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lib/App/SeismicUnixGui/sunix/data/segywrite.pm  view on Meta::CPAN

=head3 SEISMIC UNIX NOTES
 SEGYWRITE - write an SEG-Y tape					



 segywrite <stdin tape=						



 Required parameters:							

	tape=		tape device to use (see sudoc segyread)		



 Optional parameter:							

 verbose=0	silent operation				

		=1 ; echo every 'vblock' traces			

 vblock=50	echo every 'vblock' traces under verbose option 

 buff=1		for buffered device (9-track reel tape drive)	

		=0 possibly useful for 8mm EXABYTE drive	

 conv=1		=0 don't convert to IBM format			

 ebcdic=1	convert text header to ebcdic, =0 leave as ascii	

 hfile=header	ebcdic card image header file			

 bfile=binary	binary header file				

 trmin=1 first trace to write					

 trmax=INT_MAX  last trace to write			       

 endian=(autodetected)	=1 for big-endian and =0 for little-endian byte order

 errmax=0	allowable number of consecutive tape IO errors	

 format=		override value of format in binary header file	



 Note: The header files may be created with  'segyhdrs'.		





 Note: For buff=1 (default) tape is accessed with 'write', for buff=0	

	tape is accessed with fwrite. Try the default setting of buff=1 

	for all tape types.						

 Caveat: may be slow on an 8mm streaming (EXABYTE) tapedrive		

 Warning: segyread or segywrite to 8mm tape is fragile. Allow time	

	   between successive reads and writes.				

 Precaution: make sure tapedrive is set to read/write variable blocksize

	   tapefiles.							



 For more information, type:	sudoc <segywrite>			







 Warning: may return the error message "efclose: fclose failed"

	 intermittently when segyreading/segywriting to 8mm EXABYTE tape,

	 even if actual segyread/segywrite is successful. However, this

	 may indicate that your tape drive has been set to a fixed block

	 size. Tape drives should be set to variable block size before reading

	 or writing tapes in the SEG-Y format.



 Credits:

	SEP: Einar Kjartansson

	CWP: Jack, Brian, Chris

	   : John Stockwell (added EXABYTE functionality)

 Notes:

	Brian's subroutine, float_to_ibm, for converting IEEE floating

	point to IBM floating point is NOT portable and must be

	altered for non-IEEE machines.	See the subroutine notes below.



	On machines where shorts are not 2 bytes and/or ints are not 

	4 bytes, routines to convert SEGY 16 bit and 32 bit integers 

	will be required.



	The program, segyhdrs, can be used to make the ascii and binary