I added a smooth jumping animation to my 6502 dinosaur game. I also made a git repository to store the code so you can try it for yourself!. The repository should be available at https://github.com/supergoat559/6502DinosaurGame/tree/main
This is the first git repository I've made so feel free to let me know what best practices are for that.
I made a simple version of the chrome dinosaur game for the 6502. The code is attached below if you want to try it out.
https://reddit.com/link/1u29dbc/video/78rduhtbsh6h1/player
PORTB = $6000
PORTA = $6001
DDRB = $6002
DDRA = $6003
PCR = $600c
IFR = $600d
IER = $600e
digit_stack = $0200 ; 3 bytes
Sprite_Pointer = $0000 ; 2 bytes
Char_Location_Pointer = $0002 ; 1 byte
Delay_Amount_Pointer = $0003 ; 1 byte
Cactus_Location = $0004 ;1 byte
Score = $0005 ; 1 byte
E = %10000000
RW = %01000000
RS = %00100000
Dino_Char1 = %00000000
Dino_Char2 = %00000001
Cactus_Char = %00000010
Blank_Char = %00100000
.org $8000
reset:
ldx #$ff ;initialize stack pointer
txs
cli
lda #$82 ; set interrupt enable for CA1 pin
sta IER
lda #$00 ; set CA1 to be negative edge triggered
sta PCR
lda #%11111111 ; Set all pins on port B to output
sta DDRB
lda #%11100000 ; Set top 3 pins on port A to output
sta DDRA
lda #%00111000 ; Set 8-bit mode; 2-line display; 5x8 font
jsr lcd_instruction
lda #%00001100 ; Display on; cursor on; blink off
jsr lcd_instruction
lda #%00000110 ; Increment and shift cursor; don't shift display
jsr lcd_instruction
lda #%00000001 ; Clear display
jsr lcd_instruction
lda #<Dino_Walk_1
sta Sprite_Pointer
lda #>Dino_Walk_2
sta Sprite_Pointer + 1
lda #Dino_Char1
sta Char_Location_Pointer
jsr make_char ; make a custom dino sprite character at custom char location 0000
lda #<Dino_Walk_2
sta Sprite_Pointer
lda #>Dino_Walk_2
sta Sprite_Pointer + 1
lda #Dino_Char2
sta Char_Location_Pointer
jsr make_char ; make the second dino sprite character at custom char location 0001
lda #<Cactus_1
sta Sprite_Pointer
lda #>Cactus_1
sta Sprite_Pointer + 1
lda #Cactus_Char
sta Char_Location_Pointer
jsr make_char ;make cactus sprite at location 0010
lda #$0
sta Score ;set score to 0 and print it
ldx #$d
ldy #$0
jsr lcd_goto
lda Score
jsr print_int
lda #$f
sta Cactus_Location ;set cactus location to the end of the screen
lda #$ff ;set delay amount to ff
sta Delay_Amount_Pointer
loop:
lda Cactus_Location
cmp #$0
beq death ;check if cactus is colliding with the dino
ldx #$1
ldy #$1
jsr lcd_goto ;move cursor back to postion
lda #Dino_Char1 ;print frame 1
jsr print_char
jsr delay
ldx #$1
ldy #$1 ; mvoe cursor back to position
jsr lcd_goto
lda #Dino_Char2 ;print frame 2
jsr print_char
jsr delay
jsr move_cactus
jmp loop
death:
sei ;disable interrupts
ldx #$3
ldy #$0
jsr lcd_goto
ldx #$0
print_death_message:
lda Death_Message, x
beq death_loop
jsr print_char
inx
jmp print_death_message
death_loop:
jmp death_loop
Dino_Walk_1:
.byte %00000000, %00000000, %00000011, %00000101, %00010111, %00011110, %00001110, %00000100
Dino_Walk_2:
.byte %00000000, %00000000, %00000011, %00000101, %00010111, %00011110, %00001110, %00000010
Cactus_1:
.byte %00000000, %00000100, %00000101, %00010111, %00010100, %00011100, %00000100, %00000100
Death_Message:
.asciiz "You Lost"
move_cactus:
lda Cactus_Location
cmp #$f
beq clear_first_frame
lda Cactus_Location
tax
inx
ldy #$1
jsr lcd_goto
lda #Blank_Char
jsr print_char ;clear last cactus position
print_cactus:
lda Cactus_Location
pha
tax
ldy #$1
jsr lcd_goto
lda #Cactus_Char
jsr print_char ;print cactus
pla
cmp #$0
beq reset_location
decrement:
tax
dex ;decrement cactus location
txa
sta Cactus_Location
rts
reset_location:
ldx Score
inx
txa
sta Score ;increment score
ldx #$d
ldy #$0
jsr lcd_goto
lda Score
jsr print_int ;print score
lda Delay_Amount_Pointer
sbc #$5
sta Delay_Amount_Pointer ;reduce delay to speed up the game
lda #$10
jmp decrement
clear_first_frame:
ldx #$0
ldy #$1
jsr lcd_goto
lda #Blank_Char
jsr print_char
jmp print_cactus
; =================================================================
; Subroutine: print_int
; Takes an 8-bit unsigned integer in A and prints it to the LCD.
; Input: A = Integer to print (0 - 255)
; Clobbers: A, X, Y
; =================================================================
print_int:
; Handle the special case where the input number is exactly 0
cmp #0
bne not_zero
lda #'0' ; ASCII for '0'
jsr print_char
rts
not_zero:
ldx #0 ; X will keep track of how many digits we find
divide_loop:
cmp #0 ; Is our remaining value 0?
beq print_digits ; If yes, we've extracted all digits
; Divide A by 10.
; In 6502 assembly, we do this by repeatedly subtracting 10.
ldy #0 ; Y will hold the Quotient (Value / 10)
sub_10:
cmp #10
bcc done_sub ; If A < 10, division for this step is done
sbc #10 ; Subtract 10 (Note: Carry is already set due to cmp)
iny ; Increment Quotient
jmp sub_10
done_sub:
; After the subtraction loop:
; A contains the Remainder (the individual digit, 0-9)
; Y contains the Quotient (the remaining value for the next pass)
pha ; Save the remainder (digit) on the CPU stack temporarily
tya ; Move the Quotient back into A for the next round
inx ; Increment our digit counter
jmp divide_loop
print_digits:
; Our digits are currently stored backward on the CPU stack.
; Pull them off one by one and send them to the LCD.
pla ; Pull the highest-magnitude digit (e.g., hundreds, tens, then ones)
clc
adc #'0' ; Convert raw number (0-9) to ASCII character code ('0'-'9')
jsr print_char ; Print it to the screen
dex
bne print_digits ; Repeat until all extracted digits are printed
rts
lcd_wait:
pha
lda #%00000000 ;set port b as input
sta DDRB
lcd_busy:
lda #RW
sta PORTA
lda #(RW | E)
sta PORTA
lda PORTB
and #%10000000
bne lcd_busy
lda #RW
sta PORTA
lda #%11111111 ; set portb back to output
sta DDRB
pla
rts
lcd_instruction:
jsr lcd_wait
sta PORTB
lda #0 ; Clear RS/RW/E bits
sta PORTA
lda #E ; Set E bit to send instruction
sta PORTA
lda #0 ; Clear RS/RW/E bits
sta PORTA
rts
print_char:
jsr lcd_wait
sta PORTB
lda #RS ; Set RS; Clear RW/E bits
sta PORTA
lda #(RS | E) ; Set E bit to send instruction
sta PORTA
lda #RS ; Clear E bits
sta PORTA
rts
make_char:
jsr lcd_wait
lda Char_Location_Pointer
asl a
asl a
asl a
ora #%01000000
jsr lcd_instruction
ldy #0 ; Start index at 0
load_sprite_loop:
lda (Sprite_Pointer), y ; Load the byte at (Sprite + X)
jsr print_char ; Send the byte as data to the LCD
iny ; Move to the next byte
cpy #8 ; Have we sent all 8 bytes?
bne load_sprite_loop ; If not, loop back
lda #%10000000 ; Return Home (Resets address counter back to DDRAM)
jsr lcd_instruction
rts
; =================================================================
; Subroutine: lcd_goto
; Moves the cursor to an arbitrary position.
; Input: X register = Column (0 to 15)
; Y register = Row (0 for Line 1, 1 for Line 2)
; Clobbers: A
; =================================================================
lcd_goto:
cpy #0 ; Is it row 0 (Line 1)?
beq .line1 ; If yes, skip adding the row offset
; If row is 1 (Line 2), start with base address $40
txa ; Move column index to A
clc
adc #$40 ; Add $40 (Line 2 offset)
jmp .send_cmd
.line1:
txa ; For line 1, address is just the column index
.send_cmd:
ora #%10000000 ; CRITICAL: Set Bit 7 to turn this into a DDRAM command
jsr lcd_instruction ; Send the position command to the LCD
rts
delay:
pha
txa
pha
tya
pha
ldy Delay_Amount_Pointer
ldx #$ff
delay_loop:
dex
bne delay_loop
dey
bne delay_loop
pla
tay
pla
tax
pla
rts
nmi:
irq:
pha
txa
pha
tya
pha
ldx #$1
ldy #$1
jsr lcd_goto
lda #%00100000 ;blank character
jsr print_char ;print the blank character at the normal dino position, clearing it
ldx #$1
ldy #$0
jsr lcd_goto
lda #%00000000
jsr print_char ;print dino in upper position
exit_irq:
jsr delay
jsr move_cactus
jsr delay
jsr delay
jsr move_cactus
jsr delay
bit PORTA ; clear interrupt
ldx #$1
ldy #$0
jsr lcd_goto
lda #%00100000
jsr print_char ;clear upper position
pla
tay
pla
tax
pla
rti
.org $fffa
.word nmi
.word reset
.word irq
;to compile use the command vasm6502_oldstyle -Fbin -dotdir -o Dino.bin Dinosaur_game.65C02
;to write to eeprom use minipro -p AT28C256 -w Dino.binPORTB = $6000
PORTA = $6001
DDRB = $6002
DDRA = $6003
PCR = $600c
IFR = $600d
IER = $600e
digit_stack = $0200 ; 3 bytes
Sprite_Pointer = $0000 ; 2 bytes
Char_Location_Pointer = $0002 ; 1 byte
Delay_Amount_Pointer = $0003 ; 1 byte
Cactus_Location = $0004 ;1 byte
Score = $0005 ; 1 byte
E = %10000000
RW = %01000000
RS = %00100000
Dino_Char1 = %00000000
Dino_Char2 = %00000001
Cactus_Char = %00000010
Blank_Char = %00100000
.org $8000
reset:
ldx #$ff ;initialize stack pointer
txs
cli
lda #$82 ; set interrupt enable for CA1 pin
sta IER
lda #$00 ; set CA1 to be negative edge triggered
sta PCR
lda #%11111111 ; Set all pins on port B to output
sta DDRB
lda #%11100000 ; Set top 3 pins on port A to output
sta DDRA
lda #%00111000 ; Set 8-bit mode; 2-line display; 5x8 font
jsr lcd_instruction
lda #%00001100 ; Display on; cursor on; blink off
jsr lcd_instruction
lda #%00000110 ; Increment and shift cursor; don't shift display
jsr lcd_instruction
lda #%00000001 ; Clear display
jsr lcd_instruction
lda #<Dino_Walk_1
sta Sprite_Pointer
lda #>Dino_Walk_2
sta Sprite_Pointer + 1
lda #Dino_Char1
sta Char_Location_Pointer
jsr make_char ; make a custom dino sprite character at custom char location 0000
lda #<Dino_Walk_2
sta Sprite_Pointer
lda #>Dino_Walk_2
sta Sprite_Pointer + 1
lda #Dino_Char2
sta Char_Location_Pointer
jsr make_char ; make the second dino sprite character at custom char location 0001
lda #<Cactus_1
sta Sprite_Pointer
lda #>Cactus_1
sta Sprite_Pointer + 1
lda #Cactus_Char
sta Char_Location_Pointer
jsr make_char ;make cactus sprite at location 0010
lda #$0
sta Score ;set score to 0 and print it
ldx #$d
ldy #$0
jsr lcd_goto
lda Score
jsr print_int
lda #$f
sta Cactus_Location ;set cactus location to the end of the screen
lda #$ff ;set delay amount to ff
sta Delay_Amount_Pointer
loop:
lda Cactus_Location
cmp #$0
beq death ;check if cactus is colliding with the dino
ldx #$1
ldy #$1
jsr lcd_goto ;move cursor back to postion
lda #Dino_Char1 ;print frame 1
jsr print_char
jsr delay
ldx #$1
ldy #$1 ; mvoe cursor back to position
jsr lcd_goto
lda #Dino_Char2 ;print frame 2
jsr print_char
jsr delay
jsr move_cactus
jmp loop
death:
sei ;disable interrupts
ldx #$3
ldy #$0
jsr lcd_goto
ldx #$0
print_death_message:
lda Death_Message, x
beq death_loop
jsr print_char
inx
jmp print_death_message
death_loop:
jmp death_loop
Dino_Walk_1:
.byte %00000000, %00000000, %00000011, %00000101, %00010111, %00011110, %00001110, %00000100
Dino_Walk_2:
.byte %00000000, %00000000, %00000011, %00000101, %00010111, %00011110, %00001110, %00000010
Cactus_1:
.byte %00000000, %00000100, %00000101, %00010111, %00010100, %00011100, %00000100, %00000100
Death_Message:
.asciiz "You Lost"
move_cactus:
lda Cactus_Location
cmp #$f
beq clear_first_frame
lda Cactus_Location
tax
inx
ldy #$1
jsr lcd_goto
lda #Blank_Char
jsr print_char ;clear last cactus position
print_cactus:
lda Cactus_Location
pha
tax
ldy #$1
jsr lcd_goto
lda #Cactus_Char
jsr print_char ;print cactus
pla
cmp #$0
beq reset_location
decrement:
tax
dex ;decrement cactus location
txa
sta Cactus_Location
rts
reset_location:
ldx Score
inx
txa
sta Score ;increment score
ldx #$d
ldy #$0
jsr lcd_goto
lda Score
jsr print_int ;print score
lda Delay_Amount_Pointer
sbc #$5
sta Delay_Amount_Pointer ;reduce delay to speed up the game
lda #$10
jmp decrement
clear_first_frame:
ldx #$0
ldy #$1
jsr lcd_goto
lda #Blank_Char
jsr print_char
jmp print_cactus
; =================================================================
; Subroutine: print_int
; Takes an 8-bit unsigned integer in A and prints it to the LCD.
; Input: A = Integer to print (0 - 255)
; Clobbers: A, X, Y
; =================================================================
print_int:
; Handle the special case where the input number is exactly 0
cmp #0
bne not_zero
lda #'0' ; ASCII for '0'
jsr print_char
rts
not_zero:
ldx #0 ; X will keep track of how many digits we find
divide_loop:
cmp #0 ; Is our remaining value 0?
beq print_digits ; If yes, we've extracted all digits
; Divide A by 10.
; In 6502 assembly, we do this by repeatedly subtracting 10.
ldy #0 ; Y will hold the Quotient (Value / 10)
sub_10:
cmp #10
bcc done_sub ; If A < 10, division for this step is done
sbc #10 ; Subtract 10 (Note: Carry is already set due to cmp)
iny ; Increment Quotient
jmp sub_10
done_sub:
; After the subtraction loop:
; A contains the Remainder (the individual digit, 0-9)
; Y contains the Quotient (the remaining value for the next pass)
pha ; Save the remainder (digit) on the CPU stack temporarily
tya ; Move the Quotient back into A for the next round
inx ; Increment our digit counter
jmp divide_loop
print_digits:
; Our digits are currently stored backward on the CPU stack.
; Pull them off one by one and send them to the LCD.
pla ; Pull the highest-magnitude digit (e.g., hundreds, tens, then ones)
clc
adc #'0' ; Convert raw number (0-9) to ASCII character code ('0'-'9')
jsr print_char ; Print it to the screen
dex
bne print_digits ; Repeat until all extracted digits are printed
rts
lcd_wait:
pha
lda #%00000000 ;set port b as input
sta DDRB
lcd_busy:
lda #RW
sta PORTA
lda #(RW | E)
sta PORTA
lda PORTB
and #%10000000
bne lcd_busy
lda #RW
sta PORTA
lda #%11111111 ; set portb back to output
sta DDRB
pla
rts
lcd_instruction:
jsr lcd_wait
sta PORTB
lda #0 ; Clear RS/RW/E bits
sta PORTA
lda #E ; Set E bit to send instruction
sta PORTA
lda #0 ; Clear RS/RW/E bits
sta PORTA
rts
print_char:
jsr lcd_wait
sta PORTB
lda #RS ; Set RS; Clear RW/E bits
sta PORTA
lda #(RS | E) ; Set E bit to send instruction
sta PORTA
lda #RS ; Clear E bits
sta PORTA
rts
make_char:
jsr lcd_wait
lda Char_Location_Pointer
asl a
asl a
asl a
ora #%01000000
jsr lcd_instruction
ldy #0 ; Start index at 0
load_sprite_loop:
lda (Sprite_Pointer), y ; Load the byte at (Sprite + X)
jsr print_char ; Send the byte as data to the LCD
iny ; Move to the next byte
cpy #8 ; Have we sent all 8 bytes?
bne load_sprite_loop ; If not, loop back
lda #%10000000 ; Return Home (Resets address counter back to DDRAM)
jsr lcd_instruction
rts
; =================================================================
; Subroutine: lcd_goto
; Moves the cursor to an arbitrary position.
; Input: X register = Column (0 to 15)
; Y register = Row (0 for Line 1, 1 for Line 2)
; Clobbers: A
; =================================================================
lcd_goto:
cpy #0 ; Is it row 0 (Line 1)?
beq .line1 ; If yes, skip adding the row offset
; If row is 1 (Line 2), start with base address $40
txa ; Move column index to A
clc
adc #$40 ; Add $40 (Line 2 offset)
jmp .send_cmd
.line1:
txa ; For line 1, address is just the column index
.send_cmd:
ora #%10000000 ; CRITICAL: Set Bit 7 to turn this into a DDRAM command
jsr lcd_instruction ; Send the position command to the LCD
rts
delay:
pha
txa
pha
tya
pha
ldy Delay_Amount_Pointer
ldx #$ff
delay_loop:
dex
bne delay_loop
dey
bne delay_loop
pla
tay
pla
tax
pla
rts
nmi:
irq:
pha
txa
pha
tya
pha
ldx #$1
ldy #$1
jsr lcd_goto
lda #%00100000 ;blank character
jsr print_char ;print the blank character at the normal dino position, clearing it
ldx #$1
ldy #$0
jsr lcd_goto
lda #%00000000
jsr print_char ;print dino in upper position
exit_irq:
jsr delay
jsr move_cactus
jsr delay
jsr delay
jsr move_cactus
jsr delay
bit PORTA ; clear interrupt
ldx #$1
ldy #$0
jsr lcd_goto
lda #%00100000
jsr print_char ;clear upper position
pla
tay
pla
tax
pla
rti
.org $fffa
.word nmi
.word reset
.word irq
;to compile use the command vasm6502_oldstyle -Fbin -dotdir -o Dino.bin Dinosaur_game.65C02
;to write to eeprom use minipro -p AT28C256 -w Dino.bin