instruction

That is a C compiler question. Not an MSP430 question.

Such as this? 

http://forum.43oh.com/topic/878-fast-itoa-for-ccs/

raju vadarevu1 said:

is there any instruction like "  itoa();  " for msp430g2553 .

On many systems, itoa is available because it is used by printf to print integers. However, for size reasons, it might be not there and you should use sprintf instead. IAR and CSS allow to limit the support level of (s)printf, so with limited support (no float) you won't get much overhead over a plain itoa function. Also, it is not officially part of the C standard library funciton set.

Anyway, you can use this replacement

	char * itoa(int value, char* str, int base) {
		static char num[] = "0123456789abcdefghijklmnopqrstuvwxyz";
		char* wstr=str, ret = str;
		char aux;
		int sign;
		// Validate base
		if (base<2 || base>35){ *wstr='\0'; return ret; }
		// Take care of sign
		if ((sign=value) < 0) value = -value;
		// Conversion. Number is reversed.
		do *wstr++ = num[value%base]; while(value/=base);
		if(sign<0) *wstr++='-';
		*wstr--='\0';
		// Reverse string
		while(wstr>str)
			aux=*str, *wstr--=*str, *str++=aux;
		return ret;
	}