Post by thread:GOTO $-1 versus GOTO $ (was: "Re: Code error")

Andy Kunz <spam_OUTPICLISTTakeThisOuTMITVMA.MIT.EDU> wrote: > > Isn't an infinite loop done with: goto $ > > No, because PC has been incremented to point to the next > instruction. Standard notation is to do it: goto $-1 > > .... > > Here's a hint. If you have to a waste time, and you would normally > write it as > NOP > NOP > NOP > NOP > > try using the following instead. > > goto $+1 > goto $+1 Um, Andy? How do you reconcile your "$-1" infinite loop with your "$+1" two-cycle NOP? The PIC's program counter is incremented before the current instruction is executed, but the ASSEMBLER's "program counter" isn't. Perhaps you've confused the two? -Andy === Andrew Warren - .....fastfwdKILLspam@spam@ix.netcom.com === Fast Forward Engineering, Vista, California === http://www.geocities.com/SiliconValley/2499

> How do you reconcile your "$-1" infinite loop with your "$+1" > two-cycle NOP? > > The PIC's program counter is incremented before the current > instruction is executed, but the ASSEMBLER's "program counter" > isn't. Perhaps you've confused the two? I stand corrected. "goto $-1" will jump to the instruction preceding the goto "goto $" will be an endless loop "goto $+1" will jump to the next address (I was right about this one, anyway). ===== Parallax PIC16Cxx Assembler v4.7 = ==== 1 0000- device PIC16C73 2 3 0000- org 0 4 5 0000- 2800 start goto start 6 0001- 2802 goto stop 7 0002- 0000 stop nop 8 9 0003- 2802 goto $-1 10 0004- 2804 goto $ 11 0005- 2806 goto $+1 12 13 0006- end ===== Errors: 0 ===== ================================================================== Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865 Hardware & Software for Industry & R/C Hobbies "Go fast, turn right, and keep the wet side down!" ==================================================================