topic Re: Fortran IAND equivalent command in VMS DCL in Operating System - OpenVMS

Fortran IAND equivalent command in VMS DCL

Nelson Juinio — Mon, 22 May 2006 21:02:20 GMT

Good day.

Is there an equivalent VMS DCL command of Fortran IAND? I am trying to figure out how to check in DCL if a bit mask has been set for a database field. The database field has been exported to a text file and I extract the database field from the text string.

Here is the sample Fortran code that I want to copy over in DCL/VMS .COM file.

logical*4 function bit_check (arg1,arg2)
implicit none

integer*4 arg1,arg2

bit_check = 0 .ne. IAND (arg1,arg2)
return
end

Re: Fortran IAND equivalent command in VMS DCL

Robert Gezelter — Mon, 22 May 2006 21:09:44 GMT

Nelson,

The operator is ".AND."

Example:

$ X = 5
$ Y = 7
$ WRITE SYS$OUTPUT X .AND. Y

- Bob Gezelter, http://www.rlgsc.com

Re: Fortran IAND equivalent command in VMS DCL

Nelson Juinio — Mon, 22 May 2006 21:48:23 GMT

Hello Bob,

Thanks for the quick reply! Although I am not getting the result that I need.

I need to be able to check an integer symbol if it has a particular bit mask turned on.

$ open infile test.tab
$ read infile inrecord
$ flags = f$extract(104,12,inrecord)
$ show sym flags
FLAGS = " 320"
$ flag1 = 1
$ flag2 = 2
$ flag3 = 4
$ flag4 = 8
$ flag5 = 16
$ flag6 = 32
$ flag7 = 64
$ flag8 = 128
$ flag9 = 256
$ numflags = f$integer(flags)
$ show sym numflags
NUMFLAGS = 320 Hex = 00000140 Octal = 00000000500
$ if flag7 .AND. numflags then write sys$output "flag7 is on"
$ if flag9 .AND. numflags then write sys$output "flag9 is on"

The flags value of 320 is a combination of flag7 (64) and flag9 (256).

What am I doing wrong? Or is this even possible in DCL?

Thanks again!

Kind regards,
Nelson

Re: Fortran IAND equivalent command in VMS DCL

David B Sneddon — Mon, 22 May 2006 22:39:33 GMT

Try

$ if ((flag7 .AND. numflags) .ne. 0) then write sys$output "flag7 is on"
$ if ((flag9 .AND. numflags) .ne. 0) then write sys$output "flag9 is on"

Dave

Re: Fortran IAND equivalent command in VMS DCL

Thomas Ritter — Mon, 22 May 2006 22:54:19 GMT

$ if flag7 .AND. numflags then write sys$output "flag7 is on"
$ if flag9 .AND. numflags then write sys$output "flag9 is on"

The expression will be true if flag7 = numflags.
If numflags is 320 then then it will never be true. 64 is 1000000. 320 is 101000000.

You are confusioning vectors with masks.

Re: Fortran IAND equivalent command in VMS DCL

Thomas Ritter — Mon, 22 May 2006 23:03:49 GMT

Forgot, use

F$CVSI

Converts the specified bits in the specified character string to
a signed number.

Format

F$CVSI(start-bit,number-of-bits,string)

Re: Fortran IAND equivalent command in VMS DCL

Hein van den Heuvel — Mon, 22 May 2006 23:34:40 GMT

The test for TRUE is based on the LOW BIT being on or off.

Your .AND. will result in the test flag being set, but that is not bit 0.
But if the value (320 has either flag7 or flag9 set then an AND with that delivers a non-zero value. Thus, as David write test for non-zero:

$ flag7 = 64
$ x = 320
$ y = x.and.flag7
$ show symb y
Y = 64 Hex = 00000040 Octal = 00000000100
$ if y then write sys$output "true"
$ z = (x.and.flag7).ne.0
$ show symb z
Z = 1 Hex = 00000001 Octal = 00000000001
$ if z then write sys$output "true"
true
$

Hein.

Re: Fortran IAND equivalent command in VMS DCL

Steven Schweda — Tue, 23 May 2006 00:29:07 GMT

> The test for TRUE is based on the LOW BIT
> being on or off.

Same as in Fortran, right? Which is why the
test in the Fortran code was "0 .ne.[...]"

Come to think of it, who still uses IAND()
in Fortran? Logical operators (like .AND.)
have been in common use for decades.

In other words, logical operations in DCL
look and act a lot like logical operations in
Fortran, unless your Fortran dates back to
1966.

Re: Fortran IAND equivalent command in VMS DCL

Nelson Juinio — Tue, 23 May 2006 00:40:32 GMT

Thank you all for your help and valuable inputs. :)

Re: Fortran IAND equivalent command in VMS DCL

John Kamaka — Tue, 23 May 2006 21:56:06 GMT

Nelson, see the attached hack. It's not pretty but you can see how to get multiple bit values for small numbers. Sample output:

$ @cvui 320
320=101000000
flag7 is on
flag9 is on

$ @cvui 444
444=110111100
flag3 is on
flag4 is on
flag5 is on
flag6 is on
flag8 is on
flag9 is on

Re: Fortran IAND equivalent command in VMS DCL

Thomas Ritter — Tue, 23 May 2006 22:03:19 GMT

John, thanks for the correction.
Use f$cvui not f$cvsi

Lexicals

F$CVUI

Extracts bit fields from character string data and converts the
result to an unsigned number.

Format

F$CVUI(start-bit,number-of-bits,string)

Re: Fortran IAND equivalent command in VMS DCL

John Kamaka — Wed, 24 May 2006 00:49:30 GMT

Mea cupla, forgot to rename .com attachment to .txt.

Re: Fortran IAND equivalent command in VMS DCL

Jan van den Ende — Wed, 24 May 2006 12:04:22 GMT

My ususal quick way to see the bit settings of a number is to simple assign that value to a symbol and SHOW that symbol.
It displays in Octal and in Hex, and those translate character by character to the bit pattern.
Of course, in a procedure, the already given .AND. will do the trick just fine.
But even there, it is a lot more intuitive to .AND. with a %O or a %X value!

fwiw.

Proost.

Have one on me (if/when you locate me at the bar in Nashua Sheraton)

jpe