Tested a lot of north edges

asm/normal.asm

@@ -89,6 +89,7 @@ LoadRoomHorz:
 	jsr ShiftQuad
 	jsr ShiftCameraBounds
 	ldy #$01 : jsr ShiftVariablesSubDir ; flip direction
+	jsr SetupScrollIndicator
 	lda $01 : sta $fe : and #$04 : lsr #2
 	sta $ee
 	lda $01 : and #$10 : beq .end : stz $0468
@@ -116,6 +117,7 @@ LoadRoomVert:
 	jsr ShiftQuad
 	jsr ShiftCameraBounds
 	ldy #$00 : jsr ShiftVariablesSubDir ; flip direction
+	jsr SetupScrollIndicator
 	lda $01 : sta $fe : and #$04 : lsr #2
 	sta $ee
 	.end
@@ -123,6 +125,12 @@ LoadRoomVert:
 	rts
 }
 
+SetupScrollIndicator:
+    lda $ab : and #$01 : asl : sta $ac
+    lda $ab : and #$40 : clc : rol #3 : ora $ac : sta $ac
+    lda $ab : and #$20 : asl #2 : sta $ab
+    rts
+
 LookupNewRoom: ; expects data offset to be in A
 {
     rep #$30 : and #$00FF ;sanitize A reg (who knows what is in the high byte)
@@ -157,7 +165,7 @@ ShiftLowCoord:
 {
 	lda $01 : and.b #$03 ; high byte index
 	jsr CalcOpposingShift
-	lda $fe : and.b #$f0 : cmp.b #$20 : bne .lowDone
+	lda $ab : and.b #$f0 : cmp.b #$20 : bne .lowDone
 	lda OppCoordIndex,y : tax
 	lda #$80 : !add $20,x : sta $20,x
 	.lowDone
@@ -165,13 +173,13 @@ ShiftLowCoord:
 }
 
 ; expects A to be (0,1,2) (dest number) and (0,1,2) (src door number) to be stored in $04
-; $0127 will be set to a bitmask aaaa qxxf
+; $ab will be set to a bitmask aaaa qxxf
 ; a - amount of adjust
 ; f - flag, if set, then amount is pos, otherwise neg.
 ; q - quadrant, if set, then quadrant needs to be modified
 CalcOpposingShift:
 {
-	stz $fe ; set up (can you zero out 127 alone?)
+	stz $ab : stz $ac ; set up
 	cmp.b $04 : beq .noOffset ; (equal, no shifts to do)
 	phy : tay ; reserve these
 	lda $04 : tax : tya : !sub $04 : sta $04 : cmp.b #$00 : bpl .shiftPos
@@ -179,8 +187,8 @@ CalcOpposingShift:
 	cpx.b #$01 : beq .skipNegQuad
 	ora #$08
 	.skipNegQuad
-	sta $fe : lda $04 : cmp.b #$FE : beq .done ;already set $0127
-	lda $fe : eor #$60
+	sta $ab : lda $04 : cmp.b #$FE : beq .done ;already set $ab
+	lda $ab : eor #$60
 	bra .setDone
 
 	.shiftPos
@@ -188,10 +196,10 @@ CalcOpposingShift:
 	cpy.b #$01 : beq .skipPosQuad
 	ora #$08
 	.skipPosQuad
-	sta $fe : lda $04 : cmp.b #$02 : bcs .done ;already set $0127
-	lda $fe : eor #$60
+	sta $ab : lda $04 : cmp.b #$02 : bcs .done ;already set $ab
+	lda $ab : eor #$60
 
-	.setDone  sta $fe
+	.setDone  sta $ab
 	.done     ply
 	.noOffset rts
 }
@@ -199,9 +207,9 @@ CalcOpposingShift:
 
 ShiftQuad:
 {
-	lda $fe : and #$08 : cmp.b #$00 : beq .quadDone
+	lda $ab : and #$08 : beq .quadDone
 	lda ShiftQuadIndex,y : tax ; X should be set to either 1 (vertical) or 2 (horizontal) (for a9,aa quadrant)
-	lda $fe : and #$01 : cmp.b #$00 : beq .decQuad
+	lda $ab : and #$01 : beq .decQuad
 	inc $02
 	txa : sta $a8, x ; alter a9/aa
 	bra .quadDone
@@ -229,8 +237,8 @@ ShiftCameraBounds:
 {
 	lda CamBoundIndex,y : tax ; should be 0 for horz travel (vert bounds) or 4 for vert travel (horz bounds)
 	rep #$30
-	lda $fe : and #$00f0 : asl #2 : sta $06
-	lda $fe : and #$0001 : cmp #$0000 : beq .subIt
+	lda $ab : and #$00f0 : asl #2 : sta $06
+	lda $ab : and #$0001 : cmp #$0000 : beq .subIt
 	lda $0618, x : !add $06 : sta $0618, x
 	lda $061A, x : !add $06 : sta $061A, x
 	sep #$30
@@ -244,19 +252,26 @@ ShiftCameraBounds:
 
 AdjustTransition:
 {
-	lda $fe : and #$00f0 : lsr
-	sep #$20 : cmp $0126 : bcc .reset
-	rep #$20
+	lda $ab : and #$01ff : beq .reset
 	phy : ldy #$06 ; operating on vertical registers during horizontal trans
 	cpx.b #$02 : bcs .horizontalScrolling
 	ldy #$00  ; operate on horizontal regs during vert trans
 	.horizontalScrolling
-	lda $fe : and #$0001 : asl : tax
-	lda.l OffsetTable,x : adc $00E2,y : and.w #$FFFE : sta $00E2,y : sta $00E0,y
+	cmp #$0008 : bcs +
+	    pha : lda $ab : and #$0200 : beq ++
+	        pla : bra .add
+	    ++ pla : eor #$ffff : inc ; convert to negative
+	    .add jsr AdjustCamAdd : ply : bra .reset
+	+ lda $ab : and #$0200 : xba : tax
+	lda.l OffsetTable,x : jsr AdjustCamAdd
+	lda $ab : !sub #$0008 : sta $ab
 	ply : bra .done
 	.reset ; clear the $ab variable so to not disturb intra-tile doors
-	stz $fe
+	stz $ab
 	.done
-	rep #$20 : lda $00 : and #$01fc
+	lda $00 : and #$01fc
 	rtl
-}
+}
+
+AdjustCamAdd:
+    !add $00E2,y : sta $00E2,y : sta $00E0,y : rts