pcm_misc.c

linux 内核源代码

/*
 *  PCM Interface - misc routines
 *  Copyright (c) 1998 by Jaroslav Kysela <[e-mail]>
 *
 *
 *   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 <sound/driver.h>
#include <linux/time.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 */
};

static struct pcm_format_data pcm_formats[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 = {},
	},
	[SNDRV_PCM_FORMAT_S24_BE] = {
		.width = 24, .phys = 32, .le = 0, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_U24_LE] = {
		.width = 24, .phys = 32, .le = 1, .signd = 0,
		.silence = { 0x00, 0x00, 0x80 },
	},
	[SNDRV_PCM_FORMAT_U24_BE] = {
		.width = 24, .phys = 32, .le = 0, .signd = 0,
		.silence = { 0x80, 0x00, 0x00 },
	},
	[SNDRV_PCM_FORMAT_S32_LE] = {
		.width = 32, .phys = 32, .le = 1, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_S32_BE] = {
		.width = 32, .phys = 32, .le = 0, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_U32_LE] = {
		.width = 32, .phys = 32, .le = 1, .signd = 0,
		.silence = { 0x00, 0x00, 0x00, 0x80 },
	},
	[SNDRV_PCM_FORMAT_U32_BE] = {
		.width = 32, .phys = 32, .le = 0, .signd = 0,
		.silence = { 0x80, 0x00, 0x00, 0x00 },
	},
	[SNDRV_PCM_FORMAT_FLOAT_LE] = {
		.width = 32, .phys = 32, .le = 1, .signd = -1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_FLOAT_BE] = {
		.width = 32, .phys = 32, .le = 0, .signd = -1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_FLOAT64_LE] = {
		.width = 64, .phys = 64, .le = 1, .signd = -1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_FLOAT64_BE] = {
		.width = 64, .phys = 64, .le = 0, .signd = -1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_IEC958_SUBFRAME_LE] = {
		.width = 32, .phys = 32, .le = 1, .signd = -1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_IEC958_SUBFRAME_BE] = {
		.width = 32, .phys = 32, .le = 0, .signd = -1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_MU_LAW] = {
		.width = 8, .phys = 8, .le = -1, .signd = -1,
		.silence = { 0x7f },
	},
	[SNDRV_PCM_FORMAT_A_LAW] = {
		.width = 8, .phys = 8, .le = -1, .signd = -1,
		.silence = { 0x55 },
	},
	[SNDRV_PCM_FORMAT_IMA_ADPCM] = {
		.width = 4, .phys = 4, .le = -1, .signd = -1,
		.silence = {},
	},
	/* FIXME: the following three formats are not defined properly yet */
	[SNDRV_PCM_FORMAT_MPEG] = {
		.le = -1, .signd = -1,
	},
	[SNDRV_PCM_FORMAT_GSM] = {
		.le = -1, .signd = -1,
	},
	[SNDRV_PCM_FORMAT_SPECIAL] = {
		.le = -1, .signd = -1,
	},
	[SNDRV_PCM_FORMAT_S24_3LE] = {
		.width = 24, .phys = 24, .le = 1, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_S24_3BE] = {
		.width = 24, .phys = 24, .le = 0, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_U24_3LE] = {
		.width = 24, .phys = 24, .le = 1, .signd = 0,
		.silence = { 0x00, 0x00, 0x80 },
	},
	[SNDRV_PCM_FORMAT_U24_3BE] = {
		.width = 24, .phys = 24, .le = 0, .signd = 0,
		.silence = { 0x80, 0x00, 0x00 },
	},
	[SNDRV_PCM_FORMAT_S20_3LE] = {
		.width = 20, .phys = 24, .le = 1, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_S20_3BE] = {
		.width = 20, .phys = 24, .le = 0, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_U20_3LE] = {
		.width = 20, .phys = 24, .le = 1, .signd = 0,
		.silence = { 0x00, 0x00, 0x08 },
	},
	[SNDRV_PCM_FORMAT_U20_3BE] = {
		.width = 20, .phys = 24, .le = 0, .signd = 0,
		.silence = { 0x08, 0x00, 0x00 },
	},
	[SNDRV_PCM_FORMAT_S18_3LE] = {
		.width = 18, .phys = 24, .le = 1, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_S18_3BE] = {
		.width = 18, .phys = 24, .le = 0, .signd = 1,
		.silence = {},
	},
	[SNDRV_PCM_FORMAT_U18_3LE] = {
		.width = 18, .phys = 24, .le = 1, .signd = 0,
		.silence = { 0x00, 0x00, 0x02 },
	},
	[SNDRV_PCM_FORMAT_U18_3BE] = {
		.width = 18, .phys = 24, .le = 0, .signd = 0,
		.silence = { 0x02, 0x00, 0x00 },
	},
};


/**
 * snd_pcm_format_signed - Check the PCM format is signed linear
 * @format: the format to check
 *
 * Returns 1 if the given PCM format is signed linear, 0 if unsigned
 * linear, and a negative error code for non-linear formats.
 */
int snd_pcm_format_signed(snd_pcm_format_t format)
{
	int val;
	if (format < 0 || format > SNDRV_PCM_FORMAT_LAST)
		return -EINVAL;
	if ((val = pcm_formats[format].signd) < 0)
		return -EINVAL;
	return val;
}

EXPORT_SYMBOL(snd_pcm_format_signed);

/**
 * snd_pcm_format_unsigned - Check the PCM format is unsigned linear
 * @format: the format to check
 *
 * Returns 1 if the given PCM format is unsigned linear, 0 if signed
 * linear, and a negative error code for non-linear formats.
 */
int snd_pcm_format_unsigned(snd_pcm_format_t format)
{
	int val;

	val = snd_pcm_format_signed(format);
	if (val < 0)
		return val;
	return !val;
}

EXPORT_SYMBOL(snd_pcm_format_unsigned);

/**
 * snd_pcm_format_linear - Check the PCM format is linear
 * @format: the format to check
 *
 * Returns 1 if the given PCM format is linear, 0 if not.
 */
int snd_pcm_format_linear(snd_pcm_format_t format)
{
	return snd_pcm_format_signed(format) >= 0;
}

EXPORT_SYMBOL(snd_pcm_format_linear);

/**
 * snd_pcm_format_little_endian - Check the PCM format is little-endian
 * @format: the format to check
 *
 * Returns 1 if the given PCM format is little-endian, 0 if
 * big-endian, or a negative error code if endian not specified.
 */
int snd_pcm_format_little_endian(snd_pcm_format_t format)
{
	int val;
	if (format < 0 || format > SNDRV_PCM_FORMAT_LAST)
		return -EINVAL;
	if ((val = pcm_formats[format].le) < 0)
		return -EINVAL;
	return val;
}

EXPORT_SYMBOL(snd_pcm_format_little_endian);

/**
 * snd_pcm_format_big_endian - Check the PCM format is big-endian
 * @format: the format to check
 *
 * Returns 1 if the given PCM format is big-endian, 0 if
 * little-endian, or a negative error code if endian not specified.
 */
int snd_pcm_format_big_endian(snd_pcm_format_t format)
{
	int val;

	val = snd_pcm_format_little_endian(format);
	if (val < 0)
		return val;
	return !val;
}

EXPORT_SYMBOL(snd_pcm_format_big_endian);

/**
 * snd_pcm_format_width - return the bit-width of the format
 * @format: the format to check
 *
 * Returns the bit-width of the format, or a negative error code
 * if unknown format.
 */
int snd_pcm_format_width(snd_pcm_format_t format)
{
	int val;
	if (format < 0 || format > SNDRV_PCM_FORMAT_LAST)
		return -EINVAL;
	if ((val = pcm_formats[format].width) == 0)
		return -EINVAL;
	return val;
}

EXPORT_SYMBOL(snd_pcm_format_width);

/**
 * snd_pcm_format_physical_width - return the physical bit-width of the format
 * @format: the format to check
 *
 * Returns the physical bit-width of the format, or a negative error code
 * if unknown format.
 */
int snd_pcm_format_physical_width(snd_pcm_format_t format)
{
	int val;
	if (format < 0 || format > SNDRV_PCM_FORMAT_LAST)
		return -EINVAL;
	if ((val = pcm_formats[format].phys) == 0)
		return -EINVAL;
	return val;
}

EXPORT_SYMBOL(snd_pcm_format_physical_width);

/**
 * snd_pcm_format_size - return the byte size of samples on the given format
 * @format: the format to check
 *
 * Returns the byte size of the given samples for the format, or a
 * negative error code if unknown format.
 */
ssize_t snd_pcm_format_size(snd_pcm_format_t format, size_t samples)
{
	int phys_width = snd_pcm_format_physical_width(format);
	if (phys_width < 0)
		return -EINVAL;
	return samples * phys_width / 8;
}

EXPORT_SYMBOL(snd_pcm_format_size);

/**
 * snd_pcm_format_silence_64 - return the silent data in 8 bytes array
 * @format: the format to check
 *
 * Returns the format pattern to fill or NULL if error.
 */
const unsigned char *snd_pcm_format_silence_64(snd_pcm_format_t format)
{
	if (format < 0 || format > SNDRV_PCM_FORMAT_LAST)
		return NULL;
	if (! pcm_formats[format].phys)
		return NULL;
	return pcm_formats[format].silence;
}

EXPORT_SYMBOL(snd_pcm_format_silence_64);

/**
 * snd_pcm_format_set_silence - set the silence data on the buffer
 * @format: the PCM format
 * @data: the buffer pointer
 * @samples: the number of samples to set silence
 *
 * Sets the silence data on the buffer for the given samples.
 *
 * Returns zero if successful, or a negative error code on failure.
 */
int snd_pcm_format_set_silence(snd_pcm_format_t format, void *data, unsigned int samples)
{
	int width;
	unsigned char *dst, *pat;

	if (format < 0 || format > SNDRV_PCM_FORMAT_LAST)
		return -EINVAL;
	if (samples == 0)
		return 0;
	width = pcm_formats[format].phys; /* physical width */
	pat = pcm_formats[format].silence;
	if (! width)
		return -EINVAL;
	/* signed or 1 byte data */
	if (pcm_formats[format].signd == 1 || width <= 8) {
		unsigned int bytes = samples * width / 8;
		memset(data, *pat, bytes);
		return 0;
	}
	/* non-zero samples, fill using a loop */
	width /= 8;
	dst = data;
#if 0
	while (samples--) {
		memcpy(dst, pat, width);
		dst += width;
	}
#else
	/* a bit optimization for constant width */
	switch (width) {
	case 2:
		while (samples--) {
			memcpy(dst, pat, 2);
			dst += 2;
		}
		break;
	case 3:
		while (samples--) {
			memcpy(dst, pat, 3);
			dst += 3;
		}
		break;
	case 4:
		while (samples--) {
			memcpy(dst, pat, 4);
			dst += 4;
		}
		break;
	case 8:
		while (samples--) {
			memcpy(dst, pat, 8);
			dst += 8;
		}
		break;
	}
#endif
	return 0;
}

EXPORT_SYMBOL(snd_pcm_format_set_silence);

/**
 * snd_pcm_limit_hw_rates - determine rate_min/rate_max fields
 * @runtime: the runtime instance
 *
 * Determines the rate_min and rate_max fields from the rates bits of
 * the given runtime->hw.
 *
 * Returns zero if successful.
 */
int snd_pcm_limit_hw_rates(struct snd_pcm_runtime *runtime)
{
	int i;
	for (i = 0; i < (int)snd_pcm_known_rates.count; i++) {
		if (runtime->hw.rates & (1 << i)) {
			runtime->hw.rate_min = snd_pcm_known_rates.list[i];
			break;
		}
	}
	for (i = (int)snd_pcm_known_rates.count - 1; i >= 0; i--) {
		if (runtime->hw.rates & (1 << i)) {
			runtime->hw.rate_max = snd_pcm_known_rates.list[i];
			break;
		}
	}
	return 0;
}

EXPORT_SYMBOL(snd_pcm_limit_hw_rates);

/**
 * snd_pcm_rate_to_rate_bit - converts sample rate to SNDRV_PCM_RATE_xxx bit
 * @rate: the sample rate to convert
 *
 * Returns the SNDRV_PCM_RATE_xxx flag that corresponds to the given rate, or
 * SNDRV_PCM_RATE_KNOT for an unknown rate.
 */
unsigned int snd_pcm_rate_to_rate_bit(unsigned int rate)
{
	unsigned int i;

	for (i = 0; i < snd_pcm_known_rates.count; i++)
		if (snd_pcm_known_rates.list[i] == rate)
			return 1u << i;
	return SNDRV_PCM_RATE_KNOT;
}
EXPORT_SYMBOL(snd_pcm_rate_to_rate_bit);