MIPS汇编语言if语句和goto循环计数pos和neg数

您好，我正在尝试用汇编语言完成一个函数，该函数计算一维数组中的负数和非负数。我相信我已经正确地编写了大部分代码，但出于某种原因，一步一步地运行它让我相信我的“count（）”函数甚至没有被实现，因为当我在MARS中运行代码时，存储负数和非负数的寄存器从未增加。如有任何建议或帮助，将不胜感激

伪随机数生成器seed=1234应创建67个负整数和33个非负整数的数组

#========================================================================================
# Equivalents for MARS System Calls
#========================================================================================
.eqv SYS_EXIT          10
.eqv SYS_PRINT_CHAR    11
.eqv SYS_PRINT_INT      1
.eqv SYS_PRINT_STR      4
.eqv SYS_RAND_INT_RNG  42
.eqv SYS_READ_INT       5
.eqv SYS_SET_SEED      40

#========================================================================================
# Data Section
#
# Contains global data for the program.
#========================================================================================
.data 

s_neg:      .asciiz "Number of negative ints: "
s_nonneg:   .asciiz "Number of non-negative ints: "

#========================================================================================
# Text Section
#
# Contains instructions for the program.
#========================================================================================
.text
main:
    addi    $sp, $sp, -524                  # Allocate 131 words in stack frame

# SysSetSeed(1, 1234)
    addi    $v0, $zero, SYS_SET_SEED        # $v0 = SysSetSeed service code
    addi    $a0, $zero, 1                   # $a0 = pseudorandom number generator id
    addi    $a1, $zero, 1234                # $a1 = seed
    syscall                                 # SysSetSeed(1, 1234)

# for i = ...
    sw      $zero, 512($sp)                 # i = 0
    addi    $t9, $zero, 127                 # $t9 = index of last element of a
    addi    $t8, $zero, 500                 # $t8 = constant 500

main_loop_begin:
    lw      $t0, 512($sp)                   # $t0 = i
    bgt     $t0, $t9, main_loop_end         # if i > 127 drop out of loop

# a[i] = SysRandInt(1, 1000) - 500
    addi    $v0, $zero, SYS_RAND_INT_RNG    # $v0 = SysRandInt service code
    addi    $a0, $zero, 1                   # $a0 = pseudorandom number generator id
    addi    $a1, $zero, 1000                # $a1 = upper limit of range [0, 1000]
    syscall                                 # SysRandInt(1, 1000)
    sub     $t1, $a0, $t8                   # $a0 = SysRandInt(1, 1000) - 500
    sll     $t0, $t0, 2                     # $t0 = 4i
    add     $t0, $sp, $t0                   # $t0 = a + 4i = &a[i]
    sw      $t1, 0($t0)                     # a[i] = SysRandInt(1, 1000) - 500

# i = i + 1
    lw      $t0, 512($sp)                   # $t0 = i
    addi    $t0, $t0, 1                     # $t0 = i + 1
    sw      $t0, 512($sp)                   # i = i + 1
    j       main_loop_begin                 # continue looping

main_loop_end:
    move    $a0, $sp                        # $a0 = &a
    jal     count                           # Call count(a)
    sw      $v0, 516($sp)                   # neg = first return value
    sw      $v1, 520($sp)                   # nonneg = second return value

# SysPrintStr ("Number of negative ints: ")
    addi    $v0, $zero, SYS_PRINT_STR       # $v0 = SysPrintStr service code
    la      $a0, s_neg                      # $a0 = address of string to be printed
    syscall                                 # Call SysPrintStr(...)

# SysPrintInt (neg)
    addi    $v0, $zero, SYS_PRINT_INT       # $v0 = SysPrintInt service code
    lw      $a0, 516($sp)                   # $a0 = neg
    syscall                                 # SysPrintInt(neg)

# SysPrintChar('\n')
    addi    $v0, $zero, SYS_PRINT_CHAR      # $v0 = SysPrintChar service code
    addi    $a0, $zero, '\n'                # $a0 = '\n'
    syscall                                 # SysPrintChar('\n')

# SysPrintStr ("Number of non-negative ints: ")
    addi    $v0, $zero, SYS_PRINT_STR       # $v0 = SysPrintStr service code
    la      $a0, s_nonneg                   # $a0 = address of string to be printed
    syscall                                 # Call SysPrintStr(...)

# SysPrintInt (nonneg)
    addi    $v0, $zero, SYS_PRINT_INT       # $v0 = SysPrintInt service code
    lw      $a0, 520($sp)                   # $a0 = nonneg
    syscall                                 # SysPrintInt(nonneg)

# SysPrintChar('\n')
    addi    $v0, $zero, SYS_PRINT_CHAR      # $v0 = SysPrintChar service code
    addi    $a0, $zero, '\n'                # $a0 = '\n'
    syscall                                 # SysPrintChar('\n')

# Call SysExit()
    addi    $sp, $sp, 524                   # Deallocate stack frame
    addi    $v0, $zero, SYS_EXIT            # $v0 = SysExit service code
    syscall                                 # Call SysExit()

#----------------------------------------------------------------------------------------
# count() -
#----------------------------------------------------------------------------------------
count:
    jr      $ra
# int i = 0;
    addi $sp, $sp, -512 # Allocate 128 words in stack frame: i at 0($sp), $a0 at 4($sp)
    sw $a0, 4($sp) # Save $a0 (param string) in stack frame
    sw $zero, 0($sp) # Initialize i in stack frame to 0
    li $t5, 0
# int neg = 0;
    li $t2, 0
# int nonneg = 0;
    li $t3, 0

    li $t7, 128 #loads t7 with the size of the array
    begin_loop:
    beq $a0, $t7, end_loop #if last
    lw $t4, 0($s0)

# if i ← n + 1 goto end_loop
    bgt $t5, $t7, end_loop
# if arrayi >= 0 jumps to else 1 or neg + 1
    bge $a0,$0, else1  #$a0 holds arrayi 
    addi  $t2, $t2, 1
# ++i;
    lw $t5, 0($sp) # $t0 = i
    addi $t5, $t0, 1 # $t0 = i + 1
    sw $t5, 0($sp) # ++i 
    j begin_loop  #$t0 holds neg and adds 1
    else1:
# else nonneg + 1
    addi  $t3, $t3, 1   #$t1 holds nonneg and adds 1
# ++i;
    lw $t5, 0($sp) # $t0 = i
    addi $t5, $t0, 1 # $t0 = i + 1
    sw $t5, 0($sp) # ++i
# goto begin_loop
    j begin_loop # Continue looping
    end_loop:
    addi $sp, $sp, 8 # Deallocate stack frame
# return neg, nonneg
    move $t2, $v0 #
    move $t3, $v1

    jr $ra # Return
# end function

---

count

函数中的第一条指令返回给调用者。该函数的其余部分也包含一些奇怪的部分。

count

的参数应该是一个地址，但是您可以将其与值0和128进行比较。为什么地址等于0或128？而且，

$a0

似乎从未在循环中更改。当CPU有大量寄存器时，为什么要将

i

放在堆栈的最内层循环中？@Michael，堆栈是不平衡的，有一个

$s0

的顺序可能是

$a0

。过早的回归掩盖了这一切。