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: 16500,
  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   '2DUP': 30,
  89   'ROT': 31,
  90   '2DROP': 32,
  91   ',': 33,
  92   '-': 34,
  93   'CHANNEL!': 35,
  94   'HERE!': 36,
  95   '=?': 37,
  96   ':': 16800,
  97   'MODE': 14336,
  98   'EXECUTE-MODE': 16680,
  99   'QUIT': 16384,
 100   'INTERPRET': 16400
 101 }
 102 const wasmImport = {
 103   env: {
 104     pop: () => simstack.pop(),
 105     push: (val) => simstack.push(val),
 106     rinit: () => rstack.length = 0,
 107     rpop: () => rstack.pop(),
 108     rpush: (val) => rstack.push(val),
 109     sys_write: (channel, fromBuffer) => {
 110       if (channels[channel] === undefined)
 111         return
 112       const maxBytes = new DataView(
 113         wasmMem.buffer,
 114         fromBuffer,
 115         4
 116       ).getUint32(0,true)
 117       console.log(`write ch:${channel} addr:${fromBuffer} len:${maxBytes}`)
 118       channels[channel].write(fromBuffer + 4, maxBytes)
 119     },
 120     sys_read: (channel, toBuffer) => {
 121       console.log(`read ch:${channel} buf:${toBuffer} current: ${stdin}`)
 122       const lenView = new DataView(wasmMem.buffer, toBuffer, 8)
 123       const maxBytes = lenView.getUint32(0,true)
 124       console.log(`read blen:${lenView.getUint32(0,true)} cstrlen:${lenView.getUint32(4,true)}`)
 125       /* If the channel is undefined, or if there isn't enough room in
 126        * toBuffer for even one character, then, if there is enough
 127        * room for an int write a zero, exit */
 128       if (channels[channel] === undefined || maxBytes < 6) {
 129         if (maxBytes >= 4)
 130           lenView.setUint32(4,0,true)
 131       }
 132       const numBytes = channels[channel].read(toBuffer + 8, maxBytes - 4)
 133       lenView.setUint32(4,numBytes,true);
 134       console.log(`read wrote ${lenView.getUint32(4,true)} bytes, remainder: ${stdin}`)
 135       console.log(`read blen:${lenView.getUint32(0,true)} cstrlen:${lenView.getUint32(4,true)}`)   },
 136     sys_listen: (reqAddr, cbAddr) => {
 137       //TODO: call into the module to wasm fn "event" to push an event
 138       //to forth, which pushes esi to the return stack and queues the
 139       //callback function provided from listen. reqaddr could be
 140       //"fetch", in which case no channel is used.  otherwise very
 141       //similar to sys_fetch.
 142     },
 143     sys_fetch: (channel, reqAddr) => {
 144       //TODO: map to fetch promise, write to channel buffer,
 145       //javascript "fetch" as fallback, explicit handles for
 146       //"textEntry" or any third party protocols like activitypub
 147       console.log(`fetch ${channel} ${reqAddr}`)
 148     },
 149     sys_echo: (val) => output.print(`${val} `),
 150     sys_echochar: (val) => output.print(String.fromCharCode(val)),
 151     sys_reflect: (addr) => {
 152       console.log(`reflect: ${addr}: ${
 153         new DataView(wasmMem.buffer, addr, 4)
 154               .getUint32(0,true)
 155       }`)
 156     },
 157     vocab_get: (addr, u) => {
 158       const word = String.fromCharCode.apply(
 159         null,
 160         new Uint16Array(wasmMem.buffer, addr, u >> 1)
 161       )
 162       const answer = dictionary[word.toUpperCase()]
 163       console.log(`vocab_get ${word}: ${answer}`)
 164       if (answer === undefined)
 165         return 0
 166       return answer
 167     },
 168     vocab_set: (addr, u, num) => {
 169       console.log(`vocab set ${addr} ${u} ${num}`)
 170       const word = String.fromCharCode.apply(
 171         null,
 172         new Uint16Array(wasmMem.buffer, addr, u >> 1)
 173       )
 174       console.log(`vocab_set ${word}: ${num}`)
 175       dictionary[word.toUpperCase()] = num
 176       return 0
 177     },
 178     is_whitespace: (key) => /\s/.test(String.fromCharCode(key)),
 179     sys_stack: () => console.log(`[${simstack}]`),
 180     sys_parsenum: (addr, u, base) => {
 181       const word = String.fromCharCode.apply(
 182         null,
 183         new Uint16Array(wasmMem.buffer, addr, u >> 1)
 184       )
 185       const answer = Number.parseInt(word, base)
 186       console.log(`parsenum: ${addr} ${u} ${base}`)
 187       console.log(`parsenum: ${word} ${answer}`)
 188       console.log(`parsenum: ${Number.isNaN(answer)}`)
 189       if (Number.isNaN(answer))
 190         return -1
 191       new DataView(wasmMem.buffer, addr, 4).setUint32(0,answer,true)
 192       return 0
 193     },
 194     sys_words: () => {
 195       output.print(Object.getOwnPropertyNames(dictionary).toString().split(',').join('  '))
 196     }
 197   }
 198 }
 199
 200 fetch('forth.forth').then((re) => re.text()).then((txt) => {
 201   stdin = txt
 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   })
 211 })