lib: mostly implement generic hidpp defs and helpers

hidpp_open still needs to be done.

1 files changed, 139 insertions, 0 deletions

diff --git a/lib/hidpp.c b/lib/hidpp.c
new file mode 100644
index 0000000..a07d689
--- /dev/null
+++ b/lib/hidpp.c
@@ -0,0 +1,139 @@
+/*
+ * 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/>.
+ */
+
+#include <poll.h>
+#include <stdio.h>
+#include <string.h>
+#include <time.h> /* needs -lrt, for clock_gettime as timeout helper */
+#include <unistd.h>
+#include "hidpp.h"
+#include "debug.h"
+
+#define VID_LOGITECH		0x046d
+#define PID_NANO_RECEIVER	0xc52f
+#define RECEIVER_NAME "logitech-djreceiver"
+
+static inline bool is_valid_device_index(uint8_t ix)
+{
+	return ix >= 1 && ix <= MAX_DEVICES;
+}
+
+static long long unsigned get_timestamp_ms(void)
+{
+	struct timespec tp;
+
+	clock_gettime(CLOCK_MONOTONIC, &tp);
+	return tp.tv_sec * 1000 + tp.tv_nsec / 1000000;
+}
+
+static ssize_t poll_read(int fd, int timeout, void *buf, size_t count)
+{
+	int r;
+	struct pollfd pollfd = {
+		.fd = fd,
+		.events = POLLIN
+	};
+
+	r = poll(&pollfd, 1, timeout);
+	if (r < 0) {
+		perror("poll");
+		return 0;
+	} else if (r == 0) {
+		trace_log("poll timeout reached!\n");
+		return 0;
+	}
+
+	r = read(fd, buf, count);
+	if (r < 0) {
+		perror("read");
+		return 0;
+	}
+
+	return r;
+}
+
+static void hidpp_discard_messages(int fd)
+{
+	char c;
+
+	/* kernel discards remainder of message */
+	while (poll_read(fd, 1, &c, 1)) ;
+}
+
+bool hidpp_write_report(int fd, struct HidppMessage *msg)
+{
+	ssize_t r, payload_size = HIDPP_SHORT_LEN;
+
+	if (msg->report_id == HIDPP_LONG) {
+		payload_size = HIDPP_LONG_LEN;
+	}
+
+	/* start with an empty queue to avoid interference */
+	hidpp_discard_messages(fd);
+
+	trace_dump_data("wr", (uint8_t *) msg, payload_size);
+
+	r = write(fd, msg, payload_size);
+	if (r < 0) {
+		perror("write");
+	}
+
+	return payload_size == r;
+}
+
+bool hidpp_read_msg(int fd, int timeout, HidppMessage *msg,
+                    hidpp_msg_cb_t *cb, void *userdata)
+{
+	int r;
+	long long unsigned begin_ms = 0, end_ms;
+	HidppMessage response;
+
+	do {
+		end_ms = get_timestamp_ms();
+		if (begin_ms > 0)
+			timeout -= end_ms - begin_ms;
+		begin_ms = end_ms;
+		if (timeout <= 0)
+			break;
+
+		memset(&response, 0, sizeof(response));
+		r = poll_read(fd, timeout, &response, sizeof(response));
+		if (r > 0) {
+			trace_dump_data("rd", (uint8_t *) msg, r);
+
+			if (r < HIDPP_SHORT_LEN) {
+				trace_log("Impossible short read: %i\n", r);
+			} else if (response.report_id == HIDPP_SHORT ||
+			           response.report_id == HIDPP_LONG) {
+				uint8_t ix = response.device_index;
+
+				if (!is_valid_device_index(ix) && ix != 0xFF) {
+					trace_log("Invalid device index: %i\n", ix);
+				} else if (cb(&response, userdata)) {
+					/* response is accepted, return message */
+					memcpy(msg, &response, sizeof(response));
+					return true;
+				}
+			}
+		}
+	} while (1);
+
+	/* timeout expired, no report found unfortunately */
+	return false;
+}