public BigDecimal add(BigDecimal augend, MathContext mc)
{
BigDecimal larger; // operand with the largest unscaled value
BigDecimal smaller; // operand with the smallest unscaled value
BigInteger tempBI;
long diffScale = (long)this._scale - augend._scale;
int largerSignum;
// Some operand is zero or the precision is infinity
if ((augend.isZero()) || (this.isZero())
|| (mc.getPrecision() == 0)) {
return add(augend).round(mc);
}
// Cases where there is room for optimizations
if (this.aproxPrecision() < diffScale - 1) {
larger = augend;
smaller = this;
} else if (augend.aproxPrecision() < -diffScale - 1) {
larger = this;
smaller = augend;
} else {// No optimization is done
return add(augend).round(mc);
}
if (mc.getPrecision() >= larger.aproxPrecision()) {
// No optimization is done
return add(augend).round(mc);
}
// Cases where it's unnecessary to add two numbers with very different scales
largerSignum = larger.signum();
if (largerSignum == smaller.signum()) {
tempBI = Multiplication.multiplyByPositiveInt(larger.getUnscaledValue(),10)
.add(BigInteger.valueOf(largerSignum));
} else {
tempBI = larger.getUnscaledValue().subtract(
BigInteger.valueOf(largerSignum));
tempBI = Multiplication.multiplyByPositiveInt(tempBI,10)
.add(BigInteger.valueOf(largerSignum * 9));
}
// Rounding the improved adding
larger = new BigDecimal(tempBI, larger._scale + 1);
return larger.round(mc);
}
private BigDecimal dodivide(char code,BigDecimal rhs,MathContext set,int scale)
{
BigDecimal lhs;
int reqdig;
int newexp;
BigDecimal res;
int newlen;
sbyte[] var1;
int var1len;
sbyte[] var2;
int var2len;
int b2b;
int have;
int thisdigit=0;
int i=0;
int ix=0;
sbyte v2=0;
int ba=0;
int mult=0;
int start=0;
int padding=0;
int d=0;
sbyte[] newvar1=null;
sbyte lasthave=0;
int actdig=0;
sbyte[] newmant=null;
if (set.lostDigits)
checkdigits(rhs,set.digits);
lhs=this; // name for clarity
// [note we must have checked lostDigits before the following checks]
if (rhs.ind==0)
throw new System.ArithmeticException("Divide by 0"); // includes 0/0
if (lhs.ind==0)
{ // 0/x => 0 [possibly with .0s]
if (set.form!=MathContext.PLAIN)
return ZERO;
if (scale==(-1))
return lhs;
return lhs.setScale(scale);
}
/* Prepare numbers according to BigDecimal rules */
reqdig=set.digits; // local copy (heavily used)
if (reqdig>0)
{
if (lhs.mant.Length>reqdig)
lhs=clone(lhs).round(set);
if (rhs.mant.Length>reqdig)
rhs=clone(rhs).round(set);
}
else
{/* scaled divide */
if (scale==(-1))
scale=lhs.scale();
// set reqdig to be at least large enough for the computation
reqdig=lhs.mant.Length; // base length
// next line handles both positive lhs.exp and also scale mismatch
if (scale!=((int)-lhs.exp))
reqdig=(reqdig+scale)+lhs.exp;
reqdig=(reqdig-((rhs.mant.Length-1)))-rhs.exp; // reduce by RHS effect
if (reqdig<lhs.mant.Length)
reqdig=lhs.mant.Length; // clamp
if (reqdig<rhs.mant.Length)
reqdig=rhs.mant.Length; // ..
}
/* precalculate exponent */
newexp=((lhs.exp-rhs.exp)+lhs.mant.Length)-rhs.mant.Length;
/* If new exponent -ve, then some quick exits are possible */
if (newexp<0)
if (code!='D')
{
if (code=='I')
return ZERO; // easy - no integer part
/* Must be 'R'; remainder is [finished clone of] input value */
return clone(lhs).finish(set,false);
}
/* We need slow division */
res=new BigDecimal(); // where we'll build result
res.ind=(sbyte)(lhs.ind*rhs.ind); // final sign (for D/I)
res.exp=newexp; // initial exponent (for D/I)
res.mant=new sbyte[reqdig+1]; // where build the result
/* Now [virtually pad the mantissae with trailing zeros */
// Also copy the LHS, which will be our working array
newlen=(reqdig+reqdig)+1;
var1=extend(lhs.mant,newlen); // always makes longer, so new safe array
var1len=newlen; // [remaining digits are 0]
var2=rhs.mant;
var2len=newlen;
/* Calculate first two digits of rhs (var2), +1 for later estimations */
b2b=(var2[0]*10)+1;
if (var2.Length>1)
b2b=b2b+var2[1];
/* start the long-division loops */
have=0;
{for(;;){
thisdigit=0;
/* find the next digit */
{inner:for(;;){
if (var1len<var2len)
break; // V1 too low
if (var1len==var2len)
{ // compare needed
for(ix=var1len,i=0;ix>0;ix--,i++){
// var1len is always <= var1.Length
if (i<var2.Length)
v2=var2[i];
else
v2=(sbyte)0;
if (var1[i]<v2)
goto breakInner; // V1 too low
if (var1[i]>v2)
goto breakCompare; // OK to subtract
}
/* reach here if lhs and rhs are identical; subtraction will
increase digit by one, and the residue will be 0 so we
are done; leave the loop with residue set to 0 (in case
code is 'R' or ROUND_UNNECESSARY or a ROUND_HALF_xxxx is
being checked) */
thisdigit++;
res.mant[have]=(sbyte)thisdigit;
have++;
var1[0]=(sbyte)0; // residue to 0 [this is all we'll test]
// var1len=1 -- [optimized out]
goto breakOuter;
breakCompare:
/* prepare for subtraction. Estimate BA (lengths the same) */
ba=(int)var1[0]; // use only first digit
} // lengths the same
else
{/* lhs longer than rhs */
/* use first two digits for estimate */
ba=var1[0]*10;
if (var1len>1)
ba=ba+var1[1];
}
/* subtraction needed; V1>=V2 */
mult=(ba*10)/b2b;
if (mult==0)
mult=1;
thisdigit=thisdigit+mult;
// subtract; var1 reusable
var1=byteaddsub(var1,var1len,var2,var2len,(int)-mult,true);
if (var1[0]!=0)
goto inner; // maybe another subtract needed
/* V1 now probably has leading zeros, remove leading 0's and try
again. (It could be longer than V2) */
for(ix=var1len-2,start=0;start<=ix;start++){
if (var1[start]!=0)
break;
var1len--;
}
if (start==0)
goto inner;
// shift left
System.Array.Copy(var1,start,var1,0,var1len);
}
}/*inner*/
breakInner:
/* We have the next digit */
if ((have!=0)|(thisdigit!=0))
{ // put the digit we got
res.mant[have]=(sbyte)thisdigit;
have++;
if (have==(reqdig+1))
goto breakOuter; // we have all we need
if (var1[0]==0)
goto breakOuter; // residue now 0
}
/* can leave now if a scaled divide and exponent is small enough */
if (scale>=0)
if (((int)-res.exp)>scale)
goto breakOuter;
/* can leave now if not Divide and no integer part left */
if (code!='D')
if (res.exp<=0)
goto breakOuter;
res.exp=res.exp-1; // reduce the exponent
/* to get here, V1 is less than V2, so divide V2 by 10 and go for
the next digit */
var2len--;
}
}/*outer*/
breakOuter:
/* here when we have finished dividing, for some reason */
// have is the number of digits we collected in res.mant
if (have==0)
have=1; // res.mant[0] is 0; we always want a digit
if ((code=='I')|(code=='R'))
{/* check for integer overflow needed */
if ((have+res.exp)>reqdig)
throw new System.ArithmeticException("Integer overflow");
if (code=='R') {
/* We were doing Remainder -- return the residue */
if (res.mant[0]==0) // no integer part was found
return clone(lhs).finish(set,false); // .. so return lhs, canonical
if (var1[0]==0)
return ZERO; // simple 0 residue
res.ind=lhs.ind; // sign is always as LHS
/* Calculate the exponent by subtracting the number of padding zeros
we added and adding the original exponent */
padding=((reqdig+reqdig)+1)-lhs.mant.Length;
res.exp=(res.exp-padding)+lhs.exp;
/* strip insignificant padding zeros from residue, and create/copy
the resulting mantissa if need be */
d=var1len;
for(i=d-1;i>=1;i--){if(!((res.exp<lhs.exp)&(res.exp<rhs.exp)))break;
if (var1[i]!=0)
break;
d--;
res.exp=res.exp+1;
}
if (d<var1.Length)
{/* need to reduce */
newvar1=new sbyte[d];
System.Array.Copy(var1,0,newvar1,0,d); // shorten
var1=newvar1;
}
res.mant=var1;
return res.finish(set,false);
}
}
else
{/* 'D' -- no overflow check needed */
// If there was a residue then bump the final digit (iff 0 or 5)
// so that the residue is visible for ROUND_UP, ROUND_HALF_xxx and
// ROUND_UNNECESSARY checks (etc.) later.
// [if we finished early, the residue will be 0]
if (var1[0]!=0)
{ // residue not 0
lasthave=res.mant[have-1];
if (((lasthave%5))==0)
res.mant[have-1]=(sbyte)(lasthave+1);
}
}
/* Here for Divide or Integer Divide */
// handle scaled results first ['I' always scale 0, optional for 'D']
if (scale>=0) {
// say 'scale have res.exp len' scale have res.exp res.mant.Length
if (have!=res.mant.Length)
// already padded with 0's, so just adjust exponent
res.exp=res.exp-((res.mant.Length-have));
// calculate number of digits we really want [may be 0]
actdig=res.mant.Length-((((int)-res.exp)-scale));
res.round(actdig,set.roundingMode); // round to desired length
// This could have shifted left if round (say) 0.9->1[.0]
// Repair if so by adding a zero and reducing exponent
if (res.exp!=((int)-scale))
{
res.mant=extend(res.mant,res.mant.Length+1);
res.exp=res.exp-1;
}
return res.finish(set,true); // [strip if not PLAIN]
}
// reach here only if a non-scaled
if (have==res.mant.Length)
{ // got digits+1 digits
res.round(set);
have=reqdig;
}
else
{/* have<=reqdig */
if (res.mant[0]==0)
return ZERO; // fastpath
// make the mantissa truly just 'have' long
// [we could let finish do this, during strip, if we adjusted
// the exponent; however, truncation avoids the strip loop]
newmant=new sbyte[have]; // shorten
System.Array.Copy(res.mant,0,newmant,0,have);
res.mant=newmant;
}
return res.finish(set,true);
}
public BigDecimal subtract(BigDecimal subtrahend, MathContext mc)
{
long diffScale = subtrahend._scale - (long)this._scale;
int thisSignum;
BigDecimal leftOperand; // it will be only the left operand (this)
BigInteger tempBI;
// Some operand is zero or the precision is infinity
if ((subtrahend.isZero()) || (this.isZero())
|| (mc.getPrecision() == 0)) {
return subtract(subtrahend).round(mc);
}
// Now: this != 0 and subtrahend != 0
if (subtrahend.aproxPrecision() < diffScale - 1) {
// Cases where it is unnecessary to subtract two numbers with very different scales
if (mc.getPrecision() < this.aproxPrecision()) {
thisSignum = this.signum();
if (thisSignum != subtrahend.signum()) {
tempBI = Multiplication.multiplyByPositiveInt(this.getUnscaledValue(), 10)
.add(BigInteger.valueOf(thisSignum));
} else {
tempBI = this.getUnscaledValue().subtract(BigInteger.valueOf(thisSignum));
tempBI = Multiplication.multiplyByPositiveInt(tempBI, 10)
.add(BigInteger.valueOf(thisSignum * 9));
}
// Rounding the improved subtracting
leftOperand = new BigDecimal(tempBI, this._scale + 1);
return leftOperand.round(mc);
}
}
// No optimization is done
return subtract(subtrahend).round(mc);
}
