> Hi,
>   Ok here is a quick question for all of you how have far too much spare
> time ;-)
> 
> What is the best set tests to apply to an instruction word in order to
> determine if it is a store instruction ?
> 
> Cheers,
> 				Mark
> 

It depends how precise you need to be.  If you *know* that the relevant 
instruction is a load or a store of some sort, then the test
	(inst & 0x00100000) == 0
will suffice.

You can be a bit more precise:

	(inst & 0x0c100000) == 0x04000000 /* STR */
	(inst & 0x0a100000) == 0x08000000 /* STM/STC */
	(inst & 0x0e1000f0) == 0x000000b0 /* STRH */
	(inst & 0x0fb00ff0) == 0x01000090 /* SWP */

Which allows some STRH encodings to overlap into undefined instruction 
space,

Or you can go the whole hog

	(inst & 0x0c100000) == 0x04000000 /* STR */
	(inst & 0x0a100000) == 0x08000000 /* STM/STC */
	(inst & 0x0e500ff0) == 0x000000b0 /* STRH Reg offset */
	(inst & 0x0e5000f0) == 0x004000b0 /* STRH Imm offset */
	(inst & 0x0fb00ff0) == 0x01000090 /* SWP */

Of course, decoding Thumb instructions is a whole new ball game.

Richard.