pcm_misc.c

/*
 *  PCM Interface - misc routines
 *  Copyright (c) 1998 by Jaroslav Kysela <perex@perex.cz>
 *
 *
 *   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 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 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 Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */
  
#include <linux/time.h>
#include <linux/export.h>
#include <sound/core.h>
#include <sound/pcm.h>
#define SND_PCM_FORMAT_UNKNOWN (-1)

/* NOTE: "signed" prefix must be given below since the default char is
 *       unsigned on some architectures!
 */
struct pcm_format_data {
	unsigned char width;	/* bit width */
	unsigned char phys;	/* physical bit width */
	signed char le;	/* 0 = big-endian, 1 = little-endian, -1 = others */
	signed char signd;	/* 0 = unsigned, 1 = signed, -1 = others */
	unsigned char silence[8];	/* silence data to fill */
};

/* we do lots of calculations on snd_pcm_format_t; shut up sparse */
#define INT	__force int

static struct pcm_format_data pcm_formats[(INT)SNDRV_PCM_FORMAT_LAST+1] = {
	[SNDRV_PCM_FORMAT_S8] = {
		.width = 8, .phys = 8, .le = -1, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_U8] = {
		.width = 8, .phys = 8, .le = -1, .signd = 0,
		.silence = { 0x80 },
	},
	[SNDRV_PCM_FORMAT_S16_LE] = {
		.width = 16, .phys = 16, .le = 1, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_S16_BE] = {
		.width = 16, .phys = 16, .le = 0, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_U16_LE] = {
		.width = 16, .phys = 16, .le = 1, .signd = 0,
		.silence = { 0x00, 0x80 },
	},
	[SNDRV_PCM_FORMAT_U16_BE] = {
		.width = 16, .phys = 16, .le = 0, .signd = 0,
		.silence = { 0x80, 0x00 },
	},
	[SNDRV_PCM_FORMAT_S24_LE] = {
		.width = 24, .phys = 32, .le = 1, .signd = 1,
		.silence = {},
	},