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Typedefs | Enumerations | Functions
Output Interface

Typedefs

typedef struct _snd_output snd_output_t
 Internal structure for an output object. More...
 

Enumerations

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

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.

Enumeration Type Documentation

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
outputpThe 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_BUFFER output handle.

Parameters
outputThe output handle.
bufThe 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
outputThe 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
outputThe 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
outputThe output handle.
formatFormat 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
outputThe output handle.
cThe 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
outputThe output handle.
strPointer 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
outputpThe function puts the pointer to the new output object at the address specified by outputp.
fpThe FILE pointer to write to. Characters are written to the file starting at the current file position.
_closeClose 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
outputpThe function puts the pointer to the new output object at the address specified by outputp.
fileThe name of the file to open.
modeThe 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
outputThe output handle.
formatFormat string in fprintf format.
argsOther fprintf arguments.
Returns
The number of characters written, or a negative error code.

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