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/* $OpenBSD: pt2254a.c,v 1.1 2002/04/25 04:56:59 mickey Exp $ */
/*
* Copyright (c) 2002 Vladimir Popov <jumbo@narod.ru>.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Princeton Technology Corp.'s Electronic Volume Controller IC PT2254A
* http://www.princeton.com.tw
*
* PT2254A is an electronic volume controller IC utilizing CMOS Technology
* specially designed for use in audio equipment. It has two built-in
* channels making it highly suitable for mono and stereo sound applications.
* Through the specially designated signals that are applied externally to
* the data, clock and strobe input pins, PT2254A can control attenuation
* and channel balance.
*/
#include <sys/param.h>
#include <dev/ic/pt2254a.h>
u_int32_t
pt2254a_encode_volume(u_int8_t *current, u_int8_t max) {
u_int32_t ret = 0ul;
u_int8_t vol, tens, ones;
int steps;
/*
* Volume management is done nonlinear.
*
* Approximate the curve with three lines:
* low volume: y = - (48 /(max/3)) * x + 68
* middle volume: y = - (14 /(max/3)) * x + 34
* high volume: y = - (6 /(max/3)) * x + 18
*/
if (*current > 0 && *current <= max / 3) {
vol = PT2254A_MAX_ATTENUATION - (144 * (int)(*current) / max);
} else if (*current > max / 3 && *current <= 2 * max / 3) {
vol = 34 - (42 * (int)(*current) / max);
} else if (*current > 2 * max / 3) {
vol = 18 - (18 * (int)(*current) / max);
} else vol = PT2254A_MAX_ATTENUATION;
/* Report adjusted volume */
/* *current = max - (vol * max / PT2254A_MAX_ATTENUATION); */
steps = *current * PT2254A_MAX_ATTENUATION / max;
*current = steps * max / PT2254A_MAX_ATTENUATION;
tens = vol / 10;
ones = vol - tens * 10;
ret = PT2254A_ATTENUATION_MAJOR(tens) | PT2254A_ATTENUATION_MINOR(ones);
return ret;
}
u_int32_t
pt2254a_compose_register(u_int32_t lvol, u_int32_t rvol, int left, int right) {
u_int32_t ret = 0ul;
if (left == USE_CHANNEL) {
ret |= PT2254A_LEFT_CHANNEL;
ret |= lvol;
}
if (right == USE_CHANNEL) {
ret |= PT2254A_RIGHT_CHANNEL;
ret |= rvol;
}
ret |= PT2254A_ZERO_PADDING;
ret |= PT2254A_EMPTY_BIT;
return ret;
}
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