100 lines
2.8 KiB
Go
100 lines
2.8 KiB
Go
// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package math
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import (
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"fmt"
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"strconv"
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)
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// Integer limit values.
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const (
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MaxInt8 = 1<<7 - 1
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MinInt8 = -1 << 7
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MaxInt16 = 1<<15 - 1
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MinInt16 = -1 << 15
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MaxInt32 = 1<<31 - 1
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MinInt32 = -1 << 31
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MaxInt64 = 1<<63 - 1
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MinInt64 = -1 << 63
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MaxUint8 = 1<<8 - 1
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MaxUint16 = 1<<16 - 1
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MaxUint32 = 1<<32 - 1
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MaxUint64 = 1<<64 - 1
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)
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// HexOrDecimal64 marshals uint64 as hex or decimal.
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type HexOrDecimal64 uint64
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// UnmarshalText implements encoding.TextUnmarshaler.
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func (i *HexOrDecimal64) UnmarshalText(input []byte) error {
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int, ok := ParseUint64(string(input))
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if !ok {
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return fmt.Errorf("invalid hex or decimal integer %q", input)
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}
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*i = HexOrDecimal64(int)
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return nil
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}
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// MarshalText implements encoding.TextMarshaler.
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func (i HexOrDecimal64) MarshalText() ([]byte, error) {
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return []byte(fmt.Sprintf("%#x", uint64(i))), nil
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}
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// ParseUint64 parses s as an integer in decimal or hexadecimal syntax.
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// Leading zeros are accepted. The empty string parses as zero.
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func ParseUint64(s string) (uint64, bool) {
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if s == "" {
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return 0, true
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}
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if len(s) >= 2 && (s[:2] == "0x" || s[:2] == "0X") {
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v, err := strconv.ParseUint(s[2:], 16, 64)
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return v, err == nil
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}
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v, err := strconv.ParseUint(s, 10, 64)
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return v, err == nil
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}
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// MustParseUint64 parses s as an integer and panics if the string is invalid.
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func MustParseUint64(s string) uint64 {
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v, ok := ParseUint64(s)
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if !ok {
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panic("invalid unsigned 64 bit integer: " + s)
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}
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return v
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}
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// NOTE: The following methods need to be optimised using either bit checking or asm
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// SafeSub returns subtraction result and whether overflow occurred.
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func SafeSub(x, y uint64) (uint64, bool) {
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return x - y, x < y
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}
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// SafeAdd returns the result and whether overflow occurred.
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func SafeAdd(x, y uint64) (uint64, bool) {
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return x + y, y > MaxUint64-x
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}
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// SafeMul returns multiplication result and whether overflow occurred.
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func SafeMul(x, y uint64) (uint64, bool) {
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if x == 0 || y == 0 {
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return 0, false
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}
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return x * y, y > MaxUint64/x
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}
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