//go:build !go1.15
// +build !go1.15

package gmath

import (
	"math/big"
)

// FillBytes fill the buf with the abs of a in big-endian with zero extention.
// if buf is two short, then return error, while Big.Int's FillBytes panic
func FillBytes(a *big.Int, buf []byte) error {
	if (a.BitLen()+7)/8 > len(buf) {
		return ErrBufTooShort
	}

	b := ToNBytes(a, len(buf))
	copy(buf, b)
	return nil
}