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27 lines
707 B
ArmAsm
27 lines
707 B
ArmAsm
;
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; from Atari computer version by Christian Groessler, 2014
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;
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; clock_t clock (void);
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; unsigned _clocks_per_sec (void);
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;
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.export _clock
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.importzp sreg
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.include "atari5200.inc"
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.proc _clock
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ldx #5 ; Synchronize with Antic, so the interrupt won't change RTCLOK
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stx WSYNC ; while we're reading it. The synchronization is done same as
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@L1: dex ; in SETVBLV function in Atari OS.
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bne @L1
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stx sreg+1 ; Byte 3 is always zero
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stx sreg ; Byte 2 is always zero, too
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lda RTCLOK+1
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ldx RTCLOK
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rts
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.endproc
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