1 files changed, 95 insertions, 0 deletions
diff --git a/lib/hidpp.h b/lib/hidpp.h
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--- /dev/null
+++ b/lib/hidpp.h
@@ -0,0 +1,95 @@
+/*
+ * Generic HID++ definitions and helpers.
+ *
+ * Copyright (C) 2014 Peter Wu <peter@lekensteyn.nl>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HIDPP_H
+#define HIDPP_H
+#include <stdbool.h>
+#include <stdint.h>
+
+#define MAX_DEVICES 6
+
+/* report ID for short and long HID++ messages */
+#define HIDPP_SHORT             0x10
+#define HIDPP_SHORT_LEN         7
+#define HIDPP_LONG              0x11
+#define HIDPP_LONG_LEN          20
+
+typedef struct HidppMessage {
+	uint8_t report_id;
+	uint8_t device_index;
+	union {
+		struct {
+			uint8_t sub_id;
+			uint8_t address;
+		}; /**< HID++ 1.0 naming */
+		struct {
+			uint8_t feature_id;
+			uint8_t func; /* (func << 4) | swId */
+		}; /**< HID++ 2.0 naming */
+	};
+	union {
+		uint8_t params[3];
+		uint8_t params_l[16];
+	};
+} HidppMessage;
+
+/**
+ * Locates a /dev/hidrawX device for a Logitech Unifying receiver.
+ *
+ * @return A file descriptor to the hidraw device which must be closed with
+ * close().
+ */
+int hidpp_open(void);
+
+/**
+ * Callback function for new messages.
+ *
+ * @param msg[in]   An incoming HID++ message.
+ * @param userdata  Data passed through the invoker.
+ * @return true iff the no more messages should be read.
+ */
+typedef bool hidpp_msg_cb_t(HidppMessage *msg, void *userdata);
+
+/**
+ * Sends the message to the receiver device.
+ *
+ * @param fd        File descriptor of the hidraw device.
+ * @param msg[in]   The report to be delivered.
+ * @return true iff the message is properly formatted and the dispatch is
+ * successful.
+ */
+bool hidpp_write_report(int fd, struct HidppMessage *msg);
+
+/**
+ * Reads messages and try to accept on one of them.
+ *
+ * @param fd        File descriptor of the hidraw device.
+ * @param timeout   Timeout for this function in milliseconds.
+ * @param msg[out]  On success, the message is written to this pointer.
+ *                  Otherwise, the contents are unmodified.
+ * @param cb        Function that should be called for new HID++ messages.
+ *                  If true is returned, then no more messages are read. msg is
+ *                  not allowed to be modified if the callback returns false.
+ * @param userdata  Data that is passed unchanged to the callback function.
+ * @return true iff there exists a message that was accepted by the callback
+ * function within the timeout.
+ */
+bool hidpp_read_msg(int fd, int timeout, HidppMessage *msg,
+                    hidpp_msg_cb_t *cb, void *userdata);
+#endif