Experimental Physics and
Industrial Control System

Maximal field width does not work at the moment. Low level, it just reads %d%d.
Output is  not implemented because it is not clear how to do the formatting,
Why +00011-01 and not +00110-02 or +11000-04 ?
Was +00011-01 originally 1.1000000000000 or 1.11 or 1.10000000000001 ?
What are the rules for rounding and precision?

Hi Eric,

at the moment, I don't have a direct support for this. But I tried the following construct:

record (ai, "$(P):read")
{
    field(DTYP, "stream")
    field(INP,  "@proto read($(P):calc) terminal")
    field(FLNK, "$(P):calc")
}

record (calcout, "$(P):calc")
{
    field(CALC, "A*10^B")
    field(OUT, "$(P):read")
}

with the protocol

Terminator="\r\n";

read {
    in "U1";
    in "%(\$1.A)d%(\$1.B)d";
}

The protocol reads mantissa and exponent as decimal integer and put them into fields A and B of a calc record. This record calculates the value and writes it back to the input record.

I already got a request for the same format earlier but have not yet found the time to implement it.

Dirk


Eric Berryman wrote:

Hello!

I've run into a problem I'm guessing others have solved using the
Streams module.  I have a device that outputs reads in the format:

U1\r\n+00011-01\r\n

meaning 11e-01 , which would be the preferred format for using a
general format specifier in the protocol file.

What would be the format to successfully read in this number from the
Streams protocol file?
(Or, will I have to run as a string read through a c filter program,
sub record)

Thank you!
Eric

--
Dr. Dirk Zimoch
Paul Scherrer Institut, WBGB/006
5232 Villigen PSI, Switzerland
Phone +41 56 310 5182

/***************************************************************
* StreamDevice Support                                         *
*                                                              *
* (C) 1999 Dirk Zimoch ([email protected])          *
* (C) 2007 Dirk Zimoch ([email protected])                    *
*                                                              *
* This is a custom exponential format converter for            * 
* StreamDevice.                                                *
* The number is represented as two signed integers, mantissa   *
* and exponent, like in +00011-01                              *
* Please refer to the HTML files in ../doc/ for a detailed     *
* documentation.                                               *
*                                                              *
* If you do any changes in this file, you are not allowed to   *
* redistribute it any more. If there is a bug or a missing     *
* feature, send me an email and/or your patch. If I accept     *
* your changes, they will go to the next release.              *
*                                                              *
* DISCLAIMER: If this software breaks something or harms       *
* someone, it's your problem.                                  *
*                                                              *
***************************************************************/

#include "StreamFormatConverter.h"
#include "StreamError.h"
#include <math.h>

// Exponential Converter %m: format +00351-02 means +351e-2

class ExponentialConverter : public StreamFormatConverter
{
    virtual int parse(const StreamFormat&, StreamBuffer&, const char*&, bool);
    virtual int scanDouble(const StreamFormat&, const char*, double&);
};

int ExponentialConverter::
parse(const StreamFormat& fmt, StreamBuffer& info,
    const char*& source, bool scanFormat)
{
    if (!scanFormat)
    {
        error("At the moment for %%m format only input is implemented\n");
        return false;
    }
    return double_format;
}

int ExponentialConverter::
scanDouble(const StreamFormat& fmt, const char* input, double& value)
{
    int mantissa;
    int exponent;
    int length = -1;
    
    sscanf(input, "%d%d%n", &mantissa, &exponent, &length);
    if (fmt.flags & skip_flag) return length;
    if (length == -1) return -1;
    value = (double)(mantissa) * pow(10, exponent);
    return length;
}

RegisterConverter (ExponentialConverter, "m");

References:

Streams questions Eric Berryman

Re: Streams questions Dirk Zimoch

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