A basic, opinionated formatter for MIPS assembly.
The program takes in the MIPS code through STDIN and outputs the formatted code through STDOUT.
This is the unformatted code:
.data
number: .word 0
result: .word 0
.text
main:
# first, initialize the stack pointer to the highest word in memory
li $sp 0x7ffffffc
# read an integer from input
li $v0 5 # set syscall number to read_int
syscall
move $t0 $v0 # move the read integer into $t0
# store integer into variable number
sw $t0 number
# catalan's stack frame will contain 2 words: the RETURN ADDRESS and the frame pointer
# catalan takes in an integer parameter, which is another word
sub $sp $sp 4 # subtract 3 words; 1 for argument, one for $ra and one for $fp
sw $t0 12($sp) # put the input in args
jal catalan
add $sp $sp 4 # pop argument off the stack
# print the number
li $v0 1 # print_int number
lw $a0 result # load the number from result
syscall
# print a newline
li $v0 11 # print_char
li $a0 10 # newline character
syscall
# exit program
li $v0 10 # exit
syscall
catalan:
lw $t0 4($fp) # get the number from args
li $t1 1 # set $t1 to 0; counter for n
li $t2 1 # catalan(n) value
beqz $t0 catalan_end # if n is 0, then don't need to do anything
loop:
# $t3 = 2n - 1
mul $t3 $t1 2
sub $t3 $t3 1
mul $t2 $t2 2 # multiply by 2
mul $t2 $t2 $t3 # multiply by 2n - 1
add $t3 $t1 1 # n + 1
div $t2 $t2 $t3 # numerator / denominator
add $t1 $t1 1 # increment counter
ble $t1 $t0 loop # loop back if counter is less than number
catalan_end:
# store return value
sw $t2 result
# epilogue
lw $fp 8($sp) # reset $fp
add $sp $sp 8 # reset $sp
jr $ra # jump back
error:
# print -1
li $v0 1 # set syscall number to print_int
li $a0 -1 # tell it to print -1
syscallThis is the formatted code:
.data
number: .word 0
result: .word 0
.text
main:
# first, initialize the stack pointer to the highest word in memory
li $sp 0x7ffffffc
# read an integer from input
li $v0 5 # set syscall number to read_int
syscall
move $t0 $v0 # move the read integer into $t0
# store integer into variable number
sw $t0 number
# catalan's stack frame will contain 2 words: the RETURN ADDRESS and the
# frame pointer
# catalan takes in an integer parameter, which is another word
sub $sp $sp 4 # subtract 3 words; 1 for argument, one
# for $ra and one for $fp
sw $t0 12($sp) # put the input in args
jal catalan
add $sp $sp 4 # pop argument off the stack
# print the number
li $v0 1 # print_int number
lw $a0 result # load the number from result
syscall
# print a newline
li $v0 11 # print_char
li $a0 10 # newline character
syscall
# exit program
li $v0 10 # exit
syscall
catalan:
lw $t0 4($fp) # get the number from args
li $t1 1 # set $t1 to 0; counter for n
li $t2 1 # catalan(n) value
beqz $t0 catalan_end # if n is 0, then don't need to do
# anything
loop:
# $t3 = 2n - 1
mul $t3 $t1 2
sub $t3 $t3 1
mul $t2 $t2 2 # multiply by 2
mul $t2 $t2 $t3 # multiply by 2n - 1
add $t3 $t1 1 # n + 1
div $t2 $t2 $t3 # numerator / denominator
add $t1 $t1 1 # increment counter
ble $t1 $t0 loop # loop back if counter is less than number
catalan_end:
# store return value
sw $t2 result
# epilogue
lw $fp 8($sp) # reset $fp
add $sp $sp 8 # reset $sp
jr $ra # jump back
error:
# print -1
li $v0 1 # set syscall number to print_int
li $a0 -1 # tell it to print -1
syscallNotice that directives and labels are flush to the left, instructions and comments are intended by 4 characters, instruction arguments are aligned, and comments are both aligned and wrapped to 80 characters.