diff options
Diffstat (limited to 'src/math')
| -rw-r--r-- | src/math/bits/bits.go | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/src/math/bits/bits.go b/src/math/bits/bits.go index 6ca4bfe9a6..c1c7b7978a 100644 --- a/src/math/bits/bits.go +++ b/src/math/bits/bits.go @@ -516,10 +516,6 @@ func Div32(hi, lo, y uint32) (quo, rem uint32) { // half in parameter hi and the lower half in parameter lo. // Div64 panics for y == 0 (division by zero) or y <= hi (quotient overflow). func Div64(hi, lo, y uint64) (quo, rem uint64) { - const ( - two32 = 1 << 32 - mask32 = two32 - 1 - ) if y == 0 { panic(divideError) } @@ -527,9 +523,18 @@ func Div64(hi, lo, y uint64) (quo, rem uint64) { panic(overflowError) } + // If high part is zero, we can directly return the results. + if hi == 0 { + return lo / y, lo % y + } + s := uint(LeadingZeros64(y)) y <<= s + const ( + two32 = 1 << 32 + mask32 = two32 - 1 + ) yn1 := y >> 32 yn0 := y & mask32 un32 := hi<<s | lo>>(64-s) |