bitchar.c

#define BIT_0 1 
#define BIT_1 2
#define BIT_2 4 
#define BIT_3 8 
#define BIT_4 16 
#define BIT_5 32
#define BIT_6 64 
#define BIT_7 128

void bitchar(char* s, char c){
    for(unsigned char i=0;i<8;i++){
        s[i] = c & 0x80 ? '1' : '0';
        c <<= 1;
    }
    s[8]=0;
}