Ongoing GIF implementation

aee.vcxproj

@@ -81,6 +81,7 @@
   <ItemGroup>
     <ClCompile Include="bola.cpp" />
     <ClCompile Include="engendro.cpp" />
+    <ClCompile Include="gif.c" />
     <ClCompile Include="jdraw8.cpp" />
     <ClCompile Include="jfile.cpp" />
     <ClCompile Include="jgame.cpp" />

aee.vcxproj.filters

@@ -60,6 +60,9 @@
     <ClCompile Include="sprite.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="gif.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="bola.h">

gif.c

@@ -12,6 +12,7 @@
 #define COMMENT_EXTENSION      0xFE
 #define PLAINTEXT_EXTENSION    0x01
 
+#define READ(dst, size) memcpy(dst, buffer, size); buffer += size
 typedef struct
 {
     unsigned short width;
@@ -254,7 +255,7 @@ void uncompress( int code_length,
     }
 }
 
-static int read_sub_blocks( FILE* gif_file, unsigned char **data )
+static int read_sub_blocks( unsigned char* buffer, unsigned char **data )
 {
     int data_length;
     int index;
@@ -268,11 +269,7 @@ static int read_sub_blocks( FILE* gif_file, unsigned char **data )
 
     while ( 1 )
     {
-        if ( fread( &block_size, 1, 1, gif_file ) < 1 )
+		READ(&block_size, 1);
-        {
-            perror( "Invalid GIF file (too short): " );
-            return -1;
-        }
 
         if ( block_size == 0 )  // end of sub-blocks
         {
@@ -283,12 +280,7 @@ static int read_sub_blocks( FILE* gif_file, unsigned char **data )
         *data = realloc( *data, data_length );
 
         // TODO this could be split across block size boundaries
-        if ( fread( *data + index, 1, block_size, gif_file ) <
+		READ(*data + index, block_size);
-            block_size )
-        {
-            perror( "Invalid GIF file (too short): " );
-            return -1;
-        }
 
         index += block_size;
     }
@@ -296,7 +288,7 @@ static int read_sub_blocks( FILE* gif_file, unsigned char **data )
     return data_length;
 }
 
-static int process_image_descriptor( FILE* gif_file,
+static int process_image_descriptor( unsigned char* buffer,
                                     rgb *gct,
                                     int gct_size,
                                     int resolution_bits )
@@ -310,25 +302,15 @@ static int process_image_descriptor( FILE* gif_file,
     //unsigned char *uncompressed_data = NULL;
 
     // TODO there could actually be lots of these
-    if ( fread( &image_descriptor, 1, 9, gif_file ) < 9 )
+	READ(&image_descriptor, 9);
-    {
-        perror( "Invalid GIF file (too short)" );
-        disposition = 0;
-        goto done;
-    }
 
     // TODO if LCT = true, read the LCT
 
     disposition = 1;
 
-    if ( fread( &lzw_code_size, 1, 1, gif_file ) < 1 )
+	READ(&lzw_code_size, 1);
-    {
-        perror( "Invalid GIF file (too short): " );
-        disposition = 0;
-        goto done;
-    }
 
-    compressed_data_length = read_sub_blocks( gif_file, &compressed_data );
+    compressed_data_length = read_sub_blocks( buffer, &compressed_data );
 
     width = image_descriptor.image_width;
     height = image_descriptor.image_height;
@@ -349,7 +331,7 @@ done:
     return disposition;
 }
 
-static int process_extension( FILE* gif_file )
+static int process_extension( unsigned char* buffer )
 {
     extension_t extension;
     graphic_control_extension_t gce;
@@ -358,39 +340,23 @@ static int process_extension( FILE* gif_file )
     unsigned char *extension_data = NULL;
     int extension_data_length;
 
-    if ( fread( &extension, 1, 2, gif_file ) < 2 )
+	READ(&extension, 2);
-    {
-        perror( "Invalid GIF file (too short): " );
-        return 0;
-    }
 
     switch ( extension.extension_code )
     {
         case GRAPHIC_CONTROL:
-            if ( fread( &gce, 1, 4, gif_file ) < 4 )
+			READ(&gce, 4);
-            {
-                perror( "Invalid GIF file (too short): " );
-                return 0;
-            }
 
             break;
         case APPLICATION_EXTENSION:
-            if ( fread( &application, 1, 11, gif_file ) < 11 )
+			READ(&application, 11);
-            {
-                perror( "Invalid GIF file (too short): " );
-                return 0;
-            }
             break;
         case 0xFE:
             // comment extension; do nothing - all the data is in the
             // sub-blocks that follow.
             break;
         case 0x01:
-            if ( fread( &plaintext, 1, 12, gif_file ) < 12 )
+			READ(&plaintext, 12);
-            {
-                perror( "Invalid GIF file (too short): " );
-                return 0;
-            }
             break;
         default:
             fprintf( stderr, "Unrecognized extension code.\n" );
@@ -399,7 +365,7 @@ static int process_extension( FILE* gif_file )
 
     // All extensions are followed by data sub-blocks; even if it's
     // just a single data sub-block of length 0
-    extension_data_length = read_sub_blocks( gif_file, &extension_data );
+    extension_data_length = read_sub_blocks( buffer, &extension_data );
 
     if ( extension_data != NULL )
         free( extension_data );
@@ -412,7 +378,7 @@ static int process_extension( FILE* gif_file )
  *  GIF-encoded file.  This should point to the first byte in
  *  the file when invoked.
  */
-static void process_gif_stream( FILE* gif_file )
+static unsigned char* process_gif_stream(unsigned char *buffer, unsigned short* w, unsigned short* h)
 {
     unsigned char header[ 7 ];
     screen_descriptor_t screen_descriptor;
@@ -424,11 +390,7 @@ static void process_gif_stream( FILE* gif_file )
     unsigned char block_type = 0x0;
 
     // A GIF file starts with a Header (section 17)
-    if ( fread( header, 1, 6, gif_file ) != 6 )
+	READ(header, 6);
-    {
-        perror( "Invalid GIF file (too short)" );
-        return;
-    }
     header[ 6 ] = 0x0;
 
     // XXX there's another format, GIF87a, that you may still find
@@ -447,11 +409,7 @@ static void process_gif_stream( FILE* gif_file )
 
     // Can't use sizeof here since GCC does byte alignment;
     // sizeof( screen_descriptor_t ) = 8!
-    if ( fread( &screen_descriptor, 1, 7, gif_file ) < 7 )
+	READ(&screen_descriptor, 7);
-    {
-        perror( "Invalid GIF file (too short)" );
-        return;
-    }
 
     color_resolution_bits = ( ( screen_descriptor.fields & 0x70 ) >> 4 ) + 1;
 
@@ -465,26 +423,17 @@ static void process_gif_stream( FILE* gif_file )
         global_color_table = ( rgb * ) malloc( 3 * global_color_table_size );
         
         // XXX this could conceivably return a short count...
-        if ( fread( global_color_table, 1, 3 * global_color_table_size, gif_file ) <
+		READ(global_color_table, 3 * global_color_table_size);
-            3 * global_color_table_size )
-        {
-            perror( "Unable to read global color table" );
-            return;
-        }
     }
     
     while ( block_type != TRAILER )
     {
-        if ( fread( &block_type, 1, 1, gif_file ) < 1 )
+		READ(&block_type, 1);
-        {
-            perror( "Invalid GIF file (too short)" );
-            return;
-        }
         
         switch ( block_type )
         {
             case IMAGE_DESCRIPTOR:
-                if ( !process_image_descriptor( gif_file, 
+                if ( !process_image_descriptor( buffer, 
                                                global_color_table, 
                                                global_color_table_size,
                                                color_resolution_bits ) )
@@ -493,7 +442,7 @@ static void process_gif_stream( FILE* gif_file )
                 }
                 break;
             case EXTENSION_INTRODUCER:
-                if ( !process_extension( gif_file ) )
+                if ( !process_extension( buffer ) )
                 {
                     return;
                 }
@@ -509,6 +458,10 @@ static void process_gif_stream( FILE* gif_file )
 }
 
 
+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;