public decimal Next(decimal value)
{
Debug.Assert(value != decimal.MaxValue);
if (value == 0m)
{
return(epsilon);
}
var(low, mid, high, isNegative, scale) = DecimalRep.FromValue(value);
Debug.Assert(scale == DecimalRep.FromValue(value).Normalize().scale); // assert that the input is normalized
if (isNegative)
{
// get the next value closer to zero.(less negative)
if (value == -epsilon)
{
return(normalZero); // skip negative zero
}
// This should not occur, as numbers such as this are not in our normal form (not at maximum scale).
Debug.Assert(
!(
scale < 28 &&
low == transitionLow &&
mid == transitionMid &&
high == transitionHigh
)
);
if (low != 0)
{
return(new DecimalRep(
low: low - 1,
mid: mid,
high: high,
isNegative: isNegative,
scale: scale
).Value);
}
if (mid != 0)
{
return(new DecimalRep(
low: uint.MaxValue,
mid: mid - 1,
high: high,
isNegative: isNegative,
scale: scale
).Value);
}
Debug.Assert(high > 0); // otherwise value == 0m
return(new DecimalRep(
low: uint.MaxValue,
mid: uint.MaxValue,
high: high - 1,
isNegative: isNegative,
scale: scale
).Value);
}
else
{
// get the next value farther from zero.(more positive)
if (low != uint.MaxValue)
{
return(new DecimalRep(
low: low + 1,
mid: mid,
high: high,
isNegative: isNegative,
scale: scale
).Value);
}
if (mid != uint.MaxValue)
{
return(new DecimalRep(
low: 0,
mid: mid + 1,
high: high,
isNegative: isNegative,
scale: scale
).Value);
}
if (high != uint.MaxValue)
{
return(new DecimalRep(
low: 0,
mid: 0,
high: high + 1,
isNegative: isNegative,
scale: scale
).Value);
}
// the mantissa it at its maximum value. Divide the mantissa by 10 and decrease the scale.
// Since we know the value of the mantissa, we can simply assign mantissa/10 here.
low = transitionLow;
mid = transitionMid;
high = transitionHigh;
Debug.Assert(scale > 0); // otherwise value == decimal.MaxValue
scale -= 1;
var result =
new DecimalRep(
low: low + 1,
mid: mid,
high: high,
isNegative: isNegative,
scale: scale
).Value;
// Assert that the value returned really is the next possible value.
Debug.Assert(
new DecimalRep(
low: low,
mid: mid,
high: high,
isNegative: isNegative,
scale: scale
).Value <= value
);
Debug.Assert(result > value);
return(result);
}
}
public static decimal Normalize(decimal value) => DecimalRep.FromValue(value).Normalize().Value;
