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50 lines
1.0 KiB
50 lines
1.0 KiB
# Simple routine to demo a loop |
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# Compute the sum of N integers: 1 + 2 + 3 + ... + N |
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# From: http://labs.cs.upt.ro/labs/so2/html/resources/nachos-doc/mipsf.html |
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.text |
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.globl main |
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main: |
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# Print msg1 |
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li $v0,4 # print_string syscall code = 4 |
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la $a0, msg1 |
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syscall |
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# Get N from user and save |
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li $v0,5 # read_int syscall code = 5 |
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syscall |
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move $t0,$v0 # syscall results returned in $v0 |
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# Initialize registers |
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li $t1, 0 # initialize counter (i) |
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li $t2, 0 # initialize sum |
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# Main loop body |
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loop: addi $t1, $t1, 1 # i = i + 1 |
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add $t2, $t2, $t1 # sum = sum + i |
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beq $t0, $t1, exit # if i = N, continue |
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j loop |
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# Exit routine - print msg2 |
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exit: li $v0, 4 # print_string syscall code = 4 |
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la $a0, msg2 |
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syscall |
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# Print sum |
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li $v0,1 # print_string syscall code = 4 |
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move $a0, $t2 |
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syscall |
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# Print newline |
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li $v0,4 # print_string syscall code = 4 |
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la $a0, lf |
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syscall |
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li $v0,10 # exit |
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syscall |
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# Start .data segment (data!) |
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.data |
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msg1: .asciiz "Number of integers (N)? " |
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msg2: .asciiz "Sum = " |
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lf: .asciiz "\n"
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