Difference between revisions of "ARM: 64 bit operations"

Latest revision as of 14:54, 23 March 2008

Logical shift left by Rn (0-32)

       ;R0 - least significant word
       ;R1 - most significant word
       ;R2 - shift
       ;Uses R0-R3
       ;7 cycles constant
       mov	r1,r1,lsl r2
       rsb	r3,r2,#32
       orr	r1,1,r0,lsr r3
       mov	r0,r0,lsl r2

Logical shift left by Rn (0-64)

       ;R0 - least significant word
       ;R1 - most significant word
       ;R2 - shift
       ;Uses R0-R3
       ; 8-9 cycles
       rsbs	r3,r2,#32
       submi	r3,r2,#32
       movmi	r1,r0,lsl r3
       movpl	r1,r1,lsl r2
       orrpl	r1,r1,r0,lsr r3
       mov	r0,r0,lsl r2

Logical shift left by #n (0-32)

       ;R0 - least significant word
       ;R1 - most significant word
       ;Uses R0-R1
       ;3 cycles constant
       mov	r1,r1,lsl #n
       orr	r1,r1,r0,lsr #32-n
       mov	r0,r0,lsl #n

Logical shift left by #n (33-64)

       ;R0 - least significant word
       ;R1 - most significant word
       ;Uses R0-R1
       ;2 cycles constant
       mov	r1,r0,lsl #n-32
       mov	r0,#0

Logical shift left by 1

       ;R0 - least significant word
       ;R1 - most significant word
       ;Uses R0-R1
       ;2 cycles constant
       adds	r0,r0,r0
       adc	r1,r1,r1

Test for zero

       ;R0 - least significant word
       ;R1 - most significant word
       ;Uses R0-R2
       ;1 cycle constant
       orrs     r2,r1,r0