For this exercise, write the MIPS32 assembly language code that implements getin

Question

For this exercise, write the MIPS32 assembly language code that implements getint(). This implementation requires 11 instructions: four addi, one jr, two lw, two syscall, and two sw. Note, you are not being asked to write a complete program; just implement getint().

# FUNCTION: int getint (string prompt) # DESCRIPTION # Displays the prompt string (the variable 'prompt' contains the address of the string which is defined in the # . data section) using SysPrintStr(). Then calls SysReadInt() to read the integer the user enters. Returns the # integer in Svo. # PARAMETERS # $a0 prompt (addr of string to be displayed) # PSEUDOCODE # See above # RETURNS # An int in $v0 which is the integer the user typed # STACK FRAME # param prompt 4($sp) # local var n 0($sp)

Explanation / Answer

OR

the program in c is:

#include "stdafx.h"

int getInt(char[]);

int getInt(char prompt[])
{
int num;
printf("%c",&prompt);
scanf("%d",&num);
return num;
}

and its associated MIPS assmbly code will be:

_TEXT   SEGMENT
_num$ = -8                       ; size = 4
_prompt$ = 8                       ; size = 4
?getInt@@YAHQAD@Z PROC                   ; getInt, COMDAT
; Line 9
   push   ebp
   mov   ebp, esp
   sub   esp, 204               ; 000000ccH
   push   ebx
   push   esi
   push   edi
   lea   edi, DWORD PTR [ebp-204]
   mov   ecx, 51                   ; 00000033H
   mov   eax, -858993460               ; ccccccccH
   rep stosd
; Line 11
   mov   esi, esp
   lea   eax, DWORD PTR _prompt$[ebp]
   push   eax
   push   OFFSET ??_C@_02HAOIJKIC@?$CFc?$AA@
   call   DWORD PTR __imp__printf
   add   esp, 8
   cmp   esi, esp
   call   __RTC_CheckEsp
; Line 12
   mov   esi, esp
   lea   eax, DWORD PTR _num$[ebp]
   push   eax
   push   OFFSET ??_C@_02DPKJAMEF@?$CFd?$AA@
   call   DWORD PTR __imp__scanf
   add   esp, 8
   cmp   esi, esp
   call   __RTC_CheckEsp
; Line 13
   mov   eax, DWORD PTR _num$[ebp]
; Line 14
   push   edx
   mov   ecx, ebp
   push   eax
   lea   edx, DWORD PTR $LN5@getInt
   call   @_RTC_CheckStackVars@8
   pop   eax
   pop   edx
   pop   edi
   pop   esi
   pop   ebx
   add   esp, 204               ; 000000ccH
   cmp   ebp, esp
   call   __RTC_CheckEsp
   mov   esp, ebp
   pop   ebp
   ret   0
$LN5@getInt:
   DD   1
   DD   $LN4@getInt
$LN4@getInt:
   DD   -8                   ; fffffff8H
   DD   4
   DD   $LN3@getInt
$LN3@getInt:
   DB   110                   ; 0000006eH
   DB   117                   ; 00000075H
   DB   109                   ; 0000006dH
   DB   0
?getInt@@YAHQAD@Z ENDP                   ; getInt
_TEXT   ENDS
END

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