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Completed PCM documentation

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This commit is contained in:
Abramo Bagnara 2001-03-24 16:14:44 +00:00
parent 10a2d4267f
commit ddc9a186cf
13 changed files with 2899 additions and 1320 deletions
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83
src/pcm/pcm_misc.c
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@ -38,6 +38,12 @@
#include "pcm_local.h"
#endif
/**
* \brief Return sign info for a PCM sample linear format
* \param format Format
* \return 0 unsigned, 1 signed, a negative error code if format is not linear
*/
int snd_pcm_format_signed(snd_pcm_format_t format)
{
switch (snd_enum_to_int(format)) {
@ -62,6 +68,11 @@ int snd_pcm_format_signed(snd_pcm_format_t format)
}
}
/**
* \brief Return sign info for a PCM sample linear format
* \param format Format
* \return 0 signed, 1 unsigned, a negative error code if format is not linear
*/
int snd_pcm_format_unsigned(snd_pcm_format_t format)
{
int val;
@ -72,11 +83,21 @@ int snd_pcm_format_unsigned(snd_pcm_format_t format)
return !val;
}
/**
* \brief Return linear info for a PCM sample format
* \param format Format
* \return 0 non linear, 1 linear
*/
int snd_pcm_format_linear(snd_pcm_format_t format)
{
return snd_pcm_format_signed(format) >= 0;
}
/**
* \brief Return endian info for a PCM sample format
* \param format Format
* \return 0 big endian, 1 little endian, a negative error code if endian independent
*/
int snd_pcm_format_little_endian(snd_pcm_format_t format)
{
switch (snd_enum_to_int(format)) {
@ -105,6 +126,11 @@ int snd_pcm_format_little_endian(snd_pcm_format_t format)
}
}
/**
* \brief Return endian info for a PCM sample format
* \param format Format
* \return 0 little endian, 1 big endian, a negative error code if endian independent
*/
int snd_pcm_format_big_endian(snd_pcm_format_t format)
{
int val;
@ -115,6 +141,11 @@ int snd_pcm_format_big_endian(snd_pcm_format_t format)
return !val;
}
/**
* \brief Return endian info for a PCM sample format
* \param format Format
* \return 0 swapped, 1 CPU endian, a negative error code if endian independent
*/
int snd_pcm_format_cpu_endian(snd_pcm_format_t format)
{
#ifdef SNDRV_LITTLE_ENDIAN
@ -124,6 +155,11 @@ int snd_pcm_format_cpu_endian(snd_pcm_format_t format)
#endif
}
/**
* \brief Return nominal bits per a PCM sample
* \param format Sample format
* \return bits per sample, a negative error code if not applicable
*/
int snd_pcm_format_width(snd_pcm_format_t format)
{
switch (snd_enum_to_int(format)) {
@ -163,6 +199,11 @@ int snd_pcm_format_width(snd_pcm_format_t format)
}
}
/**
* \brief Return bits needed to store a PCM sample
* \param format Sample format
* \return bits per sample, a negative error code if not applicable
*/
int snd_pcm_format_physical_width(snd_pcm_format_t format)
{
switch (snd_enum_to_int(format)) {
@ -200,6 +241,12 @@ int snd_pcm_format_physical_width(snd_pcm_format_t format)
}
}
/**
* \brief Return bytes needed to store a quantity of PCM sample
* \param format Sample format
* \param samples Samples count
* \return bytes needed, a negative error code if not integer or unknown
*/
ssize_t snd_pcm_format_size(snd_pcm_format_t format, size_t samples)
{
switch (snd_enum_to_int(format)) {
@ -241,6 +288,11 @@ ssize_t snd_pcm_format_size(snd_pcm_format_t format, size_t samples)
}
}
/**
* \brief Return 64 bit expressing silence for a PCM sample format
* \param format Sample format
* \return silence 64 bit word
*/
u_int64_t snd_pcm_format_silence_64(snd_pcm_format_t format)
{
switch (snd_enum_to_int(format)) {
@ -352,21 +404,45 @@ u_int64_t snd_pcm_format_silence_64(snd_pcm_format_t format)
return 0;
}
/**
* \brief Return 32 bit expressing silence for a PCM sample format
* \param format Sample format
* \return silence 32 bit word
*/
u_int32_t snd_pcm_format_silence_32(snd_pcm_format_t format)
{
assert(snd_pcm_format_physical_width(format) <= 32);
return (u_int32_t)snd_pcm_format_silence_64(format);
}
/**
* \brief Return 16 bit expressing silence for a PCM sample format
* \param format Sample format
* \return silence 16 bit word
*/
u_int16_t snd_pcm_format_silence_16(snd_pcm_format_t format)
{
assert(snd_pcm_format_physical_width(format) <= 16);
return (u_int16_t)snd_pcm_format_silence_64(format);
}
/**
* \brief Return 8 bit expressing silence for a PCM sample format
* \param format Sample format
* \return silence 8 bit word
*/
u_int8_t snd_pcm_format_silence(snd_pcm_format_t format)
{
assert(snd_pcm_format_physical_width(format) <= 8);
return (u_int8_t)snd_pcm_format_silence_64(format);
}
/**
* \brief Silence a PCM samples buufer
* \param format Sample format
* \param data Buffer
* \return samples Samples count
*/
int snd_pcm_format_set_silence(snd_pcm_format_t format, void *data, unsigned int samples)
{
if (samples == 0)
@ -405,6 +481,7 @@ int snd_pcm_format_set_silence(snd_pcm_format_t format, void *data, unsigned int
break;
}
default:
assert(0);
return -EINVAL;
}
return 0;
@ -429,6 +506,12 @@ static int linear_formats[4*2*2] = {
SNDRV_PCM_FORMAT_U32_BE
};
/**
* \brief Compose a PCM sample linear format
* \param width Nominal bits per sample
* \param unsignd Sign: 0 signed, 1 unsigned
* \return big_endian Endianness: 0 little endian, 1 big endian
*/
snd_pcm_format_t snd_pcm_build_linear_format(int width, int unsignd, int big_endian)
{
switch (width) {