On 3/15/2013 10:27 AM, Ed Jaffe wrote:
Has anyone thought this through already and come up with what the mnemonics should be?
I'm noticing that the most often used mnemonics after subtract seem to be JP and JNP. For example: L Rx,yyyyy S Rx,zzzzz JP label1 jump if processing needed and L Rx,yyyyy S Rx,zzzzz JNP label2 jump if no processing needed According to PoOp, after SUBTRACT LOGICAL and SUBTRACT LOGICAL WITH BORROW... Resulting Condition Code: 0 -- 1 Result not zero; borrow 2 Result zero; no borrow 3 Result not zero; no borrow I'm thinking we could implement a very literal interpretation of the CC values: JNZNB - jump if not zero, no borrow (BRC 1) JZOB - jump if zero or borrow (BRC 6) and those code fragments would become: L Rx,yyyyy SL Rx,zzzzz JNZNB label1 jump if processing needed and L Rx,yyyyy SL Rx,zzzzz JZOB label2 jump if no processing needed ... OR try make the unsigned math mnemonics analogous to their signed counterparts (and possibly more programmer friendly): JPSL - jump "positive" after subtract logical (BRC 1) JNPSL - jump "not positive" after subtract logical (BRC 6) resulting in: L Rx,yyyyy SL Rx,zzzzz JPSL label1 jump if processing needed and L Rx,yyyyy SL Rx,zzzzz JNPSL label2 jump if no processing needed Still wondering what others have done in this space... -- Edward E Jaffe Phoenix Software International, Inc 831 Parkview Drive North El Segundo, CA 90245 http://www.phoenixsoftware.com/
