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- Esta tot fet una marranà, en mig de la conversió

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This commit is contained in:
Raimon Zamora
2025-02-16 21:48:07 +01:00
parent 40e98737ce
commit 29a90f4b46
7 changed files with 402 additions and 344 deletions
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378
gif.c
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@@ -2,104 +2,31 @@
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#define EXTENSION_INTRODUCER 0x21
#define IMAGE_DESCRIPTOR 0x2C
#define TRAILER 0x3B
#define GRAPHIC_CONTROL 0xF9
#define APPLICATION_EXTENSION 0xFF
#define COMMENT_EXTENSION 0xFE
#define PLAINTEXT_EXTENSION 0x01
#include <stdint.h>
#define READ(dst, size) memcpy(dst, buffer, size); buffer += size
typedef struct
{
unsigned short width;
unsigned short height;
unsigned char fields;
unsigned char background_color_index;
unsigned char pixel_aspect_ratio;
}
screen_descriptor_t;
struct rgb { uint8_t r, g, b; };
typedef struct
struct image_descriptor_t
{
unsigned char r;
unsigned char g;
unsigned char b;
}
rgb;
uint16_t left, top, width, height;
uint8_t fields;
};
typedef struct
{
unsigned short image_left_position;
unsigned short image_top_position;
unsigned short image_width;
unsigned short image_height;
unsigned char fields;
}
image_descriptor_t;
typedef struct
struct dictionary_entry_t
{
unsigned char byte;
int prev;
int len;
}
dictionary_entry_t;
int prev, len;
};
typedef struct
void uncompress( int code_length, const uint8_t *input, int input_length, uint8_t *out )
{
unsigned char extension_code;
unsigned char block_size;
}
extension_t;
typedef struct
{
unsigned char fields;
unsigned short delay_time;
unsigned char transparent_color_index;
}
graphic_control_extension_t;
typedef struct
{
unsigned char application_id[ 8 ];
unsigned char version[ 3 ];
}
application_extension_t;
typedef struct
{
unsigned short left;
unsigned short top;
unsigned short width;
unsigned short height;
unsigned char cell_width;
unsigned char cell_height;
unsigned char foreground_color;
unsigned char background_color;
}
plaintext_extension_t;
//static unsigned short width = 0;
//static unsigned short height = 0;
//static unsigned char* uncompressed_data = NULL;
void uncompress( int code_length,
const unsigned char *input,
int input_length,
unsigned char *out )
{
//int maxbits;
int i, bit;
int code, prev = -1;
dictionary_entry_t *dictionary;
int dictionary_ind;
unsigned int mask = 0x01;
uint32_t mask = 0x01;
int reset_code_length;
int clear_code; // This varies depending on code_length
int stop_code; // one more than clear code
@@ -107,44 +34,24 @@ void uncompress( int code_length,
clear_code = 1 << ( code_length );
stop_code = clear_code + 1;
// To handle clear codes
reset_code_length = code_length;
// Create a dictionary large enough to hold "code_length" entries.
// Once the dictionary overflows, code_length increases
dictionary = ( dictionary_entry_t * )
malloc( sizeof( dictionary_entry_t ) * ( 1 << ( code_length + 1 ) ) );
// Initialize the first 2^code_len entries of the dictionary with their
// indices. The rest of the entries will be built up dynamically.
// Technically, it shouldn't be necessary to initialize the
// dictionary. The spec says that the encoder "should output a
// clear code as the first code in the image data stream". It doesn't
// say must, though...
for ( dictionary_ind = 0;
dictionary_ind < ( 1 << code_length );
dictionary_ind++ )
for ( dictionary_ind = 0; dictionary_ind < ( 1 << code_length ); dictionary_ind++ )
{
dictionary[ dictionary_ind ].byte = dictionary_ind;
// XXX this only works because prev is a 32-bit int (> 12 bits)
dictionary[ dictionary_ind ].prev = -1;
dictionary[ dictionary_ind ].len = 1;
}
dictionary_ind+=2;
// 2^code_len + 1 is the special "end" code; don't give it an entry here
dictionary_ind++;
dictionary_ind++;
// TODO verify that the very last byte is clear_code + 1
while ( input_length )
{
code = 0x0;
// Always read one more bit than the code length
for ( i = 0; i < ( code_length + 1 ); i++ )
for (i=0; i<(code_length + 1); i++)
{
// This is different than in the file read example; that
// was a call to "next_bit"
bit = ( *input & mask ) ? 1 : 0;
mask <<= 1;
@@ -161,85 +68,54 @@ void uncompress( int code_length,
if ( code == clear_code )
{
code_length = reset_code_length;
dictionary = ( dictionary_entry_t * ) realloc( dictionary,
sizeof( dictionary_entry_t ) * ( 1 << ( code_length + 1 ) ) );
dictionary = ( dictionary_entry_t * ) realloc( dictionary, sizeof( dictionary_entry_t ) * ( 1 << ( code_length + 1 ) ) );
for ( dictionary_ind = 0;
dictionary_ind < ( 1 << code_length );
dictionary_ind++ )
for ( dictionary_ind = 0; dictionary_ind < ( 1 << code_length ); dictionary_ind++ )
{
dictionary[ dictionary_ind ].byte = dictionary_ind;
// XXX this only works because prev is a 32-bit int (> 12 bits)
dictionary[ dictionary_ind ].prev = -1;
dictionary[ dictionary_ind ].len = 1;
}
dictionary_ind++;
dictionary_ind++;
dictionary_ind+=2;
prev = -1;
continue;
}
else if ( code == stop_code )
{
/*if ( input_length > 1 )
{
fprintf( stderr, "Malformed GIF (early stop code)\n" );
exit( 0 );
}*/
break;
}
else if ( code == stop_code ) break;
// Update the dictionary with this character plus the _entry_
// (character or string) that came before it
if ( ( prev > -1 ) && ( code_length < 12 ) )
if ( (prev > -1) && (code_length < 12) )
{
if ( code > dictionary_ind )
if (code > dictionary_ind)
{
fprintf( stderr, "code = %.02x, but dictionary_ind = %.02x\n",
code, dictionary_ind );
fprintf( stderr, "code = %.02x, but dictionary_ind = %.02x\n", code, dictionary_ind );
exit( 0 );
}
// Special handling for KwKwK
if ( code == dictionary_ind )
{
int ptr = prev;
while ( dictionary[ ptr ].prev != -1 )
{
ptr = dictionary[ ptr ].prev;
}
while ( dictionary[ ptr ].prev != -1 ) ptr = dictionary[ ptr ].prev;
dictionary[ dictionary_ind ].byte = dictionary[ ptr ].byte;
}
else
{
int ptr = code;
while ( dictionary[ ptr ].prev != -1 )
{
ptr = dictionary[ ptr ].prev;
}
while ( dictionary[ ptr ].prev != -1 ) ptr = dictionary[ ptr ].prev;
dictionary[ dictionary_ind ].byte = dictionary[ ptr ].byte;
}
dictionary[ dictionary_ind ].prev = prev;
dictionary[ dictionary_ind ].len = dictionary[ prev ].len + 1;
dictionary_ind++;
// GIF89a mandates that this stops at 12 bits
if ( ( dictionary_ind == ( 1 << ( code_length + 1 ) ) ) &&
( code_length < 11 ) )
if ( (dictionary_ind == (1 << (code_length + 1))) && (code_length < 11) )
{
code_length++;
dictionary = ( dictionary_entry_t * ) realloc( dictionary,
sizeof( dictionary_entry_t ) * ( 1 << ( code_length + 1 ) ) );
dictionary = ( dictionary_entry_t * ) realloc( dictionary, sizeof( dictionary_entry_t ) * ( 1 << ( code_length + 1 ) ) );
}
}
prev = code;
// Now copy the dictionary entry backwards into "out"
match_len = dictionary[ code ].len;
while ( code != -1 )
{
@@ -251,198 +127,107 @@ void uncompress( int code_length,
}
code = dictionary[ code ].prev;
}
out += match_len;
}
}
static int read_sub_blocks( unsigned char* buffer, unsigned char **data )
static int read_sub_blocks( uint8_t* buffer, uint8_t **data )
{
int data_length;
int index;
unsigned char block_size;
// Everything following are data sub-blocks, until a 0-sized block is
// encountered.
data_length = 0;
int data_length = 0;
*data = NULL;
index = 0;
int index = 0;
while ( 1 )
{
READ(&block_size, 1);
if ( block_size == 0 ) // end of sub-blocks
{
break;
}
while (1) {
uint8_t block_size = *(buffer++);
if ( block_size == 0 ) break;
data_length += block_size;
*data = (unsigned char*)realloc( *data, data_length );
// TODO this could be split across block size boundaries
*data = (uint8_t*)realloc( *data, data_length );
READ(*data + index, block_size);
index += block_size;
}
return data_length;
}
unsigned char* process_image_descriptor( unsigned char* buffer,
rgb *gct,
int gct_size,
int resolution_bits )
uint8_t* process_image_descriptor( uint8_t* buffer, rgb *gct, int gct_size, int resolution_bits )
{
image_descriptor_t image_descriptor;
int compressed_data_length;
unsigned char *compressed_data = NULL;
unsigned char lzw_code_size;
int uncompressed_data_length = 0;
unsigned char *uncompressed_data = NULL;
// TODO there could actually be lots of these
READ(&image_descriptor, 9);
// TODO if LCT = true, read the LCT
uint8_t lzw_code_size;
READ(&lzw_code_size, 1);
compressed_data_length = read_sub_blocks( buffer, &compressed_data );
uint8_t *compressed_data = NULL;
const int compressed_data_length = read_sub_blocks( buffer, &compressed_data );
// width = image_descriptor.image_width;
// height = image_descriptor.image_height;
uncompressed_data_length = image_descriptor.image_width *
image_descriptor.image_height;
uncompressed_data = (unsigned char*)malloc( uncompressed_data_length );
const int uncompressed_data_length = image_descriptor.width * image_descriptor.height;
uint8_t *uncompressed_data = (uint8_t*)malloc( uncompressed_data_length );
uncompress( lzw_code_size, compressed_data, compressed_data_length,
uncompressed_data );
uncompress( lzw_code_size, compressed_data, compressed_data_length, uncompressed_data );
if ( compressed_data ) free( compressed_data );
//if ( uncompressed_data )
// free( uncompressed_data );
return uncompressed_data;
}
/**
* @param gif_file the file descriptor of a file containing a
* GIF-encoded file. This should point to the first byte in
* the file when invoked.
*/
#define rb (*(buffer++))
uint32_t* LoadPalette(uint8_t *buffer, uint16_t *size = NULL )
{
buffer += 10;
const uint8_t fields = *buffer;
uint32_t* LoadPalette(unsigned char *buffer) {
unsigned char header[7];
screen_descriptor_t screen_descriptor;
//int color_resolution_bits;
uint32_t *global_color_table = (uint32_t *)calloc(1, 1024);;
int global_color_table_size = 0; // number of entries in global_color_table
uint32_t *global_color_table = NULL;
if (size) *size = 0;
if (fields & 0x80) {
int global_color_table_size = 1 << (((fields & 0x07) + 1));
if (size) *size = global_color_table_size;
READ(header, 6);
READ(&screen_descriptor, 7);
//color_resolution_bits = ((screen_descriptor.fields & 0x70) >> 4) + 1;
global_color_table = (uint32_t *)calloc(1, 1024);
if (screen_descriptor.fields & 0x80) {
global_color_table_size = 1 << (((screen_descriptor.fields & 0x07) + 1));
//global_color_table = (rgb *)malloc(3 * global_color_table_size);
//READ(global_color_table, 3 * global_color_table_size);
for (int i=0; i<global_color_table_size;++i) {
global_color_table[i] = (buffer[0]<<16) + (buffer[1]<<8) + buffer[2];
buffer+=3;
global_color_table[i] = (buffer[0]<<16) + (buffer[1]<<8) + buffer[2];
}
}
return global_color_table;
}
static unsigned char* process_gif_stream(unsigned char *buffer, unsigned short* w, unsigned short* h)
static uint8_t* LoadGif(uint8_t *buffer, uint16_t* w, uint16_t* h)
{
unsigned char header[ 7 ];
screen_descriptor_t screen_descriptor;
int color_resolution_bits;
int global_color_table_size =0; // number of entries in global_color_table
int global_color_table_size = 0; // number of entries in global_color_table
rgb *global_color_table = NULL;
unsigned char block_type = 0x0;
buffer += 6; // Ignore header
*w = (uint16_t)*buffer; buffer+=2;
*h = (uint16_t)*buffer; buffer+=2;
const uint8_t fields = *buffer; buffer+=3;
// A GIF file starts with a Header (section 17)
READ(header, 6);
header[ 6 ] = 0x0;
const int color_resolution_bits = ( ( fields & 0x70 ) >> 4 ) + 1;
// XXX there's another format, GIF87a, that you may still find
// floating around.
/*if ( strcmp( "GIF89a", (char*)header ) )
if ( fields & 0x80 )
{
fprintf( stderr,
"Invalid GIF file (header is '%s', should be 'GIF89a')\n",
header );
return NULL;
}*/
// Followed by a logical screen descriptor
// Note that this works because GIFs specify little-endian order; on a
// big-endian machine, the height & width would need to be reversed.
// Can't use sizeof here since GCC does byte alignment;
// sizeof( screen_descriptor_t ) = 8!
READ(&screen_descriptor, 7);
*w = screen_descriptor.width;
*h = screen_descriptor.height;
color_resolution_bits = ( ( screen_descriptor.fields & 0x70 ) >> 4 ) + 1;
if ( screen_descriptor.fields & 0x80 )
{
//int i;
// If bit 7 is set, the next block is a global color table; read it
global_color_table_size = 1 <<
( ( ( screen_descriptor.fields & 0x07 ) + 1 ) );
global_color_table = ( rgb * ) malloc( 3 * global_color_table_size );
// XXX this could conceivably return a short count...
global_color_table_size = 1 << ( ( ( fields & 0x07 ) + 1 ) );
global_color_table = (rgb*)malloc( 3 * global_color_table_size );
READ(global_color_table, 3 * global_color_table_size);
}
while ( block_type != TRAILER )
uint8_t block_type = 0x0;
while ( block_type != 0x3B )
{
READ(&block_type, 1);
unsigned char size;
uint8_t size;
switch ( block_type )
{
case IMAGE_DESCRIPTOR:
return process_image_descriptor(buffer,
global_color_table,
global_color_table_size,
color_resolution_bits);
case 0x2C:
return process_image_descriptor(buffer, global_color_table, global_color_table_size, color_resolution_bits);
case 0x21:
buffer++; //size = *(buffer++); buffer += size;
do { size = *(buffer++); buffer += size; } while (size != 0);
break;
case EXTENSION_INTRODUCER:
buffer++;
size = *(buffer++);
buffer += size;
do {
size = *(buffer++);
buffer += size;
} while (size != 0);
/*if ( !process_extension( buffer ) )
{
return NULL;
}*/
break;
case TRAILER:
case 0x3B:
break;
default:
fprintf( stderr, "Bailing on unrecognized block type %.02x\n",
block_type );
fprintf( stderr, "Bailing on unrecognized block type %.02x\n", block_type );
return NULL;
}
}
@@ -450,29 +235,6 @@ static unsigned char* process_gif_stream(unsigned char *buffer, unsigned short*
}
unsigned char* LoadGif(unsigned char *buffer, unsigned short* w, unsigned short* h) {
/*unsigned char* LoadGif(unsigned char *buffer, unsigned short* w, unsigned short* h) {
return process_gif_stream(buffer, w, h);
}
/*int main( int argc, char *argv[] )
{
FILE* gif_file;
if ( argc < 2 )
{
fprintf( stderr, "Usage: %s <path-to-gif-file>\n", argv[ 0 ] );
exit( 0 );
}
gif_file = fopen( argv[ 1 ], "rb" );
if ( gif_file == NULL )
{
fprintf( stderr, "Unable to open file '%s'", argv[ 1 ] );
perror( ": " );
}
process_gif_stream( gif_file );
fclose( gif_file );
}*/