/*  sdfentcn.cpp  by K.Tsuru  */
// function ID = 3500  DRADIX, BRADIX
/***************************************************
SDouble and SDecimal classes
It provides the entry of a constant function.
userV     : given by user
snV       : pointer to the variable which sets the result, snV!=NULL
pfDefFunc : pointer to the function which calculate the constant when
            the number of figures is insufficient
maxSize   : the number of calculated figures
The function prototype is declared in "snfunc.h".
****************************************************/
#ifndef SN_H
#include "sn.h"
#endif
static const char* func = "EntryConst";

void EntryConst(const SDouble* userV, SDouble* snV,
SDouble (*pfCalcFunc)(),  uint* maxSize){

//If there is no method to evaluate or "new" operator has not been used in the constant
//function, it makes an error.
    if( (userV == NULL) && (pfCalcFunc == NULL) ) SNManager::SetError(SNManager::SYNTAX_ERR, func, 3500);
    if(snV == NULL) SNManager::SetError(SNManager::FATAL, func, 3500);
    uint max_sz  = snV->MaxSize();
    uint snVSize = snV->Head() + 1u;  // ver. 2.17 SDHead() --> Head()
    uint userSize = (userV != NULL) ? (userV->Head()+1u) : 0;

    if(snVSize < max_sz){
        if(userSize >= max_sz) *snV = *userV;   //sufficient figures is given by "userV"
        else if(pfCalcFunc != NULL) *snV = (*pfCalcFunc)(); //calculation
        else snV->SetError(snV->SYNTAX_ERR, func, 3500);    //no method to calculate
    }
    *maxSize = max_sz;
}