Provided by: libgetdata-doc_0.9.0-2.2_all bug

NAME

       gd_alter_bit,   gd_alter_carray,   gd_alter_clincom,   gd_alter_const,  gd_alter_cpolynom,
       gd_alter_crecip, gd_alter_divide,  gd_alter_lincom,  gd_alter_linterp,  gd_alter_multiply,
       gd_alter_phase,  gd_alter_polynom,  gd_alter_raw, gd_alter_recip, gd_alter_sbit — modify a
       field in a dirfile

SYNOPSIS

       #include <getdata.h>

       int gd_alter_bit(DIRFILE *dirfile, const char *field_code, const char *in_field, int
              bitnum, int numbits);

       int gd_alter_carray(DIRFILE *dirfile, const char *field_code, gd_type_t const_type, size_t
              array_len);

       int gd_alter_clincom(DIRFILE *dirfile, const char *field_code, int n_fields, const char
              **in_fields, const double complex *cm, const double complex *cb);

       int gd_alter_const(DIRFILE *dirfile, const char *field_code, gd_type_t const_type);

       int gd_alter_cpolynom(DIRFILE *dirfile, const char *field_code, int poly_ord, const char
              *in_field, const double complex *ca);

       int gd_alter_crecip(DIRFILE *dirfile, const char *field_code, const char *in_field,
              complex double cdividend);

       int gd_alter_divide(DIRFILE *dirfile, const char *field_code, const char *in_field1, const
              char *in_field2);

       int gd_alter_lincom(DIRFILE *dirfile, const char *field_code, int n_fields, const char
              **in_fields, const double *m, const double *b);

       int gd_alter_linterp(DIRFILE *dirfile, const char *field_code, const char *in_field, const
              char *table, int rename_table);

       int gd_alter_mplex(DIRFILE *dirfile, const char *field_name, const char *in_field, const
              char *count_field, int count_val, int period);

       int gd_alter_multiply(DIRFILE *dirfile, const char *field_code, const char *in_field1,
              const char *in_field2);

       int gd_alter_phase(DIRFILE *dirfile, const char *field_code, const char *in_field,
              gd_shift_t shift);

       int gd_alter_polynom(DIRFILE *dirfile, const char *field_code, int poly_ord, const char
              *in_field, const double *ca);

       int gd_alter_raw(DIRFILE *dirfile, const char *field_code, gd_type_t data_type, unsigned
              int spf, int recode);

       int gd_alter_recip(DIRFILE *dirfile, const char *field_code, const char *in_field, double
              dividend);

       int gd_alter_sbit(DIRFILE *dirfile, const char *field_code, const char *in_field, int
              bitnum, int numbits);

       int gd_alter_window(DIRFILE *dirfile, const char *field_code, const char *in_field, const
              char *check_field, gd_windop_t windop, gd_triplet_t threshold);

DESCRIPTION

       These functions provide alternatives to using the gd_alter_entry(3) function to  modify  a
       field of the indicated type in the dirfile specified by dirfile.

       In  all  of these calls, field_code indicates the the field to be modified, which may be a
       regular field, or a metafield specified by its full (slashed) field code, but  should  not
       contain  a  representation  suffix.  The meaning and valid types of other arguments may be
       obtained from the get_entry(3) and dirfile-format(5) manual pages.  The gd_shift_t type is
       a signed 64-bit integer type.  The gd_triplet_t type is defined as:

           typedef union {
             gd_int64_t i;
             gd_uint64_t u;
             double r;
           } gd_triplet_t;

       Which  element  of this gd_triplet_t union to set depends on the operator selected for the
       WINDOW field.  See gd_entry(3) for details.

       The   gd_alter_clincom()   and   gd_alter_cpolynom()   functions    are    identical    to
       gd_alter_lincom()  and  gd_alter_polynom(),  except  they  take complex scalar parameters,
       instead of purely real values.  This only matters for the input of new parameters; if  the
       scalar  parameters  are  not  changed  (by passing NULL instead of a list of scalars), the
       functions can be used interchangeably, regardless of whether the altered field has complex
       scalar parameters or not.

       If   the   corresponding   parameters   are  to  be  changed,  the  gd_alter_lincom()  and
       gd_alter_clincom() functions take pointers to three arrays of length  n_fields  containing
       the  input field names (in_fields), the gain factors (m or cm), and the offset terms (b or
       cb).  Similarly, gd_alter_polynom()  and  gd_alter_cpolynom()  take  an  array  of  length
       poly_ord + 1 containing the polynomial co-efficients (a or ca).

       Some  field  parameters have special values which indicate no change should be made to the
       parameter.  These special values are:

       NULL:  any of the string parameters, also m, b, a, cm, cb, or ca;

       0:     spf, n_fields, numbits, cdividend, dividend, or array_len;

       -1:    bitnum or period;

       GD_NULL:
              data_type or const_type;

       GD_WINDOP_UNK:
              windop.

       All field parameters introduced with  this  interface  must  contain  literal  parameters.
       Field parameters which are scalar fields cannot be introduced with these functions.  To do
       that, use gd_alter_entry(3), gd_alter_spec(3) or gd_malter_spec(3), as appropriate.

       If rename_table is non-zero, the look-up table referenced by the  LINTERP  field  will  be
       renamed  to  the  path  given by table.  If recode is non-zero, the binary file associated
       with the RAW field will be re-encoded to reflect the new field parameters.  In this  case,
       the field's I/O pointer will be reset to the beginning-of-frame.

       If  gd_alter_carray() is used to increase the length of a CARRAY field, the added elements
       will be uninitialised.  Use gd_put_carray_slice(3) or equivalent to initialise them.

       See NOTES below  for  information  on  using  gd_alter_clincom(),  gd_alter_crecip(),  and
       gd_alter_cpolynom() in the C89 GetData API.

RETURN VALUE

       On  success,  any  of  these  functions  returns  zero.   On error, -1 is returned and the
       dirfile error is set to a non-zero error value.  Possible error values are:

       GD_E_ACCMODE
               The specified dirfile was opened read-only.

       GD_E_ALLOC
               The library was unable to allocate memory.

       GD_E_BAD_CODE
               The field specified by field_code was not found, or a supplied field code did  not
               contain the appropriate prefix or suffix.

       GD_E_BAD_DIRFILE
               The supplied dirfile was invalid.

       GD_E_BAD_ENTRY
               One or more of the field parameters specified was invalid.

       GD_E_BAD_FIELD_TYPE
               The field specified by field_code was of the wrong type for the function called.

       GD_E_BAD_TYPE
               The data_type or const_type argument was invalid.

       GD_E_IO An I/O error occurred while translating the binary file associated with a modified
               RAW field, or an I/O error occurred while attempting to  rename  a  LINTERP  table
               file.

       GD_E_PROTECTED
               The  metadata  of  the  fragment  was  protected  from  change.   Or, a request to
               translate the binary file associated with a RAW field was attempted, but the  data
               of the fragment was protected.

       GD_E_UNKNOWN_ENCODING
               The encoding scheme of the indicated format specification fragment is not known to
               the library.  As a result, the library was unable to translate the binary file  be
               associated with a modified RAW field.

       GD_E_UNSUPPORTED
               The  encoding  scheme  of  the  indicated  format  specification fragment does not
               support translating the binary file associated with a modified RAW field.

       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).

NOTES

       The    C89   GetData   API   provides   different   prototypes   for   gd_alter_clincom(),
       gd_alter_cpolynom(), and gd_alter_crecip():

       #define GD_C89_API
       #include <getdata.h>

       int gd_alter_clincom(DIRFILE *dirfile, const char *field_code, int n_fields, const char
              **in_fields, const double *cm, const double *cb);

       int gd_alter_cpolynom(DIRFILE *dirfile, const char *field_code, int poly_ord, const char
              *in_fields, const double *ca);

       int gd_alter_crecip(DIRFILE *dirfile, const char *field_code, const char *in_field, const
              double cdividend[2]);

       In  this case, the array pointers passed as cm, cb or ca should have twice as many (purely
       real) elements, consisting of alternating real and imaginary parts for the  complex  data.
       That  is,  for example, ca[0] should be the real part of the first co-efficient, ca[1] the
       imaginary part of the first co-efficient, ca[2] the real part of the second  co-efficient,
       ca[3]  the imaginary part of the second co-efficient, and so on.  Similarly, the cdividend
       parameter becomes a double precision array of length two.

       For  gd_alter_clincom()  and  gd_alter_cpolynom(),  these  are   simply   different   (but
       equivalent) declarations of the C99 function entry point.  For gd_alter_crecip(), however,
       a different entry point is needed (since the cdividend parameter is  passed  by  reference
       instead   of   by   value).    In  the  interests  of  portability,  the  C89  version  of
       gd_alter_crecip() is always available, and may be accessed  as  gd_alter_crecip89(),  with
       the  C89 prototype, in both the C99 and C89 APIs.  Passing NULL as cdividend is equivalent
       to specifying a dividend of zero: it indicates no change to the dividend parameter.

SEE ALSO

       gd_alter_entry(3), gd_alter_spec(3), gd_error(3),  gd_error_string(3),  gd_malter_spec(3),
       gd_metaflush(3), gd_open(3), gd_put_carray_slice(3), dirfile-format(5)