From 9196f58bdc8b9e967261df39865215faa5d39cfa Mon Sep 17 00:00:00 2001
From: Nathan Hjelm <hjelmn@mac.com>
Date: Mon, 16 Feb 2009 21:25:18 -0300
Subject: [PATCH] Abstract clock reading into OS layer

This will differ on Linux and Darwin, at least.

[dsd: minor style tweaks]
---
 libusb/io.c             |  8 ++++----
 libusb/libusbi.h        | 15 +++++++++++++++
 libusb/os/linux_usbfs.c | 14 ++++++++++++++
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/libusb/io.c b/libusb/io.c
index b053f85..6c3aadb 100644
--- a/libusb/io.c
+++ b/libusb/io.c
@@ -972,7 +972,7 @@ static int calculate_timeout(struct usbi_transfer *transfer)
 	if (!timeout)
 		return 0;
 
-	r = clock_gettime(CLOCK_MONOTONIC, &current_time);
+	r = usbi_backend->clock_gettime(USBI_CLOCK_MONOTONIC, &current_time);
 	if (r < 0) {
 		usbi_err(ITRANSFER_CTX(transfer),
 			"failed to read monotonic clock, errno=%d", errno);
@@ -1445,7 +1445,7 @@ API_EXPORTED int libusb_wait_for_event(libusb_context *ctx, struct timeval *tv)
 		return 0;
 	}
 
-	r = clock_gettime(CLOCK_REALTIME, &timeout);
+	r = usbi_backend->clock_gettime(USBI_CLOCK_REALTIME, &timeout);
 	if (r < 0) {
 		usbi_err(ctx, "failed to read realtime clock, error %d", errno);
 		return LIBUSB_ERROR_OTHER;
@@ -1489,7 +1489,7 @@ static int handle_timeouts(struct libusb_context *ctx)
 		goto out;
 
 	/* get current time */
-	r = clock_gettime(CLOCK_MONOTONIC, &systime_ts);
+	r = usbi_backend->clock_gettime(USBI_CLOCK_MONOTONIC, &systime_ts);
 	if (r < 0)
 		goto out;
 
@@ -1807,7 +1807,7 @@ API_EXPORTED int libusb_get_next_timeout(libusb_context *ctx,
 		return 0;
 	}
 
-	r = clock_gettime(CLOCK_MONOTONIC, &cur_ts);
+	r = usbi_backend->clock_gettime(USBI_CLOCK_MONOTONIC, &cur_ts);
 	if (r < 0) {
 		usbi_err(ctx, "failed to read monotonic clock, errno=%d", errno);
 		return LIBUSB_ERROR_OTHER;
diff --git a/libusb/libusbi.h b/libusb/libusbi.h
index b51ba0b..da636b2 100644
--- a/libusb/libusbi.h
+++ b/libusb/libusbi.h
@@ -218,6 +218,11 @@ struct libusb_device_handle {
 
 #define USBI_TRANSFER_TIMED_OUT	 			(1<<0)
 
+enum {
+  USBI_CLOCK_MONOTONIC,
+  USBI_CLOCK_REALTIME
+};
+
 /* in-memory transfer layout:
  *
  * 1. struct usbi_transfer
@@ -733,6 +738,16 @@ struct usbi_os_backend {
 	int (*handle_events)(struct libusb_context *ctx,
 		struct pollfd *fds, nfds_t nfds, int num_ready);
 
+	/* Get time from specified clock. At least two clocks must be implemented
+	   by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
+
+	   Description of clocks:
+	     USBI_CLOCK_REALTIME : clock returns time since system epoch.
+	     USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
+	                             time (usually boot).
+	 */
+	int (*clock_gettime)(int clkid, struct timespec *tp);
+
 	/* Number of bytes to reserve for per-device private backend data.
 	 * This private data area is accessible through the "os_priv" field of
 	 * struct libusb_device. */
diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index 46e770c..7727ba6 100644
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -1999,6 +1999,18 @@ out:
 	return r;
 }
 
+static int op_clock_gettime(int clk_id, struct timespec *tp)
+{
+	switch (clk_id) {
+	case USBI_CLOCK_MONOTONIC:
+		return clock_gettime(CLOCK_MONOTONIC, tp);
+	case USBI_CLOCK_REALTIME:
+		return clock_gettime(CLOCK_REALTIME, tp);
+	default:
+		return LIBUSB_ERROR_INVALID_PARAM;
+  }
+}
+
 const struct usbi_os_backend linux_usbfs_backend = {
 	.name = "Linux usbfs",
 	.init = op_init,
@@ -2031,6 +2043,8 @@ const struct usbi_os_backend linux_usbfs_backend = {
 
 	.handle_events = op_handle_events,
 
+	.clock_gettime = op_clock_gettime,
+
 	.device_priv_size = sizeof(struct linux_device_priv),
 	.device_handle_priv_size = sizeof(struct linux_device_handle_priv),
 	.transfer_priv_size = sizeof(struct linux_transfer_priv),
-- 
2.7.4