373 lines
6.1 KiB
ArmAsm
373 lines
6.1 KiB
ArmAsm
#define WIDTH 60
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#define HEIGHT 40
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.bss
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# Array of longs representing the game field
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.align 4
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world: .space WIDTH*HEIGHT*4
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.data
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# Current length of the snake
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snakeLength: .long 0
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# Snake position
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snakePosX: .long WIDTH / 2
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snakePosY: .long HEIGHT / 2
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# Snake direction
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snakeDirX: .long 1
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snakeDirY: .long 0
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# Number of apples
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numApples: .long 0
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# Optional score-keeping
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score: .long 0
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# Utility strings
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snibbles: .ascii "NIBBLES"
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snibbles_end:
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sgameover: .string " Game over! Score: %i "
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sgameover_end:
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string1: .string "Started with snake length %i and %i apples!\n"
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string2: .string "Snake position: (%i, %i)\n"
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stringi: .string "%i\n"
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stringtest: .string "> %i %i %c\n"
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.text
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.global start_game
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start_game:
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# snakeLength = len
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movl 4(%esp), %eax
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movl %eax, snakeLength
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# numApples = n_apples
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movl 8(%esp), %eax
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movl %eax, numApples
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pushl %ebx
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pushl %edi
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# Call nib_init
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call nib_init
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# Seed randomness
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pushl $0
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call time
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addl $4, %esp
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pushl %eax
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call srand
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addl $4, %esp
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# Print our arguments
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#pushl numApples
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#pushl snakeLength
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#pushl $string1
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#call printf
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#addl $4*3, %esp
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# Print worm position
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#pushl snakePosY
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#pushl snakePosX
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#pushl $string2
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#call printf
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#addl $4*3, %esp
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# Initialize the snake array
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# Set every cell to a time value greater than the snake length
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movl $world, %edi
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movl snakeLength, %eax
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movl $WIDTH*HEIGHT, %ebx
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xorl %ecx, %ecx
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1:
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movl %eax, (%edi, %ecx, 4)
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incl %ecx
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cmpl %ebx, %ecx
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jl 1b
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# Spawn initial apples
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movl numApples, %ecx
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1:
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pushl %ecx
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call spawnApple
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popl %ecx
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loop 1b
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# Loop forever
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loop:
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# Sleep for a while
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pushl $250*1000
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pushl %ecx
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call usleep
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addl $4, %esp
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jmp tick
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popl %edi
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popl %ebx
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ret
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# Update stuff
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tick:
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movl $world, %edi
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# Increment cell times
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movl snakeLength, %ebx
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xorl %ecx, %ecx
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1:
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movl (%edi, %ecx, 4), %eax
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# If the value is negative it's an apple we don't want to disappear
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test %eax, %eax
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js 2f
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# No need to increment if it's already greater than snakeLength
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cmpl %ebx, %eax
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jg 2f
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# Increment the cell value
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incl %eax
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movl %eax, (%edi, %ecx, 4)
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2: incl %ecx # Loop increment
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cmpl $WIDTH*HEIGHT, %ecx
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jne 1b
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# Input
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call nib_poll_kbd
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# Down
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movl $258, %ebx
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cmpl %eax, %ebx
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jne 1f
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movl $0, snakeDirX
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movl $1, snakeDirY
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1: # Up
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movl $259, %ebx
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cmpl %eax, %ebx
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jne 1f
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movl $0, snakeDirX
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movl $-1, snakeDirY
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1: # Left
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movl $260, %ebx
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cmpl %eax, %ebx
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jne 1f
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movl $-1, snakeDirX
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movl $0, snakeDirY
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1: # Right
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movl $261, %ebx
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cmpl %eax, %ebx
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jne 1f
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movl $1, snakeDirX
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movl $0, snakeDirY
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1:
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# Move snake
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# snakePosX = (snakePosX + snakeDirY + WIDTH) % WIDTH
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movl snakePosX, %eax
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movl snakeDirX, %ebx
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addl %ebx, %eax
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addl $WIDTH, %eax # For modulo wrap-around
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xorl %edx, %edx
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movl $WIDTH, %ecx
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divl %ecx
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mov %edx, snakePosX
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# snakePosY = (snakePosY + snakeDirY + HEIGHT) % HEIGHT
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movl snakePosY, %eax
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movl snakeDirY, %ebx
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addl %ebx, %eax
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addl $HEIGHT, %eax # For modulo wrap-around
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xorl %edx, %edx
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movl $HEIGHT, %ecx
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divl %ecx
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mov %edx, snakePosY
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# Get value at head position
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movl snakePosY, %eax
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movl $WIDTH, %edx
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mull %edx
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addl snakePosX, %eax
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movl (%edi, %eax, 4), %edx
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# Collision with apple if negative
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test %edx, %edx
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js 1f
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# No need to increment if it's already greater than snakeLength
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movl snakeLength, %ebx
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cmpl %ebx, %edx
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jg 2f
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# End the game when the snake collides with itself
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jmp gameOver
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1: # Spawn a new apple
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pushl %edi
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pushl %eax
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call spawnApple
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popl %eax
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popl %edi
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# Extend the snake!
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incl snakeLength
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2:
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# Set time value to 0 at snake head position
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# i = x + y * WIDTH
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# %edi = %ebx + %ecx * $WIDTH
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movl $0, (%edi, %eax, 4)
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jmp draw
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#jmp debug_draw
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# Draw stuff
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draw:
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# Loop Y
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movl $HEIGHT, %ecx
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1:
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# Loop X
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movl $WIDTH, %ebx
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2:
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# Save loop registers
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pushl %ecx
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pushl %ebx
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subl $1, %ecx
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subl $1, %ebx
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# Call nib_put_scr
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# i = x + y * WIDTH
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# %eax = %ebx + %ecx * $WIDTH
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movl %ecx, %eax
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movl $WIDTH, %edx
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mull %edx
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addl %ebx, %eax
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# Fetch the value of the cell
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movl $world, %edi
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movl (%edi, %eax, 4), %eax
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# Compare with the snake length
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cmpl snakeLength, %eax
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# If the value is negative, it's an apple
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test %eax, %eax
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js 4f
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# If it's greater or equal to snakeLength, it's empty
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cmpl snakeLength, %eax
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jge 3f
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# Else, it's part of the snake
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pushl $'@'
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jmp 5f
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3: pushl $' '
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jmp 5f
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4: pushl $'o'
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5:
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movl %ecx, %eax # Y
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pushl %eax
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movl %ebx, %eax # X
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pushl %eax
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call nib_put_scr
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addl $4*3, %esp
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# Restore loop registers
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popl %ebx
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popl %ecx
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decl %ebx # Decrement X
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jnz 2b # End of X loop
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loop 1b # End of Y loop
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jmp loop
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# Debug drawing
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debug_draw:
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# Loop Y
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movl $HEIGHT, %ecx
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1:
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# Loop X
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movl $WIDTH, %ebx
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2:
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# Save loop registers
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pushl %ecx
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pushl %ebx
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subl $1, %ecx
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subl $1, %ebx
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# Call nib_put_scr
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# i = x + y * WIDTH
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# %edi = %ebx + %ecx * $WIDTH
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movl %ecx, %eax
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movl $WIDTH, %edx
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mull %edx
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addl %ebx, %eax
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# Fetch the value of the cell
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movl $world, %edi
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movl (%edi, %eax, 4), %eax
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pushl %eax
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movl %ecx, %eax # Y
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pushl %eax
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movl %ebx, %eax # X
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pushl %eax
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call nib_put_scr
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addl $4*3, %esp
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# Restore loop registers
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popl %ebx
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popl %ecx
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decl %ebx # Decrement X
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jnz 2b # End of X loop
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loop 1b # End of Y loop
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jmp loop
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gameOver:
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# Calculate string length
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movl $sgameover_end, %eax
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subl $sgameover, %eax
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subl $1, %eax # Discount null terminator
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# Calculate X-pos
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movl $2, %ebx
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xorl %edx, %edx
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divl %ebx
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negl %eax
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addl $WIDTH/2, %eax
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# Print game over message
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pushl snakeLength
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pushl $sgameover
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pushl %eax # X
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pushl $HEIGHT/2 # Y
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call mvprintw
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add $4*3, %esp
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call refresh
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pushl $3000*1000
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call usleep
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addl $4, %esp
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call nib_end
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spawnApple:
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pushl %ebx
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# %ecx = rand() % HEIGHT
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call rand
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xorl %edx, %edx
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movl $HEIGHT, %ebx
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divl %ebx
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movl %edx, %ecx
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# %ebx = rand() % WIDTH
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pushl %ecx
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call rand
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xorl %edx, %edx
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movl $WIDTH, %ebx
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divl %ebx
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movl %edx, %ebx
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popl %ecx
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# i = x + y * WIDTH
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# %eax = %ebx + %ecx * $WIDTH
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movl %ecx, %eax
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movl $WIDTH, %edx
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mull %edx
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addl %ebx, %eax
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# Set the cell negative to represent an apple
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movl $world, %ecx
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movl $-1, %edx
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movl %edx, (%ecx, %eax, 4)
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popl %ebx
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ret
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