Access Uart through rotating buffer

1 files changed, 38 insertions, 0 deletions

diff --git a/src/drivers/uart.c b/src/drivers/uart.c
index f6fe79b..c5514ce 100644
--- a/src/drivers/uart.c
+++ b/src/drivers/uart.c
@@ -1,5 +1,43 @@
 #include <drivers/uart.h>
 
+#define UART_BUFFER_SIZE 0x100
+struct UartBuffer {
+	char buffer[UART_BUFFER_SIZE];
+	unsigned long roffset;
+	unsigned long woffset;
+} ubuffer;
+
+void uart_init(void)
+{
+	ubuffer.roffset = 0;
+	ubuffer.woffset = 0;
+}
+
+// s = zero-terminated string
+void* uart_print(char* s)
+{
+	char* ptr = s;
+	while (1) {
+		if (*ptr == 0)
+			break;
+		ubuffer.buffer[ubuffer.woffset] = *ptr;
+		if ((ubuffer.woffset+1)%UART_BUFFER_SIZE == ubuffer.roffset)
+			return ptr;
+		ubuffer.woffset++;
+		ubuffer.woffset %= UART_BUFFER_SIZE;
+		ptr += 1;
+	}
+	return 0;
+}
+
+void uart_flush(void)
+{
+	while (ubuffer.roffset != ubuffer.woffset) {
+		uart_char(ubuffer.buffer[ubuffer.roffset++]);
+		ubuffer.roffset %= UART_BUFFER_SIZE;
+	}
+}
+
 void uart_10(unsigned long val)
 {
 	unsigned long t = val;