NAME

       gd_get_carray,  gd_get_carray_slice,  gd_get_constant  —  retrieve  CONST  or  CARRAY data from a Dirfile
       database

SYNOPSIS

       #include <getdata.h>

       int gd_get_carray_slice(DIRFILE *dirfile, const char *field_code, unsigned int start, size_t len,
              gd_type_t return_type, void *data_out);

       int gd_get_carray(DIRFILE *dirfile, const char *field_code, gd_type_t return_type, void *data_out);

       int gd_get_constant(DIRFILE *dirfile, const char *field_code, gd_type_t return_type, void *data_out);

DESCRIPTION

       The  gd_get_carray_slice()  function  queries a dirfile(5) database specified by dirfile for the CONST or
       CARRAY scalar field_code, which may contain a representation suffix.  The data in the field is  converted
       to  the  data  type specified by return_type, and stored in the user-supplied buffer data_out.  The first
       element of the field stored is given by start, and the number of elements stored is given by len.

       The  gd_get_carray()  function  behaves  similarly,  except  it  returns  the   entire   field,   as   if
       gd_get_carray_slice()  were  called  with  start  equal  to  zero  and len equal to the value returned by
       gd_array_len(3).  The gd_get_constant() function is  equivalent  to  calling  gd_get_carray_slice()  with
       start equal to zero and len equal to one.

       The  dirfile  argument  must  point to a valid DIRFILE object previously created by a call to gd_open(3).
       The argument data_out must point to a valid memory location of sufficient size to hold all the  requested
       data of the return type specified.  The number of elements returned by gd_get_carray() may be obtained by
       calling gd_array_len(3).  Unlike gd_getdata(3), calling gd_get_carray_slice() never results  in  a  short
       read; attempting to read past the end of the field will result in an error, and no data will be returned.

       The  return_type argument should be one of the following symbols, which indicates the desired return type
       of the data:

              GD_UINT8
                      unsigned 8-bit integer

              GD_INT8 signed (two's complement) 8-bit integer

              GD_UINT16
                      unsigned 16-bit integer

              GD_INT16
                      signed (two's complement) 16-bit integer

              GD_UINT32
                      unsigned 32-bit integer

              GD_INT32
                      signed (two's complement) 32-bit integer

              GD_UINT64
                      unsigned 64-bit integer

              GD_INT64
                      signed (two's complement) 64-bit integer

              GD_FLOAT32
                      IEEE-754 standard 32-bit single precision floating point number

              GD_FLOAT64
                      IEEE-754 standard 64-bit double precision floating point number

              GD_COMPLEX64
                      C99-conformant 64-bit single precision complex number

              GD_COMPLEX128
                      C99-conformant 128-bit double precision complex number

              GD_NULL the null type: the database is queried as usual, but no data is returned.  In  this  case,
                      data_out is ignored and may be NULL.

       The  return  type of the field need not be the same as the type of the data stored in the database.  Type
       conversion will be performed as necessary to return the requested  type.   If  the  field_code  does  not
       indicate a representation, but conversion from a complex value to a purely real one is required, only the
       real portion of the requested vector will be returned.

RETURN VALUE

       On success, gd_get_carray(), gd_get_carray_slice(), and gd_get_constant() return zero.   On  error,  they
       return a negative-valued error code.  Possible error codes are:

       GD_E_ALLOC
               The library was unable to allocate memory.

       GD_E_BAD_CODE
               The field specified by field_code was not found in the database.

       GD_E_BAD_DIRFILE
               An invalid dirfile was supplied.

       GD_E_BAD_FIELD_TYPE
               The supplied field_code was not a CONST nor CARRAY.

       GD_E_BAD_TYPE
               An invalid return_type was specified.

       GD_E_BOUNDS
               A request for data beyond the end of the field was made.

       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 maintainer.

       The error code is also stored in the DIRFILE object and may be retrieved after this function  returns  by
       calling   gd_error(3).    A   descriptive  error  string  for  the  error  may  be  obtained  by  calling
       gd_error_string(3).

HISTORY

       The get_constant() function appeared in GetData-0.4.0.

       In GetData-0.7.0, this function was renamed to gd_get_constant().  In this release,  the  gd_get_carray()
       and gd_get_carray_slice() functions also appeared.

       In GetData-0.10.0, the error return from these functions changed from -1 to a negative-valued error code.

SEE ALSO

       gd_array_len(3),  gd_carrays(3),  gd_error(3),  gd_error_string(3),  gd_open(3),  gd_put_carray_slice(3),
       dirfile(5)