contrib: add a HOWTO for new users

[libam7xxx.git] / src / am7xxx.c

diff --git a/src/am7xxx.c b/src/am7xxx.c
index b4e3e54..84d7e9c 100644 (file)
--- a/src/am7xxx.c
+++ b/src/am7xxx.c
@@ -53,7 +53,7 @@
 
 static void log_message(am7xxx_context *ctx,
                        int level,
-                       const char *function,
+                       const char *function_name,
                        int line,
                        const char *fmt,
                        ...) __attribute__ ((format (printf, 5, 6)));
@@ -341,7 +341,7 @@ static inline unsigned int in_80chars(unsigned int i)
 {
        /* The 3 below is the length of "xx " where xx is the hex string
         * representation of a byte */
-       return ((i+1) % (80/3));
+       return ((i + 1) % (80 / 3));
 }
 
 static void trace_dump_buffer(am7xxx_context *ctx, const char *message,
@@ -381,8 +381,9 @@ static void trace_dump_buffer(am7xxx_context *ctx, const char *message,
 static int read_data(am7xxx_device *dev, uint8_t *buffer, unsigned int len)
 {
        int ret;
-       int transferred = 0;
+       int transferred;
 
+       transferred = 0;
        ret = libusb_bulk_transfer(dev->usb_device, 0x81, buffer, len, &transferred, 0);
        if (ret != 0 || (unsigned int)transferred != len) {
                error(dev->ctx, "%s. Transferred: %d (expected %u)\n",
@@ -398,10 +399,11 @@ static int read_data(am7xxx_device *dev, uint8_t *buffer, unsigned int len)
 static int send_data(am7xxx_device *dev, uint8_t *buffer, unsigned int len)
 {
        int ret;
-       int transferred = 0;
+       int transferred;
 
        trace_dump_buffer(dev->ctx, "sending -->", buffer, len);
 
+       transferred = 0;
        ret = libusb_bulk_transfer(dev->usb_device, 0x1, buffer, len, &transferred, 0);
        if (ret != 0 || (unsigned int)transferred != len) {
                error(dev->ctx, "%s. Transferred: %d (expected %u)\n",
@@ -626,7 +628,7 @@ static int send_command(am7xxx_device *dev, am7xxx_packet_type type)
  * set up */
 static void log_message(am7xxx_context *ctx,
                        int level,
-                       const char *function,
+                       const char *function_name,
                        int line,
                        const char *fmt,
                        ...)
@@ -634,8 +636,8 @@ static void log_message(am7xxx_context *ctx,
        va_list ap;
 
        if (level == AM7XXX_LOG_FATAL || (ctx && level <= ctx->log_level)) {
-               if (function) {
-                       fprintf(stderr, "%s", function);
+               if (function_name) {
+                       fprintf(stderr, "%s", function_name);
                        if (line)
                                fprintf(stderr, "[%d]", line);
                        fprintf(stderr, ": ");
@@ -662,7 +664,7 @@ static am7xxx_device *add_new_device(am7xxx_context *ctx,
 
        new_device = malloc(sizeof(*new_device));
        if (new_device == NULL) {
-               fatal("cannot allocate a new device (%s)\n", strerror(errno));
+               debug(ctx, "cannot allocate a new device (%s)\n", strerror(errno));
                return NULL;
        }
        memset(new_device, 0, sizeof(*new_device));
@@ -718,7 +720,6 @@ static int open_device(am7xxx_context *ctx,
 
        /* the usb device has already been opened */
        if ((*dev)->usb_device) {
-               debug(ctx, "(*dev)->usb_device already set\n");
                ret = 1;
                goto out;
        }
@@ -799,7 +800,7 @@ static int open_device(am7xxx_context *ctx,
        }
 
        if (current_configuration != (*dev)->desc->configuration) {
-               debug(ctx, "libusb configuration changed (expected: %hhu, current: %hhu\n",
+               debug(ctx, "libusb configuration changed (expected: %hhu, current: %d)\n",
                      (*dev)->desc->configuration, current_configuration);
                ret = -EINVAL;
                goto out_libusb_release_interface;
@@ -1092,8 +1093,7 @@ AM7XXX_PUBLIC int am7xxx_init(am7xxx_context **ctx)
        *ctx = malloc(sizeof(**ctx));
        if (*ctx == NULL) {
                fatal("cannot allocate the context (%s)\n", strerror(errno));
-               ret = -ENOMEM;
-               goto out;
+               return -ENOMEM;
        }
        memset(*ctx, 0, sizeof(**ctx));
 
@@ -1101,8 +1101,10 @@ AM7XXX_PUBLIC int am7xxx_init(am7xxx_context **ctx)
        (*ctx)->log_level = AM7XXX_LOG_TRACE;
 
        ret = libusb_init(&((*ctx)->usb_context));
-       if (ret < 0)
+       if (ret < 0) {
+               error(*ctx, "libusb_init failed: %s\n", libusb_error_name(ret));
                goto out_free_context;
+       }
 
        libusb_set_debug((*ctx)->usb_context, LIBUSB_LOG_LEVEL_INFO);
 
@@ -1177,14 +1179,14 @@ AM7XXX_PUBLIC int am7xxx_open_device(am7xxx_context *ctx, am7xxx_device **dev,
         * is the first one to be sent to the device in order for it to
         * successfully return the correct device information.
         *
-        * So, if there is not a cached version of it (from a previous open),
-        * we ask for device info at open time,
+        * NOTE: am7xxx_get_device_info() will fetch the actual device info
+        * from the device only the very first time it's called for a given
+        * device, otherwise, it'll return a cached version of the device info
+        * (from a previous call to am7xxx_open_device(), for instance).
         */
-       if ((*dev)->device_info == NULL) {
-               ret = am7xxx_get_device_info(*dev, NULL);
-               if (ret < 0)
-                       error(ctx, "cannot get device info\n");
-       }
+       ret = am7xxx_get_device_info(*dev, NULL);
+       if (ret < 0)
+               error(ctx, "cannot get device info\n");
 
 out:
        return ret;
@@ -1211,10 +1213,9 @@ AM7XXX_PUBLIC int am7xxx_get_device_info(am7xxx_device *dev,
        int ret;
        struct am7xxx_header h;
 
-       if (dev->device_info) {
-               memcpy(device_info, dev->device_info, sizeof(*device_info));
-               return 0;
-       }
+       /* if there is a cached copy of the device info, just return that */
+       if (dev->device_info)
+               goto return_value;
 
        ret = send_command(dev, AM7XXX_PACKET_TYPE_DEVINFO);
        if (ret < 0)
@@ -1248,6 +1249,9 @@ AM7XXX_PUBLIC int am7xxx_get_device_info(am7xxx_device *dev,
        dev->device_info->unknown1 = h.header_data.devinfo.unknown1;
 #endif
 
+return_value:
+       if (device_info)
+               memcpy(device_info, dev->device_info, sizeof(*device_info));
        return 0;
 }
 
@@ -1258,7 +1262,6 @@ AM7XXX_PUBLIC int am7xxx_calc_scaled_image_dimensions(am7xxx_device *dev,
                                        unsigned int *scaled_width,
                                        unsigned int *scaled_height)
 {
-
        am7xxx_device_info device_info;
        float width_ratio;
        float height_ratio;