stkarm/src/kernel.cpp

#define UART_RBR    0x01c28000
char* const UART_THR = (char* const)0x01c28000;
#define UART_IER    0x01c28004
char* const UART_LSR = (char* const)0x01c28014;

extern "C" int printk(const char*);

extern "C" int main(int argc, char** argv) {
    char letter[2] = "A";

    for (char c = 'A'; c < 'Z'; c++) {
        letter[0] = c;

        printk("HELLO WORLD!");
        printk("\t");
        printk(letter);
        printk("\r\n");
    }

   return 0;
}

/* Never call this function directly: always use the printk,
 * which disables and reenables interrupts */
extern "C" int c_printk(const char* msg) {
    while (*msg != '\0') {
        while ((*UART_LSR & 0x20) == 0);    /* Wait for transmission */
        *UART_THR = *msg;
        msg++;
    }
    return 0;
}