From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Wed, 27 Jul 2016 19:13:41 +0000 (+0200)
Subject: Add a function to get the number of USB cards.
X-Git-Tag: 0.5~4
X-Git-Url: https://git.sesse.net/?p=bmusb;a=commitdiff_plain;h=28c6df233b806a580281eb1ae242fa108af3eb09

Add a function to get the number of USB cards.
---

diff --git a/bmusb.cpp b/bmusb.cpp
index 09473fd..fd323a6 100644
--- a/bmusb.cpp
+++ b/bmusb.cpp
@@ -884,6 +884,8 @@ void BMUSBCapture::usb_thread_func()
 	}
 }
 
+namespace {
+
 struct USBCardDevice {
 	uint16_t product;
 	uint8_t bus, port;
@@ -912,7 +914,7 @@ string get_card_description(int id, uint8_t bus, uint8_t port, uint16_t product)
 	return buf;
 }
 
-libusb_device_handle *open_card(int card_index, string *description)
+vector<USBCardDevice> find_all_cards()
 {
 	libusb_device **devices;
 	ssize_t num_devices = libusb_get_device_list(nullptr, &devices);
@@ -950,6 +952,13 @@ libusb_device_handle *open_card(int card_index, string *description)
 		return a.port < b.port;
 	});
 
+	return found_cards;
+}
+
+libusb_device_handle *open_card(int card_index, string *description)
+{
+	vector<USBCardDevice> found_cards = find_all_cards();
+
 	for (size_t i = 0; i < found_cards.size(); ++i) {
 		string tmp_description = get_card_description(i, found_cards[i].bus, found_cards[i].port, found_cards[i].product);
 		fprintf(stderr, "%s\n", tmp_description.c_str());
@@ -1000,6 +1009,18 @@ libusb_device_handle *open_card(unsigned card_index, libusb_device *dev, string
 	return devh;
 }
 
+}  // namespace
+
+int BMUSBCapture::num_cards()
+{
+	vector<USBCardDevice> found_cards = find_all_cards();
+	int ret = found_cards.size();
+	for (size_t i = 0; i < found_cards.size(); ++i) {
+		libusb_unref_device(found_cards[i].device);
+	}
+	return ret;
+}
+
 void BMUSBCapture::configure_card()
 {
 	if (video_frame_allocator == nullptr) {
diff --git a/bmusb/bmusb.h b/bmusb/bmusb.h
index 21cbc40..22a6655 100644
--- a/bmusb/bmusb.h
+++ b/bmusb/bmusb.h
@@ -175,6 +175,10 @@ class BMUSBCapture : public CaptureInterface {
 
 	~BMUSBCapture() {}
 
+	// Note: Cards could be unplugged and replugged between this call and
+	// actually opening the card (in configure_card()).
+	static int num_cards();
+
 	std::map<uint32_t, VideoMode> get_available_video_modes() const override;
 	uint32_t get_current_video_mode() const override;
 	void set_video_mode(uint32_t video_mode_id) override;