altos: Replace __critical usage with ao_arch_critical as needed

sdcc offers __critical as a machine-independent way to block
interrupts, but as gcc doesn't, we need to use a compiler-independent
construct instead. ao_arch_critical has been around since the AVR
port, but some old __critical usages remained.

This fixes a bunch of random hangs when communicating with MM over USB
or the radio as the various stdio loops were running without
interrupts blocked between the test and the sleep.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 14 insertions, 12 deletions

diff --git a/src/core/ao_stdio.c b/src/core/ao_stdio.c
index 656b23c9..8cf66a23 100644
--- a/src/core/ao_stdio.c
+++ b/src/core/ao_stdio.c
@@ -96,21 +96,23 @@ flush(void)
 __xdata uint8_t ao_stdin_ready;
 
 char
-getchar(void) __reentrant __critical
+getchar(void) __reentrant
 {
 	char c;
-	int8_t stdio = ao_cur_stdio;
+	ao_arch_critical(
+		int8_t stdio = ao_cur_stdio;
 
-	for (;;) {
-		c = ao_stdios[stdio].pollchar();
-		if (c != AO_READ_AGAIN)
-			break;
-		if (++stdio == ao_num_stdios)
-			stdio = 0;
-		if (stdio == ao_cur_stdio)
-			ao_sleep(&ao_stdin_ready);
-	}
-	ao_cur_stdio = stdio;
+		for (;;) {
+			c = ao_stdios[stdio].pollchar();
+			if (c != AO_READ_AGAIN)
+				break;
+			if (++stdio == ao_num_stdios)
+				stdio = 0;
+			if (stdio == ao_cur_stdio)
+				ao_sleep(&ao_stdin_ready);
+		}
+		ao_cur_stdio = stdio;
+		);
 	return c;
 }