Backend Interface

Data Structures

struct  rte_context
struct  rte_context_class
struct  rte_backend_class

Defines

#define RTE_OPTION_BOUNDS_INITIALIZER_(type_, def_, min_, max_, step_)   { type_ = def_ }, { type_ = min_ }, { type_ = max_ }, { type_ = step_ }
#define RTE_OPTION_BOOL_INITIALIZER(key_, label_, def_, tip_)
#define RTE_OPTION_INT_RANGE_INITIALIZER(key_, label_, def_, min_, max_, step_, tip_)
#define RTE_OPTION_INT_MENU_INITIALIZER(key_, label_, def_,menu_, entries_, tip_)
#define RTE_OPTION_REAL_RANGE_INITIALIZER(key_, label_, def_, min_, max_, step_, tip_)
#define RTE_OPTION_REAL_MENU_INITIALIZER(key_, label_, def_,menu_, entries_, tip_)
#define RTE_OPTION_STRING_INITIALIZER(key_, label_, def_, tip_)
#define RTE_OPTION_STRING_MENU_INITIALIZER(key_, label_, def_,menu_, entries_, tip_)
#define RTE_OPTION_MENU_INITIALIZER(key_, label_, def_, menu_,entries_, tip_)
#define RTE_OPTION_ARG(type, min, max)
#define RTE_OPTION_ARG_MENU(menu)   RTE_OPTION_ARG(int, 0, sizeof(menu) / sizeof(menu[0]))
#define RTE_OPTION_ARG_SAT(type, min, max)
#define RTE_2(x)   #x
#define RTE_1(x)   RTE_2(x)
#define nullcheck(X, whattodo)

Typedefs

typedef struct rte_context_class rte_context_class
typedef struct rte_backend_class rte_backend_class

Enumerations

enum  rte_state {
  RTE_STATE_NEW = 0,
  RTE_STATE_PARAM,
  RTE_STATE_READY,
  RTE_STATE_RUNNING,
  RTE_STATE_PAUSED
}
enum  rte_io_method {
  RTE_CALLBACK_MASTER = 1,
  RTE_CALLBACK_SLAVE,
  RTE_PUSH_MASTER,
  RTE_PUSH_SLAVE,
  RTE_FIFO,
  RTE_FILE,
  RTE_STDIO,
  RTE_DISCARD
}

Functions

void rte_unknown_option (rte_context *context, rte_codec *codec, const char *keyword)
void rte_invalid_option (rte_context *context, rte_codec *codec, const char *keyword,...)
void rte_asprintf (char **errstr, const char *templ,...)
char * rte_strdup (rte_context *context, char **d, const char *s)
unsigned int rte_closest_int (const int *vec, unsigned int len, int val)
unsigned int rte_closest_double (const double *vec, unsigned int len, double val)
rte_bool rte_option_string (rte_context *context, rte_codec *codec, const char *optstr)
static_inline int rte_closest_int_val (const int *vec, unsigned int len, int val)
static_inline double rte_closest_double_val (const double *vec, unsigned int len, double val)
static_inline void rte_error_reset (rte_context *context)

Detailed Description

These, together with the public RTE structures, are the definitions of the RTE backend interface from rtepriv.h. Only backends use this, not RTE clients.


Define Documentation

#define RTE_OPTION_BOOL_INITIALIZER ( key_,
label_,
def_,
tip_   ) 
Value:
{ RTE_OPTION_BOOL, key_, label_, RTE_OPTION_BOUNDS_INITIALIZER_(        \
  .num, def_, 0, 1, 1), { .num = NULL }, tip_ }

Helper macro for backends to build option lists. Use like this:

 rte_option_info myinfo = RTE_OPTION_BOOL_INITIALIZER
   ("mute", N_("Switch sound on/off"), FALSE, N_("I am a tooltip"));

N_() marks the string for i18n, see info gettext for details.

#define RTE_OPTION_INT_RANGE_INITIALIZER ( key_,
label_,
def_,
min_,
max_,
step_,
tip_   ) 
Value:
{ RTE_OPTION_INT, key_, label_,                 \
  RTE_OPTION_BOUNDS_INITIALIZER_(.num, def_, min_, max_, step_),        \
  { .num = NULL }, tip_ }

Helper macro for backends to build option lists. Use like this:

 rte_option_info myinfo = RTE_OPTION_INT_RANGE_INITIALIZER
   ("sampling", N_("Sampling rate"), 44100, 8000, 48000, 100, NULL);

Here we have no tooltip (NULL).

#define RTE_OPTION_INT_MENU_INITIALIZER ( key_,
label_,
def_,
menu_,
entries_,
tip_   ) 
Value:
{ RTE_OPTION_INT, key_, label_,         \
  RTE_OPTION_BOUNDS_INITIALIZER_(.num, def_, 0, (entries_) - 1, 1),     \
  { .num = menu_ }, tip_ }

Helper macro for backends to build option lists. Use like this:

 int mymenu[] = { 29, 30, 31 };

 rte_option_info myinfo = RTE_OPTION_INT_MENU_INITIALIZER
   ("days", NULL, 1, mymenu, 3, NULL);

No label and tooltip (NULL), i. e. this option is not to be listed in the user interface. Default is entry 1 ("30") of 3 entries.

#define RTE_OPTION_REAL_RANGE_INITIALIZER ( key_,
label_,
def_,
min_,
max_,
step_,
tip_   ) 
Value:
{ RTE_OPTION_REAL, key_, label_,                        \
  RTE_OPTION_BOUNDS_INITIALIZER_(.dbl, def_, min_, max_, step_),        \
  { .dbl = NULL }, tip_ }

Helper macro for backends to build option lists. Use like RTE_OPTION_INT_RANGE_INITIALIZER(), just with doubles but ints.

#define RTE_OPTION_REAL_MENU_INITIALIZER ( key_,
label_,
def_,
menu_,
entries_,
tip_   ) 
Value:
{ RTE_OPTION_REAL, key_, label_,                \
  RTE_OPTION_BOUNDS_INITIALIZER_(.num, def_, 0, (entries_) - 1, 1),     \
  { .dbl = menu_ }, tip_ }

Helper macro for backends to build option lists. Use like RTE_OPTION_INT_MENU_INITIALIZER(), just with an array of doubles but ints.

#define RTE_OPTION_STRING_INITIALIZER ( key_,
label_,
def_,
tip_   ) 
Value:
{ RTE_OPTION_STRING, key_, label_, RTE_OPTION_BOUNDS_INITIALIZER_(      \
  .str, def_, NULL, NULL, NULL), { .str = NULL }, tip_ }

Helper macro for backends to build option lists. Use like this:

 rte_option_info myinfo = RTE_OPTION_STRING_INITIALIZER
   ("comment", N_("Comment"), "bububaba", "Please enter a string");
#define RTE_OPTION_STRING_MENU_INITIALIZER ( key_,
label_,
def_,
menu_,
entries_,
tip_   ) 
Value:
{ RTE_OPTION_STRING, key_, label_,              \
  RTE_OPTION_BOUNDS_INITIALIZER_(.str, def_, 0, (entries_) - 1, 1),     \
  { .str = menu_ }, tip_ }

Helper macro for backends to build option lists. Use like this:

 char *mymenu[] = { "txt", "html" };

 rte_option_info myinfo = RTE_OPTION_STRING_MENU_INITIALIZER
   ("extension", "Ext", 0, mymenu, 2, N_("Select an extension"));

Remember this is like RTE_OPTION_STRING_INITIALIZER() in the sense that the rte client can pass any string as option value, not just those proposed in the menu. In contrast a plain menu option as with RTE_OPTION_MENU_INITIALIZER() expects menu indices as input.

#define RTE_OPTION_MENU_INITIALIZER ( key_,
label_,
def_,
menu_,
entries_,
tip_   ) 
Value:
{ RTE_OPTION_MENU, key_, label_,                        \
  RTE_OPTION_BOUNDS_INITIALIZER_(.num, def_, 0, (entries_) - 1, 1),     \
  { .str = menu_ }, tip_ }

Helper macro for backends to build option lists. Use like this:

 char *mymenu[] = { N_("Monday"), N_("Tuesday") };

 rte_option_info myinfo = RTE_OPTION_MENU_INITIALIZER
   ("weekday", "Weekday, 0, mymenu, 2, N_("Select a weekday"));
#define RTE_OPTION_ARG ( type,
min,
max   ) 
Value:
({                                                                      \
        type val = va_arg(args, type);                                  \
                                                                        \
        if (val < (min) || val > (max)) {                               \
                rte_invalid_option(context, codec, keyword, val);       \
                goto failed;                                            \
        }                                                               \
                val;                                                    \
})

Helper macro for backends to parse options. Use like this:

 myfunc (va_list args)
 {
   int myval = RTE_OPTION_ARG (int, -100, +200);

   :

   failed:
     return FALSE;
 }
#define RTE_OPTION_ARG_MENU ( menu   )     RTE_OPTION_ARG(int, 0, sizeof(menu) / sizeof(menu[0]))

Helper macro for backends to parse options. Use like this:

 char *mymenu[] = { N_("Monday"), N_("Tuesday") };

 myfunc (va_list args)
 {
   int myval = RTE_OPTION_ARG_MENU (mymenu); // fails if not 0 ... 1

   :

   failed:
     return FALSE;
 }
#define RTE_OPTION_ARG_SAT ( type,
min,
max   ) 
Value:
({                                                                      \
        type val = va_arg(args, type);                                  \
                                                                        \
        if (val < (min)) val = min;                                     \
        else if (val > (max)) val = max;                                \
        val;                                                            \
})

Helper macro for backends to parse options. Same as RTE_OPTION_ARG(), but saturates argument to min...max instead of failing.

#define nullcheck ( X,
whattodo   ) 
Value:
do {                                                                    \
        if ((X) == NULL) {                                              \
                const char *s = "rte:" __FILE__ ":" RTE_1(__LINE__)     \
                                ":%s: " #X " == NULL.\n";               \
                if (context)                                            \
                        rte_error_printf(context, s,                    \
                                         __PRETTY_FUNCTION__);          \
                else                                                    \
                        fprintf(stderr, s, __PRETTY_FUNCTION__);        \
                whattodo;                                               \
        }                                                               \
} while (0)

Typedef Documentation

Part of the backend interface.


Enumeration Type Documentation

enum rte_state

Context or codec state. The state field in rte_context and rte_codec must be set by the context and codec functions as documented below.

Enumerator:
RTE_STATE_NEW 

Set on success of: codec_class->_new() codec_class->option_set() context_class->_new() context_class->option_set() context_class->stop()

RTE_STATE_PARAM 

On success of: codec_class->parameters_set()

RTE_STATE_READY 

On success of: codec_class->set_input() context_class->set_output()

RTE_STATE_RUNNING 

On success of: context_class->start() (-> stop, -> pause)

RTE_STATE_PAUSED 

On success of: context_class->pause() (-> start, -> stop)

I/O mode.

Enumerator:
RTE_CALLBACK_MASTER 

rte_set_input_callback_master()

RTE_CALLBACK_SLAVE 

rte_set_input_callback_slave()

RTE_PUSH_MASTER 

rte_set_input_push_master()

RTE_PUSH_SLAVE 

rte_set_input_push_slave()

RTE_FIFO 

To be defined

RTE_FILE 

Used by frontend only

RTE_STDIO 

Used by frontend only

RTE_DISCARD 

Used by frontend only


Function Documentation

void rte_unknown_option ( rte_context context,
rte_codec codec,
const char *  keyword 
)
Parameters:
context Initialized rte_context as returned by rte_context_new().
codec Pointer to rte_codec if this refers to a codec option, NULL if context option.
keyword Keyword of the option, can be NULL or "".

RTE internal helper function for backends.

Sets the context error string.

void rte_invalid_option ( rte_context context,
rte_codec codec,
const char *  keyword,
  ... 
)
Parameters:
context Initialized rte_context as returned by rte_context_new().
codec Pointer to rte_codec if this refers to a codec option, NULL if context option.
keyword Keyword of the option, can be NULL or "".
... If the option is known, the invalid data (int, double, char *).

RTE internal helper function for backends.

Sets the context error string.

void rte_asprintf ( char **  errstr,
const char *  templ,
  ... 
)
Parameters:
errstr Place to store the allocated string or NULL.
templ See printf().
... See printf().

RTE internal helper function for backends.

Identical to GNU or BSD libc asprintf().

char* rte_strdup ( rte_context context,
char **  d,
const char *  s 
)
Parameters:
context Initialized rte_context as returned by rte_context_new().
d If non-zero, store pointer to allocated string here. When *d is non-zero, free(*d) the old string first.
s String to be duplicated.

RTE internal helper function for backends.

Same as the libc strdup(), except for d argument and setting the context error string on failure.

Returns:
NULL on failure, pointer to malloc()ed string otherwise.
unsigned int rte_closest_int ( const int *  vec,
unsigned int  len,
int  val 
)
Parameters:
vec Vector of int values.
len Length of the vector.
val Value to be compared.

RTE internal helper function for backends.

Find in a vector of int values the entry closest to val and return its index, 0 ... n.

Returns:
Index. Never fails.
unsigned int rte_closest_double ( const double *  vec,
unsigned int  len,
double  val 
)
Parameters:
vec Vector of double values.
len Length of the vector.
val Value to be compared.

RTE internal helper function for backends.

Find in a vector of double values the entry closest to val and return its index, 0 ... n.

Returns:
Index. Never fails.

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