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analyze weird bootleg input reading code a bit (nw)

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This commit is contained in:
David Haywood 2016-03-28 14:29:38 +01:00
parent a5b6ef9382
commit 82a8cea336
1 changed files with 54 additions and 0 deletions
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54
src/mame/drivers/spyhuntertec.cpp
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@ -331,6 +331,60 @@ READ8_MEMBER(spyhuntertec_state::spyhuntertec_in2_r)
ay2_porta_w 81
ay2_porta_w 01
*/
/*
-- input reading code here
A388: 3E 14 ld a,$14
A38A: 28 04 jr z,$A390
A38C: DD 23 inc ix
A38E: 3E 04 ld a,$04
A390: CD 20 A5 call $A520 << write command to sub-cpu
-- delay loop / timeout loop for reading result? value of b doesn't get used in the end
A393: 06 1F ld b,$1F << loop counter
A395: 21 02 FC ld hl,$FC02
loopstart:
A398: CB 76 bit 6,(hl)
A39A: 28 06 jr z,$A3A2 to dest2
A39C: 10 FA djnz $A398 (to loopstart)
A39E: 06 0F ld b,$0F <
A3A0: 18 1E jr $A3C0 to dest 3
dest2:
A3A2: 06 33 ld b,$33 << loop counter
loop2start:
A3A4: CB 76 bit 6,(hl)
A3A6: 20 11 jr nz,$A3B9 (to outofloop)
A3A8: CB 76 bit 6,(hl)
A3AA: 00 nop
A3AB: CB 76 bit 6,(hl)
A3AD: 20 0A jr nz,$A3B9 (to outofloop)
A3AF: 10 F3 djnz $A3A4 (to loop2start)
A3B1: 00 nop
A3B2: 00 nop
A3B3: 00 nop
A3B4: 00 nop
A3B5: 00 nop
A3B6: 00 nop
A3B7: 00 nop
A3B8: 00 nop
outofloop:
A3B9: 78 ld a,b
A3BA: FE 20 cp $20
A3BC: 38 02 jr c,$A3C0
A3BE: 06 1F ld b,$1F
dest3:
A3C0: 21 B6 A6 ld hl,$A6B6
...
*/
UINT8 ret = ioport("IN2")->read();
// printf("%04x spyhuntertec_in2_r\n", space.device().safe_pc());
return ret;