Subject: Re: [stella] An exercise in minimalism... From: Christopher Tumber <christophertumber@xxxxxxxxxx> Date: Mon, 23 Jun 2003 00:57:18 -0400 |
Maybe it's just late and I should be sleeping, but... Some time ago, Andrew wrote: >I dug up my earlier posting regarding an efficient startup. >Here's my best... > > > ; CLEARS ALL VARIABLES, STACK > ; INIT STACK POINTER > ; ALSO CLEARS TIA REGISTERS > ; DOES THIS BY "WRAPPING" THE STACK - UNUSUAL > > LDX #0 > TXS > PHA ; BEST WAY TO GET SP=$FF, X=0 > > TXA >CLEAR PHA > DEX > BNE CLEAR > > ; 9 BYTES TOTAL FOR CLEARING STACK, MEMORY > ; STACK POINTER NOW $FF, A=X==0 How about: LDX #$FF TXS INX ; BETTER WAY TO GET SP=$FF, X=0 TXA CLEAR PHA DEX BNE CLEAR ; 9 BYTES TOTAL FOR CLEARING STACK, MEMORY ; STACK POINTER NOW $FF, A=X==0 ; BUT 1 CYCLE FASTER <Ducks> Chris... ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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