public BigDecimal subtract(BigDecimal subtrahend)
{
int diffScale = this._scale - subtrahend._scale;
// Fast return when some operand is zero
if (this.isZero()) {
if (diffScale <= 0) {
return subtrahend.negate();
}
if (subtrahend.isZero()) {
return this;
}
} else if (subtrahend.isZero()) {
if (diffScale >= 0) {
return this;
}
}
// Let be: this = [u1,s1] and subtrahend = [u2,s2] so:
if (diffScale == 0) {
// case s1 = s2 : [u1 - u2 , s1]
if (Math.Max(this._bitLength, subtrahend._bitLength) + 1 < 64) {
return valueOf(this.smallValue - subtrahend.smallValue,this._scale);
}
return new BigDecimal(this.getUnscaledValue().subtract(subtrahend.getUnscaledValue()), this._scale);
} else if (diffScale > 0) {
// case s1 > s2 : [ u1 - u2 * 10 ^ (s1 - s2) , s1 ]
if(diffScale < LONG_TEN_POW.Length &&
Math.Max(this._bitLength,subtrahend._bitLength+LONG_TEN_POW_BIT_LENGTH[diffScale])+1<64) {
return valueOf(this.smallValue-subtrahend.smallValue*LONG_TEN_POW[diffScale],this._scale);
}
return new BigDecimal(this.getUnscaledValue().subtract(
Multiplication.multiplyByTenPow(subtrahend.getUnscaledValue(),diffScale)), this._scale);
} else {// case s2 > s1 : [ u1 * 10 ^ (s2 - s1) - u2 , s2 ]
diffScale = -diffScale;
if(diffScale < LONG_TEN_POW.Length &&
Math.Max(this._bitLength+LONG_TEN_POW_BIT_LENGTH[diffScale],subtrahend._bitLength)+1<64) {
return valueOf(this.smallValue*LONG_TEN_POW[diffScale]-subtrahend.smallValue,subtrahend._scale);
}
return new BigDecimal(Multiplication.multiplyByTenPow(this.getUnscaledValue(),diffScale)
.subtract(subtrahend.getUnscaledValue()), subtrahend._scale);
}
}