implement getchar() and putchar() in terms of supervisor call

1 files changed, 27 insertions, 0 deletions

diff --git a/PL0_utils.c b/PL0_utils.c
new file mode 100644
index 0000000..2cede90
--- /dev/null
+++ b/PL0_utils.c
@@ -0,0 +1,27 @@
+#include <stddef.h>
+#include <stdint.h>
+
+#include "svc_interface.h"
+
+// most generic definition possible
+// the actual function defined in svc.S
+uint32_t svc(enum svc_type, ...);
+
+void putchar(int character)
+{
+  svc(UART_PUTCHAR, character);
+}
+
+int getchar(void)
+{
+  return svc(UART_GETCHAR);
+}
+
+void puts(char *string)
+{
+  for (size_t i = 0; string[i]; i++)
+    putchar(string[i]);
+
+  putchar('\n');
+  putchar('\r');
+}