sound/core/pcm_misc.c - kernel/msm - Gitiles

 /*
  *  PCM Interface - misc routines
  *  Copyright (c) 1998 by Jaroslav Kysela <perex@suse.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 <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;
 }

 /**
  * 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;
 }

 /**
  * 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;
 }

 /**
  * 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;
 }

 /**
  * 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;
 }

 /**
  * 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;
 }

 /**
  * 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;
 }

 /**
  * 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;
 }

 /**
  * 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;
 }

 /**
  * 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;
 }

 /* [width][unsigned][bigendian] */
 static int linear_formats[4][2][2] = {
 	{{ SNDRV_PCM_FORMAT_S8, SNDRV_PCM_FORMAT_S8},
 	 { SNDRV_PCM_FORMAT_U8, SNDRV_PCM_FORMAT_U8}},
 	{{SNDRV_PCM_FORMAT_S16_LE, SNDRV_PCM_FORMAT_S16_BE},
 	 {SNDRV_PCM_FORMAT_U16_LE, SNDRV_PCM_FORMAT_U16_BE}},
 	{{SNDRV_PCM_FORMAT_S24_LE, SNDRV_PCM_FORMAT_S24_BE},
 	 {SNDRV_PCM_FORMAT_U24_LE, SNDRV_PCM_FORMAT_U24_BE}},
 	{{SNDRV_PCM_FORMAT_S32_LE, SNDRV_PCM_FORMAT_S32_BE},
 	 {SNDRV_PCM_FORMAT_U32_LE, SNDRV_PCM_FORMAT_U32_BE}}
 };

 /**
  * snd_pcm_build_linear_format - return the suitable linear format for the given condition
  * @width: the bit-width
  * @unsignd: 1 if unsigned, 0 if signed.
  * @big_endian: 1 if big-endian, 0 if little-endian
  *
  * Returns the suitable linear format for the given condition.
  */
 snd_pcm_format_t snd_pcm_build_linear_format(int width, int unsignd, int big_endian)
 {
 	if (width & 7)
 		return SND_PCM_FORMAT_UNKNOWN;
 	width = (width / 8) - 1;
 	if (width < 0 || width >= 4)
 		return SND_PCM_FORMAT_UNKNOWN;
 	return linear_formats[width][!!unsignd][!!big_endian];
 }

 /**
  * 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)
 {
 	static unsigned rates[] = {
 		/* ATTENTION: these values depend on the definition in pcm.h! */
 		5512, 8000, 11025, 16000, 22050, 32000, 44100, 48000,
 		64000, 88200, 96000, 176400, 192000
 	};
 	int i;
 	for (i = 0; i < (int)ARRAY_SIZE(rates); i++) {
 		if (runtime->hw.rates & (1 << i)) {
 			runtime->hw.rate_min = rates[i];
 			break;
 		}
 	}
 	for (i = (int)ARRAY_SIZE(rates) - 1; i >= 0; i--) {
 		if (runtime->hw.rates & (1 << i)) {
 			runtime->hw.rate_max = rates[i];
 			break;
 		}
 	}
 	return 0;
 }
	/*
	* PCM Interface - misc routines
	* Copyright (c) 1998 by Jaroslav Kysela <perex@suse.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 <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;
	}

	/**
	* 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;
	}

	/**
	* 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;
	}

	/**
	* 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;
	}

	/**
	* 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;
	}

	/**
	* 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;
	}

	/**
	* 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;
	}

	/**
	* 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;
	}

	/**
	* 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;
	}

	/**
	* 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;
	}

	/* [width][unsigned][bigendian] */
	static int linear_formats[4][2][2] = {
	{{ SNDRV_PCM_FORMAT_S8, SNDRV_PCM_FORMAT_S8},
	{ SNDRV_PCM_FORMAT_U8, SNDRV_PCM_FORMAT_U8}},
	{{SNDRV_PCM_FORMAT_S16_LE, SNDRV_PCM_FORMAT_S16_BE},
	{SNDRV_PCM_FORMAT_U16_LE, SNDRV_PCM_FORMAT_U16_BE}},
	{{SNDRV_PCM_FORMAT_S24_LE, SNDRV_PCM_FORMAT_S24_BE},
	{SNDRV_PCM_FORMAT_U24_LE, SNDRV_PCM_FORMAT_U24_BE}},
	{{SNDRV_PCM_FORMAT_S32_LE, SNDRV_PCM_FORMAT_S32_BE},
	{SNDRV_PCM_FORMAT_U32_LE, SNDRV_PCM_FORMAT_U32_BE}}
	};

	/**
	* snd_pcm_build_linear_format - return the suitable linear format for the given condition
	* @width: the bit-width
	* @unsignd: 1 if unsigned, 0 if signed.
	* @big_endian: 1 if big-endian, 0 if little-endian
	*
	* Returns the suitable linear format for the given condition.
	*/
	snd_pcm_format_t snd_pcm_build_linear_format(int width, int unsignd, int big_endian)
	{
	if (width & 7)
	return SND_PCM_FORMAT_UNKNOWN;
	width = (width / 8) - 1;
	if (width < 0 \|\| width >= 4)
	return SND_PCM_FORMAT_UNKNOWN;
	return linear_formats[width][!!unsignd][!!big_endian];
	}

	/**
	* 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)
	{
	static unsigned rates[] = {
	/* ATTENTION: these values depend on the definition in pcm.h! */
	5512, 8000, 11025, 16000, 22050, 32000, 44100, 48000,
	64000, 88200, 96000, 176400, 192000
	};
	int i;
	for (i = 0; i < (int)ARRAY_SIZE(rates); i++) {
	if (runtime->hw.rates & (1 << i)) {
	runtime->hw.rate_min = rates[i];
	break;
	}
	}
	for (i = (int)ARRAY_SIZE(rates) - 1; i >= 0; i--) {
	if (runtime->hw.rates & (1 << i)) {
	runtime->hw.rate_max = rates[i];
	break;
	}
	}
	return 0;
	}