advect_cs/input/rdda.m

% result = RDDA( file, dim, irec [options] )
%
% This routine reads the irec'th record of shape 'dim' from the
% direct-access binary file (float or double precision) 'file'.
%
% Required arguments:
%
%   file  - string  - name of file to read from
%   dim   - vector  - dimensions of the file records and the resulting array
%   irec  - integer - record number in file in which to write data
%
% Optional arguments (must appear after the required arguments):
%   prec  - string  - precision of storage in file. Default = 'real*8'.
%   ieee  - string  - IEEE bit-wise representation in file. Default = 'b'.
%
% 'prec' may take the values:
%       'real*4' - floating point, 32 bits.
%       'real*8' - floating point, 64 bits - the efault.
%
% 'ieee' may take values:
%    'ieee-be'     or 'b' - IEEE floating point with big-endian
%                           byte ordering - the default
%    'ieee-le'     or 'l' - IEEE floating point with little-endian
%                           byte ordering
%    'native'      or 'n' - local machine format
%    'cray'        or 'c' - Cray floating point with big-endian
%                           byte ordering
%    'ieee-le.l64' or 'a' - IEEE floating point with little-endian
%                           byte ordering and 64 bit long data type
%    'ieee-be.l64' or 's' - IEEE floating point with big-endian byte
%                           ordering and 64 bit long data type.
%
% eg.   T=rdda('t.data',[64 64 32],1);
%       T=rdda('t.data',[256],4,'real*4');
%       T=rdda('t.data',[128 64],2,'real*4','b');
function [arr] = rdda(file,N,k,varargin)

% Defaults
WORDLENGTH=8;
rtype='real*8';
ieee='b';

% Check optional arguments
args=char(varargin);
while (size(args,1) > 0)
 if deblank(args(1,:)) == 'real*4'
  WORDLENGTH=4;
  rtype='real*4';
 elseif deblank(args(1,:)) == 'real*8'
  WORDLENGTH=8;
  rtype='real*8';
 elseif deblank(args(1,:)) == 'n' | deblank(args(1,:)) == 'native'
  ieee='n';
 elseif deblank(args(1,:)) == 'l' | deblank(args(1,:)) == 'ieee-le'
  ieee='l';
 elseif deblank(args(1,:)) == 'b' | deblank(args(1,:)) == 'ieee-be'
  ieee='b';
 elseif deblank(args(1,:)) == 'c' | deblank(args(1,:)) == 'cray'
  ieee='c';
 elseif deblank(args(1,:)) == 'a' | deblank(args(1,:)) == 'ieee-le.l64'
  ieee='a';
 elseif deblank(args(1,:)) == 's' | deblank(args(1,:)) == 'ieee-be.l64'
  ieee='s';
 else
  sprintf(['Optional argument ' args(1,:) ' is unknown'])
  return
 end
 args=args(2:end,:);
end

nnn=prod(N);

[fid mess]=fopen(file,'r',ieee);
if fid == -1
 sprintf('Error while opening file:\n%s',mess)
 arr=0;
 return
end
st=fseek(fid,nnn*(k-1)*WORDLENGTH,'bof');
if st ~= 0
 mess=ferror(fid);
 sprintf('There was an error while positioning the file pointer:\n%s',mess)
 arr=0;
 return
end
[arr count]=fread(fid,nnn,rtype);
if count ~= nnn
 sprintf('Not enough data was available to be read: off EOF?')
 arr=0;
 return
end
st=fclose(fid);
arr=reshape(arr,N);
1	% result = RDDA( file, dim, irec [options] )
2	%
3	% This routine reads the irec'th record of shape 'dim' from the
4	% direct-access binary file (float or double precision) 'file'.
5	%
6	% Required arguments:
7	%
8	% file - string - name of file to read from
9	% dim - vector - dimensions of the file records and the resulting array
10	% irec - integer - record number in file in which to write data
11	%
12	% Optional arguments (must appear after the required arguments):
13	% prec - string - precision of storage in file. Default = 'real*8'.
14	% ieee - string - IEEE bit-wise representation in file. Default = 'b'.
15	%
16	% 'prec' may take the values:
17	% 'real*4' - floating point, 32 bits.
18	% 'real*8' - floating point, 64 bits - the efault.
19	%
20	% 'ieee' may take values:
21	% 'ieee-be' or 'b' - IEEE floating point with big-endian
22	% byte ordering - the default
23	% 'ieee-le' or 'l' - IEEE floating point with little-endian
24	% byte ordering
25	% 'native' or 'n' - local machine format
26	% 'cray' or 'c' - Cray floating point with big-endian
27	% byte ordering
28	% 'ieee-le.l64' or 'a' - IEEE floating point with little-endian
29	% byte ordering and 64 bit long data type
30	% 'ieee-be.l64' or 's' - IEEE floating point with big-endian byte
31	% ordering and 64 bit long data type.
32	%
33	% eg. T=rdda('t.data',[64 64 32],1);
34	% T=rdda('t.data',[256],4,'real*4');
35	% T=rdda('t.data',[128 64],2,'real*4','b');
36	function [arr] = rdda(file,N,k,varargin)
37
38	% Defaults
39	WORDLENGTH=8;
40	rtype='real*8';
41	ieee='b';
42
43	% Check optional arguments
44	args=char(varargin);
45	while (size(args,1) > 0)
46	if deblank(args(1,:)) == 'real*4'
47	WORDLENGTH=4;
48	rtype='real*4';
49	elseif deblank(args(1,:)) == 'real*8'
50	WORDLENGTH=8;
51	rtype='real*8';
52	elseif deblank(args(1,:)) == 'n' \| deblank(args(1,:)) == 'native'
53	ieee='n';
54	elseif deblank(args(1,:)) == 'l' \| deblank(args(1,:)) == 'ieee-le'
55	ieee='l';
56	elseif deblank(args(1,:)) == 'b' \| deblank(args(1,:)) == 'ieee-be'
57	ieee='b';
58	elseif deblank(args(1,:)) == 'c' \| deblank(args(1,:)) == 'cray'
59	ieee='c';
60	elseif deblank(args(1,:)) == 'a' \| deblank(args(1,:)) == 'ieee-le.l64'
61	ieee='a';
62	elseif deblank(args(1,:)) == 's' \| deblank(args(1,:)) == 'ieee-be.l64'
63	ieee='s';
64	else
65	sprintf(['Optional argument ' args(1,:) ' is unknown'])
66	return
67	end
68	args=args(2:end,:);
69	end
70
71	nnn=prod(N);
72
73	[fid mess]=fopen(file,'r',ieee);
74	if fid == -1
75	sprintf('Error while opening file:\n%s',mess)
76	arr=0;
77	return
78	end
79	st=fseek(fid,nnn(k-1)WORDLENGTH,'bof');
80	if st ~= 0
81	mess=ferror(fid);
82	sprintf('There was an error while positioning the file pointer:\n%s',mess)
83	arr=0;
84	return
85	end
86	[arr count]=fread(fid,nnn,rtype);
87	if count ~= nnn
88	sprintf('Not enough data was available to be read: off EOF?')
89	arr=0;
90	return
91	end
92	st=fclose(fid);
93	arr=reshape(arr,N);