i think i managed to make a working uart driver for the new interface??HEADmain

3 files changed, 38 insertions, 5 deletions

diff --git a/src/crt0.S b/src/crt0.S
index 97228c1..49d8493 100644
--- a/src/crt0.S
+++ b/src/crt0.S
@@ -62,6 +62,9 @@ _start:
 #endif
   call    __libc_init_array       # Run global initialization functions
 
+  # initialize UART
+  call uart_init
+
   call    main
   call    exit
 _exit: j _exit
diff --git a/src/syscalls.c b/src/syscalls.c
index 443c9cd..5c5d577 100644
--- a/src/syscalls.c
+++ b/src/syscalls.c
@@ -44,17 +44,21 @@ int _lseek(int file, int ptr, int dir) { return 0; }
 int _open(const char *name, int flags, int mode) { return -1; }
 
 int _read(int file, char *buf, int len) {
-  while (!uart_rx_ready())
-    ;
+  uint32_t uart_data;
+  do {
+    uart_data = UART_RXDATA;
+  } while (uart_data & UART_RXDATA_EMPTY);
 
   int i;
   for (i = 0; i < len; i++) {
-    if (!uart_rx_ready()) {
+    buf[i] = (char)uart_data;
+    uart_data = UART_RXDATA;
+    if (uart_data & UART_RXDATA_EMPTY) {
       break;
     }
-    buf[i] = uart_getc_nonblocking();
   }
-  return i;
+  // *(volatile int *)1 = i;
+  return i + 1;
 }
 
 void *_sbrk(int incr) {
@@ -91,9 +95,11 @@ int _wait(int *status) {
 }
 
 int _write(int file, char *buf, int len) {
+  // uart_puts("_write called\n");
   for (int i = 0; i < len; i++) {
     uart_putc(buf[i]);
   }
+  // *(volatile int *)0 = len;
   return len;
 }
 
diff --git a/src/uart.c b/src/uart.c
new file mode 100644
index 0000000..86bc01f
--- /dev/null
+++ b/src/uart.c
@@ -0,0 +1,24 @@
+#include "uart.h"
+
+void uart_init(void) {
+  UART_TXCTRL = UART_TXCTRL_TXEN;
+  UART_RXCTRL = UART_RXCTRL_RXEN;
+}
+
+void uart_putc(char c) {
+  while (UART_TXDATA & UART_TXDATA_FULL) {}
+  UART_TXDATA = (uint32_t)c;
+}
+
+void uart_puts(const char* s) {
+  while (*s)
+    uart_putc(*s++);
+}
+
+char uart_getc(void) {
+  uint32_t data;
+  do {
+    data = UART_RXDATA;
+  } while (data & UART_RXDATA_EMPTY);
+  return (char)data;
+}