firmware/target/arm/as3525/scrollwheel-as3525.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2009-2010 by Thomas Martitz
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21
  22 #include "config.h"
  23 #include "button.h"
  24 #include "kernel.h"
  25 #include "backlight.h"
  26
  27 void scrollwheel(unsigned int wheel_value)
  28 {
  29 #ifndef BOOTLOADER
  30     /* current wheel values, parsed from dbop and the resulting button */
  31     unsigned         btn             = BUTTON_NONE;
  32     /* old wheel values */
  33     static unsigned old_wheel_value = 0;
  34     static unsigned old_btn         = BUTTON_NONE;
  35
  36     /*
  37      * Getting BUTTON_REPEAT works like this: Remember when the btn value was
  38      * posted to the button_queue last, and if it was recent enough, generate
  39      * BUTTON_REPEAT
  40      */
  41     static long      last_wheel_post = 0;
  42
  43     /*
  44      *  Providing wheel acceleration works as follows: We increment accel
  45      * by 2 if the wheel was turned, and decrement it by 1 each tick
  46      * (no matter if it was turned), that means: the longer and faster you turn,
  47      * the higher accel will be. accel>>2 will actually posted to the button_queue
  48      */
  49     static int        accel = 0;
  50     /* We only post every 4th action, as this matches better with the physical
  51      * clicks of the wheel */
  52     static int        counter = 0;
  53     /* Read wheel
  54      * Bits 13 and 14 of DBOP_DIN change as follows (Gray Code):
  55      * Clockwise rotation   00 -> 01 -> 11 -> 10 -> 00
  56      * Counter-clockwise    00 -> 10 -> 11 -> 01 -> 00
  57      *
  58      * For easy look-up, actual wheel values act as indicies also,
  59      * which is why the table seems to be not ordered correctly
  60      */
  61     static const unsigned char wheel_tbl[2][4] =
  62     {
  63         { 2, 0, 3, 1 }, /* Clockwise rotation */
  64         { 1, 3, 0, 2 }, /* Counter-clockwise  */
  65     };
  66
  67     if(button_hold())
  68     {
  69         accel  =  counter  = 0;
  70         return;
  71     }
  72
  73     if (old_wheel_value == wheel_tbl[0][wheel_value])
  74         btn = BUTTON_SCROLL_FWD;
  75     else if (old_wheel_value == wheel_tbl[1][wheel_value])
  76         btn = BUTTON_SCROLL_BACK;
  77     else if (old_wheel_value != wheel_value && accel > ACCEL_INCREMENT)
  78     {   /* if no button is read and wheel_value changed, assume old_btn */
  79         btn = old_btn;
  80     }
  81     /* else btn = BUTTON_NONE */
  82
  83     if (btn != BUTTON_NONE)
  84     {
  85         if (btn != old_btn)
  86         {
  87             /* direction reversals nullify acceleration and counters */
  88             old_btn =  btn;
  89             accel  =  counter  = 0;
  90         }
  91         /* wheel_delta will cause lists to jump over items,
  92          * we want this for fast scrolling, but we must keep it accurate
  93          * for slow scrolling */
  94         int wheel_delta = 0;
  95         /* generate BUTTON_REPEAT if quick enough, scroll slightly faster too*/
  96         if (TIME_BEFORE(current_tick, last_wheel_post + WHEEL_REPEAT_INTERVAL))
  97         {
  98             btn |= BUTTON_REPEAT;
  99             wheel_delta = accel>>ACCEL_SHIFT;
 100         }
 101
 102         accel += ACCEL_INCREMENT;
 103
 104         /* the wheel is more reliable if we don't send every change,
 105          * every WHEEL_COUNTER_DIVth is basically one "physical click"
 106          * which should make up 1 item in lists */
 107         if (++counter >= WHEEL_COUNTER_DIV && queue_empty(&button_queue))
 108         {
 109             buttonlight_on();
 110             backlight_on();
 111             queue_post(&button_queue, btn, ((wheel_delta+1)<<24));
 112             /* message posted - reset count and remember post */
 113             counter = 0;
 114             last_wheel_post = current_tick;
 115         }
 116     }
 117     if (accel > 0)
 118         accel--;
 119
 120     old_wheel_value = wheel_value;
 121 #else
 122     (void)wheel_value;
 123 #endif
 124 }