avw_hdr_write.m

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function avw_hdr_write(avw, fileprefix, machine)

% AVW_HDR_WRITE - Write Analyze header file (*.hdr)
% 
% avw_hdr_write(avw, fileprefix, machine)
% 
% eg, avw_hdr_write(avw,'test');
% 
% avw        - a struct with .hdr field, which itself is a struct,
%              containing all fields of an Analyze header.
%              For details, see avw_hdr_read.m
% 
% fileprefix - a string, the filename without the .hdr extension.
%              If empty, may use avw.fileprefix
% 
% machine    - a string, see machineformat in fread for details.
%              The default here is 'ieee-le'.
% 
% See also, AVW_HDR_READ AVW_HDR_MAKE
%           AVW_IMG_READ AVW_IMG_WRITE
%

% $Revision: 1.9 $ $Date: 2004/03/17 06:08:18 $

% Licence:  GNU GPL, no express or implied warranties
% History:  05/2002, [e-mail]
%           02/2003, [e-mail]
%                    - more specific data history var sizes
%                    - 02/2003 confirmed, Darren
%
%                    The Analyze format and c code below is copyright 
%                    (c) Copyright, 1986-1995
%                    Biomedical Imaging Resource, Mayo Foundation
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

version = '[$Revision: 1.9 $]';
fprintf('AVW_HDR_WRITE [v%s]\n',version(12:16));  tic;

%----------------------------------------------------------------------------
% Check inputs

if ~exist('avw','var'),
    fprintf('...no input avw - calling avw_hdr_make\n');
    avw = avw_hdr_make;
elseif isempty(avw),
    fprintf('...empty input avw - calling avw_hdr_make\n');
    avw = avw_hdr_make;
elseif ~isfield(avw,'hdr'),
    fprintf('...empty input avw.hdr - calling avw_hdr_make\n');
    avw = avw_hdr_make;
end
if ~isequal(avw.hdr.hk.sizeof_hdr,348),
    msg = sprintf('...avw.hdr.hk.sizeof_hdr must be 348!\n');
    error(msg);
end

quit = 0;
if ~exist('fileprefix','var'),
    if isfield(avw,'fileprefix'),
        if ~isempty(avw.fileprefix),
            fileprefix = avw.fileprefix;
        else,
            quit = 1;
        end
    else
        quit = 1;
    end
    if quit,
        fprintf('...no input fileprefix - see help avw_hdr_write\n\n');
        helpwin avw_hdr_write;
        return;
    end
end

if ~exist('machine','var'), machine = 'ieee-le'; end

if findstr('.hdr',fileprefix),
%    fprintf('AVW_HDR_WRITE: Removing .hdr extension from ''%s''\n',fileprefix);
    fileprefix = strrep(fileprefix,'.hdr','');
end



%----------------------------------------------------------------------------
% MAIN

tic;

fid = fopen(sprintf('%s.hdr',fileprefix),'w',machine);
if fid < 0,
    msg = sprintf('Cannot write to file %s.hdr\n',fileprefix);
    error(msg);
else
    fprintf('...writing %s Analyze header.\n',machine);
    write_header(fid,avw);
end

t=toc; fprintf('...done (%5.2f sec).\n\n',t);

return





%----------------------------------------------------------------------------

function write_header(fid,avw)
    
    header_key(fid,avw.hdr.hk);
    image_dimension(fid,avw.hdr.dime);
    data_history(fid,avw.hdr.hist);
    
    % check the file size is 348 bytes
    fbytes = ftell(fid);
    fclose(fid);
    if ~isequal(fbytes,348),
        msg = sprintf('...file size is not 348 bytes!\n');
        warning(msg);
    end
    
return

%----------------------------------------------------------------------------

function header_key(fid,hk)
    
	% Original header structures - ANALYZE 7.5
	% struct header_key                      /* header key      */ 
	%       {                                /* off + size      */
	%       int sizeof_hdr                   /*  0 +  4         */
	%       char data_type[10];              /*  4 + 10         */
	%       char db_name[18];                /* 14 + 18         */
	%       int extents;                     /* 32 +  4         */
	%       short int session_error;         /* 36 +  2         */
	%       char regular;                    /* 38 +  1         */
	%       char hkey_un0;                   /* 39 +  1         */
	%       };                               /* total=40 bytes  */
    
    fseek(fid,0,'bof');
    
    fwrite(fid, hk.sizeof_hdr(1),   'int32');  % must be 348!
    
    data_type = sprintf('%-10s',hk.data_type); % ensure it is 10 chars
    fwrite(fid, hk.data_type(1:10), 'uchar');
    
    db_name   = sprintf('%-18s',hk.db_name);   % ensure it is 18 chars
    fwrite(fid, db_name(1:18),      'uchar');
    
    fwrite(fid, hk.extents(1),      'int32');
    fwrite(fid, hk.session_error(1),'int16');
    
    regular   = sprintf('%1s',hk.regular);     % ensure it is 1 char
    fwrite(fid, regular(1),         'uchar');  % might be uint8
    
    %hkey_un0  = sprintf('%1s',hk.hkey_un0);    % ensure it is 1 char
    %fwrite(fid, hkey_un0(1),        'uchar');
    fwrite(fid, hk.hkey_un0(1),     'uint8');
    
    %    >Would you set hkey_un0 as char or uint8?
    %   Really doesn't make any difference.  As far as anyone here can remember,
    %   this was just to pad to an even byte boundary for that structure.  I guess
    %   I'd suggest setting it to a uint8 value of 0 (i.e, truly zero-valued) so
    %   that it doesn't look like anything important!
    %   Denny <[e-mail]>
    
return

%----------------------------------------------------------------------------

function image_dimension(fid,dime)
    
	%struct image_dimension
	%       {                                /* off + size      */
	%       short int dim[8];                /* 0 + 16          */
	%       char vox_units[4];               /* 16 + 4          */
	%       char cal_units[8];               /* 20 + 8          */
	%       short int unused1;               /* 28 + 2          */
	%       short int datatype;              /* 30 + 2          */
	%       short int bitpix;                /* 32 + 2          */
	%       short int dim_un0;               /* 34 + 2          */
	%       float pixdim[8];                 /* 36 + 32         */
	%			/*
	%				pixdim[] specifies the voxel dimensions:
	%				pixdim[1] - voxel width
	%				pixdim[2] - voxel height
	%				pixdim[3] - interslice distance
	%					..etc
	%			*/
	%       float vox_offset;                /* 68 + 4          */
	%       float roi_scale;                 /* 72 + 4          */
	%       float funused1;                  /* 76 + 4          */
	%       float funused2;                  /* 80 + 4          */
	%       float cal_max;                   /* 84 + 4          */
	%       float cal_min;                   /* 88 + 4          */
	%       int compressed;                  /* 92 + 4          */
	%       int verified;                    /* 96 + 4          */
	%       int glmax;                       /* 100 + 4         */
	%       int glmin;                       /* 104 + 4         */
	%       };                               /* total=108 bytes */
    
	fwrite(fid, dime.dim(1:8),      'int16');
	fwrite(fid, dime.vox_units(1:4),'uchar');