bricks/_common/mphalport: Fix flush to new line.

- Fixes doing this only once by setting ended_on_new_line.
- Restores original  mp_hal_stdout_tx_flush without the new line for compatibility with sys_stdio_mphal.

Author: laurensvalk

bricks/_common/micropython.c

@@ -69,7 +69,7 @@ bool pbsys_main_stdin_event(uint8_t c) {
 static void print_final_exception(mp_obj_t exc, int ret) {
 
     // Ensure exception prints on new line.
-    mp_hal_stdout_tx_flush();
+    pb_stdout_flush_to_new_line();
 
     nlr_buf_t nlr;
     nlr.ret_val = NULL;
@@ -402,7 +402,7 @@ void pbsys_main_run_program(pbsys_main_program_t *program) {
 
     // Ensure everything is written before the user application is considered
     // done, so that the host does not receive stdout after receiving stop.
-    mp_hal_stdout_tx_flush();
+    pb_stdout_flush_to_new_line();
 }
 
 void pbsys_main_run_program_cleanup(void) {

bricks/_common/mphalport.c

@@ -87,15 +87,28 @@ void mp_hal_stdout_tx_flush(void) {
     while (!pbsys_host_tx_is_idle()) {
         MICROPY_VM_HOOK_LOOP;
     }
+}
+
+/**
+ * Flushes stdout and adds a newline if the last printed character was not a
+ * new line.
+ */
+void pb_stdout_flush_to_new_line(void) {
+
+    mp_hal_stdout_tx_flush();
 
     // A program may be interrupted in the middle of a long print, or the user
     // may have printed without a newline. Ensure we end on a new line.
     if (!ended_on_new_line) {
+
+        // We have just flushed, so we should be able to easily buffer two more
+        // characters. It is only for aesthetics, so it is not critical if this
+        // fails. We flush again below just in case.
         const char *eol = "\r\n";
         uint32_t size = strlen(eol);
         pbsys_host_stdout_write((const uint8_t *)eol, &size);
-        while (!pbsys_host_tx_is_idle()) {
-            MICROPY_VM_HOOK_LOOP;
-        }
+        ended_on_new_line = true;
+
+        mp_hal_stdout_tx_flush();
     }
 }

bricks/_common/mphalport.h

@@ -9,5 +9,4 @@ void mp_hal_set_interrupt_char(int c);
 #define mp_hal_ticks_cpu() 0
 #define mp_hal_delay_us pbdrv_clock_busy_delay_us
 
-// Platform-specific code to run on completing the poll hook.
-void pb_event_poll_hook_leave(void);
+void pb_stdout_flush_to_new_line(void);

bricks/nxt/mphalport.c

@@ -92,3 +92,7 @@ mp_uint_t mp_hal_stdout_tx_strn(const char *str, size_t len) {
 void mp_hal_stdout_tx_flush(void) {
     // currently not buffered
 }
+
+void pb_stdout_flush_to_new_line(void) {
+    // currently not buffered
+}