打印十六进制字符串查看内存地址

void puthex(unsigned long val)
{
    /* val = 0x1234ABCD */
    unsigned char c;
    int i = 0;
    
    putc('0');
    putc('x');

    for (i = 0; i < 8; i++)
    {
        c = (val >> ((7-i)*4)) & 0xf;
        if ((c >= 0) && (c <= 9))
        {
            c = '0' + c;
        }
        else if ((c >= 0xA) && (c <= 0xF))
        {
            c = 'A' + (c -  0xA);
        }
        putc(c);
    }
}