Subject: Re: [stella] Programming tricks guide From: Thomas Jentzsch <tjentzsch@xxxxxx> Date: Sun, 2 Feb 2003 10:53:10 +0100 |
Paul wrote: > Has anyone put together a guide of programming tricks? I've started a > small one with stuff like skip draw, efficient cycle wasting, paddle > reading, and well that's all I got so far. I have a few more: - the 48 pixel routine - usage of VDEL in general - BIT tricks - register and single bits reusing - avoiding page penalties - early HMOVEs - shifting vs. ANDing - branching out of the kernel flow to keep the slowest part as fast as possible - constant cycle count to avoid WSYNC - Combat missile trick - normal and Fatal Run positioning routines - Parker Bros. BRK trick - useful illegal opcodes (LAX, DCP, NOP) - exact timings for writing to PFx (in both modes) - multiple RESP tricks - constant carry status (e.g. EOR instead of CMP) to avoid CLC/SEC - counting down when looping - trying to preserve X and Y inside the kernel - using branches instead of JMPs, using JMP,...RTS instead of JSR,...RTS,RTS at the end of a subroutine - multiplication tricks with shifts vs. using a table - using TXS, TSX to save CPU cycles - ... Have fun! Thomas _______________________________________________________ Thomas Jentzsch | *** Every bit is sacred ! *** tjentzsch at web dot de | ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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