Fix gcc warnings about comparing signed and unsigned values

warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

Author: pdp7

setup.py

@@ -18,7 +18,7 @@
 else:
     kernel41 = None
 
-CFLAGS = ['-Wall', '-Werror', '-Wextra', '-Wno-missing-field-initializers', '-Wno-sign-compare']
+CFLAGS = ['-Wall', '-Werror', '-Wextra', '-Wno-missing-field-initializers' ]
 
 classifiers = ['Development Status :: 3 - Alpha',
                'Operating System :: POSIX :: Linux',

source/c_pwm.c

@@ -489,7 +489,7 @@ BBIO_err pwm_start(const char *key, float duty, float freq, int polarity)
 {
     BBIO_err err;
     char buffer[20];
-    int len;
+    ssize_t len;
 
     struct pwm_exp *pwm = lookup_exported_pwm(key);
     if (pwm == NULL) {
@@ -518,7 +518,7 @@ BBIO_err pwm_start(const char *key, float duty, float freq, int polarity)
     len = read(pwm->period_fd, buffer, sizeof(buffer));
     if (len < 0) {
         return BBIO_SYSFS;
-    } else if (len >= sizeof(buffer)) {
+    } else if (len >= (ssize_t)sizeof(buffer)) {
         // If this is the case, there's more in the file.
         // This should never happen, as it would mean that
         // the period is 10^8 seconds
@@ -534,7 +534,7 @@ BBIO_err pwm_start(const char *key, float duty, float freq, int polarity)
     len = read(pwm->duty_fd, buffer, sizeof(buffer));
     if (len < 0) {
         return BBIO_SYSFS;
-    } else if (len >= sizeof(buffer)) {
+    } else if (len >= (ssize_t)sizeof(buffer)) {
         // If this is the case, there's more in the file.
         // This should never happen, as it would mean that
         // the period is 10^8 seconds

source/common.c

@@ -339,7 +339,7 @@ BBIO_err get_pwm_key(const char *input, char *key)
 
 // TODO: fix warning
 // source/common.c:344:14: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
-BBIO_err get_adc_ain(const char *key, unsigned int *ain)
+BBIO_err get_adc_ain(const char *key, int *ain)
 {
     *ain = lookup_ain_by_key(key);
 

source/common.h

@@ -79,7 +79,7 @@ int gpio_direction[120];
 
 BBIO_err get_gpio_number(const char *key, unsigned int *gpio);
 BBIO_err get_pwm_key(const char *input, char *key);
-BBIO_err get_adc_ain(const char *key, unsigned int *ain);
+BBIO_err get_adc_ain(const char *key, int *ain);
 BBIO_err get_uart_device_tree_name(const char *name, char *dt);
 BBIO_err build_path(const char *partial_path, const char *prefix, char *full_path, size_t full_path_len);
 int get_spi_bus_path_number(unsigned int spi);

source/py_adc.c

@@ -57,7 +57,7 @@ static PyObject *py_setup_adc(__attribute__ ((unused)) PyObject *self, __attribu
 // python function read(channel)
 static PyObject *py_read(__attribute__ ((unused)) PyObject *self, PyObject *args)
 {
-    unsigned int ain;
+    int ain;
     float value;
     char *channel;
     PyObject *py_value;
@@ -100,7 +100,7 @@ static PyObject *py_read(__attribute__ ((unused)) PyObject *self, PyObject *args
 // python function read(channel)
 static PyObject *py_read_raw(__attribute__ ((unused)) PyObject *self, PyObject *args)
 {
-    unsigned int ain;
+    int ain;
     float value;
     char *channel;
     PyObject *py_value;

source/spimodule.c

@@ -169,7 +169,8 @@ static PyObject *
 SPI_readbytes(SPI *self, PyObject *args)
 {
 	uint8_t	rxbuf[MAXMSGLEN];
-	int		status, len, ii;
+	ssize_t len;
+	int		status, ii;
 	PyObject	*list;
 
 	if (!PyArg_ParseTuple(args, "i:read", &len))
@@ -178,7 +179,7 @@ SPI_readbytes(SPI *self, PyObject *args)
 	/* read at least 1 byte, no more than 1024 */
 	if (len < 1)
 		len = 1;
-	else if (len > sizeof(rxbuf))
+	else if (len > (ssize_t)sizeof(rxbuf))
 		len = sizeof(rxbuf);
 
 	memset(rxbuf, 0, sizeof rxbuf);
@@ -716,7 +717,7 @@ SPI_open(SPI *self, PyObject *args, PyObject *kwds)
 			"Bus and/or device number is invalid.");
 		return NULL;
 	}
-	if (load_device_tree(device_tree_name) == -1) {
+	if (load_device_tree(device_tree_name) == BBIO_CAPE) {
 		PyErr_SetFromErrno(PyExc_IOError);
 		return NULL;
 	}