async subsystem :)

00TheFool.inc

@@ -14,6 +14,7 @@ TheFool:
   dw FoolMap
   dw FoolTilesEnd - FoolTiles
   dw FoolTiles
+
 FoolTiles:
 	db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
 	db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$01,$00,$01,$00,$02

Async.inc

@@ -0,0 +1,260 @@
+def vAsyncAF equ $ff80
+def vAsyncHL EQU $ff82 
+def vAsyncDE EQU $ff84
+def vAsyncBC equ $ff86
+def vAsyncPC equ $ff88
+def vAsyncNext equ $ff8a
+def vAsyncAfter equ $ff8c
+
+def SAFE_ASYNC_START EQU 144
+def SAFE_ASYNC_END EQU 151
+
+DoInAsyncVBlank: 
+  di
+  push af
+  
+  ld a, l 
+  ldh [vAsyncHL], a
+  ld a, h
+  ldh [vAsyncHL+1], a
+  ld a, e
+  ldh [vAsyncDE], a
+  ld a, d
+  ldh [vAsyncDE+1], a
+  ld a, c 
+  ldh [vAsyncBC], a
+  ld a, b 
+  ldh [vAsyncBC+1], a
+  
+  pop hl
+  ld a, l 
+  ldh [vAsyncAF], a 
+  ld a, h 
+  ldh [vAsyncAF+1], a 
+  
+  ; set pu the next call!
+  ldh a, [vAsyncNext]
+  ldh [vAsyncPC], a 
+  ldh a, [vAsyncNext+1]
+  ldh [vAsyncPC+1], a ; put next into pc 
+  ldh a, [vAsyncAfter]
+  ldh [vAsyncNext], a 
+  ldh a, [vAsyncAfter+1]
+  ldh [vAsyncNext+1], a  ; puut after into next
+  ld a, 0 
+  ldh [vAsyncAfter], a ; unless this gets overwritten later, end execution after that
+  ldh [vAsyncAfter+1], a 
+  
+  ld a, LOW(DoInAsyncVBlank_EnterThread)
+  ld [INTERRUPT_LCD], a
+  ld a, HIGH(DoInAsyncVBlank_EnterThread)
+  ld [INTERRUPT_LCD + 1], a; set interrupt handler to "ENTER THREAD"
+  ld a, SAFE_ASYNC_START ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
+  ld [rLYC], a ; set LYC
+  ld hl, rIE  
+  set 1, [hl] ; enable vblank
+  ld hl, rSTAT
+  set 6, [hl] ; set the stat interrupt to LYC mode
+  ld hl, rIF 
+  res 1, [hl] ; clear the interrupt so we don't immediately fire it
+  ei
+  
+  ret 
+
+DoInAsyncVBlank_EnterThread:
+  ;stack looks like: 
+  ;c113 (SMC int @ LYC 90 pc), 004b (hw int @ LYC 90 pc), outer context pc
+
+  push hl
+  push bc
+  push de
+  push af
+
+  ;af, de, bc, hl, c113 (SMC interrupt pc), 004b (hardwired interrput pc), outer context pc
+  
+  ; check if there's anything queued up for next execution
+  ldh a, [vAsyncPC]
+  ld l, a 
+  ldh a, [vAsyncPC+1]
+  ld h, a 
+  or a, l 
+  jp z, DoInAsyncVBlank_EndThread ; if nothing is queued up, jump to cleanup
+
+  ld a, LOW(DoInAsyncVBlank_ExitThread)
+  ld [INTERRUPT_LCD], a 
+  ld a, HIGH(DoInAsyncVBlank_ExitThread)
+  ld [INTERRUPT_LCD+1], a 
+  ld a, SAFE_ASYNC_END ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
+  ld [rLYC], a  ; set lcd interrupt handler to EXIT SAFE MODE on line 153
+  
+  ; what if our async thread calls return?
+  ; we need to have a PC to return to. if that happens, we will want to
+  ; reti. 
+  ld hl, DoInAsyncVBlank_EarlyReturn
+  push hl ; address for if the thread retrns
+  
+  ldh a, [vAsyncPC]
+  ld l, a 
+  ldh a, [vAsyncPC+1]
+  ld h, a 
+  push hl ; put vAsyncPC on the stack! for jumping to it!
+  ; stack looks like: vasyncpc, early return, af, de, bc, hll, SMC interrput pc, hardwired interrupt pc, outer context pc 
+  
+  ldh a, [vAsyncAF]
+  ld l, a 
+  ldh a, [vAsyncAF+1]
+  ld h, a 
+  push hl
+  
+  ldh a, [vAsyncHL]
+  ld l, a 
+  ldh a, [vAsyncHL+1]
+  ld h, a 
+  ldh a, [vAsyncDE]
+  ld e, a 
+  ldh a, [vAsyncDE+1]
+  ld d, a 
+  ldh a, [vAsyncBC]
+  ld c, a 
+  ldh a, [vAsyncBC+1]
+  ld b, a 
+  
+  pop af; putting vAsyncAF into af requires this hoop-jumping
+  
+  ei
+  ret ; "return" to the vAsyncPC wee put on the stack previously.
+  ; this is more or less a jump, not a return.
+  ; is that the source of our problems?
+  ; after this instruction executes, stack looks like:
+  ; early return, af, de, bc, hl, PC (smc int), PC (hardwired int), PC (outer context)
+  ; and we'll be in the async thread, executing
+  
+DoInAsyncVBlank_EarlyReturn:
+  ; stack: 
+  ; af, de, bc, hl, PC (smc int @ LYC90), PC (hw int @ LYC 90), PC (outer context)
+  PRINTln "early return handle is ", DoInAsyncVBlank_EarlyReturn
+  ; save state of registers
+  di
+  push af 
+  
+  ld a, l
+  ldh [vAsyncHL], a
+  ld a, h
+  ldh [vAsyncHL+1], a
+  ld a, e
+  ldh [vAsyncDE], a 
+  ld a, d 
+  ldh [vAsyncDE+1], a 
+  ld a, c 
+  ldh [vAsyncBC], a
+  ld a, b 
+  ldh [vAsyncBC+1], a 
+  
+  pop hl
+  ld a, l 
+  ldh [vAsyncAF], a 
+  ld a, h
+  ldh [vAsyncAF+1], a 
+  
+  
+  
+  ; set pu the next call!
+  ldh a, [vAsyncNext]
+  ldh [vAsyncPC], a 
+  ldh a, [vAsyncNext+1]
+  ldh [vAsyncPC+1], a ; put next into pc 
+  ldh a, [vAsyncAfter]
+  ldh [vAsyncNext], a 
+  ldh a, [vAsyncAfter+1]
+  ldh [vAsyncNext+1], a  ; puut after into next
+  ld a, 0 
+  ldh [vAsyncAfter], a ; unless this gets overwritten later, end execution after that
+  ldh [vAsyncAfter+1], a 
+  
+  ld a, LOW(DoInAsyncVBlank_EnterThread) ; set up next call
+  ld [INTERRUPT_LCD], a 
+  ld a, HIGH(DoInAsyncVBlank_EnterThread)
+  ld [INTERRUPT_LCD+1], a 
+  ld a, SAFE_ASYNC_START
+  ld [rLYC], a  
+  
+   ; restore the pre-interrupt registers, return and enable interrupts
+  pop af 
+  pop de
+  pop bc
+  pop hl
+  reti
+
+DoInAsyncVBlank_EndThread:
+  ; end execution of the thread by disabling the interrupt
+  ; and restore the state for the outer thread
+  ld hl, rIE  
+  res 1, [hl] ; disable STAT/vblank interrupt
+  pop af
+  pop de
+  pop bc
+  pop hl
+  reti
+
+DoInAsyncVBlank_ExitThread:
+  ; at this point, it's an interrpt being called from inside the interrupt
+  ; our stack probably looks like this:
+  ; PC (smc int), PC (hardwired int), PC (inside thread), early return, af, de, bc, hl, PC (smc int), PC (hardwired int), PC (outer context)
+  ; first, save the interrpt thread registers.
+  push af 
+  
+  ld a, l
+  ldh [vAsyncHL], a
+  ld a, h
+  ldh [vAsyncHL+1], a
+  ld a, e
+  ldh [vAsyncDE], a 
+  ld a, d 
+  ldh [vAsyncDE+1], a 
+  ld a, c 
+  ldh [vAsyncBC], a
+  ld a, b 
+  ldh [vAsyncBC+1], a
+  
+  pop hl
+  ld a, l 
+  ldh [vAsyncAF], a 
+  ld a, h
+  ldh [vAsyncAF+1], a 
+  
+  ;god i'm such a genius
+  ; this was called as an interrupt inside the interrupt
+  ;so our stack looks like this:
+  ; PC (smc int), PC (hardwired int), PC (inside thread), early return, af, de, bc, hl, PC (smc int), PC (hardwired int), PC (outer context)
+  ; we've got the two PCs from the inner interrupt call stack.
+  ; get rid of them! we're running without handrails! i know what i'm doing! I hope!
+  pop hl
+  pop hl
+  ; now, save the interrupt thread's pc., which is on the stack from this 
+  ; interrupt being called.
+  pop hl
+  ld a, l 
+  ldh [vAsyncPC], a 
+  ld a, h 
+  ldh [vAsyncPC+1], a
+  ; now we are done with this entire execution of thread. now we need to set up
+  ; the next execution of this thread.
+  ld a, LOW(DoInAsyncVBlank_EnterThread)
+  ld [INTERRUPT_LCD], a 
+  ld a, HIGH(DoInAsyncVBlank_EnterThread)
+  ld [INTERRUPT_LCD+1], a 
+  ld a, SAFE_ASYNC_START ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
+  ld [rLYC], a  ; set lcd interrupt handler to EXIT SAFE MODE on line 153
+
+  ;at present the stack looks like:
+  ; early return, af, de, bc, hl, pc (smc int @ LYC 90), pc (hardwired int at LYC 90), PC (outer context)
+  ; pop the early return and discard it.
+  pop hl
+  ; and finally, we can restore the state of the registers to what they were
+  ; before this whole handler got called.
+  pop af
+  pop de 
+  pop bc 
+  pop hl
+  reti ; this is a proper return
+  

CardLibrary.inc

@@ -1,17 +1,31 @@
 SECTION "Card Data", ROM0
 
 Spreads:
+  db 5 ; length
 .nospread
   db 0
+  db 20, "      Nothing       "
+  db 20, " This is no spread. "
+.onecard
+  db 1, $21
+  db 20, "  One Card Spread   "
+  db 20, " Draw a single card."
 .tencard
   db 10, $00, $10, $20, $30, $40, $02, $12, $22, $32, $42
+  db 20, "  Ten Card Spread   "
+  db 20, "Throw more cards on."
 .fivecard
   db 5, $11, $20, $22, $31, $41
+  db 20, "  Horizontal Cross  " 
+  db 20, "  A little spicy.   "
 .threecard
-  db 3, $11, $21, $31
+  db 3, $01, $21, $41
+  db 20, " Three Card Spread  "
+  db 20, "   Old reliable.    "
+.end
 
 Cards:
-  db 5
+  db 5 ; length
   dw TheFool
   dw TheMagician
   dw TheHighPriestess

CopyRangeSafe.inc

@@ -9,6 +9,8 @@ DEF vSafeCopySTAT EQU vSafeCopyLYC + 1 ; stashes $FF41, the STAT register
 DEF vSafeCopyInterrupt EQU vSafeCopySTAT + 1 ; stashes the previous LCD interrupt
 DEF vSafeCopyInterruptEnable EQU vSafeCopyInterrupt + 2 ; stashes $FFFF, which interrupts are enabled
 
+DEF SAFE_TRANSFER_START EQU 145
+DEF SAFE_TRANSFER_END EQU 153
 
 CopyRangeSafe: 
   ; hl is source
@@ -56,7 +58,7 @@ CopyRangeSafe:
   ld [INTERRUPT_LCD], a
   ld a, h
   ld [INTERRUPT_LCD + 1], a; set interrupt handler to "ENTER SAFE MODE"
-  ld a, 143 ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
+  ld a, SAFE_TRANSFER_START ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
   ld [$ff45], a 
   ld hl, $ffff 
   set 1, [hl]
@@ -88,7 +90,7 @@ CopyRangeSafe_EnterSafeMode:
   ld [INTERRUPT_LCD], a 
   ld a, h 
   ld [INTERRUPT_LCD+1], a 
-  ld a, 153 ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
+  ld a, SAFE_TRANSFER_END ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
   ld [$ff45], a  ; set lcd interrupt handler to EXIT SAFE MODE on line 153
   ldh a, [vSafeCopySource]
   ld l, a 
@@ -145,7 +147,7 @@ CopyRangeSafe_CleanUp:
   ld [INTERRUPT_LCD], a 
   ld a, h 
   ld [INTERRUPT_LCD+1], a 
-  ld a, 143 ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
+  ld a, SAFE_TRANSFER_START ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
   ld [$ff45], a  ; set lcd interrupt handler to ENTER SAFE MODE on line 148
   pop af
   pop de
@@ -174,7 +176,7 @@ CopyRangeSafe_Done: ; called when the complete transfer is finished,
   ld [INTERRUPT_LCD], a 
   ld a, h 
   ld [INTERRUPT_LCD+1], a 
-  ld a, 143 ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
+  ld a, SAFE_TRANSFER_START ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
   ld [$ff45], a  ; set lcd interrupt handler to ENTER SAFE MODE on line 148
   pop af
   pop de
@@ -205,7 +207,7 @@ CopyRangeSafe_Done: ; called when the complete transfer is finished,
 CopyRangeSafe_Return:
   reti
 
-CopyRangeUnsafe:
+CopyRangeUnsafe: ; this is threadsafe but not vblank safe
   ; hl is source
   ; de is destination
   ; bc is length to copy

CopyTilesSafe.inc

@@ -40,7 +40,7 @@ CopyTilesSafe:
   ld [INTERRUPT_LCD], a
   ld a, h
   ld [INTERRUPT_LCD + 1], a; set interrupt handler to "ENTER SAFE MODE"
-  ld a, 148 ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
+  ld a, SAFE_TRANSFER_START ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
   ld [$ff45], a 
   ld hl, $ffff 
   set 1, [hl]
@@ -65,7 +65,7 @@ CopyTilesSafe_EnterSafeMode:
   ld [INTERRUPT_LCD], a 
   ld a, h 
   ld [INTERRUPT_LCD+1], a 
-  ld a, 153 ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
+  ld a, SAFE_TRANSFER_END ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
   ld [$ff45], a  ; set lcd interrupt handler to EXIT SAFE MODE on line 153
   ldh a, [vSafeCopySource]
   ld l, a 
@@ -120,7 +120,6 @@ CopyTilesSafe_DoneWithLine:
 
   dec b
   ld a, b 
-  cp a, 0
   
   ldh [vSafeCopyOriginalCount+1], a ; store the decremented line count
   jp nz, CopyTilesSafe_TransferLoop
@@ -151,7 +150,7 @@ CopyTilesSafe_CleanUp:
   ld [INTERRUPT_LCD], a 
   ld a, h 
   ld [INTERRUPT_LCD+1], a 
-  ld a, 148 ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
+  ld a, SAFE_TRANSFER_START ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
   ld [$ff45], a  ; set lcd interrupt handler to ENTER SAFE MODE on line 148
   pop af
   pop de
@@ -180,7 +179,7 @@ CopyTilesSafe_Done: ; called when the complete transfer is finished,
   ld [INTERRUPT_LCD], a 
   ld a, h 
   ld [INTERRUPT_LCD+1], a 
-  ld a, 148 ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
+  ld a, SAFE_TRANSFER_START ; CHANGE ME TO ADJUST SAFE TRANSFER TIMING
   ld [$ff45], a  ; set lcd interrupt handler to ENTER SAFE MODE on line 148
   pop af
   pop de
@@ -213,11 +212,11 @@ CopyTilesSafe_Return:
 
 
 CopyTilesToMapUnsafe:
-  ; copy tiles from where they are linearly packed at an origin (de)
+  ; copy tiles from where they are linearly packed at an origin (hl)
-  ; to a rectangle in the tilemap in vram (hl)
+  ; to a rectangle in the tilemap in vram (de)
   ; assuming it has height in b and width in c.
   push bc
-CopyTile:
+.copyTile
   ld a, [hl] ; load from the tile map into a
   ld [de], a ; load from a into the destination
   inc hl ; this is slower than using hli but i'm trying to work with this here
@@ -226,8 +225,8 @@ CopyTile:
   ; check if we've completed a line?
   ld a, 0
   or a, c ; check if c is zero, if it's not zero go back and copy more bytes
-  jp nz, CopyTile
+  jp nz, .copyTile
-DoneWithLine:
+.doneWithLine
   pop bc
 
   ld a, e
@@ -247,4 +246,45 @@ DoneWithLine:
   ld a, b
   cp a, 0
   jp nz, CopyTilesToMapUnsafe
+  ret
+  
+CopyTilesToMapThreadsafe:
+  ; copy tiles from where they are linearly packed at an origin (hl)
+  ; to a rectangle in the tilemap in vram (de)
+  ; assuming it has height in b and width in c.
+  di
+  ei
+  nop
+  di
+  push bc
+.copyTile
+  ld a, [hl] ; load from the tile map into a
+  ld [de], a ; load from a into the destination
+  inc hl ; this is slower than using hli but i'm trying to work with this here
+  inc de
+  dec c
+  ; check if we've completed a line?
+  ld a, 0
+  or a, c ; check if c is zero, if it's not zero go back and copy more bytes
+  jp nz, .copyTile
+.doneWithLine
+  pop bc
+
+  ld a, e
+  add a, 32
+  ld e, a
+  ld a, d
+  adc a, 0
+  ld d, a
+  ld a, e
+  sub a, c
+  ld e, a
+  ld a, d
+  sbc a, 0
+  ld d, a
+
+  dec b
+  ld a, b
+  cp a, 0
+  jp nz, CopyTilesToMapThreadsafe
   ret

ScreenCardRead.inc

@@ -8,8 +8,7 @@ ScreenCardRead:
   dw CardReadUpdate
   dw CardReadDraw
   dw CardReadTeardown
-  
+
-;; CARD READ PAGE STARTS HERE
 CardReadSetup:
 ; Turn the LCD off
   ld hl, rLCDC
@@ -37,18 +36,8 @@ CardReadSetup:
   ld c, 10 ; width
   call CopyTilesToMapUnsafe
   
-  ld a, 0 
-  ld hl, $c000
-  ld bc, 18*10
-.buildZeros
-  ld a, 0
-  ld [hl+], a 
-  ld a, b 
-  or a, c
-  dec bc
-  jp nz, .buildZeros
   
-  ld hl, $c000
+  ld hl, ZEROES
   ld de, $9800 + 10
   ld b, 18
   ld c, 10
@@ -75,37 +64,25 @@ CardReadSetup:
 
 CardReadUpdate:
   ld hl, rMYBTNP
-  bit 5, [hl]
+  bit 4, [hl]
   jp z, .doneWithB
   ld hl, ScreenMainMenu
   call ChangeScene
   ret
 .doneWithB
+  ldh a, [vSelectedCardIndex]
+  
   bit 3, [hl]  ; select the down key
   jp z, :+ ; skip the following code if down is not pressed
-  ldh a, [vSelectedCardIndex]
   inc a ; increment when they press down because the deck has card 0 at the top
-  ldh [vSelectedCardIndex], a
 :
   bit 2, [hl] ; select up key %0000_0100
   jp z, :+ ; skip the following code if up is not pressed
-  ldh a, [vSelectedCardIndex]
   dec a ; decrement when they press up because the deck has card 0 at the top
-  ldh [vSelectedCardIndex], a
-:
-  ldh a, [vSelectedCardIndex] ; load current selected tile index
-  ld hl, Cards ; deck length
-  cp a, [hl] ; ddoes the index equal the deck length?
-  jp nz, :+
-  ld a, 0 ; if the index equals the deck length replace it with zero
-  ldh [vSelectedCardIndex], a
-:
-  cp a, $FF ;  if the tile index is $FF (underflowed from dec)
-  jp nz, :+
-  ld a, [hl] 
-  dec a ;replace with deck length - 1
-  ldh [vSelectedCardIndex], a
 :
+  ld hl, Cards 
+  call ArrayClampLooping
+  ldh [vSelectedCardIndex], a ; load current selected tile index
 
   ld hl, rMYBTNP
   bit 1, [hl]
@@ -140,90 +117,13 @@ CardReadUpdate:
 
 CardReadDraw:
 ; first, we draw the spread minimap
-.drawSpread
   ldh a, [vCurrentSpread]
   ld c, a 
   ldh a, [vCurrentSpread+1]
   ld b, a 
-  ld a, [bc]
-  ld e, a 
-  ld d, 0
-  
-.foundSpread
-  push de ; length of the spread in e!
-.drawCard
-  ld a, e 
-  cp a, 0
-  jp z, .doneWithSpread
-  inc bc ; first card of spread is after the length of the spread
-  
   ld hl, $9800 + (32*12)+11
-
-  ld a, [bc] 
-  swap a
-  and a, %0000_1111
-  ld d, 0
-  ld e, a ; add a to hl
-  add hl, de
-.doneWithWalkRight
-  ld a, [bc]
-  and a, %0000_1111
-  ld d, 0
-  ld e, 32
-  jp z, .doneWithWalkDown
-.walkDown
-  dec a
-  add hl, de
-  cp a, 0
-  jp nz, .walkDown
-.doneWithWalkDown
-.drawMiniCard
-  ld [hl], $83
-  add hl, de
-  ld [hl], $84
-.doneDrawingCard
-  pop de
-  dec de
-  ld a, e
-  cp a, 0
-  jp nz, .foundSpread
-
-.doneWithSpread
-  ; highlight the selected card
-  ldh a, [vCurrentSpread]
-  ld l, a 
-  ldh a, [vCurrentSpread+1]
-  ld h, a 
-  
   ldh a, [vSelectedCardInSpread]
-  ld d, 0
+  call DrawSpreadMinimap
-  ld e, a ; index of selected card in spread
-  inc e ; skip length 
-  
-  add hl, de
-  ld b, h
-  ld c, l ; move location of selected card to bc
-  
-  ld hl, $9800 + (32*12)+11
-  ld a, [bc] ; a has card location
-  swap a
-  and a, %0000_1111
-  ld e, a 
-  add hl, de ; step right
-  ld e, 32
-  ld a, [bc]
-  and a, %0000_1111
-  jp z, CardReadDraw_DrawSelectedCard
-:
-  dec a
-  add hl, de ; step down
-  cp a, 0
-  jp nz, :-
-CardReadDraw_DrawSelectedCard:
-  ld [hl], $85
-  add hl, de
-  ld [hl], $86
-  
   
 ; okay now we draw the deck minimap
   ld a, [Cards]
@@ -384,8 +284,6 @@ INCLUDE "CopyRangeSafe.inc"
 
 INCLUDE "CopyTilesSafe.inc"
 
-INCLUDE "CardLibrary.inc"
-
 SECTION "Tile data", ROM0
   
 UITiles:

ScreenMainMenu.inc

@@ -182,7 +182,11 @@ MainMenuUpdate:
   jp z, .option3
   jp .doneWithMenuSelect
 .option1
-  jp .doneWithMenuSelect
+  ld a, 0 
+  ld [vSelectedSpreadIndex], a
+  ld hl, ScreenSpreadSelect
+  call ChangeScene
+  ret
 .option2
   jp .doneWithMenuSelect
 .option3
@@ -193,7 +197,6 @@ MainMenuUpdate:
   ld hl, ScreenCardRead 
   call ChangeScene
   ret
-  jp .doneWithMenuSelect
 .doneWithMenuSelect
   
   

ScreenSpreadSelect.inc

@@ -0,0 +1,447 @@
+DEF vSelectedSpreadIndex EQU VARIABLES_START
+DEF vPreviousSpreadIndex EQU vSelectedSpreadIndex + 1
+def vSelectedSpreadCard equ vPreviousSpreadIndex + 1
+
+ScreenSpreadSelect:
+  dw SpreadSelectSetup
+  dw SpreadSelectUpdate
+  dw SpreadSelectDraw
+  dw SpreadSelectTeardown
+  
+SpreadSelectSetup:
+  ld a, 0 
+  ldh [vSelectedCardInSpread], a 
+  ldh [vPreviousSpreadIndex], a 
+  ldh [vSelectedSpreadIndex], a 
+  
+  ld hl, ZEROES
+  ld de, $9800
+  ld b, 18
+  ld c, 20
+
+  ld a, LOW(CopyTilesToMapThreadsafe)
+  ld [vAsyncNext], a 
+  ld a, HIGH(CopyTilesToMapThreadsafe)
+  ld [vAsyncNext+1], a 
+  ld a, LOW(.loadUITiles)
+  ld [vAsyncAfter], a 
+  ld a, HIGH(.loadUITiles)
+  ld [vAsyncAfter+1], a 
+  call DoInAsyncVBlank
+  
+  ld a, HIGH(ZEROES)
+  ld de, $ffc0
+  call RunDMA
+  ret
+  
+.loadUITiles
+  ld hl, UITiles ; source
+  ld de, $8000 + $80*16; destination of copy
+  ld bc, UITilesEnd - UITiles ; length to copy
+
+  ld a, LOW(CopyRangeUnsafe)
+  ld [vAsyncNext], a 
+  ld a, HIGH(CopyRangeUnsafe)
+  ld [vAsyncNext+1], a 
+  ld a, LOW(DrawSpreadAsync)
+  ld [vAsyncAfter], a 
+  ld a, HIGH(DrawSpreadAsync)
+  ld [vAsyncAfter+1], a 
+  ret  
+  
+SpreadSelectUpdate:
+  ld hl, rMYBTNP
+  bit 4, [hl]
+  jp z, .doneB
+  ld hl, ScreenMainMenu
+  call ChangeScene
+  ret
+.doneB
+  ld a, [vSelectedSpreadIndex]
+  
+  bit 3, [hl]  ; select the down key
+  jp z, .doneDown ; skip the following code if down is not pressed
+  dec a ; increment when they press down because the deck has card 0 at the top
+.doneDown
+  bit 2, [hl] ; select up key
+  jp z, .doneUp ; skip the following code if up is not pressed
+  inc a ; decrement when they press up because the deck has card 0 at the top
+.doneUp
+  ld hl, Spreads 
+  call ArrayClampLooping
+  ldh [vSelectedSpreadIndex], a ; load current selected tile index
+  
+  ld hl, vPreviousSpreadIndex
+  cp a, [hl]
+  ret z ; we're done if previous index is same as new index
+  
+  ; execute an async call to DrawSpreadAsync.
+  ld a, LOW(DrawSpreadAsync)
+  ld [vAsyncNext], a 
+  ld a, HIGH(DrawSpreadAsync)
+  ld [vAsyncNext+1], a 
+  
+  call DoInAsyncVBlank
+  ret ; return from main thread. go back to looping.
+  
+DrawSpreadAsync:
+  ldh a, [vSelectedSpreadIndex]
+  ldh [vPreviousSpreadIndex], a 
+  
+  ; find the correct spread address
+  ld hl, Spreads
+  inc hl ; skip length of spreads
+  ld a, [vSelectedSpreadIndex]
+  inc a ; we're decing at the start so we inc first to prepare...
+  ld d, 0
+.findSpread
+  dec a
+  jp z, .spreadFound
+  
+  ld e, [hl] ; skip cards in spread
+  inc hl 
+  add hl, de
+  
+  ld e, [hl] ; skip title of spread
+  inc hl
+  add hl, de
+  
+  ld e, [hl] ; skip description
+  inc hl
+  add hl, de
+  
+  jp .findSpread
+.spreadFound
+  ld a, l 
+  ld [vCurrentSpread], a
+  ld a, h
+  ld [vCurrentSpread+1], a ; save the current spread (hl) into vcurrentspread. 
+
+  ld de, $9800 + 32*4 + 3
+  ld hl, ZEROES
+  ld b, 8
+  ld c, 10
+  
+  ld a, LOW(CopyTilesToMapThreadsafe)
+  ld [vAsyncNext], a 
+  ld a, HIGH(CopyTilesToMapThreadsafe)
+  ld [vAsyncNext+1], a 
+  ld a, LOW(.afterClear)
+  ld [vAsyncAfter], a
+  ld a, HIGH(.afterClear)
+  ld [vAsyncAfter+1], a
+  ret  ; return from async execution now that we've registered desire
+  ; to call copytilestomapthreadsafe
+  ; and then drawspread
+
+.afterClear
+  ld a, [vCurrentSpread]
+  ld l, a 
+  ld a, [vCurrentSpread+1]
+  ld h, a
+  ld d, 0 
+  ld e, [hl]
+  inc e
+  add hl, de
+  ld de, $9800 + 32
+  ld a, LOW(PrintString)
+  ld [vAsyncNext], a 
+  ld a, HIGH(PrintString)
+  ld [vAsyncNext+1], a 
+  ld a, LOW(.afterTitle)
+  ld [vAsyncAfter], a 
+  ld a, HIGH(.afterTitle)
+  ld [vAsyncAfter+1], a 
+  ret
+
+.afterTitle
+  ld de, $9800 + (32*2)
+  ld a, LOW(PrintString)
+  ld [vAsyncNext], a 
+  ld a, HIGH(PrintString)
+  ld [vAsyncNext+1], a 
+  ld a, LOW(.afterDescription)
+  ld [vAsyncAfter], a 
+  ld a, HIGH(.afterDescription)
+  ld [vAsyncAfter+1], a 
+  ret
+  
+.afterDescription
+  
+  ld hl, $9800 + 32*4 + 3
+  ldh a, [vSelectedSpreadCard]
+  ld e, a ; e contains the selected index
+  
+  ld a, LOW(DrawSpreadBigAndThreadsafe)
+  ld [vAsyncNext], a 
+  ld a, HIGH(DrawSpreadBigAndThreadsafe)
+  ld [vAsyncNext+1], a 
+  ld a, LOW(.finishAsyncUpdate)
+  ld [vAsyncAfter], a 
+  ld a, HIGH(.finishAsyncUpdate)
+  ld [vAsyncAfter+1], a 
+  ret
+  
+.finishAsyncUpdate
+  ; signal that we're done with execution of the async thread
+  ld a, 0 
+  ld [vAsyncNext], a 
+  ld [vAsyncNext+1], a 
+  ld [vAsyncAfter], a 
+  ld [vAsyncAfter+1], a 
+  ret
+  
+SpreadSelectDraw:
+  ret
+SpreadSelectTeardown:
+  ret  
+
+DrawSpreadBigAndThreadsafe:
+; hl for location on screen
+; bc for current spread address ; actually holding that in vCurrentSpread
+; e for index of selected card
+  di
+  ld a, [vCurrentSpread]
+  ld c, a 
+  ld a, [vCurrentSpread+1]
+  ld b, a 
+  ld a, [bc]
+  cp a, 0 ; length of spread
+  ret z ; return early if the spread is empty
+  ld d, a ; length of spread in d
+  inc d
+.drawCards
+  ei
+  nop
+  di
+  dec d
+  jp z, .doneWithSpread ; if we're drawing zero remaining cards, stop drawing
+  inc bc ; step forward
+  push hl  ; need this bc drawsmallcard changes hl
+  ld a, [bc]
+  call DrawBigCard
+  pop hl  
+  jp .drawCards
+.doneWithSpread 
+; stack has spread address
+; d is zero
+; e should have currently selected index
+  ld b, h
+  ld c, l ; stash hl in bc for a mo; this should be a location in vram
+  
+  ld a, [vCurrentSpread]
+  ld l, a
+  ld a, [vCurrentSpread+1]
+  ld h, a 
+  ;spread address in hl
+
+  inc e ; skip the tiles length
+  
+  add hl, de
+  ld a, [hl] ; load card descriptor into a 
+  
+  ld h, b
+  ld l, c; retrieve vram address
+  ei
+  nop
+  di
+  call DrawBigCardSelected
+  
+  ei
+  ret
+
+
+
+DrawSpreadBig:
+; hl for location on screen
+; bc for current spread address
+; e for index of selected card
+  ld a, [bc]
+  cp a, 0 ; length of spread
+  ret z ; return early if the spread is empty
+  push bc
+  ld d, a ; length of spread in d
+  inc d
+.drawCards
+  dec d
+  jp z, .doneWithSpread ; if we're drawing zero remaining cards, stop drawing
+  inc bc ; step forward
+  push hl  ; need this bc drawsmallcard changes hl
+  ld a, [bc]
+  call DrawBigCard
+  pop hl  
+  jp .drawCards
+.doneWithSpread 
+; stack has spread address
+; d is zero
+; e should have currently selected index
+  ld b, h
+  ld c, l ; stash hl in bc for a mo; this should be a location in vram
+  pop hl ; put bc from stack into hl, this is the spread address
+
+  inc e ; skip the tiles length
+  
+  add hl, de
+  ld a, [hl]
+  
+  ld h, b
+  ld l, c; retrieve
+  ;call DrawBigCardSelected
+  
+  ret
+  
+DrawBigCard: ; starting from screen location hl, draw a card at 
+;the location described in a
+; saves de and is therefore not threadsafe
+  push de
+  ld d, a 
+  swap a
+  and a, %0000_1111
+  sla a
+  ld e, a 
+
+  ld a, d
+  and a, %0000_1111
+
+  ld d, 0
+  add hl, de ; step right
+  
+  ld e, 64
+  jp z, .drawCard
+.stepDown
+  add hl, de ; step down
+  dec a
+  jp nz, .stepDown
+.drawCard
+  ld de, 32
+  ld [hl], $12
+  inc hl 
+  ld [hl], $1e
+  add hl, de
+  ld [hl], $1f
+  dec hl 
+  ld [hl], $13
+  add hl, de 
+  ld [hl], $13
+  inc hl 
+  ld [hl], $1f 
+  add hl, de
+  ld [hl], $23
+  dec hl 
+  ld [hl], $17
+  
+  pop de
+  ret 
+
+DrawBigCardSelected: ; starting from screen location hl, draw a card at 
+;the location described in a
+  push de
+  push af 
+  swap a
+  ld d, 0
+  and a, %0000_1111
+  sla a
+  ld e, a 
+  add hl, de ; step right
+  
+  ld e, 64
+  pop af
+  and a, %0000_1111
+  jp z, .drawCard
+.stepDown
+  add hl, de ; step down
+  dec a
+  jp nz, .stepDown
+.drawCard
+  ld de, 32
+  ld [hl], $12
+  inc hl 
+  ld [hl], $1e
+  add hl, de
+  ld [hl], $1f
+  dec hl 
+  ld [hl], $13
+  add hl, de 
+  ld [hl], $13
+  inc hl 
+  ld [hl], $1f 
+  add hl, de
+  ld [hl], $23
+  dec hl 
+  ld [hl], $17
+  
+  pop de
+  ret 
+
+DrawSpreadMinimap:
+; hl for location on screen
+; bc for current spread address
+; a for index of selected card
+  push af
+  push bc
+  
+  ld a, [bc]
+  ld d, 0
+  ld e, a ; length of spread in de
+.drawCards
+  ld a, e 
+  cp a, 0
+  jp z, .doneWithSpread ; if we're drawing zero remaining cards, stop drawing
+  dec e
+  inc bc ; step forward
+  
+  push hl ; need this bc drawsmallcard changes hl
+  push bc
+  ld a, [bc]
+  ld bc, $8384
+  call DrawSmallCard
+  pop bc
+  pop hl
+  
+  jp .drawCards
+.doneWithSpread ; stack has hl, bc, af at the time of jumping here
+  pop bc ; stack: af 
+  pop af
+  ld d, 0
+  ld e, a ; index of selected card in spread
+  inc e ; skip the length
+  
+  push hl ; stack: hl
+  ld h, b
+  ld l, c ; put bc in hl temporarily so we can add to hl 
+  
+  add hl, de
+  
+  ld a, [hl]
+  pop hl ; stack: empty
+  ld bc, $8586
+  call DrawSmallCard
+  
+  ret
+  
+DrawSmallCard: ; starting from screen location hl, draw a card at 
+;the location described in a, top and bottom sprite in b and c
+  push de
+  push af 
+  swap a
+  ld d, 0
+  and a, %0000_1111
+  ld e, a 
+  add hl, de ; step right
+  
+  ld e, 32
+  pop af
+  and a, %0000_1111
+  jp z, .drawCard
+:
+  dec a
+  add hl, de ; step down
+  cp a, 0
+  jp nz, :-
+.drawCard
+  ld [hl], b
+  add hl, de
+  ld [hl], c
+  
+  pop de
+  ret 

main.asm

@@ -10,6 +10,8 @@ DEF SCENE_TEARDOWN EQU SCENE_DRAW + 4
 
 DEF INTERRUPT_LCD EQU $c111
 
+def ZEROES equ $D000
+
 DEF rMYBTN EQU $FFA8
 DEF rMYBTNP EQU rMYBTN + 1
 DEF rDELTAT EQU rMYBTNP + 1
@@ -30,8 +32,20 @@ SECTION "Header", ROM0[$100]
 EntryPoint:
   ; Shut down audio circuitry
   ld a, 0
-  ld [rNR52], a ; shut down audio 
+  ldh [rNR52], a ; shut down audio 
   ldh [rDIV], a ; reset timer just in case??
+  
+  ld a, 0 
+  ld hl, ZEROES
+  ld bc, $200
+.buildZeros
+  ld a, 0
+  ld [hl+], a 
+  ld a, b 
+  or a, c
+  dec bc
+  jp nz, .buildZeros
+  
 
   ; set up the scene and interrupt vectors
   ld hl, Instructions
@@ -101,7 +115,6 @@ EntryPoint:
   call ChangeScene
   
 Loop:
-  di
   ; okay this is kinda sketchy. we want a delta time variable. 
   ; we've got two eight-bit counters, one at 4096hz and one at 16384hz
   ; we can definitely reset the faster counter.
@@ -156,7 +169,13 @@ Loop:
 
   call SCENE_DRAW - 1 ; hope this takes fewer than 9 scanlines! 
   ; either way it's going to eat into the update timing
+  ; at this point we want to make sure that scanline 153 has passed
+  ; we should check if we're past there and skip this await if necessary
+  ld b, 5
+  call AwaitLine
+  
   jp Loop
+
 ChangeScene: ; hl should be a pointer to, in sequence, setup update draw teardown
   call SCENE_TEARDOWN - 1
   
@@ -199,8 +218,11 @@ ArrayClampLooping: ; loops a to be in the array, assuming hl points to the lengt
 :
   ret ; a is return value
 
-PrintString: ; write ascii string which has been prefixed by its length.
+PrintString: ; write ascii string which has been prefixed by its length. at hl
   ld b, [hl]
+  ld a, b 
+  cp a, 0
+  ret z
   inc hl
 PrintBChars: ;write ascii characters. will not respect newlines or anything like that
   ; hl should be the source of ascii text
@@ -240,7 +262,9 @@ run_dma_tail:     ; This part must be in HRAM.
 Instructions:
   call SCENE_UPDATE + 2
   ret
-
+INCLUDE "Async.inc"
 INCLUDE "ScreenMainMenu.inc"
+INCLUDE "ScreenSpreadSelect.inc"
 INCLUDE "ScreenCardRead.inc"
-INCLUDE "ScreenSpreadSelect.inc"
+
+INCLUDE "CardLibrary.inc"