runtime: implement RPC syscall

soc/runtime/main.c

@@ -11,24 +11,12 @@
 
 #include "elf_loader.h"
 
-static void receive_sync(void)
+enum {
-{
+	MSGTYPE_KERNEL_FINISHED		= 0x01,
-	char c;
+	MSGTYPE_RPC_REQUEST			= 0x02,
-	int recognized;
+};
 
-	recognized = 0;
+static int receive_int(void)
-	while(1) {
-		c = readchar();
-		if(c == 0x5a) {
-			recognized++;
-			if(recognized == 4)
-				return;
-		} else
-			recognized = 0;
-	}
-}
-
-static int receive_length(void)
 {
 	unsigned int r;
 	int i;
@@ -36,11 +24,57 @@ static int receive_length(void)
 	r = 0;
 	for(i=0;i<4;i++) {
 		r <<= 8;
-		r |= (unsigned char)readchar();
+		r |= (unsigned char)uart_read();
 	}
 	return r;
 }
 
+static char receive_char(void)
+{
+	return uart_read();
+}
+
+static void send_int(int x)
+{
+	int i;
+
+	for(i=0;i<4;i++) {
+		uart_write((x & 0xff000000) >> 24);
+		x <<= 8;
+	}
+}
+
+static void send_sint(short int i)
+{
+	uart_write((i >> 8) & 0xff);
+	uart_write(i & 0xff);
+}
+
+static void send_char(char c)
+{
+	uart_write(c);
+}
+
+static void receive_sync(void)
+{
+	char c;
+	int recognized;
+
+	recognized = 0;
+	while(recognized < 4) {
+		c = uart_read();
+		if(c == 0x5a)
+			recognized++;
+		else
+			recognized = 0;
+	}
+}
+
+static void send_sync(void)
+{
+	send_int(0x5a5a5a5a);
+}
+
 static int download_kernel(void *buffer, int maxlength)
 {
 	int length;
@@ -48,25 +82,29 @@ static int download_kernel(void *buffer, int maxlength)
 	unsigned char *_buffer = buffer;
 
 	receive_sync();
-	length = receive_length();
+	length = receive_int();
 	if(length > maxlength)
 		return -1;
 	for(i=0;i<length;i++)
-		_buffer[i] = readchar();
+		_buffer[i] = receive_char();
+	send_char(0x4f);
 	return length;
 }
 
 static int rpc(int rpc_num, int n_args, ...)
 {
-	printf("rpc_num=%d n_args=%d\n", rpc_num, n_args);
+	send_sync();
+	send_char(MSGTYPE_RPC_REQUEST);
+	send_sint(rpc_num);
+	send_char(n_args);
 
 	va_list args;
 	va_start(args, n_args);
 	while(n_args--)
-		printf("%d\n", va_arg(args, int));
+		send_int(va_arg(args, int));
 	va_end(args);
 
-	return 1;
+	return receive_int();
 }
 
 static void gpio_set(int channel, int level)
@@ -98,9 +136,12 @@ int main(void)
 	while(1) {
 		length = download_kernel(kbuf, sizeof(kbuf));
 		if(length > 0) {
-			load_elf(syscalls, kbuf, length, kcode, sizeof(kcode));
+			if(load_elf(syscalls, kbuf, length, kcode, sizeof(kcode))) {
 				flush_cpu_icache();
 				k();
+				send_sync();
+				send_char(MSGTYPE_KERNEL_FINISHED);
+			}
 		}
 	}