diff options
Diffstat (limited to 'libgo/go/math/big/int.go')
| -rw-r--r-- | libgo/go/math/big/int.go | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/libgo/go/math/big/int.go b/libgo/go/math/big/int.go index 18f122e953c..65f32487b58 100644 --- a/libgo/go/math/big/int.go +++ b/libgo/go/math/big/int.go @@ -447,11 +447,26 @@ func (z *Int) SetBytes(buf []byte) *Int { } // Bytes returns the absolute value of x as a big-endian byte slice. +// +// To use a fixed length slice, or a preallocated one, use FillBytes. func (x *Int) Bytes() []byte { buf := make([]byte, len(x.abs)*_S) return buf[x.abs.bytes(buf):] } +// FillBytes sets buf to the absolute value of x, storing it as a zero-extended +// big-endian byte slice, and returns buf. +// +// If the absolute value of x doesn't fit in buf, FillBytes will panic. +func (x *Int) FillBytes(buf []byte) []byte { + // Clear whole buffer. (This gets optimized into a memclr.) + for i := range buf { + buf[i] = 0 + } + x.abs.bytes(buf) + return buf +} + // BitLen returns the length of the absolute value of x in bits. // The bit length of 0 is 0. func (x *Int) BitLen() int { @@ -465,8 +480,8 @@ func (x *Int) TrailingZeroBits() uint { } // Exp sets z = x**y mod |m| (i.e. the sign of m is ignored), and returns z. -// If m == nil or m == 0, z = x**y unless y <= 0 then z = 1. If m > 0, y < 0, -// and x and n are not relatively prime, z is unchanged and nil is returned. +// If m == nil or m == 0, z = x**y unless y <= 0 then z = 1. If m != 0, y < 0, +// and x and m are not relatively prime, z is unchanged and nil is returned. // // Modular exponentiation of inputs of a particular size is not a // cryptographically constant-time operation. |