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>

4 files changed, 35 insertions, 55 deletions

diff --git a/src/stm/ao_arch.h b/src/stm/ao_arch.h
index e270199e..007f7e2e 100644
--- a/src/stm/ao_arch.h
+++ b/src/stm/ao_arch.h
@@ -123,42 +123,6 @@ void ao_lcd_font_init(void);
 
 void ao_lcd_font_string(char *s);
 
-char
-ao_serial1_getchar(void);
-
-void
-ao_serial1_putchar(char c);
-
-char
-ao_serial1_pollchar(void);
-
-void
-ao_serial1_set_speed(uint8_t speed);
-
-char
-ao_serial2_getchar(void);
-
-void
-ao_serial2_putchar(char c);
-
-char
-ao_serial2_pollchar(void);
-
-void
-ao_serial2_set_speed(uint8_t speed);
-
-char
-ao_serial3_getchar(void);
-
-void
-ao_serial3_putchar(char c);
-
-char
-ao_serial3_pollchar(void);
-
-void
-ao_serial3_set_speed(uint8_t speed);
-
 extern const uint32_t	ao_radio_cal;
 
 void
diff --git a/src/stm/ao_arch_funcs.h b/src/stm/ao_arch_funcs.h
index d6ab1465..87bbe73e 100644
--- a/src/stm/ao_arch_funcs.h
+++ b/src/stm/ao_arch_funcs.h
@@ -210,6 +210,26 @@ ao_i2c_recv(void *block, uint16_t len, uint8_t i2c_index, uint8_t stop);
 void
 ao_i2c_init(void);
 
+/* ao_serial_stm.c */
+struct ao_stm_usart {
+	struct ao_fifo		rx_fifo;
+	struct ao_fifo		tx_fifo;
+	struct stm_usart	*reg;
+	uint8_t			tx_started;
+};
+
+#if HAS_SERIAL_1
+extern struct ao_stm_usart	ao_stm_usart1;
+#endif
+
+#if HAS_SERIAL_2
+extern struct ao_stm_usart	ao_stm_usart2;
+#endif
+
+#if HAS_SERIAL_3
+extern struct ao_stm_usart	ao_stm_usart3;
+#endif
+
 #define ARM_PUSH32(stack, val)	(*(--(stack)) = (val))
 
 static inline uint32_t
diff --git a/src/stm/ao_serial_stm.c b/src/stm/ao_serial_stm.c
index 00409f4a..94138edc 100644
--- a/src/stm/ao_serial_stm.c
+++ b/src/stm/ao_serial_stm.c
@@ -17,13 +17,6 @@
 
 #include <ao.h>
 
-struct ao_stm_usart {
-	struct ao_fifo		rx_fifo;
-	struct ao_fifo		tx_fifo;
-	struct stm_usart	*reg;
-	uint8_t			tx_started;
-};
-
 void
 ao_debug_out(char c)
 {
@@ -78,16 +71,19 @@ ao_usart_getchar(struct ao_stm_usart *usart)
 	return c;
 }
 
-char
+int
 ao_usart_pollchar(struct ao_stm_usart *usart)
 {
-	char	c;
+	int	c;
 	
 	ao_arch_block_interrupts();
 	if (ao_fifo_empty(usart->rx_fifo))
 		c = AO_READ_AGAIN;
-	else
-		ao_fifo_remove(usart->rx_fifo,c);
+	else {
+		uint8_t	u;
+		ao_fifo_remove(usart->rx_fifo,u);
+		c = u;
+	}
 	ao_arch_release_interrupts();
 	return c;
 }
@@ -201,7 +197,7 @@ ao_serial1_putchar(char c)
 	ao_usart_putchar(&ao_stm_usart1, c);
 }
 
-char
+int
 ao_serial1_pollchar(void)
 {
 	return ao_usart_pollchar(&ao_stm_usart1);
@@ -232,7 +228,7 @@ ao_serial2_putchar(char c)
 	ao_usart_putchar(&ao_stm_usart2, c);
 }
 
-char
+int
 ao_serial2_pollchar(void)
 {
 	return ao_usart_pollchar(&ao_stm_usart2);
@@ -263,7 +259,7 @@ ao_serial3_putchar(char c)
 	ao_usart_putchar(&ao_stm_usart3, c);
 }
 
-char
+int
 ao_serial3_pollchar(void)
 {
 	return ao_usart_pollchar(&ao_stm_usart3);
diff --git a/src/stm/ao_usb_stm.c b/src/stm/ao_usb_stm.c
index d93a0c17..9379e5cd 100644
--- a/src/stm/ao_usb_stm.c
+++ b/src/stm/ao_usb_stm.c
@@ -873,10 +873,10 @@ _ao_usb_out_recv(void)
 	ao_usb_set_stat_rx(AO_USB_OUT_EPR, STM_USB_EPR_STAT_RX_VALID);
 }
 
-static char
+static int
 _ao_usb_pollchar(void)
 {
-	char c;
+	uint8_t c;
 
 	if (!ao_usb_running)
 		return AO_READ_AGAIN;
@@ -896,10 +896,10 @@ _ao_usb_pollchar(void)
 	return c;
 }
 
-char
+int
 ao_usb_pollchar(void)
 {
-	char	c;
+	int	c;
 	ao_arch_block_interrupts();
 	c = _ao_usb_pollchar();
 	ao_arch_release_interrupts();
@@ -909,7 +909,7 @@ ao_usb_pollchar(void)
 char
 ao_usb_getchar(void)
 {
-	char	c;
+	int	c;
 
 	ao_arch_block_interrupts();
 	while ((c = _ao_usb_pollchar()) == AO_READ_AGAIN)