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|
;
; clock_t clock (void);
;
.constructor initclock
.export _clock
.forceimport ticktock ; make sure that tickcount changes
.importzp tickcount, sreg
; Make the process clock start at zero.
.segment "ONCE"
initclock:
ldx #4 - 1
@lp: stz tickcount,x
dex
bpl @lp
rts
; ------------------------------------------------------------------------
.code
; This function might be interrupted while it is reading the several bytes of
; the clock. They are read again if that happens. (We do not want to stop
; interrupts because that might cause glitches in interrupt-driven graphics
; and sound.)
.proc _clock
lda tickcount
ldy tickcount+3
sty sreg+1
ldy tickcount+2
sty sreg
ldx tickcount+1
cmp tickcount
bne _clock ; clock changed; reread it
rts
.endproc
|
