[Qemu-devel] [PATCH 2/2] msmouse: send short messages if possible.

[Gerd Hoffmann <kraxel@redhat.com>]

Keep track of button changes.  Send the extended 4-byte messages for
three button mice only in case we have something to report for the
middle button.  Use the short 3-byte messages (original protocol for
two-button microsoft mouse) otherwise.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 backends/msmouse.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/backends/msmouse.c b/backends/msmouse.c
index b1e1bea..f6504be 100644
--- a/backends/msmouse.c
+++ b/backends/msmouse.c
@@ -35,6 +35,7 @@ typedef struct {
     QemuInputHandlerState *hs;
     int axis[INPUT_AXIS__MAX];
     bool btns[INPUT_BUTTON__MAX];
+    bool btnc[INPUT_BUTTON__MAX];
     uint8_t outbuf[32];
     int outlen;
 } MouseState;
@@ -62,7 +63,7 @@ static void msmouse_chr_accept_input(CharDriverState *chr)
 static void msmouse_queue_event(MouseState *mouse)
 {
     unsigned char bytes[4] = { 0x40, 0x00, 0x00, 0x00 };
-    int dx, dy;
+    int dx, dy, count = 3;
 
     dx = mouse->axis[INPUT_AXIS_X];
     mouse->axis[INPUT_AXIS_X] = 0;
@@ -78,14 +79,19 @@ static void msmouse_queue_event(MouseState *mouse)
     /* Buttons */
     bytes[0] |= (mouse->btns[INPUT_BUTTON_LEFT]   ? 0x20 : 0x00);
     bytes[0] |= (mouse->btns[INPUT_BUTTON_RIGHT]  ? 0x10 : 0x00);
-    bytes[3] |= (mouse->btns[INPUT_BUTTON_MIDDLE] ? 0x20 : 0x00);
+    if (mouse->btns[INPUT_BUTTON_MIDDLE] ||
+        mouse->btnc[INPUT_BUTTON_MIDDLE]) {
+        bytes[3] |= (mouse->btns[INPUT_BUTTON_MIDDLE] ? 0x20 : 0x00);
+        mouse->btnc[INPUT_BUTTON_MIDDLE] = false;
+        count = 4;
+    }
 
-    if (mouse->outlen <= sizeof(mouse->outbuf) - 4) {
+    if (mouse->outlen <= sizeof(mouse->outbuf) - count) {
         /* We always send the packet of, so that we do not have to keep track
            of previous state of the middle button. This can potentially confuse
            some very old drivers for two button mice though. */
-        memcpy(mouse->outbuf + mouse->outlen, bytes, 4);
-        mouse->outlen += 4;
+        memcpy(mouse->outbuf + mouse->outlen, bytes, count);
+        mouse->outlen += count;
     } else {
         /* queue full -> drop event */
     }
@@ -107,6 +113,7 @@ static void msmouse_input_event(DeviceState *dev, QemuConsole *src,
     case INPUT_EVENT_KIND_BTN:
         btn = evt->u.btn.data;
         mouse->btns[btn->button] = btn->down;
+        mouse->btnc[btn->button] = true;
         break;
 
     default:
-- 
1.8.3.1