117 lines
2.4 KiB
NASM
117 lines
2.4 KiB
NASM
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# Pong
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# ==================================
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# Author: Joshua Potter
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# Date: 04/19/2015
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# Data Memory
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# ----------------------------------
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# Note the board has a limited amount of space, so we try and make everything
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# as compact as possible.
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.data 0x2000
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# Instruction Memory
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# ----------------------------------
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# Be sure to set memory configuration Compact, Text at 0
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# Note data memory is offset at 0x2000, screen memory at 0x4000, and keyboard at 0x6000
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.text 0x0000
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add $0, $0, $0 # NOP
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addi $sp, $0, 0x203c # top of the stack is the word at address [0x203c - 0x203f]
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init:
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addi $s0, $0, 1 # x velocity
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addi $s1, $0, 40 # y velocity
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addi $s2, $0, 580 # Ball Location
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addi $s3, $0, 42 # Left Paddle Top Left
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addi $s4, $0, 928 # Right Paddle Top Left
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addi $s5, $0, 0xup # Up Button
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addi $s6, $0, 0xdown # Down Button
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addi $s7, $0, 0xspacebar # Spacebar
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start:
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lw $t0, 0x6000($0) # Check if spacebar pressed
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bne $t0, $s7, main
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addi $a0, $0, 1200
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main: # Main Game Loop
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jal clear
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jal update_ball
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jal update_comp
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jal update_player
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jal draw
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j main
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end:
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j end # No syscalls to exit
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clear: # Reset up to $a0 screen locations to white
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addi $sp, $sp, -4
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sw $a0, 0($sp)
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addi $t0, $0, 4
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clear_loop:
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addi $t1, $a0, 0x4000 # Screen memory begins at 0x4000
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addi $a0, $a0, -1
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sw $t0, 0($t1)
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bne $a0, $0, reset_loop
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clear_end:
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lw $a0, 0($sp)
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addi $sp, $sp, 4
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jr $ra
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draw: # Draws the ball and paddles
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addi $t0, $s3, 0 # Top left corners of each paddle
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addi $t1, $s4, 0
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addi $t2, $0, 6 # Paddles are of height 7 characters
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draw_paddles:
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sw $0, 0($t0) # Black character code is 0
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sw $0, 0($t1)
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addi $t0, $t0, 40
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addi $t1, $t1, 40
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addi $t2, $t2, -1
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bne $t2, $0, draw_paddles
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draw_ball:
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sw $s2, 0($t0)
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jr $ra
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update_ball:
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add $s2, $s2, $s0 # Reposition's ball
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add $s2, $s2, $s1
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jr $ra
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update_comp: # Reposition's computer's paddle
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jr $ra
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update_player: # Repositions player's paddle
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addi $a0, $0, 0 # Set so the paddle/ball doesn't move
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lw $t0, 0x6000($0)
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beq $t0, $s5, updatep_up
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beq $t0, $s6, updatep_down
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updatep_move:
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add $s3, $s3, $a0 # Move player's paddle
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jr $ra
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updatep_up:
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addi $a0, $0, -40
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j updatep_move
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updatep_down:
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addi $a0, $0, 40
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j updatep_move
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pause:
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addi $sp, $sp, -8
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sw $ra, 4($sp)
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sw $a0, 0($sp)
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sll $a0, $a0, 16
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beq $a0, $0, pse_done
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pse_loop:
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addi $a0, $a0, -1
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bne $a0, $0, pse_loop
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pse_done:
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lw $a0, 0($sp)
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lw $ra, 4($sp)
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addi $sp, $sp, 8
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jr $ra
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