path: root/sound/pci/trident/trident_synth.c

/*
 *  Routines for Trident 4DWave NX/DX soundcards - Synthesizer
 *  Copyright (c) by Scott McNab <jedi@tartarus.uwa.edu.au>
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program 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 General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <sound/driver.h>
#include <asm/io.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <sound/core.h>
#include <sound/trident.h>
#include <sound/seq_device.h>

MODULE_AUTHOR("Scott McNab <jedi@tartarus.uwa.edu.au>");
MODULE_DESCRIPTION("Routines for Trident 4DWave NX/DX soundcards - Synthesizer");
MODULE_LICENSE("GPL");

/* linear to log pan conversion table (4.2 channel attenuation format) */
static unsigned int pan_table[63] = {
	7959, 7733, 7514, 7301, 7093, 6892, 6697, 6507, 
	6322, 6143, 5968, 5799, 5634, 5475, 5319, 5168, 
	5022, 4879, 4741, 4606, 4475, 4349, 4225, 4105, 
	3989, 3876, 3766, 3659, 3555, 3454, 3356, 3261, 
	3168, 3078, 2991, 2906, 2824, 2744, 2666, 2590, 
	2517, 2445, 2376, 2308, 2243, 2179, 2117, 2057, 
	1999, 1942, 1887, 1833, 1781, 1731, 1682, 1634, 
	1588, 1543, 1499, 1456, 1415, 1375, 1336
};

#define LOG_TABLE_SIZE 386

/* Linear half-attenuation to log conversion table in the format:
 *   {linear volume, logarithmic attenuation equivalent}, ...
 *
 * Provides conversion from a linear half-volume value in the range
 * [0,8192] to a logarithmic attenuation value in the range 0 to 6.02dB.
 * Halving the linear volume is equivalent to an additional 6dB of 
 * logarithmic attenuation. The algorithm used in log_from_linear()
 * therefore uses this table as follows:
 * 
 * - loop and for every time the volume is less than half the maximum 
 *   volume (16384), add another 6dB and halve the maximum value used
 *   for this comparison.
 * - when the volume is greater than half the maximum volume, take
 *   the difference of the volume to half volume (in the range [0,8192])
 *   and look up the log_table[] to find the nearest entry.
 * - take the logarithic component of this entry and add it to the 
 *   resulting attenuation.
 *
 * Thus this routine provides a linear->log conversion for a range of
 * [0,16384] using only 386 table entries
 *
 * Note: although this table stores log attenuation in 8.8 format, values
 * were only calculated for 6 bits fractional precision, since that is
 * the most precision offered by the trident hardware.
 */

static unsigned short log_table[LOG_TABLE_SIZE*2] =
{
	4, 0x0604, 19, 0x0600, 34, 0x05fc, 
	49, 0x05f8, 63, 0x05f4, 78, 0x05f0, 93, 0x05ec, 108, 0x05e8, 
	123, 0x05e4, 138, 0x05e0, 153, 0x05dc, 168, 0x05d8, 183, 0x05d4, 
	198, 0x05d0, 213, 0x05cc, 228, 0x05c8, 244, 0x05c4, 259, 0x05c0, 
	274, 0x05bc, 289, 0x05b8, 304, 0x05b4, 320, 0x05b0, 335, 0x05ac, 
	350, 0x05a8, 366, 0x05a4, 381, 0x05a0, 397, 0x059c, 412, 0x0598, 
	428, 0x0594, 443, 0x0590, 459, 0x058c, 474, 0x0588, 490, 0x0584, 
	506, 0x0580, 521, 0x057c, 537, 0x0578, 553, 0x0574, 568, 0x0570, 
	584, 0x056c, 600, 0x0568, 616, 0x0564, 632, 0x0560, 647, 0x055c, 
	663, 0x0558, 679, 0x0554, 695, 0x0550, 711, 0x054c, 727, 0x0548, 
	743, 0x0544, 759, 0x0540, 776, 0x053c, 792, 0x0538, 808, 0x0534, 
	824, 0x0530, 840, 0x052c, 857, 0x0528, 873, 0x0524, 889, 0x0520, 
	906, 0x051c, 922, 0x0518, 938, 0x0514, 955, 0x0510, 971, 0x050c, 
	988, 0x0508, 1004, 0x0504, 1021, 0x0500, 1037, 0x04fc, 1054, 0x04f8, 
	1071, 0x04f4, 1087, 0x04f0, 1104, 0x04ec, 1121, 0x04e8, 1138, 0x04e4