xtoa.c

AVR-GCC 自带库的原码

#include <stdlib.h>
#include <string.h>

// maximum string buffer needed, plus one for a minus sign when negative
#define MAX_LENGTH 32+1


#define XTOA(prefix, type)	\
char *prefix##toa(char* buf, type i, int base) 	{	\
    char reverse[MAX_LENGTH+1]; char* s; char sign;	\
	if (i < 0) { sign = 1; i = -i; }				\
    else sign = 0;									\
    reverse[MAX_LENGTH] = 0; s = reverse+MAX_LENGTH;\
    do { *--s = "0123456789abcdefghijklmnopqrstuvwxyz"[i % base];	\
        i /= base; } while (i);						\
    if (sign) *--s = '-'; return strcpy(buf, s); }