github.com/geraldss/go/src@v0.0.0-20210511222824-ac7d0ebfc235/runtime/internal/math/math.go (about)

     1  // Copyright 2018 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package math
     6  
     7  import "runtime/internal/sys"
     8  
     9  const MaxUintptr = ^uintptr(0)
    10  
    11  // MulUintptr returns a * b and whether the multiplication overflowed.
    12  // On supported platforms this is an intrinsic lowered by the compiler.
    13  func MulUintptr(a, b uintptr) (uintptr, bool) {
    14  	if a|b < 1<<(4*sys.PtrSize) || a == 0 {
    15  		return a * b, false
    16  	}
    17  	overflow := b > MaxUintptr/a
    18  	return a * b, overflow
    19  }