/*  sdcpi.cpp  by K.Tsuru  */
// function ID 3523 DRADIX
/*************
constant pi
In header "snmath.h" the function prototype is given below
--------
SDouble Pi(const SDouble* pi = NULL, SDouble (*pfCalcFunc)() = SNPi);
--------
Remade at version 2.30.
**************/
#ifndef SN_H
#include "sn.h"
#endif
static SDouble* pi = NULL;  //keep in the static memory
static uint piSize = 0;

void PiFree(){  //free the memory of pi
    if(piSize == 0) return;
    delete pi;      pi = NULL;      piSize = 0;
}
uint PiSize() { return piSize; }

SDouble Pi(const SDouble* userPi, SDouble (*pfCalcFunc)()){
// "new" must been done here.
    if(pi == NULL) pi = new SDouble;
    uint curMaxSize = pi->MaxSize(); // current max size
    if( piSize < curMaxSize ){
#if UsesSNConstantFile
    if(userPi == NULL){ //called by default argument
        int enough;
/**********************************************************************************
UpdateConstantFile() recursively calls this function Pi() via SetConstByFile()
of which userE != NULL, then does not come here and processing below has been
done.
**********************************************************************************/
        enough = UpdateConstantFile(Pi_FILE, Pi, pfCalcFunc, curMaxSize);
        if(enough != NO_SNC_FILE) return *pi;
    }
#endif
        pi->ShowMessage("Evaluating Pi() now.....");
        EntryConst(userPi, pi, pfCalcFunc, &piSize);
        pi->ShowMessage(" Finished.\n"); // ver. 2.17

        piSize = curMaxSize;
    }
    return *pi;
}