/*  sdmfixpt.cpp  by K.Tsuru  */
// function ID = 312, 313
/*********************************************************
SDouble and SDecimal classes
It provides functions for fixed point mode.
**********************************************************/
#ifndef SN_H
#include "sn.h"
#endif

/**********************************************************************
It goes into the fixed point mode by giving the value of fixed exponent.
In the summation of series it fixes the number of effective figures and
decreases the number of figures to evaluate.
It does not reduce the size by Reform() and does not change the exponent.
The functions FixedPoint() and PointFree() must make a pair, and called by
the same object.
***********************************************************************/
int SDouble::fixedExp = 0;
int SDouble::fixedPointMode = 0;

static SNStack <int> fixedExpStack; // ver. 2.18

// function ID = 312   DRADIX
void SDouble::FixedPoint(int exp){
    if(!fixedExpStack.Elements()){
        fixedExpStack.Push(0);
    }
    if(CutDown() != DISABLE){
        CutDown(DISABLE);
        PushCD(PushedCD() | SD_PUSH);
    }
    if(fixedExp != exp){
        fixedExpStack.Push(fixedExp);
        PushCD(PushedCD() | CH_FE);
        fixedExp = exp;
    }
    fixedPointMode++;
}
// function ID = 313   DRADIX
void SDouble::PointFree(){
    if( PushedCD() & SD_PUSH ){
        PushCD(PushedCD() & ~SD_PUSH);
        CutDown(POP);
    }
    if(PushedCD() & CH_FE){
        fixedExp = fixedExpStack.Pop();
        PushCD(PushedCD() & ~CH_FE);
    }
    int c = fixedPointMode/(FIXED_PT_MASK+1) + (fixedPointMode & FIXED_PT_MASK);
    fixedPointMode--;
    if(!c || (fixedPointMode < 0) ) SetError(SYNTAX_ERR,"PointFree", 313);
}