Re: A83: Rotation instructions


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Re: A83: Rotation instructions




Unlike 68000 asm, the C in RLC and RRC means "Circular" rather than "Carry".
Makes more sense, doesn't it?

Linus

On 07-Aug-98, Anders Jensen wrote:

>Here is diagrams of all the shifting/rotation instructions. 
>Understanding them should be simple, the instructions simply moves the 
>bits in the arrows direction. Bit 0 is the least significant, bit 7 the 
>most.

>RLC: (Rotate Left Carry)

>       ->-->-->-->-->-->-->-
>      /                     \
>  C<-7<-6<-5<-4<-3<-2<-1<-0<-

>RL: (Rotate Left)
>  ->-->-->-->-->-->-->-->-
> /                         \
> C<-7<-6<-5<-4<-3<-2<-1<-0<-  

>RRC: (Rotate Right Carry)
>  -<--<--<--<--<--<--<--
> /                      \
> ->7->6->5->4->3->2->1->0->C

>RR: (Rotate Right)
>  -<--<--<--<--<--<--<--
> /                      \
> ->7->6->5->4->3->2->1->0->C

>SLA: (Shift Left Arithmetic)
> C<-7<-6<-5<-4<-3<-2<-1<-0 (bit 0 gets value 0)

>SRA: (Shift Right Arithmetic)
>7->6->5->4->3->2->1->0->C (bit 7 stays UNCHANGED)

>SRL: (Shift Right Logic)
>7->6->5->4->3->2->1->0->C (bit 7 gets value 0)

>Hope you can use it.

>Anders


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