Subject: Re: [stella] A question about ROR and ROL From: "Matthew W. Miller" <mattm@xxxxxxxxxxx> Date: Tue, 14 Sep 1999 22:49:26 -0400 (EDT) |
On Tue, 14 Sep 1999, Pete Holland wrote: >Does ROR, when it rotates the bits, rotate them all, or does it just >move them over and, any bits at the end, just dump them? It seems like >ASL and LSR do the later, and I can't image redundant commands in >computer programming, but I just want to make sure. ROL rotates the memory/accumulator and Carry left one bit, in a circle: .--------------------------. `-- C <- 7 6 5 4 3 2 1 0 <-' ROR, right one bit in a circle: .--------------------------. `-> C -> 7 6 5 4 3 2 1 0 --' ASL shifts memory/accumulator left one bit, sets bit 0 to 0, and moves the former bit 7 to Carry: C <- 7 6 5 4 3 2 1 0 <- #0 LSR shifts memory/accumulator right one bit, sets bit 7 to 0, and moves the former bit 0 to Carry: #0 -> 7 6 5 4 3 2 1 0 -> C Matthew W. Miller -- mattm@xxxxxxxxxxx -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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