这是一个heapsort的mips代码。当我尝试运行它时,我收到以下错误消息 第149行的语法错误(数组:.word 54,23,56,32,99,7,4,2,88,9,11,21,39,55,100,101,43,1,3,69,-5, - 24,-17,0) 第14行的另一个指令引用未定义符号。 我已经多次看过它,但我仍然没有看到任何错误。如果您发现任何问题,请告诉我。 这是代码:
.text
.globl main
main:
la $a0, array # a0 = &array
la $t0, size
lw $a1, 0($t0) # a1 = size(array)
jal heapsort
# print the array
move $t0, $a0
add $t1, $zero, $zero
printloop:
li $v0, 1
lw $a0, 0($t0)
addi $t0, $t0, 4
addi $t1, $t1, 1
syscall
li $v0, 4
la $a0, space
syscall
bne $t1, $a1, printloop # while( t1 != size )
li $v0, 4
la $a0, newline
syscall
done:
jr $ra
heapsort: # a0 = &array, a1 = size(array)
addi $sp, $sp, -8
sw $a1, 0($sp) # save size
sw $a2, 4($sp) # save a2
sw $ra, 8($sp) # save return address
move $a2, $a1 # n will be stored in a2
addi $a2, $a2, -1 # n = size - 1
ble $a2,$zero, end_heapsort # if (n <= 0 ) return;
jal make_heap # a0 = arr, a1 = size
add $a1, $zero, $zero # clear $a1
heapsort_loop:
# swap(array[0],array[n])
lw $t0, 0($a0)
sll $t1, $a2, 2 #t1 = bytes(n)
add $t1, $t1, $a0
lw $t2, 0($t1)
sw $t0, 0($t1)
sw $t2, 0($a0)
addi $a2, $a2, -1 # n--
jal bubble_down # a0 = &array, a1 = 0, a2 = n
bnez $a2, heapsort_loop
end_heapsort:
lw $ra, 8($sp)
lw $a2, 4($sp)
lw $a1, 0($sp)
addi $sp, $sp, 8
jr $ra
make_heap: # a0 = &array, a1 = size
addi $sp, $sp, -12
sw $a1, 0($sp)
sw $a2, 4($sp)
sw $ra, 8($sp)
addi $a2, $a1, -1 # a2 = size - 1
addi $a1, $a1, -1 # start_index = size - 1
srl $a1, $a1, 1 # start_index /= 2
blt $a1, $zero, end_make_heap # if(start_index < 0) return
make_heap_loop:
jal bubble_down # a0 = &array, a1 = start_index, a2 = size-1
addi $a1, $a1, -1
ble $zero, $a1, make_heap_loop
end_make_heap:
lw $ra, 8($sp)
lw $a2, 4($sp)
lw $a1, 0($sp)
addi $sp, $sp, 12
jr $ra
#bubble_down is a leaf in the call graph
bubble_down: # a0 = &array, a1 = s_idx, a2 = end
move $t0, $a1 # index = s_idx
sll $t1, $t0, 2 # child = index*2+1
addi $t1, $t1, 1
bgt $t1, $a2, end_bubble_down
bubble_down_loop:
#if ( child < end && arr[child] < arr[child+1] )
ble $a2, $t1, skipinc
sll $t3, $t1, 2 # get bytes(child)
add $t3, $t3, $a0
lw $t3, 0($t3) # t3 = arr[child]
sll $t4, $t1, 2 #get bytes(child)
addi $t4, $t4, 4 #t4 = bytes(child+1)
add $t4, $t4, $a0
lw $t4, 0($t4) #t4 = arr[child+1]
ble $t4, $t3, skipinc
addi $t1, $t1, 1 # child++
skipinc:
sll $t3, $t0, 2 # get bytes(index)
add $t3, $t3, $a0
lw $t4, 0($t3) #t4 = arr[index], t3 = &arr[index]
sll $t5, $t1, 2 # get bytes(child)
add $t5, $t5, $a0
lw $t6, 0($t5) #t6 = arr[child], t5 = &arr[child]
ble $t6, $t4, end_bubble_down
# swap(arr[index],arr[child]
# note: t4 = arr[index], t6 = arr[child], t3 = &arr[index], t5 = &arr[child]
sw $t4, 0($t5)
sw $t6, 0($t3)
move $t0, $t1 # index = child
sll $t1, $t0, 1 # child = index*2+1
addi $t1, $t1, 1
ble $t1, $a2, bubble_down_loop
end_bubble_down:
jr $ra
.data
# the array that holds unordered data
array: .word 54,23,56,32,99,7,4,2,88,9,11,21,39,55,100,101,43,1,3,69,-5,-24,-17,0
size: .word 24
space: .asciiz " "
newline: .asciiz "\n"
答案 0 :(得分:2)
可以通过在数组.word中的每个“,”之后放置一个空格来修复语法错误: 所以“54,23,56,32,99,7,4,2,......”
答案 1 :(得分:1)
我无法重现您使用QtSpim 9.1.12 for Windows描述的错误。因此,您要么使用不同版本的QtSpim,其行为不同,和/或没有运行您向我们展示的确切代码,和/或在重新加载汇编代码之前没有重新初始化模拟器。
你做但是代码中有错误。好吧,也许不止一个,但至少有一个是显而易见的:
在done:
,您尝试使用jr $ra
结束您的计划。但是,您已在$ra
更改了jal heapsort
的值而未保留它。那么在最后jr $ra
发生的事情是你将跳回到打印代码,然后再执行。您在那里做的第一件事是$t0 = $a0
,其中$a0
应包含array
的地址。但是$a0
不再包含数组的地址,因为在jr $ra
la $a0, newline
之前{。}}。
TL; DR:每当您执行jal
时,您都需要修改$ra
。如果稍后需要先前的$ra
值,则需要保留它(在另一个寄存器,内存变量或堆栈中)。