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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
+ 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