XDF_OPEN(3) xdffileio library manual XDF_OPEN(3)NAME
xdf_open - Open a xDF file for reading or writing
SYNOPSIS
#include <xdfio.h>
struct xdf* xdf_open(const char* filename, int mode,
enum xdffiletype type);
DESCRIPTION
xdf_open() opens a xDF the file refered by the path filename for reading or writing.
If mode is XDF_READ, the file is opened for reading. Thus it must exist and type should be either XDF_ANY or set to the type of the file
refered by type. Otherwise, the function will fail.
If mode is XDF_WRITE, the file is opened for writing. Thus the path filename must not refered to an existing file: the function will fail
if the file exist. This behavior prevents to overwrite any previous recording. type should be also be set to the desired type of data for-
mat (XDF_ANY will result in a error).
The possible file type values are defined in the header file <xdfio.h>
RETURN VALUE
The function returns an handle to xDF file opened in case of success. Otherwise, NULL is returned and errno is set appropriately.
ERRORS
In addition to the errors related to calls to open(3) or read(3), the following errors can occur:
EILSEQ The file that is being opened does not correspond to a supported file format or is not of the type specified.
ENOMEM The system is unable to allocate resources.
EINVAL mode is neither XDF_READ nor XDF_WRITE, or filename is NULL.
SEE ALSO xdf_close(3)EPFL 2010 XDF_OPEN(3)
Check Out this Related Man Page
XDF_SET_CHCONF(3) xdffileio library manual XDF_SET_CHCONF(3)NAME
xdf_set_chconf, xdf_get_chconf - set or get the configuration of a channel descriptor handle
SYNOPSIS
#include <xdfio.h>
int xdf_set_chconf(struct xdfch* ch, enum xdffield field, ...);
int xdf_get_chconf(const struct xdfch* ch, enum xdffield field, ...);
DESCRIPTION
xdf_set_chconf() sets the configuration of the channel referenced by ch according to the variable list of argument. This list is composed
of successive couple grouping one variable of type enum xdffield defining the feature to be set and a value whose type depends on the pre-
vious field type. The list must finish by XDF_NOF.
xdf_get_chconf() gets the configuration of the channel referenced by ch according to the variable list of argument. The variable list is
the same list terminated by XDF_NOF as for xdf_set_chconf() excepting that the second part of the couple is not that value but a pointer to
the value.
Both functions process the argument list from left to right. This means that if a particular field request provokes an error, none of the
field requests on its right will be processed. The order of processing is also important for field requests that influences the value of
other fields (like XDF_CF_STOTYPE).
Here is the list of admissible value. The expected type of value is provided in the parenthesis (the expected type of the value for
xdf_set_chconf(), or a pointer to this type for xdf_get_chconf()). The default value of each field is provided in squared brackets (however
these defaults can be overridden by a call to xdf_set_conf(3) if the file is open for writing. If the file is opened for reading, the
default are meaningful only for the fields XDF_CF_ARR*). If a list of data formats is specified in curl brackets, it means that the field
is supported only in those formats (no list means that all formats support the field):
XDF_CF_ARRINDEX (int) [0]
Specify the array from/to which the channel value should be transfered. If the mode of the file is XDF_READ and the value is nega-
tive, the channel will not be read. If the mode is XDF_WRITE and the value is negative, the function will fail.
XDF_CF_ARROFFSET (int) [0 for channel 0, packed channels for the rest]
Specify the offset in the array from/to which the channel value should be transfered.
XDF_CF_ARRDIGITAL (int) [0 if writing, 1 if reading]
Indicate that the data in the array from/to which the channel value should be transfered is provided in digital unit. This means in
practice that no scaling is performed during the transfer from/to the disk (non zero indicate no scaling).
XDF_CF_ARRTYPE (enum xdftype) [same as XDF_CF_STOTYPE]
specify the type in the channel should casted to/from when accessed in the array.
XDF_CF_PMIN (double) [min of XDF_CF_ARRTYPE]
Set/get the minimal value that a physical value can get. Cannot be set if XDF_READ.
XDF_CF_PMAX (double) [max of XDF_CF_ARRTYPE]
Set/get the maximal value that a physical value can get. Cannot be set if XDF_READ.
XDF_CF_STOTYPE (enum xdftype) [any datatype supported by file type]
Specify the type stored in the file of the channel value. If the XDF file has been opened in XDF_READ, this field cannot be set. If
this field is successfully set, it will set as well the digital minimum (XDF_CF_DMIN) and the digital maximum (XDF_CF_MAX) to the
minimum and maximum values allowed by the data type.
XDF_CF_DMIN (double) [min of XDF_CF_STOTYPE]
Set/get the minimal value that a digital value can get. Cannot be set if XDF_READ. This is also automatically set by XDF_CF_STOTYPE.
XDF_CF_DMAX (double) [min of XDF_CF_STOTYPE]
Set/get the maximal value that a digital value can get. Cannot be set if XDF_READ. This is also automatically set by XDF_CF_STOTYPE.
XDF_CF_LABEL (const char*) [""]
Set/get the label of the channel. Cannot be set if XDF_READ.
XDF_CF_UNIT (const char*) [""] {EDF BDF GDF}
Set/get the unit of the channel. Cannot be set if XDF_READ.
XDF_CF_TRANSDUCTER (const char*) [""] {EDF BDF GDF}
Set/get the type of sensor used for this channel. Cannot be set if XDF_READ.
XDF_CF_PREFILTERING (const char*) [""] {EDF BDF GDF}
Set/get the information about the filters already applied on channel data. Cannot be set if XDF_READ.
XDF_CF_ELECPOS (double[3]) [0,0,0] {GDF}
Position of the sensor/electrode expressed in X,Y,Z components Cannot be set if XDF_READ.
XDF_CF_IMPEDANCE (double) [0] {GDF}
Impedance of the sensor/electrode. Cannot be set if XDF_READ.
RETURN VALUE
The two functions returns 0 in case of success. Otherwise -1 is returned and errno is set appropriately.
ERROR
EINVAL ch is NULL or field is not a proper value of the enumeration xdffield
EPERM The request submitted to xdf_set_chconf() is not allowed for this channel or is forbidden for file opened with the mode XDF_READ.
EDOM The value set in xdf_set_chconf() as digital or physical min/max (fields XDF_CF_{D/P}{MIN/MAX}) goes beyond the limits of respec-
tively the stored or array data type.
EXAMPLES
Example of usage of xdf_set_chconf():
/* Assume xdf referenced an XDF file opened for writing */
unsigned int iarray = 2, offset = 0;
const char label[] = "Channel EEG";
hchxdf ch = xdf_add_channel(xdf);
xdf_set_chconf(ch, XDF_CF_ARRINDEX, iarray,
XDF_CF_ARROFFSET, offset,
XDF_CF_LABEL, label,
XDF_NOF);
Example of usage of xdf_get_chconf():
/* Assume xdf referenced an XDF file opened for reading */
unsigned int iarray, offset;
const char label[128];
hchxdf ch = xdf_get_channel(xdf, 1);
xdf_get_chconf(ch, XDF_CF_ARRINDEX, &iarray,
XDF_CF_ARROFFSET, &offset,
XDF_CF_LABEL, &label,
XDF_NOF);
printf("iarray = %u
", iarray);
printf("offset = %u
", offset);
printf("label = %s
", label);
SEE ALSO xdf_copy_chconf(3)EPFL 2010 XDF_SET_CHCONF(3)