Fixed stack-based clip/unclip

equates.s

@@ -39,12 +39,12 @@ lastCompiledTerrainY = $75	; The highest Y value that the compiled renderer must
 ; Terrain constants
 TERRAINWIDTH = 640		; In pixels
 MAXTERRAINHEIGHT = 100	; In pixels
-COMPILEDTERRAINROW = TERRAINWIDTH/4+3	; In words, +3 to make room for clipping jump at end of row
+COMPILEDTERRAINROW = TERRAINWIDTH/4+4	; In words, +4 to make room for clipping jump at end of row
 VISIBLETERRAINWIDTH = TERRAINWIDTH/4	; In words- width minus jump return padding
 VISIBLETERRAINWINDOW = 80				; In words
 MAXSPANSPERROW = 15
 SPANROWBYTES = MAXSPANSPERROW*2 + 2		; In bytes
-
+CLIPPEDTERRAINSTACK = $3fff				; Location of stack where clipped terrain data lives
 
 ; Terrain data, stored as height values 2 pixels wide (bytes)
 terrainDataFar = $02f500

gamemanager.s

@@ -99,12 +99,9 @@ gameplayLoopRender:
 	;
 
 	; Render the terrain if needed
-;	lda terrainDirty
-;	beq gameplayLoopProjectiles
+	lda terrainDirty
+	beq gameplayLoopProjectiles
 	BORDER_COLOR #$3
-	jsr unclipTerrain
-	jsl unrenderTerrainSpans
-	jsr clipTerrain
 	jsl renderTerrainSpans
 	jsr renderTerrain
 

macros.s

@@ -30,7 +30,7 @@
 
 .macro DBR bankNum
 	BITS8
-	lda bankNum
+	lda #bankNum
 	pha
 	plb
 	BITS16
@@ -109,7 +109,7 @@
 .macro FASTGRAPHICS			;34 cycles, 12 bytes
 	sei						;2
 	phd						;4
-	sep #%00100000	;		 3   16-bit A only, to preserve X/Y
+	sep #%00100000	;		 3   8-bit A only, to preserve X/Y
 	.a8
 
 	lda STACKCTL			;5
@@ -125,7 +125,7 @@
 
 
 .macro SLOWGRAPHICS			;28 cycles, 12 bytes
-	sep #%00100000	;        3    16-bit A only, to preserve X/Y
+	sep #%00100000	;        3    8-bit A only, to preserve X/Y
 	.a8
 
 	lda STACKREGISTER		;4
@@ -177,6 +177,16 @@ nobrk:
 	pla
 .endmacro
 
+.macro BREAK_NOSTACK
+	lda breakpoint
+	beq nobrk
+	lda #1
+	sta $e1c029
+	brk
+nobrk:	
+.endmacro
+
+
 .macro HARDBRK
 	pha
 	lda #1

terrain.s

@@ -20,7 +20,7 @@ renderTerrain:
 	tcs					; 2
 
 	sec
-	lda #compiledTerrainEnd-VISIBLETERRAINWINDOW-3
+	lda #compiledTerrainEnd-VISIBLETERRAINWINDOW-4
 	sbc mapScrollPos
 	sta PARAML0
 
@@ -32,6 +32,7 @@ renderTerrainLoop:
 	jmp (PARAML0)
 
 renderRowComplete:
+
 	lda PARAML0
 	sec
 	sbc #COMPILEDTERRAINROW
@@ -127,44 +128,43 @@ craterTerrainDone:
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; clipTerrain
 ;
+; Saves the compiled terrain data that we overwrite into
+; a buffer at $E04000. We do this by shadowing the stack
+; to that area and pushing.
 ;
 clipTerrain:
 	SAVE_AXY
 
+	; Shadow stack into $E04000 to save clipped data fast
+	tsc
+	sta STACKPTR
+	lda #CLIPPEDTERRAINSTACK
+	tcs
+
 	sec
-	lda #COMPILEDTERRAINROW*MAXTERRAINHEIGHT-3
+	lda #COMPILEDTERRAINROW*MAXTERRAINHEIGHT-4
 	sbc mapScrollPos
 	tay
+
 	ldx #0
 
 clipTerrainLoop:
-	clc		; Compute buffer to use for saved data
-	txa
-	asl
-	asl
-	adc #clippedTerrainData;-4
-	sta PARAML0
-
 	lda	compiledTerrain,y
-	sta (PARAML0)	; Preserve data we're overwriting
-	inc PARAML0
-	inc PARAML0
-
-	and #$ff00
-	ora #$004c	; jmp in low byte
-
+	pha
+	lda #$4cea		; NOP followed by JMP
 	sta compiledTerrain,y
-	iny
 
+	iny
+	iny
 	lda	compiledTerrain,y
-	sta (PARAML0)	; Preserve data we're overwriting
+	pha
 
 	lda #renderRowComplete
 	sta compiledTerrain,y
 
 	tya
 	sec
-	sbc #COMPILEDTERRAINROW+1
+	sbc #COMPILEDTERRAINROW+2
 	tay
 
 	inx
@@ -172,6 +172,12 @@ clipTerrainLoop:
 	bcc clipTerrainLoop
 	beq clipTerrainLoop
 
+	; Put stack back where it belongs
+	tsc
+	sta clippedTerrainStackPtr
+	lda STACKPTR
+	tcs
+
 	RESTORE_AXY
 	rts
 
@@ -179,42 +185,52 @@ clipTerrainLoop:
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; unclipTerrain
 ;
+; Restores the compiled terrain data that we wrote
+; to a buffer at $E04000. We do this by mapping the stack
+; to $4000, then using stack-relative addressing to pull the data.
+; We can't pop the data because it's all stored in reverse.
 ;
+; On first move-left unclip every second row is unclipped incorrectly
 unclipTerrain:
 	SAVE_AXY
 
+	phd
+	lda #(CLIPPEDTERRAINSTACK & $ff00)
+	pha
+	pld		; Point direct page at our clip data
+
 	sec
-	lda #COMPILEDTERRAINROW*MAXTERRAINHEIGHT-3
+	lda #COMPILEDTERRAINROW*MAXTERRAINHEIGHT-4
 	sbc mapScrollPos
 	tay
-	ldx #0
+
+	lda clippedTerrainStackPtr
+	and #$00ff
+	tax
+	inx
 
 unclipTerrainLoop:
-	clc		; Compute buffer that saved data is in
-	txa
-	asl
-	asl
-	adc #clippedTerrainData;-4
-	sta PARAML0
-
-	lda	(PARAML0)
+	lda	2,x
 	sta compiledTerrain,y
-	inc PARAML0
-	inc PARAML0
+	iny
 	iny
 
-	lda	(PARAML0)
+	lda 0,x
 	sta compiledTerrain,y
 
 	tya
 	sec
-	sbc #COMPILEDTERRAINROW+1
+	sbc #COMPILEDTERRAINROW+2
 	tay
 
 	inx
-	cpx lastCompiledTerrainY
-	bcc unclipTerrainLoop
-	beq unclipTerrainLoop
+	inx
+	inx
+	inx
+	cpx #$100		; When x hits the top of the stack, we're done
+	bne unclipTerrainLoop
+
+	pld
 
 	RESTORE_AXY
 	rts
@@ -471,13 +487,10 @@ generateTerrainLoop:
 
 compiledTerrain:
 	.repeat COMPILEDTERRAINROW * MAXTERRAINHEIGHT
-	.byte 0
+	.byte $00
 	.endrepeat
 compiledTerrainEnd:
 
-clippedTerrainData:
-	.repeat MAXTERRAINHEIGHT
-	.byte 0,0,0,0	; xx,jmp,addr
-	.endrepeat
-
+clippedTerrainStackPtr:
+	.word 0
 

terrain_e1.s

@@ -10,7 +10,7 @@
 .include "equates.s"
 .include "macros.s"
 
-UNRENDERCACHESTACK = $7ff
+UNRENDERCACHESTACK = $7ff	; Stack downwards from bottom of VRAM. Mirrored from $01 into $E1!
 
 OP16