mips - 如何在 MIPS 中连接两个字符串？

Question

concat:
    lb $t0, 0($a0)                   # $t0 = string1[i]
    beq $t0, $0, string2             # if end of string1, go to string2
    sb $t0, 0($a2)                   # stringconcat[i] = string1[i]
    addi $a0, $a0, 1                 # increment index into string1
    addi $a2, $a2, 1                 # increment index into stringconcat
    j concat                         # loop back

string2:
    lb $t0, 0($a1)                   # $t0 = string2[j]
    beq $t0, $0, done                # if end of string2, return
    sb $t0, 0($a2)                   # stringconcat[j] = string2[j]
    addi $a1, $a1, 1                 # increment index into string2
    addi $a2, $a2, 1                 # increment index into stringconcat

done:
    sb $0, 0($a2)                    # append null to end of string
    jr $ra

我是 MIPS 的新手，我将此代码作为作业，我不知道要添加什么以使其在 QtSpim 上运行，请帮忙。

Answer 1

string2您在第二个循环结束时错过了跳回。

string2:
  lb $t0, 0($a1)
  beq $t0, $0, done
  sb $t0, 0($a2)
  addi $a1, $a1, 1
  addi $a2, $a2, 1
  j string2                        # Missing line!

---

为了完整起见，bellow 是一个基于您的代码的完整工作程序。它将字符串:"Bull"和连接"Dozer"成: "BullDozer":

.data
  first: .asciiz "Bull"
  second: .asciiz "Dozer"
  .align 2
  result: .space 10       #10 bytes for result: strlen("Bull") + strlen("Dozer") + 1
  .align 2

.globl main
.text
  main:
    la $a0, first
    la $a1, second
    la $a2, result

  concat:
    lb $t0, 0($a0)          # $t0 = string1[i]
    beq $t0, $0, string2    # if end of string1, go to string2
    sb $t0, 0($a2)          # stringconcat[i] = string1[i]
    addi $a0, $a0, 1        # increment index into string1
    addi $a2, $a2, 1        # increment index into stringconcat
    j concat                # loop back

  string2:
    lb $t0, 0($a1)          # $t0 = string2[j]
    beq $t0, $0, done       # if end of string2, return
    sb $t0, 0($a2)          # stringconcat[j] = string2[j]
    addi $a1, $a1, 1        # increment index into string2
    addi $a2, $a2, 1        # increment index into stringconcat
    j string2               # **Missing line!**

  done:
    sb $0, 0($a2)           # append null to end of string
    jr $ra