Cycle neutral branching#

General Information

Author: Michael J. Mahon
Assembler: generic

From Michael J. Mahon:

I've found it useful to devise macros to do certain conditional operations in constant time. For example, "increment Y if carry set" (with A volatile) is:

BCS *+3	  ; Branch to INY
LDA $C8	  ; $C8 = INY

If Carry is set, the branch takes 3 cycles and the INY 2. If Carry is clear, the branch takes 2 cycles and the LDA 3. So this CINY macro always takes 5 cycles.

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« This page (revision-1) was last changed on 13-Mar-2010 15:15 by Carsten Strotmann