gd_get_carray_slice(3) GETDATA gd_get_carray_slice(3)NAME
gd_get_carray, gd_get_carray_slice, gd_get_constant — retrieve CONST
orY 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 speci‐
fied by dirfile for the CONST or CARRAY scalar array field_code, which
may contain a representation suffix. The data in the field is convert‐
ed 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_carray_len(3). The
gd_get_constant() function is equivalent to calling gd_get_car‐
ray_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_carray_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 num‐
ber
GD_NULL the null type: the database is queried as usual, but
no data is returned. In this case, data_out is ig‐
nored 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 nec‐
essary to return the requested type. If the field_code does not indi‐
cate 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() and gd_get_carray_slice() return zero. On
error, they return -1 and set the dirfile error to a non-zero 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 was not found in the data‐
base.
GD_E_BAD_DIRFILE
An invalid dirfile was supplied.
GD_E_BAD_FIELD_TYPE
The supplied field_code was not a CONST nor CARRAY. The caller
should use gd_getdata(3) or gd_get_string(3) instead.
GD_E_BAD_REPR
The representation suffix specified in field_code, or in one of
the field codes it uses for input, was invalid.
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 per‐
form the task. This indicates a bug in the library. Please
report the incident to the maintainer.
The dirfile error may be retrieved by calling gd_error(3). A descrip‐
tive error string for the last error encountered may be obtained from a
call to gd_error_string(3).
SEE ALSOdirfile(5), gd_carray_len(3), gd_carrays(3), gd_error(3), gd_er‐
ror_string(3), gd_get_constant(3), gd_open(3), gd_put_carray_slice(3)Version 0.8.0 4 July 2012 gd_get_carray_slice(3)