updated micro:coin
This commit is contained in:
Peli de Halleux
parent
614c3b0950
commit
c1fd464cb5
@ -27,300 +27,14 @@ Build yourself a [@boardname@ wallet](/projects/wallet) to hold your coins!
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## ~
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## ~
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## Full source code
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## Code
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**JavaScript only!** This program uses features that won't work in blocks...
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The code uses blocks from [radio-blockchain](https://makecode.microbit.org/pkg/microsoft/pxt-radio-blockchain) package.
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```typescript
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* Click on **Advanced**, then **Add Package**
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/*
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* search for **blockchain** and add **radio-blockchain**
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* micro:coin, A minimalistic blockchain for micro:bit
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*
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* DISCLAIMER: this is just an example.
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*
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*/
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/**
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* Message types sent over radio.
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*/
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enum Message {
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// ask peer to get the full chain
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QueryChain = 1,
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// a block flying around
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Block = 2
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}
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/**
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* A block is an immutable (can't change it) piece of a block chain.
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* The block chain is like a list where each block is built from
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* the previous block.
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*/
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class Block {
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// index in the chain
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index: number;
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// timestamp on the device when the block was created
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timestamp: number;
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// in this implementation, data is the device serial number
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data: number;
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// hash of the previous block as a single unsigned byte
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previousHash: number; // uint8
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// hash of the current block as a single unsigned byte
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hash: number; // uint8
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/**
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* Construct the block and computes the hash
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*/
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constructor(
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index: number,
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timestamp: number,
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data: number,
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previousHash: number) {
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this.index = index;
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this.timestamp = timestamp;
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this.data = data;
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this.previousHash = previousHash;
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this.hash = this.computeHash();
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}
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/**
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* Compute the hash of the current block
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*/
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computeHash() {
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let s = "" + this.index + this.timestamp + this.data + this.previousHash;
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/**
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* This function takes a string and hashes it into a number. It simply takes the sum of characters,
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* it's not great but will work for a super-simple example.
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*/
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let sum = 0;
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for (let i = 0; i < s.length; i++)
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sum += s.charCodeAt(i);
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return sum % 0xff;
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}
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/**
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* Create the next block with the given data
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*/
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next(data: number) {
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return new Block(this.index + 1, input.runningTime(), data, this.hash);
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}
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/**
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* Render the block as a string
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*/
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toString() {
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return `block ${this.index} ${this.timestamp} ${this.data} ${this.hash}`;
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}
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/**
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* Send the block over radio
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*/
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broadcast() {
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serial.writeLine(`broadcast ${this}`);
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/**
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* We pack all the block data into a buffer and send it over radio
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*/
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const buf = pins.createBuffer(16);
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buf.setNumber(NumberFormat.UInt8LE, 0, Message.Block);
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buf.setNumber(NumberFormat.UInt8LE, 1, this.hash);
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buf.setNumber(NumberFormat.UInt8LE, 2, this.previousHash);
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buf.setNumber(NumberFormat.Int32LE, 4, this.index);
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buf.setNumber(NumberFormat.Int32LE, 4 + 4, this.timestamp);
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buf.setNumber(NumberFormat.Int32LE, 4 + 8, this.data);
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radio.sendBuffer(buf)
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}
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/**
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* Try to read the block from the buffer. If anything is wrong, return undefined.
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*/
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static receive(buf: Buffer): Block {
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// check the message type
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if (buf.getNumber(NumberFormat.UInt8LE, 0) != Message.Block)
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return undefined;
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// read all the parts of the block back from the buffer
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const b = new Block(
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buf.getNumber(NumberFormat.Int32LE, 4), // index
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buf.getNumber(NumberFormat.Int32LE, 4 + 4), // timestamp
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buf.getNumber(NumberFormat.Int32LE, 4 + 8), // data
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buf.getNumber(NumberFormat.UInt8LE, 2) // previoushash
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);
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const h = buf.getNumber(NumberFormat.UInt8LE, 1); // hash
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if (b.hash != h) {
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serial.writeLine(`received invalid block ${b.hash} != ${h}`);
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return undefined;
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}
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serial.writeLine(`received ${b}`);
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return b;
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}
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}
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/**
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* A block chain is a sequence of block
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*/
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class BlockChain {
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id: number; // device serial number
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chain: Block[];
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/**
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* Constructs a new coin with the given id
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*/
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constructor(id: number) {
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this.id = id;
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this.chain = [];
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// if ID is set, this coin is a mirror of a peer coin
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// otherwise add genesis block
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if (!this.id) {
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this.chain.push(new Block(0, input.runningTime(), 0, 0));
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this.id = control.deviceSerialNumber();
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}
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}
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/**
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* Grab the last block in the chain
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*/
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lastBlock() {
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return this.chain[this.chain.length - 1];
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}
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/**
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* Add a new block with your coin in the chain
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*/
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addCoin() {
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this.chain.push(this.lastBlock().next(this.id));
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this.lastBlock().broadcast();
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}
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/**
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* Test if we have all the blocks in the chain available
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*/
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isComplete() {
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for (let i = 0; i < this.chain.length; ++i)
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if (!this.chain[i]) return false; // missing block
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return this.lastBlock().index == this.chain.length - 1;
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}
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/**
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* Test if the block chain is valid
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*/
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isValid() {
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if (!this.isComplete()) {
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serial.writeLine("coin not complete");
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return false;
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}
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for (let i = 0; i < this.chain.length - 1; ++i) {
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const prev = this.chain[i];
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const next = this.chain[i + 1];
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if (prev.index + 1 != next.index) {
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serial.writeLine("invalid index");
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return false;
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}
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if (prev.hash != next.previousHash) {
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serial.writeLine("invalid prev hash");
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}
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if (next.computeHash() != next.hash) {
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serial.writeLine("invalid hash");
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return false;
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}
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}
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return true;
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}
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/**
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* Insert a block received over the radio
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*/
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insert(block: Block) {
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this.chain[block.index] = block;
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}
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/**
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* We've received a block chain and we are trying to replace the chain if it's been updated.
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*/
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replace(other: BlockChain) {
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if (other.isValid() && other.chain.length > me.chain.length) {
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serial.writeLine("replacing chain");
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this.chain = other.chain.slice(0, other.chain.length);
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this.lastBlock().broadcast()
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basic.showIcon(IconNames.SmallSquare)
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}
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}
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/**
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* Broadcast the chains
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*/
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broadcastChain() {
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for (let i = 0; i < this.chain.length; ++i) {
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this.chain[i].broadcast();
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}
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}
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}
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/**
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* Request all peers (or a single on) for the entire chain
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*/
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function broadcastQueryChain(serialNumber: number = 0) {
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const msg = pins.createBuffer(6);
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msg.setNumber(NumberFormat.UInt8LE, 0, Message.QueryChain);
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msg.setNumber(NumberFormat.Int32LE, 2, serialNumber);
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radio.sendBuffer(msg);
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}
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const me = new BlockChain(0);
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const peers: BlockChain[] = [];
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/**
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* Get or create a block chain to store the blocks of a peer
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*/
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function peer(id: number): BlockChain {
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for (let i = 0; i < peers.length; ++i) {
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if (peers[i].id == id) return peers[i];
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}
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const r = new BlockChain(id);
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peers.push(r);
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return r;
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}
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/**
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* Settings for the radio receiver
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*/
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radio.setGroup(42);
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radio.setTransmitSerialNumber(true);
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radio.onDataPacketReceived(({ receivedBuffer, serial: serialNumber }) => {
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// processing a message received by ppers
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let id: number;
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switch (receivedBuffer[0]) {
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case Message.QueryChain:
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// so a peer asking to broadcast the chain
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serial.writeLine("msg: query chain");
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id = receivedBuffer.getNumber(NumberFormat.Int32LE, 2);
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// either all peers should send or just me
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if (!id || id == me.id) {
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me.broadcastChain();
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me.broadcastChain(); // send it twice as we might loose patterns
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}
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break;
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case Message.Block:
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// so we've received a block from a peer
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serial.writeLine("msg: block");
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const other = peer(serialNumber);
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const block = Block.receive(receivedBuffer);
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if (!block) return; // something got corrupted
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other.insert(block);
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serial.writeLine(`check ${other.lastBlock().index} > ${me.lastBlock().index}`)
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// if the other chain is longer, we should update ours maybe
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if (other.lastBlock().index > me.lastBlock().index) {
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if (!other.isComplete()) {
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// we don't have the entire chain
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serial.writeLine(`peer incomplete`)
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broadcastQueryChain(serialNumber);
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} else {
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// we have a full chain, try replacing it
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serial.writeLine(`peer complete, try replace`)
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me.replace(other);
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}
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}
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break;
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}
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})
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```blocks
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// shaking is mining...
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// shaking is mining...
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input.onGesture(Gesture.Shake, () => {
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input.onGesture(Gesture.Shake, () => {
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led.stopAnimation()
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led.stopAnimation()
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@ -328,7 +42,7 @@ input.onGesture(Gesture.Shake, () => {
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basic.pause(200) // display a short pause
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basic.pause(200) // display a short pause
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if (Math.random(3) == 0) { // 30% chances to add a transaction
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if (Math.random(3) == 0) { // 30% chances to add a transaction
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// we found a coin!!!
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// we found a coin!!!
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me.addCoin();
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blockchain.addBlock(1);
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basic.showIcon(IconNames.Diamond);
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basic.showIcon(IconNames.Diamond);
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} else {
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} else {
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// missed!
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// missed!
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@ -336,34 +50,32 @@ input.onGesture(Gesture.Shake, () => {
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}
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}
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})
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})
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// show my score
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// show my coins
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input.onButtonPressed(Button.A, () => {
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input.onButtonPressed(Button.A, () => {
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led.stopAnimation()
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led.stopAnimation()
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let score = 0;
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let coins = blockchain.valuesFrom(blockchain.id()).length;
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for (let i = 0; i < me.chain.length; ++i) {
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basic.showNumber(coins);
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if (me.chain[i].data == me.id)
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basic.showString("COINS");
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score++;
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}
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basic.showNumber(score);
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})
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})
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// show the block chain size
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// show the block chain size
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input.onButtonPressed(Button.B, () => {
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input.onButtonPressed(Button.B, () => {
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led.stopAnimation()
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led.stopAnimation()
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basic.showNumber(me.chain.length - 1);
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basic.showNumber(blockchain.length());
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})
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basic.showString("BLOCKS");
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input.onButtonPressed(Button.AB, () => {
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led.stopAnimation()
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for (let i = 1; i < me.chain.length; ++i) {
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basic.showNumber(me.chain[i].data);
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}
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})
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})
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// ask neighbors for chains
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// instructions on how to play
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broadcastQueryChain();
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basic.showString("A=SCORE B=CHAIN SHAKE=MINE", 100)
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basic.showString("A=SCORE B=CHAIN SHAKE=MINE", 100)
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```
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```
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## How does it work?
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The [radio-blockchain](https://makecode.microbit.org/pkg/microsoft/pxt-radio-blockchain) uses
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radio to transmit blocks between @boardname@. You read it all by reading the JavaScript sources at https://github.com/microsoft/pxt-radio-blockchain or the code below.
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[main.ts](https://github.com/Microsoft/pxt-radio-blockchain/blob/master/main.ts) contains the full JavaScript source of the blockhain. Have a good read!
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## References
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## References
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* https://medium.com/@lhartikk/a-blockchain-in-200-lines-of-code-963cc1cc0e54
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* https://medium.com/@lhartikk/a-blockchain-in-200-lines-of-code-963cc1cc0e54
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@ -373,4 +85,5 @@ basic.showString("A=SCORE B=CHAIN SHAKE=MINE", 100)
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```package
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```package
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radio
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radio
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github:Microsoft/pxt-radio-blockchain
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```
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```
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Loading…
Reference in New Issue
Block a user