Decimal.fromIntegral

Decimal fromIntegral(
          long  v,  ref  DecimalContext ctx)

static @safe pure nothrow @nogc

Construction from a signed integer under a context: values beyond the format's digits round (statuses ROUNDED/INEXACT).

Decimal fromIntegral(
          ulong  v,  ref  DecimalContext ctx)

static @safe pure nothrow @nogc

Ditto (unsigned).