/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_image_decoders_GIF2_H
#define mozilla_image_decoders_GIF2_H

#define MAX_LZW_BITS 12
#define MAX_BITS 4097  // 2^MAX_LZW_BITS+1
#define MAX_COLORS 256
#define MIN_HOLD_SIZE 256

enum { GIF_TRAILER = 0x3B };               // ';'
enum { GIF_IMAGE_SEPARATOR = 0x2C };       // ','
enum { GIF_EXTENSION_INTRODUCER = 0x21 };  // '!'
enum { GIF_GRAPHIC_CONTROL_LABEL = 0xF9 };
enum { GIF_APPLICATION_EXTENSION_LABEL = 0xFF };

// A GIF decoder's state
typedef struct gif_struct {
  // LZW decoder state machine
  uint8_t* stackp;  // Current stack pointer
  int datasize;
  int codesize;
  int codemask;
  int avail;  // Index of next available slot in dictionary
  int oldcode;
  uint8_t firstchar;
  int bits;       // Number of unread bits in "datum"
  int32_t datum;  // 32-bit input buffer

  // Output state machine
  int64_t pixels_remaining;  // Pixels remaining to be output.

  // Parameters for image frame currently being decoded
  int tpixel;                // Index of transparent pixel
  int32_t disposal_method;   // Restore to background, leave in place, etc.
  uint32_t* local_colormap;  // Per-image colormap
  uint32_t local_colormap_buffer_size;  // Size of the buffer containing the
                                        // local colormap.
  int local_colormap_size;              // Size of local colormap array.
  uint32_t delay_time;                  // Display time, in milliseconds,
                                        // for this image in a multi-image GIF

  // Global (multi-image) state
  int version;           // Either 89 for GIF89 or 87 for GIF87
  int32_t screen_width;  // Logical screen width & height
  int32_t screen_height;
  uint8_t global_colormap_depth;   // Depth of global colormap array
  uint16_t global_colormap_count;  // Number of colors in global colormap
  int images_decoded;              // Counts images for multi-part GIFs
  int loop_count;  // Netscape specific extension block to control
                   // the number of animation loops a GIF
                   // renders.

  bool is_transparent;  // TRUE, if tpixel is valid

  uint16_t prefix[MAX_BITS];             // LZW decoding tables
  uint32_t global_colormap[MAX_COLORS];  // Default colormap if local not
                                         //   supplied
  uint8_t suffix[MAX_BITS];              // LZW decoding tables
  uint8_t stack[MAX_BITS];               // Base of LZW decoder stack

} gif_struct;

#endif  // mozilla_image_decoders_GIF2_H
