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InitMovementBuffer::
ld [wMovementBufferObject], a
xor a
ld [wMovementBufferCount], a
ld a, $0 ; was BANK(wMovementBuffer) in G/S
ld [wUnusedMovementBufferBank], a
ld a, LOW(wMovementBuffer)
ld [wUnusedMovementBufferPointer], a
ld a, HIGH(wMovementBuffer)
ld [wUnusedMovementBufferPointer + 1], a
ret
DecrementMovementBufferCount::
ld a, [wMovementBufferCount]
and a
ret z
dec a
ld [wMovementBufferCount], a
ret
AppendToMovementBuffer::
push hl
push de
ld hl, wMovementBufferCount
ld e, [hl]
inc [hl]
ld d, 0
ld hl, wMovementBuffer
add hl, de
ld [hl], a
pop de
pop hl
ret
AppendToMovementBufferNTimes::
push af
ld a, c
and a
jr nz, .okay
pop af
ret
.okay
pop af
.loop
call AppendToMovementBuffer
dec c
jr nz, .loop
ret
ComputePathToWalkToPlayer::
push af
; compare x coords, load left/right into h, and x distance into d
ld a, b
sub d
ld h, LEFT
jr nc, .got_x_distance
dec a
cpl
ld h, RIGHT
.got_x_distance
ld d, a
; compare y coords, load up/down into l, and y distance into e
ld a, c
sub e
ld l, UP
jr nc, .got_y_distance
dec a
cpl
ld l, DOWN
.got_y_distance
ld e, a
; if the x distance is less than the y distance, swap h and l, and swap d and e
cp d
jr nc, .done
ld a, h
ld h, l
ld l, a
ld a, d
ld d, e
ld e, a
.done
pop af
ld b, a
; Add movement in the longer direction first...
ld a, h
call .GetMovementData
ld c, d
call AppendToMovementBufferNTimes
; ... then add the shorter direction.
ld a, l
call .GetMovementData
ld c, e
call AppendToMovementBufferNTimes
ret
.GetMovementData:
push de
push hl
ld l, b
ld h, 0
add hl, hl
add hl, hl
ld e, a
ld d, 0
add hl, de
ld de, .MovementData
add hl, de
ld a, [hl]
pop hl
pop de
ret
.MovementData:
slow_step DOWN
slow_step UP
slow_step LEFT
slow_step RIGHT
step DOWN
step UP
step LEFT
step RIGHT
big_step DOWN
big_step UP
big_step LEFT
big_step RIGHT
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