From 9a4df61005d0ea219abe70f83b7291db75275218 Mon Sep 17 00:00:00 2001
From: Hauke Petersen <hauke.petersen@fu-berlin.de>
Date: Fri, 1 Apr 2016 10:54:55 +0200
Subject: [PATCH 1/2] drivers/periph: fixed UNDEF values to UINT_MAX

---
 drivers/include/periph/adc.h   | 4 +++-
 drivers/include/periph/i2c.h   | 3 ++-
 drivers/include/periph/pwm.h   | 3 ++-
 drivers/include/periph/timer.h | 4 +++-
 drivers/include/periph/uart.h  | 3 ++-
 5 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/include/periph/adc.h b/drivers/include/periph/adc.h
index 6f60181f1a..2f7a1d685b 100644
--- a/drivers/include/periph/adc.h
+++ b/drivers/include/periph/adc.h
@@ -43,6 +43,8 @@
 #ifndef PERIPH_ADC_H
 #define PERIPH_ADC_H
 
+#include <limits.h>
+
 #include "periph_cpu.h"
 #include "periph_conf.h"
 
@@ -73,7 +75,7 @@ typedef unsigned int adc_t;
  * @{
  */
 #ifndef ADC_UNDEF
-#define ADC_UNDEF           (0xffff)
+#define ADC_UNDEF           (UINT_MAX)
 #endif
 /** @} */
 
diff --git a/drivers/include/periph/i2c.h b/drivers/include/periph/i2c.h
index 81ffebc4d6..e1af640d43 100644
--- a/drivers/include/periph/i2c.h
+++ b/drivers/include/periph/i2c.h
@@ -55,6 +55,7 @@
 #define I2C_H
 
 #include <stdint.h>
+#include <limits.h>
 
 #include "periph_cpu.h"
 /**
@@ -91,7 +92,7 @@ extern "C" {
  * @{
  */
 #ifndef I2C_UNDEF
-#define I2C_UNDEF           (-1)
+#define I2C_UNDEF           (UINT_MAX)
 #endif
 /** @} */
 
diff --git a/drivers/include/periph/pwm.h b/drivers/include/periph/pwm.h
index a54d1bef8c..f469748be7 100644
--- a/drivers/include/periph/pwm.h
+++ b/drivers/include/periph/pwm.h
@@ -22,6 +22,7 @@
 #define PERIPH_PWM_H
 
 #include <stdint.h>
+#include <limits.h>
 
 #include "periph_cpu.h"
 #include "periph_conf.h"
@@ -53,7 +54,7 @@ extern "C" {
  * @{
  */
 #ifndef PWM_UNDEF
-#define PWM_UNDEF           (-1)
+#define PWM_UNDEF           (UINT_MAX)
 #endif
 /** @} */
 
diff --git a/drivers/include/periph/timer.h b/drivers/include/periph/timer.h
index c60bccea9a..9408a78239 100644
--- a/drivers/include/periph/timer.h
+++ b/drivers/include/periph/timer.h
@@ -21,6 +21,8 @@
 #ifndef PERIPH_TIMER_H
 #define PERIPH_TIMER_H
 
+#include <limits.h>
+
 #include "periph_cpu.h"
 /** @todo remove dev_enums.h include once all platforms are ported to the updated periph interface */
 #include "periph/dev_enums.h"
@@ -42,7 +44,7 @@ extern "C" {
  * @brief   Default value for timer not defined
  */
 #ifndef TIMER_UNDEF
-#define TIMER_UNDEF         (-1)
+#define TIMER_UNDEF         (UINT_MAX)
 #endif
 
 /**
diff --git a/drivers/include/periph/uart.h b/drivers/include/periph/uart.h
index 42fa74e509..d245180b7a 100644
--- a/drivers/include/periph/uart.h
+++ b/drivers/include/periph/uart.h
@@ -46,6 +46,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <limits.h>
 
 #include "periph_cpu.h"
 #include "periph_conf.h"
@@ -79,7 +80,7 @@ typedef unsigned int uart_t;
  * @{
  */
 #ifndef UART_UNDEF
-#define UART_UNDEF          (-1)
+#define UART_UNDEF          (UINT_MAX)
 #endif
 /** @} */
 

From 1367df0805159ace422991d9ab94b8d68c41e017 Mon Sep 17 00:00:00 2001
From: Hauke Petersen <hauke.petersen@fu-berlin.de>
Date: Fri, 8 Apr 2016 10:49:34 +0200
Subject: [PATCH 2/2] tests/periph_uart: fixed signedness issues

---
 tests/periph_uart/main.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/tests/periph_uart/main.c b/tests/periph_uart/main.c
index b741e698c4..940e745643 100644
--- a/tests/periph_uart/main.c
+++ b/tests/periph_uart/main.c
@@ -51,15 +51,15 @@ static char printer_stack[THREAD_STACKSIZE_MAIN];
 
 static int parse_dev(char *arg)
 {
-    int dev = atoi(arg);
-    if (dev == UART_STDIO_DEV) {
-        printf("Error: The selected UART_DEV(%i) is used for the shell!\n", dev);
-        return -2;
-    }
-    if (dev < 0 || (uart_t) dev >= UART_NUMOF) {
+    unsigned dev = (unsigned)atoi(arg);
+    if (dev >= UART_NUMOF) {
         printf("Error: Invalid UART_DEV device specified (%i).\n", dev);
         return -1;
     }
+    else if (UART_DEV(dev) == UART_STDIO_DEV) {
+        printf("Error: The selected UART_DEV(%i) is used for the shell!\n", dev);
+        return -2;
+    }
     return dev;
 }
 
@@ -179,7 +179,7 @@ int main(void)
     printf("UART used for STDIO (the shell): UART_DEV(%i)\n\n", UART_STDIO_DEV);
 
     /* initialize ringbuffers */
-    for (uart_t i = 0; i < UART_NUMOF; i++) {
+    for (unsigned i = 0; i < UART_NUMOF; i++) {
         ringbuffer_init(&(ctx[i].rx_buf), ctx[i].rx_mem, UART_BUFSIZE);
     }