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4cade/src/ui.offscreen.a

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;License:MIT
;(c) 2018-2020 by 4am
;
; functions for managing which HGR page is showing, and doing things on the other one
;
; - GetOffscreenAddress
; - LoadTitleOffscreen
; - LoadCoverOffscreen
; - LoadHelpOffscreen
; - LoadGameTitleOffscreen
; - UnpackHGRTitle
; - ResyncPage
; - ShowOtherPage
; - ShowOtherDHGRPage
; - ToggleOffscreenPage
; - ClearScreens
; - ClearOffscreen
; - ClearHGR1
; - ClearMem
;
; Public variables
; - OffscreenPage
;
;------------------------------------------------------------------------------
; GetOffscreenAddress
; get high byte of HGR page that is currently not showing
;
; in: none
; out: A = high byte of offscreen HGR page (#$20 or #$40)
; preserves X/Y
;------------------------------------------------------------------------------
GetOffscreenAddress
Ignore = * + 1 ; discard IRQs, particularly on the IIc
lda #$40
OffscreenPage = * + 1
bne + ; SMC
; 0 = currently showing HGR page 2
; (so offscreen is page 1 @ $2000)
; 1 = currently showing HGR page 1
; (so offscreen is page 2 @ $4000)
+ lsr
rts
;------------------------------------------------------------------------------
; LoadTitleOffscreen
; load title screen in the HGR page that is currently not showing
;
; in: none
; out: all flags and registers clobbered
;------------------------------------------------------------------------------
LoadTitleOffscreen
lda #<kTitleRecord
+HIDE_NEXT_2_BYTES
;------------------------------------------------------------------------------
; LoadHelpOffscreen
; load help screen in the HGR page that is currently not showing
;
; in: none
; out: all flags and registers clobbered
;------------------------------------------------------------------------------
LoadHelpOffscreen
lda #<kHelpBackgroundRecord
+HIDE_NEXT_2_BYTES
;------------------------------------------------------------------------------
; LoadCoverOffscreen
; load cover screen in the HGR page that is currently not showing
;
; in: none
; out: all flags and registers clobbered
;------------------------------------------------------------------------------
LoadCoverOffscreen
lda #<kCoverRecord
LoadOffscreenFromAY
sta @indexlo
jsr ForceHGRMode
jsr GetOffscreenAddress
sta @addrhi
jsr LoadIndexedFile
!byte $00
@addrhi !byte $FD ; SMC
@indexlo !byte $FD ; SMC
!byte >kCoverRecord ; all of these are on the same page
rts
LoadGameTitleOffscreen
; in: gGameToLaunch = index into gSearchStore (word)
jsr GetGameToLaunch
jsr okvs_next_field
jsr okvs_next_field_PTR_is_already_set
; (PTR) -> length-prefixed game info bitfield
; Y = 0
iny ; Y = 1
lda (PTR), y ; A = game info bitfield
bpl .LoadHGRGameTitleOffscreen ; bit 7 = 1 if game has DHGR title, 0 if HGR title
jsr SwitchToBank2
- iny
lda (PTR), y
sta OKVS_CACHE-1, y
cpy #6
bne -
LoadIndexedDHRFile
jsr SwitchToBank2
lda #0
sta OKVS_CACHE
lda #$20 ; load first $2000 bytes into auxiliary memory
sta OKVS_CACHE + 5
jsr GetOffscreenAddress
sta @dhgr_addr_aux + 1
sta @dhgr_addr_main + 1
jsr LoadAuxIndexedFile
@dhgr_addr_aux
!word $FD00 ; SMC high byte
!word OKVS_CACHE
jsr SwitchToBank2
lda OKVS_CACHE + 2 ; offset += $2000 (note: stored in big-endian)
clc
adc #$20
sta OKVS_CACHE + 2
bcc +
inc OKVS_CACHE + 1
+ jsr LoadIndexedFile ; load next $2000 bytes into main memory
@dhgr_addr_main
!word $FD00 ; SMC high byte
!word OKVS_CACHE
rts
.LoadHGRGameTitleOffscreen
jsr ForceHGRMode
jsr GetOffscreenAddress
sta @hgr_addr + 1
eor #$1F
sta @poke+2
sta @peek+2
@poke sta $3FFD ; SMC high byte to clear screen hole before load
+LD16 PTR
+ST16 @hgrIndexRecordPtr
jsr LoadIndexedFile
@hgr_addr
!word $FD00 ; SMC high byte
@hgrIndexRecordPtr
!word $FDFD ; SMC
@peek lda $3FFD ; SMC high byte
cmp #$4C ; Check if screen hole now contains a JMP
beq OFFSCREENRTS ; if so, file was not packed, so skip unpack
; /!\ execution falls through here to UnpackHGRTitle
;------------------------------------------------------------------------------
; UnpackHGRTitle
; unpack data from screen holes of the off screen HGR page
;
;------------------------------------------------------------------------------
UnpackHGRTitle
jsr GetOffscreenAddress
sta src+2
ora #$1E
sta dest+2
lda #$00
sta src+1
sta dest+1
lda #3
sta $E0
loop
ldx #0
-- ldy #$78
src
- lda $0000,y ;smc
dest
sta $0000,x ;smc
inx
iny
bpl -
tya ; y = #$80
eor src+1
sta src+1
bne +
inc src+2
+ cpx #$78
bne --
lda dest+1
eor #$80
sta dest+1
bne +
inc dest+2
+ dec $E0
bpl loop
OFFSCREENRTS
rts
;------------------------------------------------------------------------------
; ClearScreens
; clear and display text screen and then clear both hires screens
; (in this order so that the erasing isn't visible)
;
; in: none
; out: $400..$7FF and $2000..$5FFF cleared
;------------------------------------------------------------------------------
ClearScreens
jsr Home
lda #$20 ; clear both hi-res pages
ldx #$40 ; to flash previous bits of the launcher UI)
bne ClearMem ; always
;------------------------------------------------------------------------------
; ClearOffscreen
; clear $2000..$3FFF or $4000..$5FFF, depending on which HGR page is not
; visible right now
; does not change HGR mode
;
; in: none
; out: $2000..$3FFF or $4000..$5FFF cleared
; A = #$80
; X = #$00
; Y = #$00
; Z = 1
;------------------------------------------------------------------------------
ClearOffscreen
jsr GetOffscreenAddress
+HIDE_NEXT_2_BYTES
ClearHGR1
lda #$20 ; note to self: LDX #$20 can't move here
ldx #$20
ClearMem
ldy #$2C ; BIT
bne + ; always
;------------------------------------------------------------------------------
; CopyHGR
;
; in: source and destination page pointers set
; out: all registers clobbered
; 8kb memory region duplicated
;------------------------------------------------------------------------------
CopyHGR
ldx #$20
ldy #$B9 ; LDA $0000,Y opcode
+ sty PageFrom
sta PageTo+2
ClearToBlack
lda #$00
ClearGR
ldy #0
PageFrom lda $FD00,y ; SMC address high byte, also SMC opcode (might be BIT)
PageTo sta $FD00,y ; SMC address high byte
iny
bne PageFrom
inc PageFrom+2
inc PageTo+2
dex
bne PageFrom
sta READMAINMEM
rts
ResyncPage
jsr ToggleOffscreenPage
; /!\ execution falls through here to ShowOtherPage
;------------------------------------------------------------------------------
; ShowOtherPage
; switch to the HGR page that is not currently showing
;
; in: none
; out: A = new value of OffscreenPage
; preserves X/Y
;------------------------------------------------------------------------------
ShowOtherPage
jsr ToggleOffscreenPage
bne +
bit PAGE2 ; show page 2
rts
+ bit PAGE1 ; show page 1
rts
ShowOtherDHGRPage
jsr ToggleOffscreenPage
jmp DHGRMode
;------------------------------------------------------------------------------
; ToggleOffscreenPage
; switch the internal variable that tracks which HGR page is showing
; (does not affect screen)
;
; in: none
; out: A = new value of OffscreenPage
; preserves X/Y
;------------------------------------------------------------------------------
ToggleOffscreenPage
lda OffscreenPage
eor #$01
sta OffscreenPage
rts
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