248 lines
3.2 KiB
ArmAsm
248 lines
3.2 KiB
ArmAsm
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;==============================
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; Handle Keypress
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;==============================
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handle_keypress:
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lda KEYPRESS
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bmi keypress
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jmp no_keypress
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keypress:
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and #$7f ; clear high bit
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check_left:
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cmp #'A'
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beq left_pressed
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cmp #8 ; left key
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bne check_right
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left_pressed:
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dec CURSOR_X
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jmp done_keypress
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check_right:
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cmp #'D'
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beq right_pressed
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cmp #$15 ; right key
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bne check_up
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right_pressed:
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inc CURSOR_X
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jmp done_keypress
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check_up:
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cmp #'W'
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beq up_pressed
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cmp #$0B ; up key
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bne check_down
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up_pressed:
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dec CURSOR_Y
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dec CURSOR_Y
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jmp done_keypress
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check_down:
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cmp #'S'
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beq down_pressed
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cmp #$0A
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bne check_return
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down_pressed:
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inc CURSOR_Y
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inc CURSOR_Y
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jmp done_keypress
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check_return:
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cmp #' '
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beq return_pressed
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cmp #13
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bne done_keypress
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return_pressed:
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lda IN_SPECIAL
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beq not_special_return
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special_return:
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jsr handle_special
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; special case, don't make cursor visible
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jmp no_keypress
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not_special_return:
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lda IN_RIGHT
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beq not_right_return
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right_return:
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jsr turn_right
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jmp no_keypress
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not_right_return:
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lda IN_LEFT
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beq not_left_return
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left_return:
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jsr turn_left
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jmp no_keypress
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not_left_return:
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jsr go_forward
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jmp no_keypress
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done_keypress:
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lda #1 ; make cursor visible
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sta CURSOR_VISIBLE
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no_keypress:
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bit KEYRESET
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rts
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;============================
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; handle_special
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;===========================
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; set up jump table fakery
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handle_special:
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ldy #LOCATION_SPECIAL_FUNC+1
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lda (LOCATION_STRUCT_L),Y
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pha
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dey
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lda (LOCATION_STRUCT_L),Y
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pha
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rts
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;=============================
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; change direction
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;=============================
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change_direction:
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; load background
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lda DIRECTION
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asl
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clc
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adc #LOCATION_NORTH_BG
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tay
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lda (LOCATION_STRUCT_L),Y
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sta LZSA_SRC_LO
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iny
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lda (LOCATION_STRUCT_L),Y
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sta LZSA_SRC_HI
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lda #$c ; load to page $c00
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jsr decompress_lzsa2_fast
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rts
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;=============================
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; change location
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;=============================
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change_location:
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; reset pointer to not visible, centered
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lda #0
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sta CURSOR_VISIBLE
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lda #20
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sta CURSOR_X
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sta CURSOR_Y
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lda LOCATION
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asl
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tay
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lda locations,Y
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sta LOCATION_STRUCT_L
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lda locations+1,Y
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sta LOCATION_STRUCT_H
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jsr change_direction
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rts
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;==========================
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; go forward
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;===========================
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go_forward:
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; update new location
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lda DIRECTION
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clc
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adc #LOCATION_NORTH_EXIT
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tay
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lda (LOCATION_STRUCT_L),Y
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cmp #$ff
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beq cant_go_forward
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sta LOCATION
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; update new direction
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lda DIRECTION
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clc
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adc #LOCATION_NORTH_EXIT_DIR
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tay
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lda (LOCATION_STRUCT_L),Y
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sta DIRECTION
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jsr change_location
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cant_go_forward:
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rts
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;==========================
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; turn left
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;===========================
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turn_left:
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lda DIRECTION
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cmp #DIRECTION_N
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beq go_west
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cmp #DIRECTION_W
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beq go_south
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cmp #DIRECTION_S
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beq go_east
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bne go_north
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;==========================
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; turn right
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;===========================
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turn_right:
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lda DIRECTION
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cmp #DIRECTION_N
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beq go_east
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cmp #DIRECTION_E
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beq go_south
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cmp #DIRECTION_S
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beq go_west
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bne go_north
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go_north:
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lda #DIRECTION_N
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jmp done_turning
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go_east:
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lda #DIRECTION_E
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jmp done_turning
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go_south:
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lda #DIRECTION_S
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jmp done_turning
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go_west:
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lda #DIRECTION_W
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jmp done_turning
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done_turning:
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sta DIRECTION
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jsr change_direction
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rts
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