mirror of https://github.com/cc65/cc65.git
55 lines
1.6 KiB
ArmAsm
55 lines
1.6 KiB
ArmAsm
;
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; Colin Leroy-Mira <colin@colino.net>, 2024
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;
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; void __fastcall__ sleep(unsigned s)
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;
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;
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.export _sleep
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.import _get_iigs_speed
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.import _set_iigs_speed
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.import WAIT
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.importzp tmp1
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.include "accelerator.inc"
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; This functions uses the Apple2 WAIT ROM routine to waste a certain
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; amount of cycles and returns approximately after the numbers of
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; seconds passed in AX.
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;
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; It takes 1023730 cycles when called with AX=1 (1,0007s),
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; 10236364 cycles when called with AX=10 (10,006 seconds),
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; 306064298 cycles with AX=300 (299.2 seconds).
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;
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; Caveat: IRQs firing during calls to sleep will make the sleep longer
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; by the amount of cycles it takes to handle the IRQ.
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;
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_sleep:
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stx tmp1 ; High byte of s in X
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tay ; Low byte in A
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ora tmp1
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bne :+
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rts
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: jsr _get_iigs_speed ; Save current CPU speed
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pha
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lda #SPEED_SLOW ; Down to 1MHz for consistency around WAIT
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jsr _set_iigs_speed
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sleep_1s:
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ldx #$0A ; Loop 10 times
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sleep_100ms:
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lda #$C7 ; Sleep about 99ms
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jsr WAIT
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lda #$0D ; About 1ms
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jsr WAIT
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dex
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bne sleep_100ms
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dey
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bne sleep_1s
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dec tmp1
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bmi done
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dey ; Down to #$FF
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bne sleep_1s
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done:
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pla ; Restore CPU speed
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jmp _set_iigs_speed
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