- [CHG] Renombrat "gif.c" a "gif.h"
- [FIX] El codi de exemple petava
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gif.h
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240
gif.h
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <fcntl.h>
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#include <stdint.h>
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#define READ(dst, size) memcpy(dst, buffer, size); buffer += size
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struct rgb { uint8_t r, g, b; };
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struct image_descriptor_t
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{
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uint16_t left, top, width, height;
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uint8_t fields;
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};
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struct dictionary_entry_t
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{
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unsigned char byte;
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int prev, len;
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};
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void uncompress( int code_length, const uint8_t *input, int input_length, uint8_t *out )
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{
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int i, bit;
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int code, prev = -1;
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dictionary_entry_t *dictionary;
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int dictionary_ind;
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uint32_t mask = 0x01;
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int reset_code_length;
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int clear_code; // This varies depending on code_length
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int stop_code; // one more than clear code
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int match_len;
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clear_code = 1 << ( code_length );
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stop_code = clear_code + 1;
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reset_code_length = code_length;
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dictionary = ( dictionary_entry_t * )
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malloc( sizeof( dictionary_entry_t ) * ( 1 << ( code_length + 1 ) ) );
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for ( dictionary_ind = 0; dictionary_ind < ( 1 << code_length ); dictionary_ind++ )
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{
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dictionary[ dictionary_ind ].byte = dictionary_ind;
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dictionary[ dictionary_ind ].prev = -1;
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dictionary[ dictionary_ind ].len = 1;
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}
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dictionary_ind+=2;
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while ( input_length )
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{
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code = 0x0;
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for (i=0; i<(code_length + 1); i++)
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{
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bit = ( *input & mask ) ? 1 : 0;
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mask <<= 1;
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if ( mask == 0x100 )
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{
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mask = 0x01;
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input++;
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input_length--;
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}
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code = code | ( bit << i );
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}
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if ( code == clear_code )
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{
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code_length = reset_code_length;
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dictionary = ( dictionary_entry_t * ) realloc( dictionary, sizeof( dictionary_entry_t ) * ( 1 << ( code_length + 1 ) ) );
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for ( dictionary_ind = 0; dictionary_ind < ( 1 << code_length ); dictionary_ind++ )
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{
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dictionary[ dictionary_ind ].byte = dictionary_ind;
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dictionary[ dictionary_ind ].prev = -1;
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dictionary[ dictionary_ind ].len = 1;
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}
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dictionary_ind+=2;
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prev = -1;
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continue;
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}
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else if ( code == stop_code ) break;
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if ( (prev > -1) && (code_length < 12) )
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{
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if (code > dictionary_ind)
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{
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fprintf( stderr, "code = %.02x, but dictionary_ind = %.02x\n", code, dictionary_ind );
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exit( 0 );
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}
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if ( code == dictionary_ind )
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{
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int ptr = prev;
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while ( dictionary[ ptr ].prev != -1 ) ptr = dictionary[ ptr ].prev;
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dictionary[ dictionary_ind ].byte = dictionary[ ptr ].byte;
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}
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else
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{
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int ptr = code;
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while ( dictionary[ ptr ].prev != -1 ) ptr = dictionary[ ptr ].prev;
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dictionary[ dictionary_ind ].byte = dictionary[ ptr ].byte;
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}
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dictionary[ dictionary_ind ].prev = prev;
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dictionary[ dictionary_ind ].len = dictionary[ prev ].len + 1;
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dictionary_ind++;
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if ( (dictionary_ind == (1 << (code_length + 1))) && (code_length < 11) )
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{
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code_length++;
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dictionary = ( dictionary_entry_t * ) realloc( dictionary, sizeof( dictionary_entry_t ) * ( 1 << ( code_length + 1 ) ) );
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}
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}
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prev = code;
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match_len = dictionary[ code ].len;
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while ( code != -1 )
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{
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out[ dictionary[ code ].len - 1 ] = dictionary[ code ].byte;
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if ( dictionary[ code ].prev == code )
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{
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fprintf( stderr, "Internal error; self-reference." );
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exit( 0 );
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}
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code = dictionary[ code ].prev;
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}
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out += match_len;
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}
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}
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static int read_sub_blocks( uint8_t* buffer, uint8_t **data )
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{
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int data_length = 0;
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*data = NULL;
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int index = 0;
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while (1) {
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uint8_t block_size = *(buffer++);
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if ( block_size == 0 ) break;
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data_length += block_size;
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*data = (uint8_t*)realloc( *data, data_length );
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READ(*data + index, block_size);
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index += block_size;
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}
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return data_length;
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}
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uint8_t* process_image_descriptor( uint8_t* buffer, rgb *gct, int gct_size, int resolution_bits )
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{
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image_descriptor_t image_descriptor;
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READ(&image_descriptor, 9);
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uint8_t lzw_code_size;
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READ(&lzw_code_size, 1);
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uint8_t *compressed_data = NULL;
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const int compressed_data_length = read_sub_blocks( buffer, &compressed_data );
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const int uncompressed_data_length = image_descriptor.width * image_descriptor.height;
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uint8_t *uncompressed_data = (uint8_t*)malloc( uncompressed_data_length );
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uncompress( lzw_code_size, compressed_data, compressed_data_length, uncompressed_data );
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if ( compressed_data ) free( compressed_data );
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return uncompressed_data;
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}
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uint32_t* LoadPalette(uint8_t *buffer, uint16_t *size = NULL )
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{
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buffer += 10;
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const uint8_t fields = *buffer;
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uint32_t *global_color_table = (uint32_t *)calloc(1, 1024);;
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if (size) *size = 0;
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if (fields & 0x80) {
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int global_color_table_size = 1 << (((fields & 0x07) + 1));
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if (size) *size = global_color_table_size;
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for (int i=0; i<global_color_table_size;++i) {
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buffer+=3;
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global_color_table[i] = (buffer[0]<<16) + (buffer[1]<<8) + buffer[2];
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}
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}
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return global_color_table;
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}
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static uint8_t* LoadGif(uint8_t *buffer, uint16_t* w, uint16_t* h)
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{
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int global_color_table_size = 0; // number of entries in global_color_table
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rgb *global_color_table = NULL;
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buffer += 6; // Ignore header
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*w = *((uint16_t*)buffer); buffer+=2;
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*h = *((uint16_t*)buffer); buffer+=2;
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const uint8_t fields = *buffer; buffer+=3;
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const int color_resolution_bits = ( ( fields & 0x70 ) >> 4 ) + 1;
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if ( fields & 0x80 )
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{
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global_color_table_size = 1 << ( ( ( fields & 0x07 ) + 1 ) );
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global_color_table = (rgb*)malloc( 3 * global_color_table_size );
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READ(global_color_table, 3 * global_color_table_size);
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}
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uint8_t block_type = 0x0;
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while ( block_type != 0x3B )
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{
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READ(&block_type, 1);
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uint8_t size;
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switch ( block_type )
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{
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case 0x2C:
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return process_image_descriptor(buffer, global_color_table, global_color_table_size, color_resolution_bits);
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case 0x21:
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buffer++; //size = *(buffer++); buffer += size;
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do { size = *(buffer++); buffer += size; } while (size != 0);
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break;
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case 0x3B:
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break;
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default:
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fprintf( stderr, "Bailing on unrecognized block type %.02x\n", block_type );
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return NULL;
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}
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}
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return NULL;
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}
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/*unsigned char* LoadGif(unsigned char *buffer, unsigned short* w, unsigned short* h) {
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return process_gif_stream(buffer, w, h);
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}*/
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