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Developer’s Manual March, 2003 B-13
Intel
®
80200 Processor based on Intel
®
XScale
™
Microarchitecture
Optimization Guide
B.3.2 Bit Field Manipulation
The Intel
®
80200 processor shift and logical operations provide a useful way of manipulating bit
fields. Bit field operations can be optimized as follows:
;Set the bit number specified by r1 in register r0
mov r2, #1
orr r0, r0, r2, asl r1
;Clear the bit number specified by r1 in register r0
mov r2, #1
bic r0, r0, r2, asl r1
;Extract the bit-value of the bit number specified by r1 of the
;value in r0 storing the value in r0
mov r1, r0, asr r1
and r0, r1, #1
;Extract the higher order 8 bits of the value in r0 storing
;the result in r1
mov r1, r0, lsr #24