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Diffstat (limited to 'riscos/gifread.c')
| -rw-r--r-- | riscos/gifread.c | 915 |
1 files changed, 915 insertions, 0 deletions
diff --git a/riscos/gifread.c b/riscos/gifread.c new file mode 100644 index 000000000..77406afd3 --- /dev/null +++ b/riscos/gifread.c @@ -0,0 +1,915 @@ +/* + * This file is part of NetSurf, http://netsurf.sourceforge.net/ + * Licensed under the GNU General Public License, + * http://www.opensource.org/licenses/gpl-license + * Copyright 2004 Richard Wilson <not_ginger_matt@sourceforge.net> + */ + + +#include <stdio.h> +#include <string.h> +#include <stdlib.h> +#include "gifread.h" +#include "netsurf/utils/log.h" +#include "oslib/osspriteop.h" +#include "oslib/osfile.h" + + +/* READING GIF FILES + ================= + + The functions provided by this file allow for efficient progressive GIF + decoding. Whilst the initialisation does not ensure that there is + sufficient image data to complete the entire frame, it does ensure that + the information provided is valid. Any subsequent attempts to decode an + initialised GIF are guaranteed to succeed, and any bytes of the image + not present are assumed to be totally transparent. + + To begin decoding a GIF, the 'gif' structure must be initialised with + the 'gif_data' and 'buffer_size' set to their initial values. The + 'buffer_position' should initially be 0, and will be internally updated + as the decoding commences. The caller should then repeatedly call + gif_initialise() with the structure until the function returns 1, or + no more data is avaliable. + + Once the initialisation has begun, the decoder completes the variables + 'frame_count' and 'frame_count_partial'. The former being the total + number of frames that have been successfully initialised, and the + latter being the number of frames that a partial amount of data is + available for. This assists the caller in managing the animation whilst + decoding is continuing. + + To decode a frame, the caller must use gif_decode_frame() which updates + the current 'frame_image' to reflect the desired frame. The required + 'background_action' is also updated to reflect how the frame should be + plotted. The caller must not assume that the current 'frame_image' will + be valid between calls if initialisation is still occuring, and should + either always request that the frame is decoded (no processing will + occur if the 'decoded_frame' has not been invalidated by initialisation) + or perform the check itself. + + It should be noted that gif_finalise() should always be called, even if + no frames were initialised. + + [rjw] - Fri 2nd April 2004 +*/ + + + +/* Internal GIF routines +*/ +static int gif_initialise_sprite(struct gif_animation *gif, unsigned int width, unsigned int height); +static int gif_initialise_frame(struct gif_animation *gif); +static unsigned int gif_interlaced_line(unsigned int height, unsigned int y); + + + +/* Internal LZW routines +*/ +static int gif_next_LZW(struct gif_animation *gif); +static int gif_next_code(struct gif_animation *gif, int code_size); +static int gif_next_block(struct gif_animation *gif, unsigned char *buf); +#define gif_read_LZW(gif) ((stack_pointer > stack) ? *--stack_pointer : gif_next_LZW(gif)) + +/* General LZW values. They are shared for all GIFs being decoded, and + thus we can't handle progressive decoding efficiently without having + the data for each image which would use an extra 10Kb or so per GIF. +*/ +static int stack[(1 << GIF_MAX_LZW) * 2]; +static int *stack_pointer; +static int code_size, set_code_size; +static int max_code, max_code_size; +static int clear_code, end_code; +static int curbit, lastbit, get_done, last_byte; +static int return_clear; +static int zero_data_block = FALSE; + + + +/* Initialises any workspace held by the animation and attempts to decode + any information that hasn't already been decoded. + If an error occurs, all previously decoded frames are retained. + + @return -5 for GIF frame data error + -4 for insufficient data to process any more frames + -3 for memory error + -2 for GIF error + -1 for insufficient data to do anything + 0 for successful decoding + 1 for successful decoding (all frames completely read) +*/ +int gif_initialise(struct gif_animation *gif) { + unsigned char *gif_data; + unsigned int index; + int return_value; + + /* Check for sufficient data to be a GIF + */ + if (gif->buffer_size < 13) { + return -1; + } + + /* Get our current processing position + */ + gif_data = gif->gif_data + gif->buffer_position; + + /* See if we should initialise the GIF + */ + if (gif->buffer_position == 0) { + + /* The 12th byte must be a 0 for the block terminator + */ + if (gif_data[12] != 0x00) return GIF_DATA_ERROR; + + /* We want everything to be NULL before we start so we've no chance + of freeing bad pointers (paranoia) + */ + gif->frame_image = NULL; + gif->frame_pointers = NULL; + gif->frame_delays = NULL; + gif->local_colour_table = NULL; + gif->global_colour_table = NULL; + + /* The caller may have been lazy and not reset any values + */ + gif->frame_count = 0; + gif->frame_count_partial = 0; + gif->decoded_frame = 0xffffffff; + + /* Check we are a GIF + */ + if (strncmp(gif_data, "GIF", 3) != 0) return GIF_DATA_ERROR; + gif_data += 3; + + /* Check we are a GIF type 87a or 89a + */ + if ((strncmp(gif_data, "87a", 3) != 0) && + (strncmp(gif_data, "89a", 3) != 0)) { + LOG(("Unknown GIF format - proceeding anyway")); + } + gif_data += 3; + + /* Get our GIF data. Quite often the width/height are lies, so we don't fill them in + */ + gif->width = 0; // Can't trust the supplied value + gif->height = 0; // Can't trust the supplied value +// gif->width = (gif_data[0] | (gif_data[1] << 8)); +// gif->height = (gif_data[2] | (gif_data[3] << 8)); + gif->global_colours = (gif_data[4] & 0x80); + gif->colour_table_size = (2 << (gif_data[4] & 0x07)); + gif->background_colour = gif_data[5]; + gif->aspect_ratio = gif_data[6]; + gif_data += 7; + + /* Allocate some data irrespective of whether we've got any colour tables. We + always get the maximum size in case a GIF is lying to us. It's far better + to give the wrong colours than to trample over some memory somewhere. + */ + gif->global_colour_table = (unsigned int *)calloc(GIF_MAX_COLOURS, sizeof(int)); + gif->local_colour_table = (unsigned int *)calloc(GIF_MAX_COLOURS, sizeof(int)); + if ((gif->global_colour_table == NULL) || (gif->local_colour_table == NULL)) { + gif_finalise(gif); + return GIF_INSUFFICIENT_MEMORY; + } + + /* Set the first colour to a value that will never occur in reality so we + know if we've processed it + */ + gif->global_colour_table[0] = 0xaa000000; + + /* Initialise enough workspace for 4 frame initially + */ + if ((gif->frame_delays = (unsigned int *)malloc(sizeof(int))) == NULL) { + gif_finalise(gif); + return GIF_INSUFFICIENT_MEMORY; + } + if ((gif->frame_pointers = (unsigned int *)malloc(sizeof(int))) == NULL) { + gif_finalise(gif); + return GIF_INSUFFICIENT_MEMORY; + } + gif->frame_holders = 1; + + /* Initialise the sprite header + */ + if ((gif->frame_image = (osspriteop_header *)malloc(sizeof(osspriteop_header))) == NULL) { + gif_finalise(gif); + return GIF_INSUFFICIENT_MEMORY; + } + gif->frame_image->size = sizeof(osspriteop_header); + strcpy(gif->frame_image->name, "gif"); + gif->frame_image->left_bit = 0; + gif->frame_image->right_bit = 31; + gif->frame_image->width = 0; + gif->frame_image->height = 0; + gif->frame_image->image = sizeof(osspriteop_header); + gif->frame_image->mask = sizeof(osspriteop_header); + gif->frame_image->mode = (os_mode) 0x301680b5; + + /* Remember we've done this now + */ + gif->buffer_position = gif_data - gif->gif_data; + } + + /* Do the colour map if we haven't already. As the top byte is always 0xff or 0x00 + depending on the transparency we know if it's been filled in. + */ + if (gif->global_colour_table[0] == 0xaa000000) { + /* Check for a global colour map signified by bit 7 + */ + if (gif->global_colours) { + if (gif->buffer_size < (gif->colour_table_size * 3 + 12)) { + return GIF_INSUFFICIENT_DATA; + } +// LOG(("Found global colour table with %i entries", gif->colour_table_size)); + for (index = 0; index < gif->colour_table_size; index++) { + gif->global_colour_table[index] = gif_data[0] | (gif_data[1] << 8) | + (gif_data[2] << 16) | 0xff000000; + gif_data += 3; + } + gif->buffer_position = (gif_data - gif->gif_data); + } else { +// LOG(("No global colour table")); + /* Create a default colour table with the first two colours as black and white + */ + gif->global_colour_table[0] = 0xff000000; + gif->global_colour_table[1] = 0xffffffff; + } + } + + /* Repeatedly try to decode frames + */ + while ((return_value = gif_initialise_frame(gif)) == 0); + + /* If there was a memory error tell the caller + */ + if ((return_value == GIF_INSUFFICIENT_MEMORY) || + (return_value == GIF_DATA_ERROR)) { + return return_value; + } + + /* If we didn't have some frames then a GIF_INSUFFICIENT_DATA becomes a + GIF_INSUFFICIENT_FRAME_DATA + */ + if ((return_value == GIF_INSUFFICIENT_DATA) && (gif->frame_count_partial > 0)) { + return_value = GIF_INSUFFICIENT_FRAME_DATA; + } + + /* Return how many we got + */ + return return_value; +} + + + +/** Updates the sprite memory size + + @return -3 for a memory error + 0 for success +*/ +static int gif_initialise_sprite(struct gif_animation *gif, unsigned int width, unsigned int height) { + struct osspriteop_header *buffer; + unsigned int max_width; + unsigned int max_height; + unsigned int frame_bytes; + + /* Check if we've changed + */ + if ((width <= gif->width) && (height <= gif->height)) return 0; + + /* Get our maximum values + */ + max_width = (width > gif->width) ? width : gif->width; + max_height = (height > gif->height) ? height : gif->height; + frame_bytes = max_width * max_height * 4 + sizeof(osspriteop_header); + + /* Allocate some more memory + */ + if ((buffer = (osspriteop_header *)realloc(gif->frame_image, frame_bytes)) == NULL) { + return GIF_INSUFFICIENT_MEMORY; + } + gif->frame_image = buffer; + + /* Update the sizes + */ + gif->width = max_width; + gif->height = max_height; + + /* Update our sprite image + */ + buffer->size = frame_bytes; + buffer->width = max_width - 1; + buffer->height = max_height - 1; + + /* Invalidate our currently decoded image + */ + gif->decoded_frame = 0xffffffff; + return 0; +} + + +/* Attempts to initialise the next frame + + @return -4 for insufficient data to process the entire frame + -3 for a memory error + -2 for a data error + -1 for insufficient data to process anything + 0 for success + 1 for success (GIF terminator found) +*/ +int gif_initialise_frame(struct gif_animation *gif) { + unsigned int frame; + unsigned int *temp_buf; + + unsigned char *gif_data, *gif_end; + int gif_bytes; + unsigned int flags = 0; + unsigned int width, height, offset_x, offset_y; + unsigned int extension_size, colour_table_size; + unsigned int block_size; + unsigned int more_images; + + /* Get the frame to decode and our data position + */ + frame = gif->frame_count; + + /* Get our buffer position etc. + */ + gif_data = (unsigned char *)(gif->gif_data + gif->buffer_position); + gif_end = (unsigned char *)(gif->gif_data + gif->buffer_size); + gif_bytes = (gif_end - gif_data); + + /* Check we have enough data for at least the header, or if we've finished + */ + if ((gif_bytes > 0) && (gif_data[0] == 0x3b)) return 1; + if (gif_bytes < 11) return -1; + + /* We could theoretically get some junk data that gives us millions of frames, so + we ensure that we don't have a silly number + */ + if (frame > 4096) return GIF_DATA_ERROR; + + /* Get some memory to store our pointers in etc. + */ + if (gif->frame_holders <= frame) { + /* Allocate more memory + */ + if ((temp_buf = (unsigned int *)realloc(gif->frame_delays, + (frame + 1) * sizeof(int))) == NULL) { + return GIF_INSUFFICIENT_MEMORY; + } + gif->frame_delays = temp_buf; + if ((temp_buf = (unsigned int *)realloc(gif->frame_pointers, + (frame + 1) * sizeof(int))) == NULL) { + return GIF_INSUFFICIENT_MEMORY; + } + gif->frame_pointers = temp_buf; + + /* Remember we allocated it + */ + gif->frame_holders = frame + 1; + } + + /* Store our frame pointer. We would do it when allocating except we + start off with one frame allocated so we can always use realloc. + */ +// LOG(("Set frame number %i to offset %i", frame, gif->buffer_position)); + gif->frame_pointers[frame] = gif->buffer_position; + gif->frame_delays[frame] = 100; // Paranoia + + /* Invalidate any previous decoding we have of this frame + */ + if (gif->decoded_frame == frame) gif->decoded_frame = 0xffffffff; + + /* We pretend to initialise the frames, but really we just skip over all + the data contained within. This is all basically a cut down version of + gif_decode_frame that doesn't have any of the LZW bits in it. + */ + more_images = 1; + while (more_images != 0) { + + /* Ensure we have some data + */ + if ((gif_end - gif_data) < 10) return GIF_INSUFFICIENT_FRAME_DATA; + + /* Decode the extensions + */ + while (gif_data[0] == 0x21) { + /* Get the extension size + */ + extension_size = gif_data[2]; + + /* Check we've enough data for the extension then header + */ + if ((gif_end - gif_data) < (int)(extension_size + 13)) return GIF_INSUFFICIENT_FRAME_DATA; + /* Graphic control extension - store the frame delay. + */ + if (gif_data[1] == 0xf9) { + gif->frame_delays[frame] = gif_data[4] | (gif_data[5] << 8); + more_images = ((gif->frame_delays[frame]) == 0); + } + /* Move to the first sub-block + */ + gif_data += 2; + + /* Skip all the sub-blocks + */ + while (gif_data[0] != 0x00) { + gif_data += gif_data[0] + 1; + if ((gif_end - gif_data) < 10) return GIF_INSUFFICIENT_FRAME_DATA; + } + gif_data++; + } + + /* We must have at least one image descriptor + */ + if (gif_data[0] != 0x2c) return GIF_FRAME_DATA_ERROR; + + /* Do some simple boundary checking + */ + offset_x = gif_data[1] | (gif_data[2] << 8); + offset_y = gif_data[3] | (gif_data[4] << 8); + width = gif_data[5] | (gif_data[6] << 8); + height = gif_data[7] | (gif_data[8] << 8); +// LOG(("Found image %ix%i with offset (%i,%i)", width, height, offset_x, offset_y)); + + /* Boundary checking - shouldn't ever happen except with junk data + */ + if (gif_initialise_sprite(gif, (offset_x + width), (offset_y + height))) { + return GIF_INSUFFICIENT_MEMORY; + } + + /* Decode the flags + */ + flags = gif_data[9]; + colour_table_size = 2 << (flags & 0x07); + + /* Move our data onwards and remember we've got a bit of this frame + */ + gif_data += 10; + gif_bytes = (gif_end - gif_data); + gif->frame_count_partial = frame + 1; + + /* Skip the local colour table + */ + if (flags & 0x80) { + gif_data += 3 * colour_table_size; + if ((gif_bytes = (gif_end - gif_data)) < 0) return GIF_INSUFFICIENT_FRAME_DATA; + } + + /* Ensure we have a correct code size + */ + if (gif_data[0] > GIF_MAX_LZW) return GIF_DATA_ERROR; + + /* Move our data onwards + */ + gif_data++; + if (--gif_bytes < 0) return GIF_INSUFFICIENT_FRAME_DATA; + + /* Repeatedly skip blocks until we get a zero block or run out of data + */ + block_size = 0; + while (block_size != 1) { + /* Skip the block data + */ + block_size = gif_data[0] + 1; + if ((gif_bytes -= block_size) < 0) return GIF_INSUFFICIENT_FRAME_DATA; + gif_data += block_size; + } + + /* Check for end of data + */ + if ((gif_bytes < 1) || (gif_data[0] == 0x3b)) more_images = 0; + } + + /* Check if we've finished + */ + if (gif_bytes < 1) { + return GIF_INSUFFICIENT_FRAME_DATA; + } else { + gif->buffer_position = gif_data - gif->gif_data; + gif->frame_count = frame + 1; + if (gif_data[0] == 0x3b) return 1; + } + return 0; +} + + +/** Decodes a GIF frame. + + @return -5 for GIF frame data error + -4 for insufficient data to complete the frame + -2 for GIF error (invalid frame header) + -1 for insufficient data to do anything + 0 for successful decoding +*/ +int gif_decode_frame(struct gif_animation *gif, unsigned int frame) { + unsigned int index = 0; + unsigned char *gif_data; + unsigned char *gif_end; + int gif_bytes; + unsigned int width, height, offset_x, offset_y; + unsigned int flags, colour_table_size, interlace; + unsigned int *colour_table; + unsigned int *frame_data = 0; // Set to 0 for no warnings + unsigned int *frame_scanline; + unsigned int extension_size; + int transparency_index = -1; + unsigned int transparent_colour = 0; // Set to 0 for no warnings + unsigned int save_buffer_position; + unsigned int frame_data_size; + unsigned int return_value = 0; + unsigned int x, y, decode_y; + int colour; + + unsigned int more_images; + + /* Ensure we have a frame to decode + */ + if (frame > gif->frame_count_partial) return GIF_INSUFFICIENT_DATA; + if (frame == gif->decoded_frame) return 0; + + /* Get the start of our frame data and the end of the GIF data + */ + gif_data = gif->gif_data + gif->frame_pointers[frame]; + gif_end = gif->gif_data + gif->buffer_size; + gif_bytes = (gif_end - gif_data); + + /* Check we have enough data for the header + */ + if (gif_bytes < 9) return GIF_INSUFFICIENT_DATA; + + /* Clear the previous frame totally. We can't just pretend we've got a smaller + sprite and clear what we need as some frames have multiple images which would + produce errors. + */ + frame_data = (unsigned int*)((char *)gif->frame_image + sizeof(osspriteop_header)); + if ((frame == 0) || (gif->decoded_frame == 0xffffffff)) { + memset((char*)frame_data, 0x00, gif->width * gif->height * sizeof(int)); + } + gif->decoded_frame = frame; + + /* Save the buffer position + */ + save_buffer_position = gif->buffer_position; + gif->buffer_position = gif_data - gif->gif_data; + + /* We've got to do this more than one time if we've got multiple images + */ + gif->background_action = 0; + more_images = 1; + while (more_images != 0) { + + /* Ensure we have some data + */ + gif_data = gif->gif_data + gif->buffer_position; + if ((gif_end - gif_data) < 10) return GIF_INSUFFICIENT_FRAME_DATA; + + /* Decode the extensions + */ + while (gif_data[0] == 0x21) { + + /* Get the extension size + */ + extension_size = gif_data[2]; + + /* Check we've enough data for the extension then header + */ + if ((gif_end - gif_data) < (int)(extension_size + 13)) return GIF_INSUFFICIENT_FRAME_DATA; + /* Graphic control extension - store the frame delay. + */ + if (gif_data[1] == 0xf9) { + flags = gif_data[3]; + if (flags & 0x01) transparency_index = gif_data[6]; + gif->background_action = ((flags & 0x1c) >> 2); + more_images = ((gif_data[4] | (gif_data[5] << 8)) == 0); + } + /* Move to the first sub-block + */ + gif_data += 2; + + /* Skip all the sub-blocks + */ + while (gif_data[0] != 0x00) { + gif_data += gif_data[0] + 1; + if ((gif_end - gif_data) < 10) return GIF_INSUFFICIENT_FRAME_DATA; + } + gif_data++; + } + + /* Decode the header + */ + if (gif_data[0] != 0x2c) return GIF_DATA_ERROR; + offset_x = gif_data[1] | (gif_data[2] << 8); + offset_y = gif_data[3] | (gif_data[4] << 8); + width = gif_data[5] | (gif_data[6] << 8); + height = gif_data[7] | (gif_data[8] << 8); +// LOG(("Decoding %ix%i at offset (%i,%i)", width, height, offset_x, offset_y)); + + /* Boundary checking - shouldn't ever happen except unless the data has been + modified since initialisation. + */ + if ((offset_x + width > gif->width) || (offset_y + height > gif->height)) { + return GIF_DATA_ERROR; + } + + /* Decode the flags + */ + flags = gif_data[9]; + colour_table_size = 2 << (flags & 0x07); + interlace = flags & 0x40; + + /* Move through our data + */ + gif_data += 10; + gif_bytes = (int)(gif_end - gif_data); + + /* Initialise our sprite to be totally transparent if we should + */ +// gif->frame_offset_x = offset_x; +// gif->frame_offset_y = offset_y; +// gif->frame_image->width = width; +// gif->frame_image->height = height; + + /* Set up the colour table + */ + if (flags & 0x80) { +// LOG(("Found local colour table")); + if (gif_bytes < (int)(3 * colour_table_size)) return GIF_INSUFFICIENT_FRAME_DATA; + colour_table = gif->local_colour_table; + for (index = 0; index < colour_table_size; index++) { + colour_table[index] = gif_data[0] | (gif_data[1] << 8) | + (gif_data[2] << 16) | 0xff000000; + gif_data += 3; + } + gif_bytes = (int)(gif_end - gif_data); + } else { + colour_table = gif->global_colour_table; + } + /* Initialise the LZW decoding + */ + set_code_size = gif_data[0]; + gif->buffer_position = (gif_data - gif->gif_data) + 1; + + /* Set our code variables + */ + code_size = set_code_size + 1; + clear_code = (1 << set_code_size); + end_code = clear_code + 1; + max_code_size = 2 * clear_code; + max_code = clear_code + 2; + curbit = lastbit = 0; + last_byte = 2; + get_done = 0; + return_clear = 1; + stack_pointer = stack; + + /* Set the transparent colour as transparent + */ + if (transparency_index >= 0) { + transparent_colour = colour_table[transparency_index]; + colour_table[transparency_index] = 0x00000000; + } + + /* Decompress the data + */ + if ((gif->background_action == 2) || (gif->background_action == 3)) { + frame_data_size = width * height; + for (y = 0; y < height; y++) { + if (interlace) { + decode_y = gif_interlaced_line(height, y) + offset_y; + } else { + decode_y = y + offset_y; + } + frame_scanline = frame_data + offset_x + (decode_y * gif->width); + for (x = 0; x < width; x++) { + if ((colour = gif_read_LZW(gif)) >= 0) { + *frame_scanline++ = colour_table[colour]; + } else { + LOG(("%i bytes of %i read", index, frame_data_size)); + return_value = GIF_INSUFFICIENT_FRAME_DATA; + goto gif_decode_frame_exit; + } + } + } + } else { + frame_data_size = width * height; + for (y = 0; y < height; y++) { + if (interlace) { + decode_y = gif_interlaced_line(height, y) + offset_y; + } else { + decode_y = y + offset_y; + } + frame_scanline = frame_data + offset_x + (decode_y * gif->width); + for (x = 0; x < width; x++) { + if ((colour = gif_read_LZW(gif)) >= 0) { + if (colour == transparency_index) { + *frame_scanline++; + } else { + *frame_scanline++ = colour_table[colour]; + } + } else { + LOG(("%i bytes of %i read", index, frame_data_size)); + return_value = GIF_INSUFFICIENT_FRAME_DATA; + goto gif_decode_frame_exit; + } + } + } + } +gif_decode_frame_exit: + + /* Unset the transparent colour + */ + if (transparency_index >= 0) { + colour_table[transparency_index] = transparent_colour; + } + + /* Check for end of data + */ + gif_bytes = gif->buffer_size - gif->buffer_position; + if ((gif_bytes < 1) || (gif_data[0] == 0x3b)) more_images = 0; + gif->buffer_position++; + } + + /* Restore the buffer position + */ + gif->buffer_position = save_buffer_position; + + /* Success! + */ + return return_value; + +} + +static unsigned int gif_interlaced_line(unsigned int height, unsigned int y) { + if ((y << 3) < height) return (y << 3); + y -= ((height + 7) >> 3); + if ((y << 3) < (height - 4)) return (y << 3) + 4; + y -= ((height + 3) >> 3); + if ((y << 2) < (height - 2)) return (y << 2) + 2; + y -= ((height + 1) >> 2); + return (y << 1) + 1; + +/* if ((y & 7) == 0) return (y >> 3); + offset = (height + 7) >> 3; + if ((y & 7) == 4) return offset + ((y - 4) >> 3); + offset += (height + 3) >> 3; + if ((y & 3) == 2) return offset + ((y - 2) >> 2); + return offset + ((height + 1) >> 2) + ((y - 1) >> 1); +*/ +} + +/* Releases any workspace held by the animation +*/ +void gif_finalise(struct gif_animation *gif) { + /* Release all our memory blocks + */ + free(gif->frame_image); + gif->frame_image = NULL; + free(gif->frame_pointers); + gif->frame_pointers = NULL; + free(gif->frame_delays); + gif->frame_delays = NULL; + free(gif->local_colour_table); + gif->local_colour_table = NULL; + free(gif->global_colour_table); + gif->global_colour_table = NULL; +} + + +static int gif_next_LZW(struct gif_animation *gif) { + static int table[2][(1<< GIF_MAX_LZW)]; + static int firstcode, oldcode; + int code, incode; + unsigned int i, block_size; + + while ((code = gif_next_code(gif, code_size)) >= 0) { + if (code == clear_code) { + /* Check we have a valid clear code + */ + if (clear_code >= (1 << GIF_MAX_LZW)) return -2; + + /* Initialise our table + */ + for (i = 0; i < clear_code; ++i) { + table[0][i] = 0; + table[1][i] = i; + } + for (; i < (1 << GIF_MAX_LZW); ++i) { + table[0][i] = table[1][i] = 0; + } + + /* Update our LZW parameters + */ + code_size = set_code_size + 1; + max_code_size = 2 * clear_code; + max_code = clear_code + 2; + stack_pointer = stack; + do { + firstcode = oldcode = gif_next_code(gif, code_size); + } while (firstcode == clear_code); + return firstcode; + } + + if (code == end_code) { + /* Skip to the end of our data so multi-image GIFs work + */ + if (zero_data_block) return -2; + block_size = 0; + while (block_size != 1) { + block_size = gif->gif_data[gif->buffer_position] + 1; + gif->buffer_position += block_size; + } + return -2; + } + + /* Fill the stack with some data + */ + incode = code; + + if (code >= max_code) { + *stack_pointer++ = firstcode; + code = oldcode; + } + + while (code >= clear_code) { + *stack_pointer++ = table[1][code]; + if (code == table[0][code]) return(code); + if (((char *)stack_pointer - (char *)stack) >= (int)sizeof(stack)) return(code); + code = table[0][code]; + } + + *stack_pointer++ = firstcode = table[1][code]; + + if ((code = max_code) < (1 << GIF_MAX_LZW)) { + table[0][code] = oldcode; + table[1][code] = firstcode; + ++max_code; + if ((max_code >= max_code_size) && (max_code_size < (1 << GIF_MAX_LZW))) { + max_code_size *= 2; + ++code_size; + } + } + + oldcode = incode; + + if (stack_pointer > stack) return *--stack_pointer; + } + return code; +} + +static int gif_next_code(struct gif_animation *gif, int code_size) { + static unsigned char buf[280]; + static int maskTbl[16] = {0x0000, 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, + 0x00ff, 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff}; + int i, j, end; + long ret; + + if (return_clear) { + return_clear = 0; + return clear_code; + } + + end = curbit + code_size; + if (end >= lastbit) { + int count; + if (get_done) return -1; + buf[0] = buf[last_byte - 2]; + buf[1] = buf[last_byte - 1]; + if ((count = gif_next_block(gif, &buf[2])) == 0) get_done = 1; + if (count < 0) return -1; + last_byte = 2 + count; + curbit = (curbit - lastbit) + 16; + lastbit = (2 + count) * 8; + end = curbit + code_size; + } + + j = end / 8; + i = curbit / 8; + if (i == j) { + ret = (long)buf[i]; + } else if (i + 1 == j) { + ret = (long)buf[i] | ((long)buf[i+1] << 8); + } else { + ret = (long)buf[i] | ((long)buf[i+1] << 8) | ((long)buf[i+2] << 16); + } + + ret = (ret >> (curbit % 8)) & maskTbl[code_size]; + curbit += code_size; + return (int)ret; +} + +static int gif_next_block(struct gif_animation *gif, unsigned char *buf) { + unsigned int block_size; + unsigned char *gif_data; + + gif_data = gif->gif_data + gif->buffer_position; + zero_data_block = ((block_size = gif_data[0]) == 0); + + if ((gif->buffer_position + block_size) >= gif->buffer_size) { + LOG(("Insufficient data to read %i bytes", block_size)); + return -1; + } + if (block_size > 0) memcpy(buf, gif_data + 1, block_size); + gif->buffer_position += block_size + 1; + return((int)block_size); +} |