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51 lines
1.0 KiB
51 lines
1.0 KiB
5 years ago
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# 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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