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Neon816: VDC access words

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mgcaret 2019-12-14 14:41:23 -08:00
parent bdcbfb2766
commit 343dd83cdd
2 changed files with 49 additions and 1 deletions
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2
platforms/Neon816/Neon816-hw.inc
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@ -91,7 +91,7 @@ SPI2ctrl3 = $10001F ; init = $05
; VDC
; *****************
VDCio = $100120 ; read: 1 byte, write: 1 or 2 bytes
VDCbase = $100120 ; base address, there are $20 registers
; *****************
; FDC

48
platforms/Neon816/platform-lib.s
View File

@ -209,6 +209,54 @@ dword I2C2_FETCH,"I2C2@+"
.a16
eword
dword VDC_C_STORE,"VDCC!"
jsr _popay ; pop offset
phy ; save low word
jsr _popay ; pop value to write
pla ; get offset back
phx ; save SP
tax ; offset to x reg
sep #SHORT_A ; whew! that was fun!
.a8
tya ; value to A
sta f:VDCbase,x
rep #SHORT_A
.a16
plx ; restore SP
NEXT
eword
dword VDC_C_FETCH,"VDCC@"
jsr _popay ; pop offet
phx ; save SP
tya
tax
sep #SHORT_A ; whew! that was fun!
.a8
lda f:VDCbase,x
rep #SHORT_A
.a16
plx ; restore SP
and #$00FF
tay
lda #$0000
PUSHNEXT
eword
dword VDC_STORE,"VDC!"
jsr _popay ; again! again! again!
phy
jsr _popay
pla
phx
tax
tya
sta f:VDCbase,x
rep #SHORT_A
.a16
plx ; restore SP
NEXT
eword
dend