cc65/libsrc/pce/clock.s

;
; 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
initial import, completely untested, does not compile yet 2014-11-29 13:18:48 +00:00			`;`
			`; clock_t clock (void);`
			`;`

Fixed and improved some pce comments. 2015-11-17 14:14:15 +00:00			`.constructor initclock`
Fixed bugs; and, improved the efficiency of some pce library functions. 2015-11-26 20:06:20 +00:00			`.export _clock`
Style changes. 2015-10-02 14:50:22 +00:00
Fixed and improved some pce comments. 2015-11-17 14:14:15 +00:00			`.forceimport ticktock ; make sure that tickcount changes`
Fixed bugs; and, improved the efficiency of some pce library functions. 2015-11-26 20:06:20 +00:00			`.importzp tickcount, sreg`
make sure clocktick starts at zero 2015-07-16 14:54:40 +00:00
Fixed and improved some pce comments. 2015-11-17 14:14:15 +00:00
			`; Make the process clock start at zero.`

Renamed INITBSS to INIT and INIT to ONCE. The way we want to use the INITBSS segment - and especially the fact that it won't have the type bss on all ROM based targets - means that the name INITBSS is misleading. After all INIT is the best name from my perspective as it serves several purposes and therefore needs a rather generic name. Unfortunately this means that the current INIT segment needs to be renamed too. Looking for a short (ideally 4 letter) name I came up with ONCE as it contains all code (and data) accessed only once during initialization. 2016-03-06 20:26:22 +00:00			`.segment "ONCE"`
make sure clocktick starts at zero 2015-07-16 14:54:40 +00:00			`initclock:`
Fixed bugs; and, improved the efficiency of some pce library functions. 2015-11-26 20:06:20 +00:00			`ldx #4 - 1`
			`@lp: stz tickcount,x`
style fixes 2015-08-29 13:58:57 +00:00			`dex`
			`bpl @lp`
			`rts`
Fixed bugs; and, improved the efficiency of some pce library functions. 2015-11-26 20:06:20 +00:00
			`; ------------------------------------------------------------------------`
			`.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`