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/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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
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