Exemple #1
0
/* calcDiff returns a bool given two block headers.  This bool is
true if the correct dificulty adjustment is seen in the "next" header.
Only feed it headers n-2016 and n-1, otherwise it will calculate a difficulty
when no adjustment should take place, and return false.
Note that the epoch is actually 2015 blocks long, which is confusing. */
func calcDiffAdjust(start, end wire.BlockHeader, p *chaincfg.Params) uint32 {
	duration := end.Timestamp.UnixNano() - start.Timestamp.UnixNano()
	if duration < minRetargetTimespan {
		log.Printf("whoa there, block %s off-scale high 4X diff adjustment!",
			end.BlockSha().String())
		duration = minRetargetTimespan
	} else if duration > maxRetargetTimespan {
		log.Printf("Uh-oh! block %s off-scale low 0.25X diff adjustment!\n",
			end.BlockSha().String())
		duration = maxRetargetTimespan
	}

	// calculation of new 32-byte difficulty target
	// first turn the previous target into a big int
	prevTarget := blockchain.CompactToBig(start.Bits)
	// new target is old * duration...
	newTarget := new(big.Int).Mul(prevTarget, big.NewInt(duration))
	// divided by 2 weeks
	newTarget.Div(newTarget, big.NewInt(int64(targetTimespan)))

	// clip again if above minimum target (too easy)
	if newTarget.Cmp(p.PowLimit) > 0 {
		newTarget.Set(p.PowLimit)
	}

	// calculate and return 4-byte 'bits' difficulty from 32-byte target
	return blockchain.BigToCompact(newTarget)
}
Exemple #2
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// This example demonstrates how to convert a target difficulty into the compact
// "bits" in a block header which represent that target difficulty .
func ExampleBigToCompact() {
	// Convert the target difficulty from block 300000 in the main block
	// chain to compact form.
	t := "0000000000000000896c00000000000000000000000000000000000000000000"
	targetDifficulty, success := new(big.Int).SetString(t, 16)
	if !success {
		fmt.Println("invalid target difficulty")
		return
	}
	bits := blockchain.BigToCompact(targetDifficulty)

	fmt.Println(bits)

	// Output:
	// 419465580
}
Exemple #3
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func TestBigToCompact(t *testing.T) {
	tests := []struct {
		in  int64
		out uint32
	}{
		{0, 0},
		{-1, 25231360},
	}

	for x, test := range tests {
		n := big.NewInt(test.in)
		r := blockchain.BigToCompact(n)
		if r != test.out {
			t.Errorf("TestBigToCompact test #%d failed: got %d want %d\n",
				x, r, test.out)
			return
		}
	}
}