfo, int pool_id, size_t sizeofobject);

  void *(*alloc_large) (j_common_ptr cinfo, int pool_id,

                        size_t sizeofobject);

  JSAMPARRAY (*alloc_sarray) (j_common_ptr cinfo, int pool_id,

                              JDIMENSION samplesperrow, JDIMENSION numrows);

  JBLOCKARRAY (*alloc_barray) (j_common_ptr cinfo, int pool_id,

                               JDIMENSION blocksperrow, JDIMENSION numrows);

  jvirt_sarray_ptr (*request_virt_sarray) (j_common_ptr cinfo, int pool_id,

                                           boolean pre_zero,

                                           JDIMENSION samplesperrow,

                                           JDIMENSION numrows,

                                           JDIMENSION maxaccess);

  jvirt_barray_ptr (*request_virt_barray) (j_common_ptr cinfo, int pool_id,

                                           boolean pre_zero,

                                           JDIMENSION blocksperrow,

                                           JDIMENSION numrows,

                                           JDIMENSION maxaccess);

  void (*realize_virt_arrays) (j_common_ptr cinfo);

  JSAMPARRAY (*access_virt_sarray) (j_common_ptr cinfo, jvirt_sarray_ptr ptr,

                                    JDIMENSION start_row, JDIMENSION num_rows,

                                    boolean writable);

  JBLOCKARRAY (*access_virt_barray) (j_common_ptr cinfo, jvirt_barray_ptr ptr,

                                     JDIMENSION start_row, JDIMENSION num_rows,

                                     boolean writable);

  void (*free_pool) (j_common_ptr cinfo, int pool_id);

  void (*self_destruct) (j_common_ptr cinfo);

  /* Limit on memory allocation for this JPEG object.  (Note that this is

   * merely advisory, not a guaranteed maximum; it only affects the space

   * used for virtual-array buffers.)  May be changed by outer application

   * after creating the JPEG object.

   */

  long max_memory_to_use;

  /* Maximum allocation request accepted by alloc_large. */

  long max_alloc_chunk;

};

/* Routine signature for application-supplied marker processing methods.

 * Need not pass marker code since it is stored in cinfo->unread_marker.

 */

typedef boolean (*jpeg_marker_parser_method) (j_decompress_ptr cinfo);