static FT_ULong
ft_lzw_file_io( FT_LZWFile zip,
FT_ULong pos,
FT_Byte* buffer,
FT_ULong count )
{
FT_ULong result = 0;
FT_Error error;
/* Teset inflate stream if we're seeking backwards. */
/* Yes, that is not too efficient, but it saves memory :-) */
if ( pos < zip->pos )
{
error = ft_lzw_file_reset( zip );
if ( error )
goto Exit;
}
/* skip unwanted bytes */
if ( pos > zip->pos )
{
error = ft_lzw_file_skip_output( zip, (FT_ULong)( pos - zip->pos ) );
if ( error )
goto Exit;
}
if ( count == 0 )
goto Exit;
/* now read the data */
for (;;)
{
FT_ULong delta;
delta = (FT_ULong)( zip->limit - zip->cursor );
if ( delta >= count )
delta = count;
FT_MEM_COPY( buffer, zip->cursor, delta );
buffer += delta;
result += delta;
zip->cursor += delta;
zip->pos += delta;
count -= delta;
if ( count == 0 )
break;
error = ft_lzw_file_fill_output( zip );
if ( error )
break;
}
Exit:
return result;
}
static FT_ULong
ft_lzw_file_io( FT_LZWFile zip,
FT_ULong pos,
FT_Byte* buffer,
FT_ULong count )
{
FT_ULong result = 0;
FT_Error error;
/* seeking backwards. */
if ( pos < zip->pos )
{
/* If the new position is within the output buffer, simply */
/* decrement pointers, otherwise we reset the stream completely! */
if ( ( zip->pos - pos ) <= (FT_ULong)( zip->cursor - zip->buffer ) )
{
zip->cursor -= zip->pos - pos;
zip->pos = pos;
}
else
{
error = ft_lzw_file_reset( zip );
if ( error )
goto Exit;
}
}
/* skip unwanted bytes */
if ( pos > zip->pos )
{
error = ft_lzw_file_skip_output( zip, (FT_ULong)( pos - zip->pos ) );
if ( error )
goto Exit;
}
if ( count == 0 )
goto Exit;
/* now read the data */
for (;;)
{
FT_ULong delta;
delta = (FT_ULong)( zip->limit - zip->cursor );
if ( delta >= count )
delta = count;
FT_MEM_COPY( buffer + result, zip->cursor, delta );
result += delta;
zip->cursor += delta;
zip->pos += delta;
count -= delta;
if ( count == 0 )
break;
error = ft_lzw_file_fill_output( zip );
if ( error )
break;
}
Exit:
return result;
}