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HEAD
UrForth: added "almost ANS test suite" (and UrForth passes it ;-)
[urasm.git]
/
libs
/
delayt.zas
blob
c69c9b7c46a51e2472f65b5e8f9258241aec6e0b
1
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Z80 delay routine
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;; by Jan Bobrowski, license GPL
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;; wait hl T (including call; hl>=141)
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;; IN:
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;; HL: number of t-states
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;; OUT:
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;; AF,BC,HL: dead
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delay:
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ld bc,-141
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add hl,bc
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ld bc,-23
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.loop:
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add hl,bc
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jr c,.loop
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ld a,l
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add a,15
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jr nc,.g0
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cp 8
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jr c,.g1
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or 0
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.g0:
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inc hl
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.g1:
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rra
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jr c,.b0
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nop
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.b0:
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rra
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jr nc,.b1
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or 0
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.b1:
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rra
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ret nc
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ret