On 02 Feb 2005 21:57:39 +0100, Peter Osterlund <[EMAIL PROTECTED]> wrote:

> Please try this patch instead. It works well with my alps touchpad. (I
> don't have a synaptics touchpad.) It does the following:
> 
> * Compensates for the lack of floating point arithmetic by keeping
>   track of remainders from the integer divisions.
> * Removes the xres/yres scaling so that you get the same speed in the
>   X and Y directions even if your screen is not square.
> * Sets scale factors so that the speed for synaptics and alps should
>   be equal to each other and equal to the synaptics speed from 2.6.10.

Thanks a lot, Peter. I think I like the result even better than the one
after the simple-minded removal that I posted. It's possible that when
I accepted the case of (pktcount == 1) it hurt smoothness.

Do you think it makes sense to zero fractions when pktcount is dropped?
Also, I think the extra unary minus is uncoth.

-- Pete

--- linux-2.6.11-rc2/drivers/input/mousedev.c   2005-01-22 14:54:14.000000000 
-0800
+++ linux-2.6.11-rc2-lem/drivers/input/mousedev.c       2005-02-02 
14:03:07.000000000 -0800
@@ -71,6 +71,7 @@
        struct mousedev_hw_data packet;
        unsigned int pkt_count;
        int old_x[4], old_y[4];
+       int frac_dx, frac_dy;
        unsigned long touch;
 };
 
@@ -117,24 +118,31 @@
 
 static void mousedev_touchpad_event(struct input_dev *dev, struct mousedev 
*mousedev, unsigned int code, int value)
 {
-       int size;
+       int size, tmp;
+       enum {  FRACTION_DENOM = 100 };
 
        if (mousedev->touch) {
+               size = dev->absmax[ABS_X] - dev->absmin[ABS_X];
+               if (size == 0) size = xres;
                switch (code) {
                        case ABS_X:
-                               size = dev->absmax[ABS_X] - dev->absmin[ABS_X];
-                               if (size == 0) size = xres;
                                fx(0) = value;
-                               if (mousedev->pkt_count >= 2)
-                                       mousedev->packet.dx = ((fx(0) - fx(1)) 
/ 2 + (fx(1) - fx(2)) / 2) * xres / (size * 2);
+                               if (mousedev->pkt_count >= 2) {
+                                       tmp = ((value - fx(2)) * (250 * 
FRACTION_DENOM)) / size;
+                                       tmp += mousedev->frac_dx;
+                                       mousedev->packet.dx = tmp / 
FRACTION_DENOM;
+                                       mousedev->frac_dx = tmp - 
mousedev->packet.dx * FRACTION_DENOM;
+                               }
                                break;
 
                        case ABS_Y:
-                               size = dev->absmax[ABS_Y] - dev->absmin[ABS_Y];
-                               if (size == 0) size = yres;
                                fy(0) = value;
-                               if (mousedev->pkt_count >= 2)
-                                       mousedev->packet.dy = -((fy(0) - fy(1)) 
/ 2 + (fy(1) - fy(2)) / 2) * yres / (size * 2);
+                               if (mousedev->pkt_count >= 2) {
+                                       tmp = ((fy(2) - value) * (250 * 
FRACTION_DENOM)) / size;
+                                       tmp += mousedev->frac_dy;
+                                       mousedev->packet.dy = tmp / 
FRACTION_DENOM;
+                                       mousedev->frac_dy = tmp - 
mousedev->packet.dy * FRACTION_DENOM;
+                               }
                                break;
                }
        }
@@ -268,6 +276,8 @@
                        clear_bit(0, &mousedev_mix.packet.buttons);
                }
                mousedev->touch = mousedev->pkt_count = 0;
+               mousedev->frac_dx = 0;
+               mousedev->frac_dy = 0;
        }
        else
                if (!mousedev->touch)
-
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