Output Interface


Typedefs

typedef _snd_output snd_output_t
 Internal structure for an output object.
typedef enum _snd_output_type snd_output_type_t

Enumerations

enum  _snd_output_type { SND_OUTPUT_STDIO, SND_OUTPUT_BUFFER }

Functions

int snd_output_stdio_open (snd_output_t **outputp, const char *file, const char *mode)
 Creates a new output object writing to a file.
int snd_output_stdio_attach (snd_output_t **outputp, FILE *fp, int _close)
 Creates a new output object using an existing stdio FILE pointer.
int snd_output_buffer_open (snd_output_t **outputp)
 Creates a new output object with an auto-extending memory buffer.
size_t snd_output_buffer_string (snd_output_t *output, char **buf)
 Returns the address of the buffer of a SND_OUTPUT_TYPE_BUFFER output handle.
int snd_output_close (snd_output_t *output)
 Closes an output handle.
int snd_output_printf (snd_output_t *output, const char *format,...)
 Writes formatted output (like fprintf(3)) to an output handle.
int snd_output_vprintf (snd_output_t *output, const char *format, va_list args)
 Writes formatted output (like fprintf(3)) to an output handle.
int snd_output_puts (snd_output_t *output, const char *str)
 Writes a string to an output handle (like fputs(3)).
int snd_output_putc (snd_output_t *output, int c)
 Writes a character to an output handle (like putc(3)).
int snd_output_flush (snd_output_t *output)
 Flushes an output handle (like fflush(3)).

Detailed Description

The output functions present an interface similar to the stdio functions on top of different underlying output destinations.

Many PCM debugging functions (snd_pcm_xxx_dump_xxx) use such an output handle to be able to write not only to the screen but also to other destinations, e.g. to files or to memory buffers.


Typedef Documentation

typedef struct _snd_output snd_output_t

Internal structure for an output object.

The ALSA library uses a pointer to this structure as a handle to an output object. Applications don't access its contents directly.

Examples:
/test/latency.c, /test/pcm.c, and /test/pcm_min.c.

typedef enum _snd_output_type snd_output_type_t

Output type.


Enumeration Type Documentation

enum _snd_output_type

Output type.

Enumerator:
SND_OUTPUT_STDIO  Output to a stdio stream.
SND_OUTPUT_BUFFER  Output to a memory buffer.


Function Documentation

int snd_output_buffer_open ( snd_output_t **  outputp  ) 

Creates a new output object with an auto-extending memory buffer.

Parameters:
outputp The function puts the pointer to the new output object at the address specified by outputp.
Returns:
Zero if successful, otherwise a negative error code.

size_t snd_output_buffer_string ( snd_output_t output,
char **  buf 
)

Returns the address of the buffer of a SND_OUTPUT_TYPE_BUFFER output handle.

Parameters:
output The output handle.
buf The functions puts the current address of the buffer at the address specified by buf.
Returns:
The current size of valid data in the buffer.
The address of the buffer may become invalid when output functions or snd_output_close are called.

int snd_output_close ( snd_output_t output  ) 

Closes an output handle.

Parameters:
output The output handle to be closed.
Returns:
Zero if successful, otherwise a negative error code.

int snd_output_flush ( snd_output_t output  ) 

Flushes an output handle (like fflush(3)).

Parameters:
output The output handle.
Returns:
Zero if successful, otherwise EOF.
If the underlying destination is a stdio stream, this function calls fflush. If the underlying destination is a memory buffer, the write position is reset to the beginning of the buffer. =:-o

int snd_output_printf ( snd_output_t output,
const char *  format,
  ... 
)

Writes formatted output (like fprintf(3)) to an output handle.

Parameters:
output The output handle.
format Format string in fprintf format.
... Other fprintf arguments.
Returns:
The number of characters written, or a negative error code.

int snd_output_putc ( snd_output_t output,
int  c 
)

Writes a character to an output handle (like putc(3)).

Parameters:
output The output handle.
c The character.
Returns:
Zero if successful, otherwise a negative error code or EOF.

int snd_output_puts ( snd_output_t output,
const char *  str 
)

Writes a string to an output handle (like fputs(3)).

Parameters:
output The output handle.
str Pointer to the string.
Returns:
Zero if successful, otherwise a negative error code or EOF.

int snd_output_stdio_attach ( snd_output_t **  outputp,
FILE *  fp,
int  _close 
)

Creates a new output object using an existing stdio FILE pointer.

Parameters:
outputp The function puts the pointer to the new output object at the address specified by outputp.
fp The FILE pointer to write to. Characters are written to the file starting at the current file position.
_close Close flag. Set this to 1 if snd_output_close should close fp by calling fclose.
Returns:
Zero if successful, otherwise a negative error code.
Examples:
/test/latency.c, and /test/pcm.c.

int snd_output_stdio_open ( snd_output_t **  outputp,
const char *  file,
const char *  mode 
)

Creates a new output object writing to a file.

Parameters:
outputp The function puts the pointer to the new output object at the address specified by outputp.
file The name of the file to open.
mode The open mode, like fopen(3).
Returns:
Zero if successful, otherwise a negative error code.

int snd_output_vprintf ( snd_output_t output,
const char *  format,
va_list  args 
)

Writes formatted output (like fprintf(3)) to an output handle.

Parameters:
output The output handle.
format Format string in fprintf format.
args Other fprintf arguments.
Returns:
The number of characters written, or a negative error code.


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