File indexing completed on 2024-04-28 08:46:54

 /*
  * This file is part of WorkMan, the civilized CD player library
  * Copyright (C) 1991-1997 by Steven Grimm (original author)
  * Copyright (C) by Dirk Försterling <milliByte@DeathsDoor.com>
  * Copyright (C) 2004-2006 Alexander Kern <alex.kern@gmx.de>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public
  * License along with this library; if not, write to the Free
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
  *
  * Vendor-specific drive control routines for Sony CDU-8012 series.
  */
 
 #include <stdio.h>
 #include <errno.h>
 #include "include/wm_config.h"
 #include "include/wm_struct.h"
 #include "include/wm_scsi.h"
 
 #define PAGE_AUDIO 0x0e
 
 static int max_volume = 255;
 
 /*
  * On the Sony CDU-8012 drive, the amount of sound coming out the jack
  * increases much faster toward the top end of the volume scale than it
  * does at the bottom.  To make up for this, we make the volume scale look
  * sort of logarithmic (actually an upside-down inverse square curve) so
  * that the volume value passed to the drive changes less and less as you
  * approach the maximum slider setting.  Additionally, only the top half
  * of the volume scale is valid; the bottom half is all silent.  The actual
  * formula looks like
  *
  *     max^2 - (max - vol)^2   max
  * v = --------------------- + ---
  *            max * 2           2
  *
  * Where "max" is the maximum value of the volume scale, usually 100.
  */
 static int scale_volume(int vol, int max)
 {
     vol = (max*max - (max - vol) * (max - vol)) / max;
     return ((vol + max) / 2);
 }
 
 /*
  * Given a value between min_volume and max_volume, return the standard-scale
  * volume value needed to achieve that hardware value.
  *
  * Rather than perform floating-point calculations to reverse the above
  * formula, we simply do a binary search of scale_volume()'s return values.
  */
 static int unscale_volume(int vol, int max)
 {
     int ret_vol = 0, top = max, bot = 0, scaled = 0;
 
     vol = (vol * 100 + (max_volume - 1)) / max_volume;
 
     while (bot <= top)
     {
         ret_vol = (top + bot) / 2;
         scaled = scale_volume(ret_vol, max);
         if (vol <= scaled)
             top = ret_vol - 1;
         else
             bot = ret_vol + 1;
     }
 
     /* Might have looked down too far for repeated scaled values */
     if (vol < scaled)
         ret_vol++;
 
     if (ret_vol < 0)
         ret_vol = 0;
     else if (ret_vol > max)
         ret_vol = max;
 
     return ret_vol;
 }
 
 /*
  * Set the volume using the wacky scale outlined above.  The Sony drive
  * responds to the standard set-volume command.
  *
  * Get the volume.  Sun's CD-ROM driver doesn't support this operation, even
  * though their drive does.  Dumb.
  */
 static int sony_get_volume( struct wm_drive *d, int *left, int *right )
 {
     unsigned char mode[16];
 
     /* Get the current audio parameters first. */
     if (wm_scsi_mode_sense(d, PAGE_AUDIO, mode))
         return -1;
 
     *left = mode[9];
     *right = mode[11];
 
     return 0;
 }
 
 static int sony_scale_volume(int *left, int *right)
 {
     *left = scale_volume(*left, 100);
     *right = scale_volume(*right, 100);
 
     return 0;
 }
 
 static int sony_unscale_volume(int *left, int *right)
 {
     *left = unscale_volume(*left, 100);
     *right = unscale_volume(*right, 100);
 
     return 0;
 }
 
 int sony_fixup(struct wm_drive *d)
 {
     d->proto.get_volume = sony_get_volume;
     d->proto.scale_volume = sony_scale_volume;
     d->proto.unscale_volume = sony_unscale_volume;
 
     return 0;
 }