C / C++ / MFC

#include "stdafx.h"

int _tmain(int argc, _TCHAR* argv[])
{
	#pragma pack (1)
		unsigned long table[3] = {0};
	#pragma pack(pop)

	char szError[] = "Invalid choice.\n";
	char szPrompt[] = "Enter a number between 1 and 3:\n";
	char szNotify[] = "You entered jump number: %d";
	char szFmt[] = "%d";
	int iChoice =0;
	int iSizeArray = (sizeof(table) / sizeof(table[0]));

	__asm
	{
		lea esi, table			;Load address of table into esi
		mov edx, DWORD PTR jump1		;Move address of jump1 into edx
		mov [esi], edx			;Move edx into table[0]
		add esi, 4				;Increment esi by size of unsigned long
		mov edx, DWORD PTR jump2		;Move address of jump2 into edx
		mov [esi], edx			;Move edx into table[1]
		add esi, 4				;Increment esi by size of unsigned long
		mov edx, DWORD PTR jump3		;Move address of jump3 into edx
		mov [esi], edx			;Move edx into table[2]
		lea eax, szPrompt			;Load effective address of prompt
		push eax				;push eax onto stack
#ifdef _DLL						;Are we dynamically linked to C runtime?
		call DWORD PTR printf		;Call dynamic linked printf
#else
		call printf				;Call static linked printf
#endif
		add esp, 4				;adjust stack pointer because we pushed eax
		lea eax, iChoice			;Load effective address of iChoice
		push eax				;Push it onto the stack
		lea ebx, szFmt			;Load effective address of fmt
		push ebx				;Push it on the stack
#ifdef _DLL						;Are we dynamically linked to C runtime?
		call DWORD PTR scanf		;Call dynamic linked scanf
#else
		call scanf				;Call static linked scanf
#endif
		add esp, 8				;adjust stack pointer because we pushed eax and ebx
		mov eax, iChoice			;Move iChoice value into eax
		mov ebx, iSizeArray		;Move the size of our array into ebx 
		cmp eax, ebx				;compare
		ja error				;Jump to the error lable if iChoice is larger than table array
		dec eax					;Decrement iChoice by 1 because the table is zero based array
		lea esi, table			;Load address of table into esi
		mov eax,[esi + 4*eax]		;Move value of table array onto eax by calculating offset
		jmp eax				;Jump to address stored in eax
jump1:
		mov eax, 1				;Move number 1 into eax
		jmp notify				;Absolute jump to notify label
jump2:
		mov eax, 2				;Move number 1 into eax
		jmp notify				;Absolute jump to notify label
jump3:
		mov eax, 3				;Move number 1 into eax
		jmp notify				;Absolute jump to notify label
error:
		lea eax, szError			;Load effective address of error
		push eax				;push eax onto stack
#ifdef _DLL						;Are we dynamically linked to C runtime?
		call DWORD PTR printf		;Call dynamic linked printf
#else
		call printf				;Call static linked printf
#endif
		add esp, 4				;adjust stack pointer because we pushed eax
		jmp end				;Absolute jump to end label
notify:
		push eax
		lea ebx, szNotify			;Load effective address of notify
		push ebx
#ifdef _DLL						;Are we dynamically linked to C runtime?
		call DWORD PTR printf		;Call dynamic linked printf
#else
		call scanf				;Call static linked printf
#endif
		add esp, 8				;adjust stack pointer because we pushed eax and ebx
end:
	}
	return 0;
}

switch(count%4) {
case 0:
   // do step
   goto case1;
case 1:
   // do step
   goto case2;
case 2:
   // do step
   goto case3;
case 3:
   // do step
   count-=4;
   if (count>0) goto case0;
}

Luc Pattyn

Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.

prithaa wrote:

But when I press F5 and debug the code the code doesnt proceed further