From 23249681abc0a943359d6d4c3476c479a829a8e0 Mon Sep 17 00:00:00 2001
From: Michael Lotz <mmlr@mlotz.ch>
Date: Wed, 1 Jun 2011 23:34:03 +0000
Subject: [PATCH] Since we never actually read more than one mouse_movement at
 a time and we only ever wait for reports on demand, there's no need for
 buffering at all. This removes some unnecessary copying and ring buffer
 overhead, the ring buffer will now in fact not be created at all.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@41864 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 .../input/usb_hid/MouseProtocolHandler.cpp    | 51 ++++++++++---------
 .../input/usb_hid/MouseProtocolHandler.h      |  3 +-
 2 files changed, 29 insertions(+), 25 deletions(-)

diff --git a/src/add-ons/kernel/drivers/input/usb_hid/MouseProtocolHandler.cpp b/src/add-ons/kernel/drivers/input/usb_hid/MouseProtocolHandler.cpp
index 4f80bf723f..4355c455ec 100644
--- a/src/add-ons/kernel/drivers/input/usb_hid/MouseProtocolHandler.cpp
+++ b/src/add-ons/kernel/drivers/input/usb_hid/MouseProtocolHandler.cpp
@@ -25,7 +25,7 @@
 MouseProtocolHandler::MouseProtocolHandler(HIDReport &report,
 	HIDReportItem &xAxis, HIDReportItem &yAxis)
 	:
-	ProtocolHandler(report.Device(), "input/mouse/usb/", 512),
+	ProtocolHandler(report.Device(), "input/mouse/usb/", 0),
 	fReport(report),
 	fXAxis(xAxis),
 	fYAxis(yAxis),
@@ -106,24 +106,29 @@ MouseProtocolHandler::AddHandlers(HIDDevice &device, HIDCollection &collection,
 
 
 status_t
-MouseProtocolHandler::Control(uint32 *cookie, uint32 op, void *buffer, size_t length)
+MouseProtocolHandler::Control(uint32 *cookie, uint32 op, void *buffer,
+	size_t length)
 {
 	switch (op) {
 		case MS_READ:
-			while (RingBufferReadable() == 0) {
-				status_t result = _ReadReport();
-				if (result != B_OK)
+		{
+			if (length < sizeof(mouse_movement))
+				return B_BUFFER_OVERFLOW;
+
+			while (true) {
+				status_t result = _ReadReport(buffer);
+				if (result != B_INTERRUPTED)
 					return result;
 			}
-
-			return RingBufferRead(buffer, sizeof(mouse_movement));
+		}
 
 		case MS_NUM_EVENTS:
 		{
-			int32 count = RingBufferReadable() / sizeof(mouse_movement);
-			if (count == 0 && fReport.Device()->IsRemoved())
+			if (fReport.Device()->IsRemoved())
 				return B_DEV_NOT_READY;
-			return count;
+
+			// we are always on demand, so 0 queued events
+			return 0;
 		}
 
 		case MS_SET_CLICKSPEED:
@@ -140,7 +145,7 @@ MouseProtocolHandler::Control(uint32 *cookie, uint32 op, void *buffer, size_t le
 
 
 status_t
-MouseProtocolHandler::_ReadReport()
+MouseProtocolHandler::_ReadReport(void *buffer)
 {
 	status_t result = fReport.WaitForReport(B_INFINITE_TIMEOUT);
 	if (result != B_OK) {
@@ -156,19 +161,19 @@ MouseProtocolHandler::_ReadReport()
 		}
 
 		// signal that we simply want to try again
-		return B_OK;
+		return B_INTERRUPTED;
 	}
 
-	mouse_movement info;
-	memset(&info, 0, sizeof(info));
+	mouse_movement *info = (mouse_movement *)buffer;
+	memset(info, 0, sizeof(mouse_movement));
 
 	if (fXAxis.Extract() == B_OK && fXAxis.Valid())
-		info.xdelta = fXAxis.Data();
+		info->xdelta = fXAxis.Data();
 	if (fYAxis.Extract() == B_OK && fYAxis.Valid())
-		info.ydelta = -fYAxis.Data();
+		info->ydelta = -fYAxis.Data();
 
 	if (fWheel != NULL && fWheel->Extract() == B_OK && fWheel->Valid())
-		info.wheel_ydelta = -fWheel->Data();
+		info->wheel_ydelta = -fWheel->Data();
 
 	for (uint32 i = 0; i < B_MAX_MOUSE_BUTTONS; i++) {
 		HIDReportItem *button = fButtons[i];
@@ -176,14 +181,14 @@ MouseProtocolHandler::_ReadReport()
 			break;
 
 		if (button->Extract() == B_OK && button->Valid())
-			info.buttons |= (button->Data() & 1) << (button->UsageID() - 1);
+			info->buttons |= (button->Data() & 1) << (button->UsageID() - 1);
 	}
 
 	fReport.DoneProcessing();
 	TRACE("got mouse report\n");
 
 	bigtime_t timestamp = system_time();
-	if (info.buttons != 0) {
+	if (info->buttons != 0) {
 		if (fLastButtons == 0) {
 			if (fLastClickTime + fClickSpeed > timestamp)
 				fClickCount++;
@@ -192,10 +197,10 @@ MouseProtocolHandler::_ReadReport()
 		}
 
 		fLastClickTime = timestamp;
-		info.clicks = fClickCount;
+		info->clicks = fClickCount;
 	}
 
-	fLastButtons = info.buttons;
-	info.timestamp = timestamp;
-	return RingBufferWrite(&info, sizeof(mouse_movement));
+	fLastButtons = info->buttons;
+	info->timestamp = timestamp;
+	return B_OK;
 }
diff --git a/src/add-ons/kernel/drivers/input/usb_hid/MouseProtocolHandler.h b/src/add-ons/kernel/drivers/input/usb_hid/MouseProtocolHandler.h
index ac598b9a6c..6ad2aa6b72 100644
--- a/src/add-ons/kernel/drivers/input/usb_hid/MouseProtocolHandler.h
+++ b/src/add-ons/kernel/drivers/input/usb_hid/MouseProtocolHandler.h
@@ -33,9 +33,8 @@ public:
 									size_t length);
 
 private:
-			status_t			_ReadReport();
+			status_t			_ReadReport(void *buffer);
 
-private:
 			HIDReport &			fReport;
 
 			HIDReportItem &		fXAxis;