Lpc2000

--- In lpc2000@yahoogroups.com, "James Dabbs" <jdabbs@t...> wrote:
> Is there a clever, quick way to do 16-bit and 32-bit byte swaps in 
ARM
> with only one or two instructions?
> 
> Thanks,
> 
> James Dabbs

For such nuggets I really suggest the ARM System Developer's Guide 
which has the following:


@ r0 is source/dest
@ r1,r2 are scratch

mvn  r2, #0x0000FF00
eor  r1, r0, r0, ROR #16
and  r1, r2,r1, LSR #8
eor  r0, r1, r0, ROR #8

or

eor r1,r0,r0,ROR #16
mov r1,r1, LSR#8
bic r1,r1,#0xFF00
EOR r0, r1, r0,ROR #8


To swap two 16-bits in a 32-bit

mov r0,r0,ROR #16