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Long string support.

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This commit is contained in:
Andrew Johnson
2009-03-25 23:06:18 +00:00
parent ed4a2972d6
commit f98d74b064
1 changed files with 20 additions and 5 deletions
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documentation/RELEASE_NOTES.html
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@@ -2,9 +2,6 @@
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta content="text/html; charset=iso-8859-1">
<meta content="text/html; charset=iso-8859-1">
<meta content="text/html; charset=iso-8859-1">
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1">
<title>EPICS Base R3.14.x Release Notes</title>
</head>
@@ -15,9 +12,26 @@
<h2 align="center">Changes between 3.14.10 and 3.14.11</h2>
<!-- Insert new items below here ... -->
<p></p>
<h4>Long string support</h4>
<h3>Darwin no longer uses _environ</h3>
<p>The IOC now provides support for strings longer than 40 characters through
Channel Access in a manner that is fully backwards compatible with older
versions of the CA library, although not all CA clients can make use of this at
the moment.</p>
<p>Adding the suffix '$' to the field name of an IOC PV name (through either
Channel Access or Database Access) causes the native type of that field to be
reported as an array of DBF_CHAR, as long as the field type is DBF_STRING,
DBF_INLINK, DBF_OUTLINK or DBF_FWDLINK. It is then possible to use a DBF_CHAR
array to read, write and monitor values from that field, and the 40 character
string length limit imposed by the DBF_STRING type is replaced by the amount of
storage allocated for the string on the IOC (for link fields the limit is
related to the maximum length of a record name). Both MEDM and EDM can already
present such DBF_CHAR arrays as strings in their text widgets (although you do
have to configure the widget to format it as text), so this solution already
works with some CA clients, although by no means all clients support it yet.</p>
<h4>Darwin no longer uses _environ</h4>
<p>The Darwin version of epicsEnvShow (in src/libCom/osi/os/Darwin/osdEnv.c)
now uses _NSGetEnviron() to get the pointer to the environment string
@@ -27,6 +41,7 @@ table.</p>
<p>The existing routines used to hash strings have been replaced by a new
pair of functions that are prototyped in the epicsString.h header file:</p>
<pre>unsigned int epicsStrHash(const char *str, unsigned int seed);
unsigned int epicsMemHash(const char *str, size_t length, unsigned int seed);</pre>