collapseos/arch/z80/sms/blk/626
Virgil Dupras 7d568bd782 sms: simplify and solidify ports-related drivers
Add _TRA!, _THA!, _TRB!, _THB! routines to easily handle those pins'
value without stepping on other pins like the drivers previously
did. For SDC driver, it's going to be important soon because it turns
out that I can't get away with "always on" CS, so I'll need a scheme
where it's important that TH/TR pins have stable values.
2020-11-02 18:53:57 -05:00

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CODE _TRB! HL POP, chkPS, ( B0 -> B6, B1 -> B2 )
L RR, RLA, RLA, RLA, RLA, L RR, RLA, RLA, RLA,
0x44 ANDi, L A LDrr, CPORT_CTL INAi,
0xbb ANDi, L ORr, CPORT_CTL OUTiA,
;CODE
CODE _THB! HL POP, chkPS, ( B0 -> B7, B1 -> B3 )
L RR, RLA, RLA, RLA, RLA, L RR, RLA, RLA, RLA, RLA,
0x88 ANDi, L A LDrr, CPORT_CTL INAi,
0x77 ANDi, L ORr, CPORT_CTL OUTiA,
;CODE
CODE _D1@ CPORT_D1 INAi, PUSHA, ;CODE
CODE _D2@ CPORT_D2 INAi, PUSHA, ;CODE