yaole
79 lines
1.4 KiB
Go
79 lines
1.4 KiB
Go
//go:build gmp
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// +build gmp
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package gmp
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/*
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#cgo LDFLAGS: -lgmp
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#include <gmp.h>
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#include <stdlib.h>
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*/
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import "C"
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import (
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"math/big"
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)
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const MaxBase = 62
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// itoa is like utoa but it prepends a '-' if neg && x != 0.
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func itoa(x []byte, neg bool, base int) string {
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if base < 2 || base > MaxBase {
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panic("invalid base")
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}
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// x == 0
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if len(x) == 0 {
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return "0"
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}
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// len(x) > 0
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n := new(big.Int).SetBytes(x)
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if neg {
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n.Neg(n)
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}
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return n.Text(base)
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}
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// Text returns the string representation of x in the given base.
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// Base must be between 2 and 62, inclusive. The result uses the
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// lower-case letters 'a' to 'z' for digit values 10 to 35, and
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// the upper-case letters 'A' to 'Z' for digit values 36 to 61.
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// No prefix (such as "0x") is added to the string. If x is a nil
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// pointer it returns "<nil>".
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func (x *Int) Text(base int) string {
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if x == nil {
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return "<nil>"
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}
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nat := x.Bytes()
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return string(itoa(nat, x.Sign() < 0, base))
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}
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// Bits return the bits of x
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func (x *Int) Bits() uint {
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// return uint(C.mpz_bitcnt(x.i))
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panic("unimplement")
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}
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// ToNBytes ouput a bytes to fix n bytes. extend as 0.
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func toNBytes(b *Int, n int) []byte {
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abs := b.Bytes()
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l := len(abs)
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var s []byte
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// l==n is the most case (255/256)
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if l >= n {
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s = abs[l-n : l]
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} else {
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s = make([]byte, n)
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copy(s[n-l:], abs)
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}
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return s
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}
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func (x *Int) FillBytes(b []byte) []byte {
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bb := toNBytes(x, len(b))
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copy(b, bb)
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return b
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}
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