char cppToUpper(char c)
{
    if (c > 122 || c < 97 )
	   return c;
    else return c - 32;
}

 
char cToUpper(int c)
{
    //
    //cout << cLowerLimit;
    _asm
    {
 
    //Copy the character onto the arithmetic register for single bytes
	   mov eax, c;
 
    //Test the Upper Limit
	   cmp eax, 122; // Compare the Character to 122
	   ja End;  //  Jump to the end if above -- the character is too high to be a lower case letter
 
    //Test the lower limit
	   cmp eax, 97 //Compare the character to 97
	   jb End; // Jump to the end if below == the character is too low to be a lower case letter
 
	   //Now the operation begins
	   sub eax, 32; //Subtract 32 from the character in the register
 
 
     End:
	 // mov result, al; //Move the Character in the register into the result variable
 
    }
 
 
}

 
.686
.model flat, stdcall
option casemap :none
 
.code
 
cUpperCase2 proc cValue:DWORD
 
  mov eax, cValue
 
  cmp eax, 122
 
  ja TEnd
 
  cmp eax, 97
 
  jb TEnd
 
  sub eax, 32
 
 
 
  TEnd:
 
    ret
 
cUpperCase2 endp
 
end

 
char cppToUpper(char c)
{
01271680  push        ebp  
01271681  mov         ebp,esp 
01271683  sub         esp,0C0h 
01271689  push        ebx  
0127168A  push        esi  
0127168B  push        edi  
0127168C  lea         edi,[ebp-0C0h] 
01271692  mov         ecx,30h 
01271697  mov         eax,0CCCCCCCCh 
0127169C  rep stos    dword ptr es:[edi] 
    if (c > 122 || c < 97 )
0127169E  movsx       eax,byte ptr [c] 
012716A2  cmp         eax,7Ah 
012716A5  jg          cppToUpper+30h (12716B0h) 
012716A7  movsx       eax,byte ptr [c] 
012716AB  cmp         eax,61h 
012716AE  jge         cppToUpper+37h (12716B7h) 
	   return c;
012716B0  mov         al,byte ptr [c] 
012716B3  jmp         cppToUpper+3Eh (12716BEh) 
012716B5  jmp         cppToUpper+3Eh (12716BEh) 
    else return c - 32;
012716B7  movsx       eax,byte ptr [c] 
012716BB  sub         eax,20h 
}
012716BE  pop         edi  
012716BF  pop         esi  
012716C0  pop         ebx  
012716C1  mov         esp,ebp 
012716C3  pop         ebp  
012716C4  ret

 
#include "stdafx.h"
#include <iostream>
#include <string>
#include "windows.h"
#include "time.h"
using namespace std;
extern "C" int _stdcall cUpperCase2(char c);
 
class stopwatch
{
public:
 stopwatch() : start(clock()){} //start counting time
 ~stopwatch();
private:
 clock_t start;
};
 
stopwatch::~stopwatch()
{
 clock_t total = clock()-start; //get elapsed time
 cout<<"total of ticks for this activity: "<<total<<endl;
 cout <<"in seconds: "<< double(total/CLK_TCK) <<endl;
}
 
void main()
{
bool bAgain = true;
 
    while (bAgain)
    {
//     unsigned long lTimeNow = t_time;
 
 
 
	   	char c = 'a';
		char d = '!';
		char e;
 
	//cout << "A lowercase character will be converted to Uppercase:" << endl;
	//cin >> c;
	  {
		   stopwatch watch;
		   for (int i=0; i < 10000000; i++) 
		   {
			 e= cUpperCase2(c);
			 e= cUpperCase2(d);
		   }
 
	    }
		  cout << "That was the external function written in assembler." << endl;
 
	    {
		   stopwatch watch;
		   for (int i=0; i < 10000000; i++) 
		   {
 
			 // cout << cppToUpper(c);
			 //cout << cppToUpper(d);
			 e= cppToUpper(c);
			 e= cppToUpper(d);
		   }
 
	    }
	    cout << "That was C++\n";
	   {
		   stopwatch watch;
		   for (int i=0; i < 10000000; i++) 
		   {
			 e= cToUpper(c);
			 e= cToUpper(d);
		   }
 
	    }
	        cout << "That was in line assembler\n";
 
 
 
	    cout << "Enter a letter and hit enter to exit (a will repeat) . . ." << endl;
	    cin >> c;
 
	//return 0;
	    if (c != 'a')
		  bAgain = false;
 
    }	
 
}