X-Git-Url: https://sigrok.org/gitweb/?p=libsigrok.git;a=blobdiff_plain;f=libsigrok.h;h=9c69474e3f0f3260811f4a3286eb6cb565b728ae;hp=79a767717f4d12746c4ad97cbb1dd9aeeb76ec02;hb=ba7dd8bbb8168cba432a844259a3e239aa5f36d7;hpb=409a811b8c078341185badadda8f4be380a5f88d
diff --git a/libsigrok.h b/libsigrok.h
index 79a76771..9c69474e 100644
--- a/libsigrok.h
+++ b/libsigrok.h
@@ -17,8 +17,8 @@
* along with this program. If not, see .
*/
-#ifndef LIBSIGROK_SIGROK_H
-#define LIBSIGROK_SIGROK_H
+#ifndef LIBSIGROK_LIBSIGROK_H
+#define LIBSIGROK_LIBSIGROK_H
#include
#include
@@ -41,9 +41,9 @@ extern "C" {
*
* The correct way to get/use the libsigrok API functions is:
*
- * @code{.c}
- * #include
- * @endcode
+ @code{.c}
+ #include
+ @endcode
*/
/*
@@ -64,14 +64,16 @@ extern "C" {
/** Status/error codes returned by libsigrok functions. */
enum {
- SR_OK = 0, /**< No error. */
- SR_ERR = -1, /**< Generic/unspecified error. */
- SR_ERR_MALLOC = -2, /**< Malloc/calloc/realloc error. */
- SR_ERR_ARG = -3, /**< Function argument error. */
- SR_ERR_BUG = -4, /**< Errors hinting at internal bugs. */
- SR_ERR_SAMPLERATE = -5, /**< Incorrect samplerate. */
- SR_ERR_NA = -6, /**< Not applicable. */
- SR_ERR_DEV_CLOSED = -7, /**< Device is closed, but needs to be open. */
+ SR_OK = 0, /**< No error. */
+ SR_ERR = -1, /**< Generic/unspecified error. */
+ SR_ERR_MALLOC = -2, /**< Malloc/calloc/realloc error. */
+ SR_ERR_ARG = -3, /**< Function argument error. */
+ SR_ERR_BUG = -4, /**< Errors hinting at internal bugs. */
+ SR_ERR_SAMPLERATE = -5, /**< Incorrect samplerate. */
+ SR_ERR_NA = -6, /**< Not applicable. */
+ SR_ERR_DEV_CLOSED = -7, /**< Device is closed, but must be open. */
+ SR_ERR_TIMEOUT = -8, /**< A timeout occurred. */
+ SR_ERR_CHANNEL_GROUP = -9, /**< A channel group must be specified. */
/*
* Note: When adding entries here, don't forget to also update the
@@ -79,7 +81,6 @@ enum {
*/
};
-#define SR_MAX_NUM_PROBES 64 /* Limited by uint64_t. */
#define SR_MAX_PROBENAME_LEN 32
/* Handy little macros */
@@ -130,6 +131,7 @@ enum {
#define SR_PRIV
#endif
+/** Type definition for callback function for data reception. */
typedef int (*sr_receive_data_callback_t)(int fd, int revents, void *cb_data);
/** Data types used by sr_config_info(). */
@@ -141,21 +143,32 @@ enum {
SR_T_RATIONAL_PERIOD,
SR_T_RATIONAL_VOLT,
SR_T_KEYVALUE,
+ SR_T_UINT64_RANGE,
+ SR_T_DOUBLE_RANGE,
+ SR_T_INT32,
};
/** Value for sr_datafeed_packet.type. */
enum {
+ /** Payload is sr_datafeed_header. */
SR_DF_HEADER = 10000,
+ /** End of stream (no further data). */
SR_DF_END,
+ /** Payload is struct sr_datafeed_meta */
SR_DF_META,
+ /** The trigger matched at this point in the data feed. No payload. */
SR_DF_TRIGGER,
+ /** Payload is struct sr_datafeed_logic. */
SR_DF_LOGIC,
+ /** Payload is struct sr_datafeed_analog. */
SR_DF_ANALOG,
+ /** Beginning of frame. No payload. */
SR_DF_FRAME_BEGIN,
+ /** End of frame. No payload. */
SR_DF_FRAME_END,
};
-/** Values for sr_datafeed_analog.mq. */
+/** Measured quantity, sr_datafeed_analog.mq. */
enum {
SR_MQ_VOLTAGE = 10000,
SR_MQ_CURRENT,
@@ -163,7 +176,9 @@ enum {
SR_MQ_CAPACITANCE,
SR_MQ_TEMPERATURE,
SR_MQ_FREQUENCY,
+ /** Duty cycle, e.g. on/off ratio. */
SR_MQ_DUTY_CYCLE,
+ /** Continuity test. */
SR_MQ_CONTINUITY,
SR_MQ_PULSE_WIDTH,
SR_MQ_CONDUCTANCE,
@@ -174,22 +189,37 @@ enum {
/** Logarithmic representation of sound pressure relative to a
* reference value. */
SR_MQ_SOUND_PRESSURE_LEVEL,
+ /** Carbon monoxide level */
SR_MQ_CARBON_MONOXIDE,
+ /** Humidity */
SR_MQ_RELATIVE_HUMIDITY,
+ /** Time */
+ SR_MQ_TIME,
};
-/** Values for sr_datafeed_analog.unit. */
+/** Unit of measured quantity, sr_datafeed_analog.unit. */
enum {
+ /** Volt */
SR_UNIT_VOLT = 10000,
+ /** Ampere (current). */
SR_UNIT_AMPERE,
+ /** Ohm (resistance). */
SR_UNIT_OHM,
+ /** Farad (capacity). */
SR_UNIT_FARAD,
+ /** Kelvin (temperature). */
SR_UNIT_KELVIN,
+ /** Degrees Celsius (temperature). */
SR_UNIT_CELSIUS,
+ /** Degrees Fahrenheit (temperature). */
SR_UNIT_FAHRENHEIT,
+ /** Hertz (frequency, 1/s, [Hz]). */
SR_UNIT_HERTZ,
+ /** Percent value. */
SR_UNIT_PERCENTAGE,
+ /** Boolean value. */
SR_UNIT_BOOLEAN,
+ /** Time in seconds. */
SR_UNIT_SECOND,
/** Unit of conductance, the inverse of resistance. */
SR_UNIT_SIEMENS,
@@ -214,6 +244,14 @@ enum {
* represented as the fraction of number of particles of the substance.
*/
SR_UNIT_CONCENTRATION,
+ /** Revolutions per minute. */
+ SR_UNIT_REVOLUTIONS_PER_MINUTE,
+ /** Apparent power [VA]. */
+ SR_UNIT_VOLT_AMPERE,
+ /** Real power [W]. */
+ SR_UNIT_WATT,
+ /** Consumption [Wh]. */
+ SR_UNIT_WATT_HOUR,
};
/** Values for sr_datafeed_analog.flags. */
@@ -260,42 +298,61 @@ enum {
/** Sound pressure level represented as a percentage of measurements
* that were over a preset alarm level. */
SR_MQFLAG_SPL_PCT_OVER_ALARM = 0x10000,
+ /** Time is duration (as opposed to epoch, ...). */
+ SR_MQFLAG_DURATION = 0x20000,
+ /** Device is in "avg" mode, averaging upon each new value. */
+ SR_MQFLAG_AVG = 0x40000,
};
+/**
+ * @struct sr_context
+ * Opaque structure representing a libsigrok context.
+ *
+ * None of the fields of this structure are meant to be accessed directly.
+ *
+ * @see sr_init(), sr_exit().
+ */
struct sr_context;
+/** Packet in a sigrok data feed. */
struct sr_datafeed_packet {
uint16_t type;
const void *payload;
};
+/** Header of a sigrok data feed. */
struct sr_datafeed_header {
int feed_version;
struct timeval starttime;
};
+/** Datafeed payload for type SR_DF_META. */
struct sr_datafeed_meta {
GSList *config;
};
+/** Logic datafeed payload for type SR_DF_LOGIC. */
struct sr_datafeed_logic {
uint64_t length;
uint16_t unitsize;
void *data;
};
+/** Analog datafeed payload for type SR_DF_ANALOG. */
struct sr_datafeed_analog {
- /** The probes for which data is included in this packet. */
- GSList *probes;
+ /** The channels for which data is included in this packet. */
+ GSList *channels;
+ /** Number of samples in data */
int num_samples;
- /** Measured quantity (voltage, current, temperature, and so on). */
+ /** Measured quantity (voltage, current, temperature, and so on).
+ * Use SR_MQ_VOLTAGE, ... */
int mq;
- /** Unit in which the MQ is measured. */
+ /** Unit in which the MQ is measured. Use SR_UNIT_VOLT, ... */
int unit;
- /** Bitmap with extra information about the MQ. */
+ /** Bitmap with extra information about the MQ. Use SR_MQFLAG_AC, ... */
uint64_t mqflags;
/** The analog value(s). The data is interleaved according to
- * the probes list. */
+ * the channels list. */
float *data;
};
@@ -314,6 +371,7 @@ struct sr_input {
void *internal;
};
+/** Input (file) format driver. */
struct sr_input_format {
/** The unique ID for this input format. Must not be NULL. */
char *id;
@@ -327,9 +385,10 @@ struct sr_input_format {
/**
* Check if this input module can load and parse the specified file.
*
- * @param filename The name (and path) of the file to check.
+ * @param[in] filename The name (and path) of the file to check.
*
- * @return TRUE if this module knows the format, FALSE if it doesn't.
+ * @retval TRUE This module knows the format.
+ * @retval FALSE This module does not know the format.
*/
int (*format_match) (const char *filename);
@@ -339,9 +398,10 @@ struct sr_input_format {
* @param in A pointer to a valid 'struct sr_input' that the caller
* has to allocate and provide to this function. It is also
* the responsibility of the caller to free it later.
- * @param filename The name (and path) of the file to use.
+ * @param[in] filename The name (and path) of the file to use.
*
- * @return SR_OK upon success, a negative error code upon failure.
+ * @retval SR_OK Success
+ * @retval other Negative error code.
*/
int (*init) (struct sr_input *in, const char *filename);
@@ -362,7 +422,8 @@ struct sr_input_format {
* the responsibility of the caller to free it later.
* @param filename The name (and path) of the file to use.
*
- * @return SR_OK upon success, a negative error code upon failure.
+ * @retval SR_OK Success
+ * @retval other Negative error code.
*/
int (*loadfile) (struct sr_input *in, const char *filename);
};
@@ -377,7 +438,7 @@ struct sr_output {
/**
* The device for which this output module is creating output. This
- * can be used by the module to find out probe names and numbers.
+ * can be used by the module to find out channel names and numbers.
*/
struct sr_dev_inst *sdi;
@@ -398,6 +459,7 @@ struct sr_output {
void *internal;
};
+/** Output (file) format driver. */
struct sr_output_format {
/**
* A unique ID for this output format. Must not be NULL.
@@ -417,6 +479,7 @@ struct sr_output_format {
*/
char *description;
+ /** Datafeed type, SR_DF_HEADER, etc. */
int df_type;
/**
@@ -431,7 +494,8 @@ struct sr_output_format {
*
* @param o Pointer to the respective 'struct sr_output'.
*
- * @return SR_OK upon success, a negative error code otherwise.
+ * @retval SR_OK Success
+ * @retval other Negative error code.
*/
int (*init) (struct sr_output *o);
@@ -455,7 +519,7 @@ struct sr_output_format {
* data_out
parameter, so the caller knows not to try
* and g_free() it.
*
- * Note: This API call is obsolete, use recv() instead.
+ * Note: This API call is obsolete, use receive() instead.
*
* @param o Pointer to the respective 'struct sr_output'.
* @param data_in Pointer to the input data buffer.
@@ -463,7 +527,8 @@ struct sr_output_format {
* @param data_out Pointer to the allocated output buffer.
* @param length_out Length (in bytes) of the output.
*
- * @return SR_OK upon success, a negative error code otherwise.
+ * @retval SR_OK Success
+ * @retval other Negative error code.
*/
int (*data) (struct sr_output *o, const uint8_t *data_in,
uint64_t length_in, uint8_t **data_out,
@@ -487,51 +552,106 @@ struct sr_output_format {
* it stored in the data_out
and length_out
* parameters, or NULL if no output was generated.
*
- * Note: This API call is obsolete, use recv() instead.
+ * Note: This API call is obsolete, use receive() instead.
*
* @param o Pointer to the respective 'struct sr_output'.
* @param event_type Type of event that occured.
* @param data_out Pointer to the allocated output buffer.
* @param length_out Length (in bytes) of the output.
*
- * @return SR_OK upon success, a negative error code otherwise.
+ * @retval SR_OK Success
+ * @retval other Negative error code.
*/
int (*event) (struct sr_output *o, int event_type, uint8_t **data_out,
- uint64_t *length_out);
+ uint64_t *length_out);
- GString *(*recv) (struct sr_output *o, const struct sr_dev_inst *sdi,
- const struct sr_datafeed_packet *packet);
+ /**
+ * This function is passed a copy of every packed in the data feed.
+ * Any output generated by the output module in response to the
+ * packet should be returned in a newly allocated GString
+ * out
, which will be freed by the caller.
+ *
+ * Packets not of interest to the output module can just be ignored,
+ * and the out
parameter set to NULL.
+ *
+ * @param o Pointer to the respective 'struct sr_output'.
+ * @param sdi The device instance that generated the packet.
+ * @param packet The complete packet.
+ * @param out A pointer where a GString * should be stored if
+ * the module generates output, or NULL if not.
+ *
+ * @retval SR_OK Success
+ * @retval other Negative error code.
+ */
+ int (*receive) (struct sr_output *o, const struct sr_dev_inst *sdi,
+ const struct sr_datafeed_packet *packet, GString **out);
+ /**
+ * This function is called after the caller is finished using
+ * the output module, and can be used to free any internal
+ * resources the module may keep.
+ *
+ * @retval SR_OK Success
+ * @retval other Negative error code.
+ */
int (*cleanup) (struct sr_output *o);
};
+/** Constants for probe type. */
enum {
- SR_PROBE_LOGIC = 10000,
- SR_PROBE_ANALOG,
+ /** Probe type is logic probe. */
+ SR_PROBE_LOGIC = 10000,
+ /** Probe type is analog probe. */
+ SR_PROBE_ANALOG,
};
-struct sr_probe {
- /* The index field will go: use g_slist_length(sdi->probes) instead. */
+/** Information on single channel. */
+struct sr_channel {
+ /** Number of channels, starting at 0. */
int index;
+ /** Channel type (SR_PROBE_LOGIC, ...) */
int type;
+ /** Is this channel enabled? */
gboolean enabled;
+ /** Name of channel. */
char *name;
+ /** Trigger string, format like used by sigrok-cli */
char *trigger;
};
+/** Structure for groups of channels that have common properties. */
+struct sr_channel_group {
+ /** Name of the channel group. */
+ char *name;
+ /** List of sr_channel structs of the channels belonging to this group. */
+ GSList *channels;
+ /** Private data for driver use. */
+ void *priv;
+};
+
+/** Used for setting or getting value of a config item. */
struct sr_config {
+ /** Config key like SR_CONF_CONN, etc. */
int key;
+ /** Key-specific data. */
GVariant *data;
};
+/** Information about a config key. */
struct sr_config_info {
+ /** Config key like SR_CONF_CONN, etc. */
int key;
+ /** Data type like SR_T_CHAR, etc. */
int datatype;
+ /** Id string, e.g. "serialcomm". */
char *id;
+ /** Name, e.g. "Serial communication". */
char *name;
+ /** Verbose description (unused currently). */
char *description;
};
+/** Constants for device classes */
enum {
/*--- Device classes ------------------------------------------------*/
@@ -556,6 +676,15 @@ enum {
/** The device can measure humidity. */
SR_CONF_HYGROMETER,
+ /** The device can measure energy consumption. */
+ SR_CONF_ENERGYMETER,
+
+ /** The device can demodulate signals. */
+ SR_CONF_DEMODULATOR,
+
+ /** Programmable power supply. */
+ SR_CONF_POWER_SUPPLY,
+
/*--- Driver scan options -------------------------------------------*/
/**
@@ -585,7 +714,7 @@ enum {
* flow 0 no flow control
* 1 hardware-based (RTS/CTS) flow control
* 2 software-based (XON/XOFF) flow control
- *
+ *
* This is always an optional parameter, since a driver typically
* knows the speed at which the device wants to communicate.
*/
@@ -641,6 +770,72 @@ enum {
/** Number of vertical divisions, as related to SR_CONF_VDIV. */
SR_CONF_NUM_VDIV,
+ /** Sound pressure level frequency weighting. */
+ SR_CONF_SPL_WEIGHT_FREQ,
+
+ /** Sound pressure level time weighting. */
+ SR_CONF_SPL_WEIGHT_TIME,
+
+ /** Sound pressure level measurement range. */
+ SR_CONF_SPL_MEASUREMENT_RANGE,
+
+ /** Max hold mode. */
+ SR_CONF_HOLD_MAX,
+
+ /** Min hold mode. */
+ SR_CONF_HOLD_MIN,
+
+ /** Logic low-high threshold range. */
+ SR_CONF_VOLTAGE_THRESHOLD,
+
+ /** The device supports using an external clock. */
+ SR_CONF_EXTERNAL_CLOCK,
+
+ /**
+ * The device supports swapping channels. Typical this is between
+ * buffered and unbuffered channels.
+ */
+ SR_CONF_SWAP,
+
+ /** Center frequency.
+ * The input signal is downmixed by this frequency before the ADC
+ * anti-aliasing filter.
+ */
+ SR_CONF_CENTER_FREQUENCY,
+
+ /** The device supports setting the number of logic probes. */
+ SR_CONF_NUM_LOGIC_PROBES,
+
+ /** The device supports setting the number of analog probes. */
+ SR_CONF_NUM_ANALOG_PROBES,
+
+ /** Output voltage. */
+ SR_CONF_OUTPUT_VOLTAGE,
+
+ /** Maximum output voltage. */
+ SR_CONF_OUTPUT_VOLTAGE_MAX,
+
+ /** Output current. */
+ SR_CONF_OUTPUT_CURRENT,
+
+ /** Maximum output current. */
+ SR_CONF_OUTPUT_CURRENT_MAX,
+
+ /** Enabling/disabling output. */
+ SR_CONF_OUTPUT_ENABLED,
+
+ /** Channel output configuration. */
+ SR_CONF_OUTPUT_CHANNEL,
+
+ /** Over-voltage protection (OVP) */
+ SR_CONF_OVER_VOLTAGE_PROTECTION,
+
+ /** Over-current protection (OCP) */
+ SR_CONF_OVER_CURRENT_PROTECTION,
+
+ /** Choice of clock edge for external clock ("r" or "f"). */
+ SR_CONF_CLOCK_EDGE,
+
/*--- Special stuff -------------------------------------------------*/
/** Scan options supported by the driver. */
@@ -658,8 +853,22 @@ enum {
/** The device supports specifying the capturefile unit size. */
SR_CONF_CAPTURE_UNITSIZE,
- /** The device supports setting the number of probes. */
- SR_CONF_CAPTURE_NUM_PROBES,
+ /** Power off the device. */
+ SR_CONF_POWER_OFF,
+
+ /**
+ * Data source for acquisition. If not present, acquisition from
+ * the device is always "live", i.e. acquisition starts when the
+ * frontend asks and the results are sent out as soon as possible.
+ *
+ * If present, it indicates that either the device has no live
+ * acquisition capability (for example a pure data logger), or
+ * there is a choice. sr_config_list() returns those choices.
+ *
+ * In any case if a device has live acquisition capabilities, it
+ * is always the default.
+ */
+ SR_CONF_DATA_SOURCE,
/*--- Acquisition modes ---------------------------------------------*/
@@ -693,28 +902,44 @@ enum {
SR_CONF_DATALOG,
};
+/** Device instance data
+ */
struct sr_dev_inst {
+ /** Device driver. */
struct sr_dev_driver *driver;
+ /** Index of device in driver. */
int index;
+ /** Device instance status. SR_ST_NOT_FOUND, etc. */
int status;
+ /** Device instance type. SR_INST_USB, etc. */
int inst_type;
+ /** Device vendor. */
char *vendor;
+ /** Device model. */
char *model;
+ /** Device version. */
char *version;
- GSList *probes;
+ /** List of channels. */
+ GSList *channels;
+ /** List of sr_channel_group structs */
+ GSList *channel_groups;
+ /** Device instance connection data (used?) */
void *conn;
+ /** Device instance private data (used?) */
void *priv;
};
-/** Types of device instances (sr_dev_inst). */
+/** Types of device instance, struct sr_dev_inst.type */
enum {
/** Device instance type for USB devices. */
SR_INST_USB = 10000,
/** Device instance type for serial port devices. */
SR_INST_SERIAL,
+ /** Device instance type for SCPI devices. */
+ SR_INST_SCPI,
};
-/** Device instance status. */
+/** Device instance status, struct sr_dev_inst.status */
enum {
/** The device instance was not found. */
SR_ST_NOT_FOUND = 10000,
@@ -728,62 +953,83 @@ enum {
SR_ST_STOPPING,
};
+/** Device driver data. See also http://sigrok.org/wiki/Hardware_driver_API . */
struct sr_dev_driver {
/* Driver-specific */
+ /** Driver name. Lowercase a-z, 0-9 and dashes (-) only. */
char *name;
+ /** Long name. Verbose driver name shown to user. */
char *longname;
+ /** API version (currently 1). */
int api_version;
+ /** Called when driver is loaded, e.g. program startup. */
int (*init) (struct sr_context *sr_ctx);
+ /** Called before driver is unloaded.
+ * Driver must free all resouces held by it. */
int (*cleanup) (void);
+ /** Scan for devices. Driver should do all initialisation required.
+ * Can be called several times, e.g. with different port options.
+ * \retval NULL Error or no devices found.
+ * \retval other GSList of a struct sr_dev_inst for each device.
+ * Must be freed by caller!
+ */
GSList *(*scan) (GSList *options);
+ /** Get list of device instances the driver knows about.
+ * \returns NULL or GSList of a struct sr_dev_inst for each device.
+ * Must not be freed by caller!
+ */
GSList *(*dev_list) (void);
+ /** Clear list of devices the driver knows about. */
int (*dev_clear) (void);
+ /** Query value of a configuration key in driver or given device instance.
+ * @see sr_config_get().
+ */
int (*config_get) (int id, GVariant **data,
- const struct sr_dev_inst *sdi);
+ const struct sr_dev_inst *sdi,
+ const struct sr_channel_group *cg);
+ /** Set value of a configuration key in driver or a given device instance.
+ * @see sr_config_set(). */
int (*config_set) (int id, GVariant *data,
- const struct sr_dev_inst *sdi);
+ const struct sr_dev_inst *sdi,
+ const struct sr_channel_group *cg);
+ /** Probe status change.
+ * @see sr_dev_probe_enable(), sr_dev_trigger_set(). */
+ int (*config_probe_set) (const struct sr_dev_inst *sdi,
+ struct sr_channel *ch, unsigned int changes);
+ /** Apply configuration settings to the device hardware.
+ * @see sr_config_commit().*/
+ int (*config_commit) (const struct sr_dev_inst *sdi);
+ /** List all possible values for a configuration key in a device instance.
+ * @see sr_config_list().
+ */
int (*config_list) (int info_id, GVariant **data,
- const struct sr_dev_inst *sdi);
+ const struct sr_dev_inst *sdi,
+ const struct sr_channel_group *cg);
/* Device-specific */
+ /** Open device */
int (*dev_open) (struct sr_dev_inst *sdi);
+ /** Close device */
int (*dev_close) (struct sr_dev_inst *sdi);
+ /** Begin data acquisition on the specified device. */
int (*dev_acquisition_start) (const struct sr_dev_inst *sdi,
void *cb_data);
+ /** End data acquisition on the specified device. */
int (*dev_acquisition_stop) (struct sr_dev_inst *sdi,
void *cb_data);
/* Dynamic */
+ /** Device driver private data. Initialized by init(). */
void *priv;
};
-struct sr_session {
- /** List of struct sr_dev pointers. */
- GSList *devs;
- /** List of struct datafeed_callback pointers. */
- GSList *datafeed_callbacks;
- GTimeVal starttime;
-
- unsigned int num_sources;
-
- /*
- * Both "sources" and "pollfds" are of the same size and contain pairs
- * of descriptor and callback function. We can not embed the GPollFD
- * into the source struct since we want to be able to pass the array
- * of all poll descriptors to g_poll().
- */
- struct source *sources;
- GPollFD *pollfds;
- int source_timeout;
-
- /*
- * These are our synchronization primitives for stopping the session in
- * an async fashion. We need to make sure the session is stopped from
- * within the session thread itself.
- */
- GMutex stop_mutex;
- gboolean abort_session;
-};
+/**
+ * @struct sr_session
+ *
+ * Opaque data structure representing a libsigrok session. None of the fields
+ * of this structure are meant to be accessed directly.
+ */
+struct sr_session;
#include "proto.h"
#include "version.h"