void A(void) {
int num;
int sender_pid;
while (1) {
msg* p = (msg*)request_memory_block();
uart1_put_string("Waiting for KCD\r\n");
p = (msg*)(receive_message(&sender_pid));
if (p->mtext[0] == '%' && p->mtext[1] == 'Z') {
uart1_put_string("Received %Z from KCD\r\n");
release_memory_block(p);
break;
} else {
release_memory_block(p);
}
}
num = 0;
while (1) {
char b[8];
msg* p = (msg*)request_memory_block();
itoa(num, b);
p->mtype = 3;
p->mtext = b;
send_message(6,p);
uart1_put_string(b);
uart1_put_string("Sent Message from A to B\r\n");
num++;
release_processor();
}
// note that Process A does not de-allocate
// any received envelopes in the second loop
}
/**
* Prints five numbers and then releases a memory block
*/
void test_proc_p1_b_2(void) {
int i = 0;
int ret_val = 20;
void* p_mem_blk;
p_mem_blk = request_memory_block();
set_process_priority(PID_P2, MEDIUM);
while ( 1) {
if ( i != 0 && i % 5 == 0 ) {
uart1_put_string("\n\r");
ret_val = release_memory_block(p_mem_blk);
#ifdef DEBUG_0
printf("proc2: ret_val=%d\n", ret_val);
#endif /* DEBUG_0 */
if ( ret_val == -1 ) {
break;
}
}
uart1_put_char('0' + i % 10);
i++;
}
uart1_put_string("proc2: end of testing\n\r");
set_process_priority(PID_P2, LOWEST);
while ( 1 ) {
release_processor();
}
}
/**
* @brief: a process that prints 4x5 numbers
*/
void test_proc_p1_a_2(void) {
int i = 0;
int ret_val = 20;
int counter = 0;
while ( 1) {
if ( i != 0 && i % 5 == 0 ) {
uart1_put_string("\n\r");
counter++;
if ( counter == 4 ) {
ret_val = set_process_priority(PID_P1, HIGH);
break;
} else {
ret_val = release_processor();
}
#ifdef DEBUG_0
printf("proc2: ret_val=%d\n", ret_val);
#endif /* DEBUG_0 */
}
uart1_put_char('0' + i % 10);
i++;
}
uart1_put_string("proc2 end of testing\n\r");
while ( 1 ) {
release_processor();
}
}
/**
* @brief: c UART0 IRQ Handler
*/
void c_UART0_IRQHandler(void)
{
uint8_t IIR_IntId; // Interrupt ID from IIR
LPC_UART_TypeDef *pUart = (LPC_UART_TypeDef *)LPC_UART0;
#ifdef DEBUG_0
uart1_put_string("Entering c_UART0_IRQHandler\n\r");
#endif // DEBUG_0
/* Reading IIR automatically acknowledges the interrupt */
IIR_IntId = (pUart->IIR) >> 1 ; // skip pending bit in IIR
if (IIR_IntId & IIR_RDA) { // Receive Data Avaialbe
/* read UART. Read RBR will clear the interrupt */
g_char_in = pUart->RBR;
#ifdef DEBUG_0
uart1_put_string("Reading a char = ");
uart1_put_char(g_char_in);
uart1_put_string("\n\r");
#endif // DEBUG_0
g_buffer[12] = g_char_in; // nasty hack
g_send_char = 1;
} else if (IIR_IntId & IIR_THRE) {
/* THRE Interrupt, transmit holding register becomes empty */
if (*gp_buffer != '\0' ) {
g_char_out = *gp_buffer;
#ifdef DEBUG_0
//uart1_put_string("Writing a char = ");
//uart1_put_char(g_char_out);
//uart1_put_string("\n\r");
// you could use the printf instead
printf("Writing a char = %c \n\r", g_char_out);
#endif // DEBUG_0
pUart->THR = g_char_out;
gp_buffer++;
} else {
#ifdef DEBUG_0
uart1_put_string("Finish writing. Turning off IER_THRE\n\r");
#endif // DEBUG_0
pUart->IER ^= IER_THRE; // toggle the IER_THRE bit
pUart->THR = '\0';
g_send_char = 0;
gp_buffer = g_buffer;
}
} else { /* not implemented yet */
#ifdef DEBUG_0
uart1_put_string("Should not get here!\n\r");
#endif // DEBUG_0
return;
}
}
void k_rtx_init(void)
{
__disable_irq();
uart_irq_init(0); // uart0, interrupt-driven
timer_init(0); // uart0, interrupt-driven
uart1_init(); // uart1, polling
memory_init();
process_init();
__enable_irq();
uart1_put_string("Type 'S' in COM0 terminal to switch between proc1 and proc2 or wait for them to switch between themselves\n\r");
uart1_put_string("An input other than 'S' in COM0 terminal will be have no effect.\n\r");
/* start the first process */
k_release_processor();
}
int main()
{
LPC_UART_TypeDef *pUart;
SystemInit();
__disable_irq();
uart0_irq_init(); // uart0 interrupt driven, for RTX console
uart1_init(); // uart1 polling, for debugging
#ifdef DEBUG_0
init_printf(NULL, putc);
#endif // DEBUG_0
__enable_irq();
uart1_put_string("COM1> Type a character at COM0 terminal\n\r");
pUart = (LPC_UART_TypeDef *) LPC_UART0;
//while( 1 ) {
if (g_send_char == 0) {
/* Enable RBR, THRE is disabled */
pUart->IER = IER_RLS | IER_RBR;
} else if (g_send_char == 1) {
/* Enable THRE, RBR left as enabled */
pUart->IER = IER_THRE | IER_RLS | IER_RBR;
}
//}
}
void test_proc_p1_a_3(void) {
while (1) {
uart1_put_string("proc3: \n\r");
release_processor();
}
}
int k_delayed_send(int destination_proc_id, void *message_envelope, int delay) {
msg_metadata *metadata = reserve_message_metadata(message_envelope);
if (metadata == NULL) {
return RTX_ERR;
}
if (message_envelope == NULL) {
uart1_put_string("k_send_message is NULL. Bad!\n");
return RTX_ERR;
}
__disable_irq();
metadata->sender_pid = gp_current_process->pid;
metadata->destination_pid = destination_proc_id;
metadata->send_time = k_get_time() + delay;
if (g_delayed_messages_count == (BLOCK_SIZE / sizeof(void *))) {
// Overflow is... unlikely.
ASSERT(0)
}
g_delayed_messages[g_delayed_messages_count++] = message_envelope;
__enable_irq();
return RTX_OK;
}
void proc6(void)
{
while(1) {
uart1_put_string("proc6: \n\r");
release_processor();
}
}
void B(void) {
int sender_pid;
while (1) {
msg* p;
p = (msg*)(receive_message(&sender_pid));
uart1_put_string("Sent Message from B to C\r\n");
send_message(7,p);
release_processor();
}
}
//TC 2: Blocked on receive & preemption
void proc2(void) {
MSG_BUF* envelope = 0;
char* msg1 = "SE 350";
char* msg2 = "LAB";
envelope = (MSG_BUF*)request_memory_block();
strcpy(envelope->mtext, msg1);
send_message(1, envelope);
//TC 3: IPC
envelope = (MSG_BUF*)request_memory_block();
strcpy(envelope->mtext, msg2);
send_message(3, envelope);
envelope = (MSG_BUF*)receive_message(NULL);
if (strcmp(envelope->mtext, msg2) == 0) {
prev_success = 1;
} else {
prev_success = 0;
}
release_memory_block(envelope);
if (prev_success) {
uart1_put_string("G003_test: test ");
uart1_put_char(3 + 48);
uart1_put_string(" OK\n\r");
pass = pass + 1;
} else {
uart1_put_string("G003_test: test ");
uart1_put_char(3 + 48);
uart1_put_string(" FAIL\n\r");
}
set_process_priority(4, HIGH);
while (1) {
release_processor();
}
}
void test_proc_p1_b_6(void) {
int i = 0;
while (1) {
if ( i < 2 ) {
uart1_put_string("proc6: \n\r");
}
release_processor();
i++;
}
}
void proc5(void)
{
int i=0;
while(1) {
if ( i < 2 ) {
uart1_put_string("proc5: \n\r");
}
release_processor();
i++;
}
}
/**
* @brief: c UART0 IRQ Handler
*/
void c_UART0_IRQHandler(void)
{
uint8_t IIR_IntId; // Interrupt ID from IIR
uint8_t g_char_in;
LPC_UART_TypeDef *pUart = (LPC_UART_TypeDef *)LPC_UART0;
#ifdef DEBUG_1
uart1_put_string("Entering c_UART0_IRQHandler\n\r");
#endif // DEBUG_1
/* Reading IIR automatically acknowledges the interrupt */
IIR_IntId = (pUart->IIR) >> 1 ; // skip pending bit in IIR
if (IIR_IntId & IIR_RDA) { // Receive Data Avaialbe
/* read UART. Read RBR will clear the interrupt */
g_char_in = pUart->RBR;
//call iprocess hander for uart
UART_IProcessHandler(g_char_in);
} else if (IIR_IntId & IIR_THRE) {
/* THRE Interrupt, transmit holding register becomes empty */
UART_IProcessHandler(NULL);
#ifdef DEBUG_1
uart1_put_string("Finish writing. Turning off IER_THRE\n\r");
#endif // DEBUG_1
pUart->IER ^= IER_THRE; // toggle the IER_THRE bit
//pUart->THR = '\0';
} else { /* not implemented yet */
#ifdef DEBUG_1
uart1_put_string("Should not get here!\n\r");
#endif // DEBUG_1
}
}
/**
* Prints five uppercase letters and request a memory block.
*/
void test_proc_p1_b_1(void) {
int i = 0;
void* p_mem_blk;
while ( 1 ) {
if ( i != 0 && i % 5 == 0 ) {
uart1_put_string("\n\r");
p_mem_blk = request_memory_block();
#ifdef DEBUG_0
printf("proc1: p_mem_blk=0x%x\n", p_mem_blk);
#endif /* DEBUG_0 */
}
uart1_put_char('A' + i % 26);
i++;
}
}
/**
* @brief call back function for printf
* NOTE: first paramter p is not used for now.
*/
void putc(void *p, char c)
{
if (p != NULL) {
if (active_uart == 0) {
uart0_put_string("putc: first parameter needs to be NULL");
} else {
uart1_put_string("putc: first parameter needs to be NULL");
}
} else {
if (active_uart == 0) {
uart0_put_char(c);
} else {
uart1_put_char(c);
}
}
}
/**
* @brief: a process that prints 5x6 numbers
* and then yields the cpu.
*/
void proc2(void)
{
int i = 0;
int ret_val = 20;
int x = 0;
while ( 1) {
if ( i != 0 && i%5 == 0 ) {
uart1_put_string("\n\r");
if ( i%30 == 0 ) {
ret_val = release_processor();
#ifdef DEBUG_0
printf("proc2: ret_val=%d\n", ret_val);
#endif /* DEBUG_0 */
}
for ( x = 0; x < 500000; x++); // some artifical delay
}
uart1_put_char('0' + i%10);
i++;
}
}
int k_send_message(int destination_proc_id, void *message_envelope) {
PCB *receiving_proc;
msg_metadata *metadata = reserve_message_metadata(message_envelope);
if (metadata == NULL) {
return RTX_ERR;
}
if (message_envelope == NULL) {
uart1_put_string("k_send_message is NULL. Bad!\n");
return RTX_ERR;
}
__disable_irq();
metadata->sender_pid = gp_current_process->pid;
metadata->destination_pid = destination_proc_id;
receiving_proc = k_get_pcb_from_pid(destination_proc_id);
list_push(&receiving_proc->msg_queue, message_envelope);
if (receiving_proc->state == BLOCKED_ON_RECEIVE) {
receiving_proc->state = READY;
k_dequeue_process(destination_proc_id);
k_enqueue_process(destination_proc_id);
if (k_get_proc_table_from_pid(destination_proc_id)->m_priority <
k_get_proc_table_from_pid(metadata->sender_pid)->m_priority) {
__enable_irq();
k_release_processor();
__disable_irq();
}
}
__enable_irq();
return RTX_OK;
}
void null_proc(void) {
uart1_put_string("Running null process\n\r");
while(1) {
release_processor();
}
}
//TC 4: KCD and CRT
void proc4(void) {
MSG_BUF* msg = NULL;
msg = (MSG_BUF*)request_memory_block();
msg->mtype = KCD_REG;
msg->mtext[0] = '%';
msg->mtext[1] = 'T';
msg->mtext[2] = 'E';
msg->mtext[3] = 'S';
msg->mtext[4] = 'T';
msg->mtext[4] = '\0';
send_message(PID_KCD, msg);
msg = (MSG_BUF*)request_memory_block();
msg->mtype = CRT_DISPLAY;
strcpy(msg->mtext, "Input %TEST and press enter:\n\r");
send_message(PID_CRT, msg);
msg = receive_message(NULL);
if (strcmp(msg->mtext, "%TEST") == 0) {
prev_success = 1;
} else {
prev_success = 0;
}
release_memory_block(msg);
if (prev_success) {
uart1_put_string("G003_test: test ");
uart1_put_char(4 + 48);
uart1_put_string(" OK\n\r");
pass = pass + 1;
} else {
uart1_put_string("G003_test: test ");
uart1_put_char(4 + 48);
uart1_put_string(" FAIL\n\r");
}
uart1_put_string("G003_test: ");
uart1_put_char(pass + 48);
uart1_put_string("/");
uart1_put_char(total + 48);
uart1_put_string(" tests OK\n\r");
uart1_put_string("G003_test: ");
uart1_put_char((total - pass) + 48);
uart1_put_string("/");
uart1_put_char(total + 48);
uart1_put_string(" tests FAIL\n\r");
uart1_put_string("G003_test: END\n\r");
while (1) {
release_processor();
}
}
//TC 1: Delayed message sending & no preemption
void proc1(void) {
MSG_BUF* envelope = NULL;
char* msg = "SE 350";
uart1_put_string("\n\r");
uart1_put_string("G003_test: START\n\r");
uart1_put_string("G003_test: total ");
uart1_put_char(total + 48);
uart1_put_string(" tests\n\r");
prev_pid = 1;
envelope = (MSG_BUF*)request_memory_block();
strcpy(envelope->mtext, msg);
delayed_send(1, envelope, 5000);
envelope = (MSG_BUF*)receive_message(NULL);
if (strcmp(envelope->mtext, msg) == 0) {
prev_success = 1;
} else {
prev_success = 0;
}
release_memory_block(envelope);
if (prev_success) {
uart1_put_string("G003_test: test ");
uart1_put_char(1 + 48);
uart1_put_string(" OK\n\r");
pass = pass + 1;
} else {
uart1_put_string("G003_test: test ");
uart1_put_char(1 + 48);
uart1_put_string(" FAIL\n\r");
}
//TC 2: Blocked on receive & preemption
envelope = (MSG_BUF*)receive_message(NULL);
prev_success = 1; // Checks if you ever get here.
release_memory_block(envelope);
if (prev_success) {
uart1_put_string("G003_test: test ");
uart1_put_char(2 + 48);
uart1_put_string(" OK\n\r");
pass = pass + 1;
} else {
uart1_put_string("G003_test: test ");
uart1_put_char(2 + 48);
uart1_put_string(" FAIL\n\r");
}
while (1) {
release_processor();
}
}
void proc5(void) {
//END of TC 3d: all processes except proc5 are blocked
if (prev_pid == 4 && prev_success) {
uart1_put_string("G003_test: test ");
uart1_put_char(3 + 48);
uart1_put_string(" OK\n\r");
pass = pass + 1;
} else {
uart1_put_string("G003_test: test ");
uart1_put_char(3 + 48);
uart1_put_string(" FAIL\n\r");
}
uart1_put_string("G003_test: ");
uart1_put_char(pass + 48);
uart1_put_string("/");
uart1_put_char(total + 48);
uart1_put_string(" tests OK\n\r");
uart1_put_string("G003_test: ");
uart1_put_char((total - pass) + 48);
uart1_put_string("/");
uart1_put_char(total + 48);
uart1_put_string(" tests FAIL\n\r");
uart1_put_string("G003_test: END\n\r");
while (1) {
mem[index++] = request_memory_block();
}
}
void proc6(void) {
// TC 2a: change itself to be lower than the max: PASS if prev pid is 1
if (prev_pid != 1) {
prev_success = 0;
// At here, priority of the procs:
// 1: LOW
// 2, 3, 4, 5: LOWEST
// 6: MEDIUM
}
//TC 2b: set itself to a higher one with currently being the higeest -> still itself
prev_pid = 6;
set_process_priority(6, HIGH);
//TC 2b: set itself to a higher one with currently being the higeest -> still itself: PASS if prev_pid is 6
if (prev_pid != 6) {
prev_success = 0;
// At here, priority of the procs:
// 1: LOW
// 2, 3, 4, 5: LOWEST
// 6: HIGH
}
//TC 2c: set itself to be the same as the currently highest other than itself -> switch to that highest
prev_pid = 6;
set_process_priority(6, LOW);
// TC 2d: change a proc s.t. B=A to B>A, A is current
if (prev_pid != 1) {
prev_success = 0;
// At here, priority of the procs:
// 1: LOW
// 2, 3, 4, 5: LOWEST
// 6: HIGH
}
// TC 2e: change a proc s.t. B<A to B=A, A is current, then B should be run
prev_pid = 6;
set_process_priority(1, HIGH);
// TC 2g: change a proc s.t. B<A to B>A, A is current, then jump to B
if (prev_pid != 1) {
prev_success = 0;
// At here, priority of the procs:
// 1: MEDIUM
// 2, 3, 4, 5: LOWEST
// 6: HIGH
}
// TC 2h: change itself to be the same priority of itself: no change
prev_pid = 6;
set_process_priority(6, HIGH);
// Finish TC 2
if (prev_pid == 6 && prev_success) {
uart1_put_string("G003_test: test ");
uart1_put_char(2 + 48);
uart1_put_string(" OK\n\r");
pass = pass + 1;
} else {
uart1_put_string("G003_test: test ");
uart1_put_char(2 + 48);
uart1_put_string(" FAIL\n\r");
}
// END of TC 2
prev_success = 1;
// Start of TC 3
// TC 3a: null process operations
// 1: MEDIUM
// 2, 3, 4, 5: LOWEST
// 6: HIGH
if (set_process_priority(0, LOW) != RTX_ERR) {
prev_success = 0;
}
set_process_priority(1, LOW);
set_process_priority(2, MEDIUM);
// TC 3b: allocate all memory blocks, free one, return
// 1: LOW
// 2: MEDIUM
// 3, 4, 5: LOWEST
// 6: HIGH, will be blocked
while (prev_pid == 6) {
mem[index++] = request_memory_block();
} // proc 6 should be preempted and go to 2
// TC 3b: proc_6 is return from blocked queue to ready queue and is the highest priority process
if (prev_pid != 2) {
prev_success = 0;
}
prev_pid = 6;
// TC 3c: with 2 procs at highest priority, block both procs, then release memory in another proc to return to proc_6
set_process_priority(3, HIGH); // jumps to proc_3
// 1: LOW
// 2: MEDIUM
// 3: HIGH, blocked
// 4, 5: LOWEST
// 6: HIGH, will be blocked
prev_pid = 6;
mem[index++] = request_memory_block(); // blocks proc_6, goes to proc_2
}
void proc1(void) {
// Start of TC 1
//TC 1: allocation and deallocation
void* test_blk1 = NULL;
void* test_blk2 = NULL;
int status1 = 1;
int status2 = 1;
uart1_put_string("\n\r");
uart1_put_string("G003_test: START\n\r");
uart1_put_string("G003_test: total ");
uart1_put_char(total + 48);
uart1_put_string(" tests\n\r");
test_blk1 = request_memory_block();
test_blk2 = request_memory_block();
if (test_blk1 == test_blk2 || test_blk1 == NULL || test_blk2 == NULL) {
prev_success = 0;
}
status1 = release_memory_block(test_blk1);
status2 = release_memory_block(test_blk2);
if (status1 != 0 || status2 != 0) {
prev_success = 0;
}
// End of TC 1
if (prev_success) {
uart1_put_string("G003_test: test ");
uart1_put_char(1 + 48);
uart1_put_string(" OK\n\r");
pass = pass + 1;
} else {
uart1_put_string("G003_test: test ");
uart1_put_char(1 + 48);
uart1_put_string(" FAIL\n\r");
}
prev_success = 1;
// Start of TC 2
// TC 2a: change itself to be lower than the max
prev_pid = 1;
set_process_priority(1, LOW);
// set_process_priority(1, HIGH);
if (prev_pid != 6) {
prev_success = 0;
}
// At here, priority of the procs:
// 1: LOW
// 2, 3, 4, 5: LOWEST
// 6: LOW
// TC 2d: change a proc s.t. B=A to B>A, A is current
prev_pid = 1;
set_process_priority(6, HIGH); // should go to 6
// TC 2e: change a proc s.t. B<A to B=A, A is current, then B should be run
if (prev_pid != 6) {
prev_success = 0;
}
// At here, priority of the procs:
// 1: HIGH
// 2, 3, 4, 5: LOWEST
// 6: HIGH
// TC 2f: change a proc s.t. B=A to B<A, A is current, then still A
prev_pid = 1;
set_process_priority(6, LOW);
// TC 2f: change a proc s.t. B=A to B<A, A is current, then still A
if (prev_pid != 1) {
prev_success = 0;
}
// At here, priority of the procs:
// 1: HIGH
// 2, 3, 4, 5: LOWEST
// 6: LOW
// TC 2g: change a proc s.t. B<A to B>A, A is current, then jump to B
// First, change itself to be MEDIUM
set_process_priority(1, MEDIUM);
if (prev_pid != 1) {
prev_success = 0;
}
prev_pid = 1;
// Then, change 6 to HIGH
set_process_priority(6, HIGH);
// If TC 2 ever reaches here, TC 2 fails
if (prev_pid == 1) {
uart1_put_string("G003_test: test ");
uart1_put_char(2 + 48);
uart1_put_string(" FAIL\n\r");
}
// TC 3d: Block everything and preempt to null process after starvation
if (prev_pid != 3) {
prev_success = 0;
}
// 1: MEDIUM
// 2: LOW
// 3: HIGH, blocked
// 4, 5: LOWEST
// 6: HIGH, blocked
prev_pid = 1;
mem[index++] = request_memory_block();
}
/**
* @brief: c UART0 IRQ Handler
*/
void uart_iprocess(void)
{
uint8_t IIR_IntId; // Interrupt ID from IIR
LPC_UART_TypeDef *pUart = (LPC_UART_TypeDef *)LPC_UART0;
__disable_irq();
#ifdef DEBUG_0
//uart1_put_string("Entering c_UART0_IRQHandler\n\r");
#endif // DEBUG_0
/* Reading IIR automatically acknowledges the interrupt */
IIR_IntId = (pUart->IIR) >> 1 ; // skip pending bit in IIR
if (IIR_IntId & IIR_RDA) { // Receive Data Avaialbe
/* read UART. Read RBR will clear the interrupt */
// Perform a 'context switch'
PCB *old_proc = gp_current_process;
gp_current_process = k_get_process(PID_UART_IPROC);
g_char_in = pUart->RBR;
#ifdef DEBUG_0
uart1_put_string("Reading a char = ");
uart1_put_char(g_char_in);
uart1_put_string("\n\r");
#endif // DEBUG_0
// process the character. If it is a hotkey, call the corresponding function
// If we are reading, fall through to default and add to the command buffer
switch (g_char_in) {
case '\r':
case '\n':
if (g_is_reading) {
// We've finished reading a command, send it to the KCD process
MSG_BUF *message;
g_is_reading = 0;
strcpy("\n\r", (char *)(g_in_buffer + g_in_index));
if (is_memory_available()) {
message = k_request_memory_block();
message->mtype = DEFAULT;
strcpy((char *)g_in_buffer, message->mtext);
k_send_message(PID_KCD, message);
}
g_in_index = 0;
}
break;
case '%':
if (!g_is_reading) {
// Start reading a command
g_is_reading = 1;
g_in_index = 1;
g_in_buffer[0] = '%';
break;
}
#if defined(DEBUG_0) && defined(_DEBUG_HOTKEYS)
case READY_Q_COMMAND:
if (!g_is_reading) {
print_ready();
break;
}
case MEMORY_Q_COMMAND:
if (!g_is_reading) {
print_mem_blocked();
break;
}
case RECEIVE_Q_COMMAND:
if (!g_is_reading) {
print_receive_blocked();
break;
}
case MESSAGE_COMMAND:
if (!g_is_reading) {
print_messages();
break;
}
#endif /* DEBUG HOTKEYS */
default:
if (g_is_reading) {
// TODO: check bounds
g_in_buffer[g_in_index++] = g_char_in;
}
}
gp_current_process = old_proc;
} else if (IIR_IntId & IIR_THRE) {
/* THRE Interrupt, transmit holding register becomes empty */
// Check for messages and load the buffer
// Perform a 'context switch' to the i-process
MSG_BUF *message;
PCB *old_proc = gp_current_process;
gp_current_process = k_get_process(PID_UART_IPROC);
// Don't block waiting for a message
while (is_message(PID_UART_IPROC)) {
int sender = PID_CRT;
char *c;
// Receive message and copy it to the buffer
message = k_receive_message(&sender);
c = message->mtext;
//dprintf("Copying message to buffer: %s\n\r", message->mtext);
if (*c != '\0') {
do {
g_out_buffer[g_out_end] = *c;
g_out_end = (g_out_end + 1) % OUTPUT_BUFF_SIZE;
c++;
} while (g_out_end != g_out_start && *c != '\0');
}
k_release_memory_block(message);
}
// Check if there is something in the circular buffer
if (g_out_start != g_out_end) {
g_char_out = g_out_buffer[g_out_start];
pUart->THR = g_char_out;
g_out_start = (g_out_start + 1) % OUTPUT_BUFF_SIZE;
} else {
// nothing to print, disable the THRE interrupt
pUart->IER ^= IER_THRE; // toggle (disable) the IER_THRE bit
}
gp_current_process = old_proc;
} else { /* not implemented yet */
#ifdef DEBUG_0
//uart1_put_string("Should not get here!\n\r");
#endif // DEBUG_0
__enable_irq();
return;
}
__enable_irq();
}
void print_debug(char* message) {
#ifdef DEBUG_0
uart1_put_string(message);
#endif
}