1 files changed, 276 insertions, 0 deletions
diff --git a/map/loading.gbasm b/map/loading.gbasm
new file mode 100644
index 0000000..8b3f414
--- /dev/null
+++ b/map/loading.gbasm
@@ -0,0 +1,276 @@
+Load_Map:
+	LD A, $mem_viewport_x
+	SUB $02
+	LD C, A
+	ADD $10
+	LD E, A
+	LD A, $mem_viewport_y
+	SUB $02
+	LD B, A
+	ADD $10
+	LD D, A
+	Load_Map.For_Y:
+		Load_Map.For_X:
+			LD A, C
+			CALL =Load_Block
+
+			INC C
+			LD A, C
+			CP E
+			JR NZ, =Load_Map.For_X
+
+		INC B
+		LD A, B
+		CP D
+		JR NZ, =Load_Map.For_Y
+
+	RET
+
+Load_Row: ; (+1/-1 direction in B)
+	PUSH AF
+	PUSH BC
+	PUSH DE
+	LD A, B
+	CP $01
+	JR NZ, =Load_Row.Up
+
+	LD A, $mem_viewport_y
+	ADD $0C
+	LD B, A
+	JR =Load_Row.Set_X_Limits
+
+	Load_Row.Up:
+	LD A, $mem_viewport_y
+	SUB $02
+	LD B, A
+
+	Load_Row.Set_X_Limits:
+	LD A, $mem_viewport_x
+	SUB $03
+	LD D, A
+	LD A, $mem_viewport_x
+	ADD $0D
+	LD E, A
+	Load_Row.For_X:
+		LD A, D
+		CALL =Load_Block
+
+		INC D
+		LD A, D
+		CP E
+		JR NZ, =Load_Row.For_X
+
+	POP DE
+	POP BC
+	POP AF
+	RET
+
+Load_Column: ; (+1/-1 direction in B)
+	PUSH AF
+	PUSH BC
+	PUSH DE
+	LD A, B
+	CP $01
+	JR NZ, =Load_Column.Left
+
+	LD A, $mem_viewport_x
+	ADD $0C
+	LD D, A
+	JR =Load_Column.Set_Y_Limits
+
+	Load_Column.Left:
+	LD A, $mem_viewport_x
+	SUB $02
+	LD D, A
+
+	Load_Column.Set_Y_Limits:
+	LD A, $mem_viewport_y
+	SUB $03
+	LD B, A
+	LD A, $mem_viewport_y
+	ADD $0D
+	LD E, A
+	Load_Column.For_Y:
+		LD A, D
+		CALL =Load_Block
+
+		INC B
+		LD A, B
+		CP E
+		JR NZ, =Load_Column.For_Y
+
+	POP DE
+	POP BC
+	POP AF
+	RET
+
+Load_Block: ; X in A, Y in B
+	PUSH BC
+	PUSH AF
+	PUSH DE
+
+	; Construct Tile Map address from A and B in DE
+	PUSH AF
+	PUSH BC
+
+	AND $0f
+	LD C, A
+	LD A, B
+	AND $0f
+	LD B, A
+	LD A, C
+
+	LD D, $00
+	LD E, $00
+	LD E, B
+	SWAP E
+	SLA E
+	RL D
+	SLA E
+	RL D
+	SLA A
+	OR E
+	LD E, A
+ 	LD A, D
+	OR $98
+	LD D, A
+	POP BC
+	POP AF
+
+	PUSH AF
+	PUSH DE
+
+	LD C, $00
+	LD D, A
+
+	; Checking down block
+	LD A, D
+	INC B
+	CALL =Is_Solid
+	OR C
+	LD C, A
+	DEC B
+	SLA C
+
+	; Checking up block
+	LD A, D
+	DEC B
+	CALL =Is_Solid
+	OR C
+	LD C, A
+	INC B
+	SLA C
+
+	; Checking right block
+	LD A, D
+	INC A
+	CALL =Is_Solid
+	OR C
+	LD C, A
+	SLA C
+
+	; Checking left block
+	LD A, D
+	DEC A
+	CALL =Is_Solid
+	OR C
+	LD C, A
+	SLA C
+
+	SLA C
+
+	LD A, C
+	ADD $20
+	LD C, A
+
+	POP DE
+	POP AF
+
+	CALL =Is_Solid
+
+	CP $00
+	JR Z, =Load_Block.Empty
+	Load_Block.Solid:
+		LD A, C
+		LD (DE), A
+		LD A, E
+		OR $20
+		LD E, A
+		LD A, C
+		OR $02
+		LD (DE), A
+		INC E
+		LD A, C
+		OR $03
+		LD (DE), A
+		LD A, E
+		AND $DF
+		LD E, A
+		LD A, C
+		OR $01
+		LD (DE), A
+
+		JR =Load_Block.End
+
+	Load_Block.Empty:
+		LD A, $00
+		LD (DE), A
+		LD A, E
+		OR $20
+		LD E, A
+		LD A, $00
+		LD (DE), A
+		INC E
+		LD A, $00
+		LD (DE), A
+		LD A, E
+		AND $DF
+		LD E, A
+		LD A, $00
+		LD (DE), A
+
+	Load_Block.End:
+
+	POP DE
+	POP AF
+	POP BC
+	RET
+
+Is_Solid: ; X in A, Y in B, Result A
+	PUSH BC
+
+	CP $20
+	JR NC, =Is_Solid.Solid
+
+	LD C, A
+	LD A, B
+	CP $20
+	JR NC, =Is_Solid.Solid
+	LD A, C
+
+	LD H, $00
+	CP $10
+	RL B
+	AND $0f
+	CP $08
+	RL B
+	AND $07
+	LD L, A
+
+	LD C, B
+	LD B, $c8
+	LD A, (BC)
+
+	AND (HL)
+	CP $01
+	LD A, $00
+	RL A
+
+	POP BC
+ 	RET
+
+	Is_Solid.Solid:
+	LD A, $01
+	POP BC
+
+	RET