math/bits: add Rem, Rem32, Rem64
The Div functions in math/bits (Div, Div32, and Div64) compute both
quotients and remainders, but they panic if the quotients do not not
fit a 32/64 uint.
Since, on the other hand, the remainder will always fit the size of
the divisor, it is useful to have Div variants that only compute the
remainder, and don't panic on a quotient overflow.
This change adds to the math/bits package three new functions:
Rem(hi, lo, y uint) uint
Rem32(hi, lo, y uint32) uint32
Rem64(hi, lo, y uint64) uint64
which can be used to compute (hi,lo)%y even when the quotient
overflows the uint size.
Fixes #28970
Change-Id: I119948429f737670c5e5ceb8756121e6a738dbdc
Reviewed-on: https://go-review.googlesource.com/c/go/+/197838
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>