EPICS Controls Argonne National Laboratory

Experimental Physics and
Industrial Control System

2002  2003  2004  <20052006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024  Index 2002  2003  2004  <20052006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024 
<== Date ==> <== Thread ==>

Subject: Re: ICE and TIPC
From: Kay-Uwe Kasemir <[email protected]>
To: Andrew Johnson <[email protected]>
Cc: EPICS Core Talk <[email protected]>
Date: Wed, 27 Jul 2005 12:49:08 -0400
Hi:

On Jul 27, 2005, at 12:15, Andrew Johnson wrote:
I am considering an implementation of variable length strings that does not require the reallocation and copying of data as the string is extended. This would use a fixed allocation size block, and chain these blocks together as needed to make up the complete storage for the string.
Strings are the very data type where I think the end user has to see
a contiguous string. In C/C++, the (const char *) is the only common denominator between string classes, all of which of course based on divine revelation
but incompatible except for c_str()/CStr()/...

Eric Norum has an R3.14 IOC with very limited RAM that uses a waveform record to allow its flash eprom to be reprogrammed, but his memory requirements are such that he can only fit one waveform buffer in memory. If we require another copy of the data this IOC would probably not be able to fit in memory.
I don't see a realistic way around the fact that support for arbitrary types
will require more memory.
Both buffer memory and additional code.
Similar to V3, something like EPICS_CA_MAX_ARRAY_BYTES
will define the biggest data type that your IOC can handle.
Given the same IOC memory, it will be a smaller number for V4 than it's now for V3.
If you want to handle huge image but don't have the memory for it,
you'll have to work around it by writing the image line by line
into a smaller line array.

-Kay


Replies:
Re: ICE and TIPC Andrew Johnson
References:
ICE and TIPC Marty Kraimer
Re: ICE and TIPC Kay-Uwe Kasemir
Re: ICE and TIPC Ralph Lange
Re: ICE and TIPC Kay-Uwe Kasemir
Re: ICE and TIPC Andrew Johnson

Navigate by Date:
Prev: Re: ICE and TIPC Andrew Johnson
Next: Re: ICE and TIPC Marty Kraimer
Index: 2002  2003  2004  <20052006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024 
Navigate by Thread:
Prev: Re: ICE and TIPC Andrew Johnson
Next: Re: ICE and TIPC Andrew Johnson
Index: 2002  2003  2004  <20052006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024 
ANJ, 02 Feb 2012 Valid HTML 4.01! · Home · News · About · Base · Modules · Extensions · Distributions · Download ·
· Search · EPICS V4 · IRMIS · Talk · Bugs · Documents · Links · Licensing ·