SIMPLE SOLUTIONS

GD_BOF(3) - man page online | library functions

Report the start of data in a field.

Chapter
17 August 2011
gd_bof(3)                                    GETDATA                                    gd_bof(3)

NAME

gd_bof — report the start of data in a field

SYNOPSIS

#include <getdata.h> off_t gd_bof(DIRFILE *dirfile, const char *field_code);

DESCRIPTION

The gd_bof() function queries a dirfile(5) database specified by dirfile and returns the sample number of the beginning-of-field marker for the vector field given by field_code. The caller should not assume that the beginning-of-field marker falls on a frame boundary. The beginning-of-field marker is never negative. For a RAW field, the beginning-of-field corresponds to the frame offset of that field (see gd_frameoffset(3)). The beginning-of-field for all other vector field type is the same as the beginning-of-field of whichever of its input fields that starts latest. The begin‐ ning-of-field marker for the special field INDEX is always zero. The beginning-of-field marker for a field containing no data is in the same location as, or after, its end-of-field marker (see gd_eof(3)). For a RAW field, the difference be‐ tween the locations of the beginning- and end-of-field markers indicates the number of samples of data actually stored on disk. The dirfile argument must point to a valid DIRFILE object previously created by a call to gd_open(3).

RETURN VALUE

Upon successful completion, gd_bof() returns the sample number of the end-of-field marker for the indicated field. On error, it returns -1 and sets the dirfile error to a non-zero error value. Possible error values are: GD_E_ALLOC The library was unable to allocate memory. GD_E_BAD_CODE The field specified by field_code or one of the fields it uses as input was not found in the database. GD_E_BAD_DIRFILE The supplied dirfile was invalid. GD_E_DIMENSION A scalar field was found where a vector field was expected in the definition of field_code or one of its inputs, or else field_code itself specified a scalar field. GD_E_INTERNAL_ERROR An internal error occurred in the library while trying to perform the task. This indicates a bug in the library. Please report the incident to the GetData devel‐ opers. GD_E_RECURSE_LEVEL Too many levels of recursion were encountered while trying to resolve field_code. This usually indicates a circular dependency in field specification in the dirfile. The dirfile error may be retrieved by calling gd_error(3). A descriptive error string for the last error encountered can be obtained from a call to gd_error_string(3).

SEE ALSO

dirfile(5), dirfile-encoding(5), gd_open(3), gd_eof(3), gd_error(3), gd_error_string(3), gd_nframes(3)
Version 0.8.0 17 August 2011 gd_bof(3)
This manual Reference Other manuals
gd_bof(3) referred by gd_bof64(3) | gd_eof(3) | gd_getdata(3) | gd_nframes(3)
refer to dirfile(5) | dirfile-encoding(5) | gd_cbopen(3) | gd_eof(3) | gd_error(3) | gd_error_string(3) | gd_frameoffset(3) | gd_nframes(3)