On Thu, May 10, 2007 at 10:06:27AM +0200, Frank Pepermans wrote: > I'm trying to get AS3 to parse an IFF file, more specifically the EA IFF > 85 file format, using the byteArray. > > For now the best documentation I've found is this link > http://www.martinreddy.net/gfx/2d/IFF.txt and a C script called > IFFDigest. > > > > Now since I've never done anything in C, there are some sections in the > code which aren't exactly clear, for example : > > > > /* ID typedef and builder for 68000 Lattice C. */ > typedef LONG ID; /* 4 chars in ' ' through '~' */ > #define MakeID(a,b,c,d) ( (a)<<<<24 | (b)<<<<16 | (c)<<<<8 | (d) ) > > /* Globally reserved IDs. */ > #define ID_FORM MakeID('F','O','R','M') > #define ID_LIST MakeID('L','I','S','T') > #define ID_PROP MakeID('P','R','O','P') > #define ID_CAT MakeID('C','A','T',' ') > #define ID_FILLER MakeID(' ',' ',' ',' ')
This code is taking the four 8-bit-bytes of the IDs and assembling them into a single 32-bit value. i.e. it turns "F"-"O"-"R"-"M" into 0x464F524D. This is presumably an optimisation so that it can compare ID values a whole 32-bit-word at a time, rather than requiring four byte-wise comparisions. Are you porting DeluxePaint to Flash? ;) ta, dave -- http://david.holroyd.me.uk/ _______________________________________________ Flashcoders@chattyfig.figleaf.com To change your subscription options or search the archive: http://chattyfig.figleaf.com/mailman/listinfo/flashcoders Brought to you by Fig Leaf Software Premier Authorized Adobe Consulting and Training http://www.figleaf.com http://training.figleaf.com
