altos: Make stdio 8-bit clean by making pollchar return int

We were stealing one value (0xff) in the return value from pollchar to
indicate 'not ready yet'. Instead of doing that, use the integer value
-1 and have pollchar return an int instead of a char. That
necessitated cleaning a few other bits to make sure that 0xff wouldn't
get promoted to -1 on accident.

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

1 files changed, 1 insertions, 1 deletions

diff --git a/src/core/ao_packet.h b/src/core/ao_packet.h
index 0eafd3b2..08b184d6 100644
--- a/src/core/ao_packet.h
+++ b/src/core/ao_packet.h
@@ -62,7 +62,7 @@ ao_packet_flush(void);
 void
 ao_packet_putchar(char c) __reentrant;
 
-char
+int
 ao_packet_pollchar(void);
 
 #if PACKET_HAS_MASTER