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/*
* Copyright (c) 1995 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the Computer Systems
* Engineering Group at Lawrence Berkeley Laboratory.
* 4. Neither the name of the University nor of the Laboratory may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
static const char rcsid[] =
"@(#) $Header: /cs/research/mice/starship/src/local/CVS_repository/vic/rate-variable.cc,v 1.1.1.1 1998/02/18 18:03:41 ucacsva Exp $ (LBL)";
#include <stdlib.h>
#include "sys-time.h"
#include "Tcl.h"
/*
* The following command & the associate service procedure
* creates a `rate variable'. Reading a rate variable returns
* the time rate of change of its value. Writing a rate variable
* updates the rate of change estimate. A rate variable can be
* either simple or an array element. It must be global. This
* routine is called as:
* rate_variable varname filter_const
* where 'varname' is the variable name (e.g., "foo" or "foo(bar)")
* and 'filter_const' is a smoothing constant for the rate estimate.
* It should be >0 and <1 (a value of 1 will result in no smoothing).
*/
struct rv_data {
double rate;
double filter;
timeval lastupdate;
int lastval;
char format[16];
};
class RateVariable : public TclObject {
public:
RateVariable(const char* name) : TclObject(name) { }
protected:
static char* update_rate_var(ClientData, Tcl_Interp*, char* name1,
char* name2, int flags);
int command(int argc, const char*const* argv);
} rate_variable_cmd("rate_variable");
char* RateVariable::update_rate_var(ClientData clientData, Tcl_Interp* tcl,
char* name1, char* name2, int flags)
{
rv_data* rv = (rv_data*)clientData;
if (rv == NULL)
return ("no clientdata for rate var");
if (flags & TCL_TRACE_WRITES) {
/*
* the variable has been written with a new value.
* compute the rate of change & make that its vale
* for subsequent reads.
*/
char res[128];
flags &= TCL_GLOBAL_ONLY;
char* cv = Tcl_GetVar2(tcl, name1, name2, flags);
if (cv == NULL)
return (tcl->result);
int curval = atoi(cv);
double rate = 0.;
timeval tv;
gettimeofday(&tv, 0);
if (rv->lastupdate.tv_sec != 0) {
/* not first time through */
double dt = double(tv.tv_sec - rv->lastupdate.tv_sec) +
double(tv.tv_usec -
rv->lastupdate.tv_usec) * 1e-6;
if (dt <= 0.)
/* have to wait until next clock tick */
return NULL;
double dv = double(curval - rv->lastval);
if (dv >= 0.) {
rate = rv->rate;
rate += (dv/dt - rate) * rv->filter;
/* work around tcl f.p. precision bug */
if (rate < 1e-12)
rate = 0.;
}
}
rv->rate = rate;
rv->lastupdate = tv;
rv->lastval = curval;
sprintf(res, rv->format, rate);
Tcl_SetVar2(tcl, name1, name2, res, flags);
} else if (flags & (TCL_TRACE_DESTROYED|TCL_INTERP_DESTROYED)) {
delete rv;
}
return NULL;
}
int RateVariable::command(int argc, const char *const*argv)
{
Tcl& tcl = Tcl::instance();
const char* fmt;
if (argc == 4)
fmt = argv[3];
else if (argc == 3)
fmt = "%g";
else {
tcl.result("usage: rate_variable varname filter_const");
return (TCL_ERROR);
}
double fconst = atof(argv[2]);
if (fconst <= 0. || fconst > 1.) {
tcl.result("rate_variable: invalid filter constant");
return (TCL_ERROR);
}
rv_data* rv = new rv_data;
rv->filter = fconst;
rv->rate = 0.;
rv->lastupdate.tv_sec = 0;
rv->lastval = 0;
strcpy(rv->format, fmt);
int sts = Tcl_TraceVar(tcl.interp(), (char*)argv[1],
TCL_TRACE_WRITES|TCL_TRACE_UNSETS|TCL_GLOBAL_ONLY,
update_rate_var, (ClientData)rv);
if (sts != TCL_OK)
delete rv;
return (sts);
}
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