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|
Load_Map:
LD C, $fd
LD B, $fd
Load_Map.For_Y:
Load_Map.For_X:
LD A, C
CALL =Load_Block
INC C
LD A, C
CP $0d
JR NZ, =Load_Map.For_X
INC B
LD A, B
CP $0d
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 (X and B being AND with 0x0f)
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
PUSH DE
CP $15
JR NC, =Is_Solid.Not_Empty
CP $02
JR C, =Is_Solid.Not_Empty
LD A, B
CP $05
JR NC, =Is_Solid.Not_Empty
CP $02
JR C, =Is_Solid.Not_Empty
Is_Solid.Empty:
LD A, $00
JP =Is_Solid.End
Is_Solid.Not_Empty:
LD A, $01
Is_Solid.End:
POP DE
POP BC
RET
|
