function writesegyfile(sgyfile, datain, sampint, numsamps, numtraces, segfmt, byteorder)
if nargin < 3
error('Invalid number of arguments: at least 3 required (segyfile, datain, sampint)');
end
if nargin < 4
numsamps = size(datain,1);
end
if nargin < 5
numtraces = size(datain,2);
end
if nargin < 6
segfmt = 5;
end
if nargin < 7
byteorder = 'be';
end
switch lower(byteorder)
case {'be', 'bigendian', 'ieee-be'}
platform='ieee-be';
case {'le', 'littleendian', 'ieee-le'}
platform = 'ieee-le';
otherwise
error(['Invalid byte order parameter: ' byteorder]);
end
fid = fopen(sgyfile, 'w', platform);
textLine{1} = char(['File generated ' datestr(now)]);
switch segfmt
case 1
textLine{1} = 'IBM Floating point fmt (not implemented)';
dformat = 'float32'; % 4 bytes, should be IBM floating point
case 2
textLine{2} = '4-byte integer format';
dformat = 'int32'; % 4 bytes, signed.
case 3
textLine{3} = '2-byte integer format';
dformat = 'int16'; % 2 bytes, signed.
case 4
textLine{4} = 'WARNING BAD DATA: Fixed point w/gain code format (not implemented)'
error('Can not write this format. (Fixed point with gain code.)');
case 5
textLine{5} = 'IEEE Floating point format';
dformat = 'float32'; % 4 bytes presumably IEEE floating point
case 8
textLine{8} = '1-byte integer format';
dformat = 'uchar8'; % 4 bytes presumably IEEE floating point
otherwise
error(['invalid format specified: ', num2str(segfmt)]);
end
textLine{39} = 'SEG Y rev1'; % ooh, bleeding edge
textLine{40} = 'END EBCDIC'; %
% Next line should contain 80 spaces
textLine{41} = ' ';
for i = 1:40
if isempty(textLine{i})
textLine{i} = ' ';
end
end
textHdrBlock = char(textLine);
textHdrBlock = [reshape(sprintf('C%2d ',1:40),4,40)' textHdrBlock(1:40,1:76)];
textHdrBlock = ascii2ebcdic(textHdrBlock);
count = fwrite(fid, textHdrBlock', 'uchar');
if count ~= 3200
error(['EBCDIC header is too short. Size is only ', num2str(count), '.']);
end
temp = zeros(27,1);
temp(6) = sampint*1000000;
temp(8) = numsamps;
temp(10) = segfmt;
if (fwrite(fid, temp(1:3), 'ulong') ~= 3) | ...
(fwrite(fid, temp(4:27), 'ushort') ~= 24) | ...
(fwrite(fid, zeros(170,1), 'ushort') ~= 170) ;
error('The binary header has been truncated.')
end
clear temp
tracewrit = 1;
trcount = 0;
traceheader = zeros(120,1);
traceheader(floor((29+1)/2)) = 1; % seismic data
traceheader(floor((35+1)/2)) = 1; % production data
traceheader(floor((115+1)/2)) = numsamps; % number of samples for this trace
while tracewrit <= numtraces
trcount = fwrite(fid, traceheader, 'ushort');
count = fwrite(fid, datain(:, tracewrit), dformat);
if count ~= numsamps
error(['Problem writing trace ', num2str(tracewrit), '.'])
end
tracewrit = tracewrit + 1;
end
fclose(fid);
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