Question

我已经坚持这个家庭作业问题已经有一段时间了，并希望得到一些帮助。

到目前为止，我已经提出了这个问题：

     f:
       lw $t0, a
       lw $t1, b
       lw $t2, c
       lw $t3, d
       addi $sp, $sp, -4

让我感到困惑的部分是return语句。我不知道该怎么做。这是家庭作业的问题。

！（http://imgur.com/a/1lqzT）

Answer 1

这显然是一个家庭作业问题。

    .data

    .text
f:
# load arguments IN into temporary registers
    lw $t0, 0($sp)
    lw $t1, 4($sp)
    lw $t2, 8($sp)
    lw $t3, 12($sp)

# $t4 <-- calling func(a, b)

# backup $ra register on the stack
   addi $sp, $sp, -4
   sw $ra, 0($sp)

# allocate words for all required backup registers
    addi $sp, $sp, -16

# store the values as backup on the stack
    sw $t0, 0($sp)
    sw $t1, 4($sp)
    sw $t2, 8($sp)
    sw $t3, 12($sp)

# allocate space for all the arguments (arguments in & argument out)
    addi $sp, $sp, -12

# store arguments IN on the stack:
    sw $t0, 0($sp)
    sw $t1, 4($sp)

# call the subprogram func
    jal func

# read arguments OUT from stack
    lw $t4, 8($sp)

# deallocate space for arguments IN and OUT
    addi $sp, $sp, 12

# restore the backup values:
    lw $t0, 0($sp)
    lw $t1, 4($sp)
    lw $t2, 8($sp)
    lw $t3, 12($sp)

# deallocate space for backed up registers
    addi $sp, $sp, 16

# restore $ra value
    lw $ra, 0($sp)

# deallocate space for $ra
    addi $sp, $sp, 4


# $t4 <-- calling func(func(a, b), c + d)

# backup $ra register on the stack
   addi $sp, $sp, -4
   sw $ra, 0($sp)

# allocate words for all required backup registers
    addi $sp, $sp, -20

# store the values as backup on the stack
    sw $t0, 0($sp)
    sw $t1, 4($sp)
    sw $t2, 8($sp)
    sw $t3, 12($sp)
    sw $t4, 16($sp)

# allocate space for all the arguments (arguments in & argument out)
    addi $sp, $sp, -12

# store arguments IN on the stack:
    sw $t4, 0($sp)

    add $t5, $t2, $t3
    sw $t5, 4($sp)

# call the subprogram func
    jal func

# read arguments OUT from stack
    lw $t6, 8($sp)

# deallocate space for arguments IN and OUT
    addi $sp, $sp, 12

# restore the backup values:
    lw $t0, 0($sp)
    lw $t1, 4($sp)
    lw $t2, 8($sp)
    lw $t3, 12($sp)
    lw $t4, 16($sp)

# deallocate space for backed up registers
    addi $sp, $sp, 20

# restore $ra value
    lw $ra, 0($sp)

# deallocate space for $ra
    addi $sp, $sp, 4

# return $t6
    sw $t6, 16($sp)    

f_end:
    jr $ra

C函数对MIPS

1 个答案: