forth.js

   1 'use strict'
   2 let txtdiv = document.createElement("div")
   3 document.body.appendChild(txtdiv)
   4 const output = {
   5   print: (string) => txtdiv.textContent += string
   6 }
   7 let wasmMem
   8 let forth
   9
  10 /* Input capture */
  11 let stdin = ""
  12 document.addEventListener('keydown', (event) => {
  13   console.log(`keydown: ${event.key}`)
  14   if (event.key != "F5") {
  15     event.preventDefault()
  16     event.stopPropagation()
  17     switch (event.key) {
  18     case "Enter":
  19       txtdiv = document.createElement("div")
  20       document.body.appendChild(txtdiv)
  21       forth()
  22       output.print("__ok.")
  23       txtdiv = document.createElement("div")
  24       document.body.appendChild(txtdiv)
  25       break
  26     case "Backspace":
  27       stdin = stdin.substring(0, stdin.length - 1)
  28       txtdiv.textContent = txtdiv.textContent.substring(0, txtdiv.textContent.length - 1)
  29       break
  30     default:
  31       if (event.key.length == 1) {
  32         stdin += event.key
  33         output.print(event.key)
  34       }
  35       break
  36     }
  37   }
  38 })
  39
  40 const channels = [{
  41   read: (writeAddr, maxBytes) => {
  42     const maxChars = maxBytes >> 1
  43     const bufView = new Uint16Array(wasmMem.buffer, writeAddr, maxChars)
  44     let i
  45     for (i = 0; i < maxChars && i < stdin.length; i++)
  46       bufView[i] = stdin.charCodeAt(i)
  47     stdin = stdin.substring(maxChars)
  48     return i << 1
  49   },
  50   write: (readAddr, maxBytes) =>
  51     output.print(String.fromCharCode.apply(
  52       null,
  53       new Uint16Array(wasmMem.buffer, readAddr, maxBytes)
  54     ))
  55 }]
  56 const simstack = []
  57 const rstack = []
  58 const dictionary = {
  59   ';': 1,
  60   'LIT': 2,
  61   RINIT: 3,
  62   WORD: 696,
  63   KEY: 5,
  64   DUP: 6,
  65   '+': 7,
  66   'NOOP2': 8,
  67   '.': 9,
  68   '@': 10,
  69   '!': 11,
  70   EXECUTE: 12,
  71   NOOP: 13,
  72   'JZ:': 14,
  73   'JNZ:': 15,
  74   DROP: 16,
  75   'WS?': 17,
  76   'JMP:': 18,
  77   'WPUTC': 19,
  78   'WB0': 20,
  79   'FIND': 21,
  80   'NUMBER': 22,
  81   'W!LEN': 23,
  82   'J-1:': 24,
  83   'BYE': 25,
  84   'SWAP': 26,
  85   'WORDS': 27,
  86   'HERE': 28,
  87   'DEFINE': 29,
  88   ':': 900,
  89   'MODE': 384,
  90   'WBUF': 256,
  91   'EXECUTE-MODE': 800,
  92   'QUIT': 600,
  93   'INTERPRET': 512
  94 }
  95 const wasmImport = {
  96   env: {
  97     pop: () => simstack.pop(),
  98     push: (val) => simstack.push(val),
  99     rinit: () => rstack.length = 0,
 100     rpop: () => rstack.pop(),
 101     rpush: (val) => rstack.push(val),
 102     sys_write: (channel, fromBuffer) => {
 103       if (channels[channel] === undefined)
 104         return
 105       const maxBytes = new DataView(
 106         wasmMem.buffer,
 107         fromBuffer,
 108         4
 109       ).getUint32(0,true)
 110       console.log(`write ch:${channel} addr:${fromBuffer} len:${maxBytes}`)
 111       channels[channel].write(fromBuffer + 4, maxBytes)
 112     },
 113     sys_read: (channel, toBuffer) => {
 114       console.log(`read ch:${channel} buf:${toBuffer} current: ${stdin}`)
 115       const lenView = new DataView(wasmMem.buffer, toBuffer, 8)
 116       const maxBytes = lenView.getUint32(0,true)
 117       console.log(`read blen:${lenView.getUint32(0,true)} cstrlen:${lenView.getUint32(4,true)}`)
 118       /* If the channel is undefined, or if there isn't enough room in
 119        * toBuffer for even one character, then, if there is enough
 120        * room for an int write a zero, exit */
 121       if (channels[channel] === undefined || maxBytes < 6) {
 122         if (maxBytes >= 4)
 123           lenView.setUint32(4,0,true)
 124       }
 125       const numBytes = channels[channel].read(toBuffer + 8, maxBytes - 4)
 126       lenView.setUint32(4,numBytes,true);
 127       console.log(`read wrote ${lenView.getUint32(4,true)} bytes, remainder: ${stdin}`)
 128       console.log(`read blen:${lenView.getUint32(0,true)} cstrlen:${lenView.getUint32(4,true)}`)   },
 129     sys_listen: (reqAddr, cbAddr) => {
 130       //TODO: call into the module to wasm fn "event" to push an event
 131       //to forth, which pushes esi to the return stack and queues the
 132       //callback function provided from listen. reqaddr could be
 133       //"fetch", in which case no channel is used.  otherwise very
 134       //similar to sys_fetch.
 135     },
 136     sys_fetch: (channel, reqAddr) => {
 137       //TODO: map to fetch promise, write to channel buffer,
 138       //javascript "fetch" as fallback, explicit handles for
 139       //"textEntry" or any third party protocols like activitypub
 140       console.log(`fetch ${channel} ${reqAddr}`)
 141     },
 142     sys_echo: (val) => output.print(`${val} `),
 143     sys_echochar: (val) => output.print(String.fromCharCode(val)),
 144     sys_reflect: (addr) => {
 145       console.log(`reflect: ${addr}: ${
 146         new DataView(wasmMem.buffer, addr, 4)
 147               .getUint32(0,true)
 148       }`)
 149     },
 150     vocab_get: (addr) => {
 151       const bytes = new DataView(
 152         wasmMem.buffer,
 153         addr,
 154         4
 155       ).getUint32(0,true)
 156       const word = String.fromCharCode.apply(
 157         null,
 158         new Uint16Array(wasmMem.buffer, addr + 4, bytes >> 1)
 159       )
 160       const answer = dictionary[word.toUpperCase()]
 161       console.log(`vocab_get ${word}: ${answer}`)
 162       if (answer === undefined)
 163         return 0
 164       return answer
 165     },
 166     vocab_set: (addr, num) => {
 167       const bytes = new DataView(
 168         wasmMem.buffer,
 169         addr,
 170         4
 171       ).getUint32(0,true)
 172       const word = String.fromCharCode.apply(
 173         null,
 174         new Uint16Array(wasmMem.buffer, addr + 4, bytes >> 1)
 175       )
 176       console.log(`vocab_set ${word}: ${num}`)
 177       dictionary[word.toUpperCase()] = num
 178       return 0
 179     },
 180     is_whitespace: (key) => /\s/.test(String.fromCharCode(key)),
 181     sys_stack: () => console.log(`[${simstack}]`),
 182     sys_parsenum: (addr, base) => {
 183       const byteV = new DataView(
 184         wasmMem.buffer,
 185         addr,
 186         4
 187       )
 188       const word = String.fromCharCode.apply(
 189         null,
 190         new Uint16Array(wasmMem.buffer, addr + 4, byteV.getUint32(0,true) >> 1)
 191       )
 192       const answer = Number.parseInt(word, base)
 193       byteV.setUint32(0,Number.isNaN(answer),true)
 194       return answer
 195     },
 196     sys_words: () => {
 197       output.print(Object.getOwnPropertyNames(dictionary).toString().split(',').join('  '))
 198     }
 199   }
 200 }
 201
 202 fetch('forth.wasm')
 203   .then(re => re.arrayBuffer())
 204   .then(buf => WebAssembly.instantiate(buf, wasmImport))
 205   .then(result => {
 206     wasmMem = result.instance.exports.memory
 207     forth = result.instance.exports.main
 208     console.log('wasm loaded');
 209     forth()
 210   })