diff --git a/node/frepw.js b/node/frepw.js
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+++ b/node/frepw.js
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+#!/usr/bin/env node
+//
+// frepw.js
+// functional representation solver, worker version
+//
+// usage:
+// pcb.py | node --experimental-worker frepw.js [dpi [filename]]
+// with:
+// https://gitlab.cba.mit.edu/pub/libraries/blob/master/python/pcb.py
+//
+// Neil Gershenfeld 12/9/18
+// (c) Massachusetts Institute of Technology 2018
+//
+// This work may be reproduced, modified, distributed,
+// performed, and displayed for any purpose, but must
+// acknowledge this project. Copyright is retained and
+// must be preserved. The work is provided as is; no
+// warranty is provided, and users accept all liability.
+//
+const fs = require("fs")
+const os = require("os")
+const {Worker} = require('worker_threads')
+//
+// get frep from stdin
+//
+var input = ''
+process.stdin.on('readable',() => {
+ var chunk = process.stdin.read()
+ if (chunk != null)
+ input += chunk
+ })
+process.stdin.on('end',() => {
+ render(JSON.parse(input))
+ })
+//
+// render function
+//
+function render(frep) {
+ //
+ // check arguments
+ //
+ if (frep.zmin != frep.zmax) {
+ console.log('> 2D not (yet) supported')
+ process.exit()
+ }
+ if (frep.type != 'RGB') {
+ console.log('types other than RGB not (yet) supported')
+ process.exit()
+ }
+ if (process.argv.length == 2) {
+ var dpi = 100
+ var filename = 'out.png'
+ console.log('output to out.png at 100 DPI')
+ }
+ else if (process.argv.length == 3) {
+ var dpi = parseInt(process.argv[2])
+ var filename = 'out.png'
+ console.log('output to out.png at '+dpi+' DPI')
+ }
+ else if (process.argv.length == 4) {
+ var dpi = parseInt(process.argv[2])
+ var filename = process.argv[3]
+ console.log('output to '+filename+' at '+dpi+' DPI')
+ }
+ //
+ // set variables
+ //
+ var delta = (25.4/dpi)/frep.mm_per_unit
+ var width = Math.floor(1+(frep.xmax-frep.xmin)/delta)
+ var height = Math.floor(1+(frep.ymax-frep.ymin)/delta)
+ var buf = new SharedArrayBuffer(width*height*4)
+ var data = new Uint8Array(buf)
+ //
+ // worker thread
+ //
+ var thread =
+ `
+ const Worker = require('worker_threads')
+ Worker.parentPort.on('message',(msg) => {
+ var fn = Function('X','Y','Z','return('+msg.fn+')')
+ var data = new Uint8Array(msg.buf)
+ var width = msg.width
+ var height = msg.height
+ var xmin = msg.xmin
+ var ymin = msg.ymin
+ var delta = msg.delta
+ var z = msg.z
+ var index = msg.index
+ var workers = msg.workers
+ var start = Math.round(width*index/workers)
+ var stop = Math.round(width*(index+1)/workers)-1
+ console.log(index+': '+start+'-'+stop)
+ var x,y,f
+ for (let row = 0; row < height; ++row) {
+ y = ymin+(height-1-row)*delta
+ for (let col = start; col <= stop; ++col) {
+ x = xmin+col*delta
+ f = fn(x,y,z)
+ data[row*width*4+col*4+0] = (f & 255)
+ data[row*width*4+col*4+1] = ((f >> 8) & 255)
+ data[row*width*4+col*4+2] = ((f >> 16) & 255)
+ data[row*width*4+col*4+3] = 255
+ }
+ }
+ Worker.parentPort.postMessage(index)
+ })
+ `
+ //
+ // start workers
+ //
+ var workers = os.cpus().length
+ console.log('start '+workers+' workers')
+ var count = 0
+ for (let i = 0; i < workers; ++i) {
+ var worker = new Worker(thread,{eval:true})
+ //
+ // worker message handler
+ //
+ worker.on('message',(msg) => {
+ console.log('done: '+msg)
+ count += 1
+ //
+ // check if done
+ //
+ if (count == workers) {
+ var dpm = 1000*dpi/25.4
+ fs.writeFileSync(filename,PNG(data,width,height,dpm))
+ console.log('wrote '+width+'x'+height)
+ process.exit()
+ }
+ })
+ worker.postMessage({index:i,workers:workers,
+ delta:delta,width:width,height:height,xmin:frep.xmin,ymin:frep.ymin,z:frep.zmin,
+ buf:buf,fn:frep.function})
+ }
+ }
+//
+// PNG function
+//
+function PNG(array,width,height,dpm) {
+ //
+ // PNG buffer
+ //
+ var length =
+ 8 // signature
+ + 25 // IHDR
+ + 21 // pHYs
+ + 12 // IDAT length, type, CRC
+ + 2 // zlib header
+ + 4 // zlib checksum
+ + 5*(Math.ceil((height+width*height*4)/0xffff)) // block headers
+ + width*height*4 // pixels
+ + height // scanline filters
+ + 12 // IEND
+ var buf = new ArrayBuffer(length)
+ var arr = new Uint8Array(buf)
+ var view = new DataView(buf)
+ //
+ // checksum functions
+ //
+ var CRC32table = []
+ for (let n = 0; n < 256; ++n) {
+ var crc = new Uint32Array(1)
+ crc[0] = n
+ for (let i = 0; i < 8; ++i) {
+ if (crc[0] & 1)
+ crc[0] = 0xedb88320 ^ (crc[0] >>> 1)
+ else
+ crc[0] = crc[0] >>> 1
+ }
+ CRC32table[n] = crc[0]
+ }
+ function CRC32(buf,start,stop) {
+ var crc = new Uint32Array(1)
+ crc[0] = 0xffffffff
+ for (let i = start; i < stop; ++i)
+ crc[0] = CRC32table[(crc[0] ^ buf[i]) & 0xff] ^ (crc[0] >>> 8);
+ crc[0] = crc[0] ^ 0xffffffff
+ return(crc[0])
+ }
+ var CRCAdler32 = new Uint32Array([1,0,0])
+ function Adler32(byte,crc) {
+ crc[0] = (crc[0]+byte)%65521
+ crc[1] = (crc[1]+crc[0])%65521
+ crc[2] = (crc[1]<<16)+crc[0]
+ return(crc)
+ }
+ //
+ var ptr = 0
+ var LengthPtr,DataStart,CRCstart,AdlerStart
+ //
+ // signature
+ //
+ arr.set([137,80,78,71,13,10,26,10],ptr)
+ ptr += 8
+ //
+ // IHDR length
+ //
+ view.setUint32(ptr,13,false)
+ ptr += 4
+ //
+ // IHDR type
+ //
+ CRCstart = ptr
+ arr.set([73,72,68,82],ptr)
+ ptr += 4
+ //
+ // IHDR data
+ //
+ view.setUint32(ptr,width,false) // width
+ ptr += 4
+ view.setUint32(ptr,height,false) // height
+ ptr += 4
+ arr.set([8,6,0,0,0],ptr)// 8 bit depth, RGBA, deflate compression, adaptive filter
+ ptr += 5
+ //
+ // IHDR CRC
+ //
+ view.setUint32(ptr,CRC32(arr,CRCstart,ptr),false)
+ ptr += 4
+ //
+ // pHYs length
+ //
+ view.setUint32(ptr,9,false)
+ ptr += 4
+ //
+ // pHYs type
+ //
+ CRCstart = ptr
+ arr.set([112,72,89,115],ptr)
+ ptr += 4
+ //
+ // pHYs data
+ //
+ view.setUint32(ptr,dpm) // x pixels per unit
+ ptr += 4
+ view.setUint32(ptr,dpm) // y pixels per unit
+ ptr += 4
+ view.setUint8(ptr,1) // meter unit
+ ptr += 1
+ //
+ // pHYs CRC
+ //
+ view.setUint32(ptr,CRC32(arr,CRCstart,ptr),false)
+ ptr += 4
+ //
+ // IDAT length location
+ //
+ LengthPtr = ptr
+ ptr += 4
+ //
+ // IDAT type
+ //
+ CRCstart = ptr
+ arr.set([73,68,65,84],ptr)
+ ptr += 4
+ //
+ // IDAT data
+ //
+ // IDAT data zlib header
+ //
+ DataStart = ptr
+ arr.set([0x78,0x01],ptr)
+ ptr += 2
+ //
+ // IDAT data deflate blocks
+ //
+ var BlockSize = 0xffff
+ var BlockByte = 0
+ var DataSize = height+width*height*4
+ var DataByte = 0
+ function BlockData(byte) {
+ if (BlockByte == 0) { // start of new block
+ if (DataByte+BlockSize < DataSize) {
+ var BlockLength = BlockSize
+ view.setUint8(ptr,0) // block header, not last block, no compression
+ ptr += 1
+ }
+ else if (DataByte+BlockSize == DataSize) {
+ var BlockLength = BlockSize
+ view.setUint8(ptr,1) // block header, last block, no compression
+ ptr += 1
+ }
+ else {
+ var BlockLength = DataSize-DataByte
+ view.setUint8(ptr,1) // block header, last block, no compression
+ ptr += 1
+ }
+ view.setUint16(ptr,BlockLength,true) // block length, little-endian
+ ptr += 2
+ view.setUint16(ptr,0xffff ^ view.getUint16(ptr-2,true),true) // block length one's complement
+ ptr += 2
+ }
+ CRCAdler32 = Adler32(byte,CRCAdler32) // update zlib checksum
+ view.setUint8(ptr,byte) // save byte to PNG buffer
+ ptr += 1 // move PNG pointer
+ DataByte += 1 // move data counter
+ BlockByte += 1 // move block counter
+ if (BlockByte == BlockSize) // end of deflate block
+ BlockByte = 0 // next byte starts new block
+ }
+ //
+ // IDAT data scan lines
+ //
+ for (let row = 0; row < height; ++row) {
+ BlockData(0) // scan line, no filter
+ for (let col = 0; col < width; ++col) {
+ BlockData(array[row*width*4+col*4+0]) // R
+ BlockData(array[row*width*4+col*4+1]) // G
+ BlockData(array[row*width*4+col*4+2]) // B
+ BlockData(array[row*width*4+col*4+3]) // A
+ }
+ }
+ //
+ // IDAT data zlib checksum
+ //
+ view.setUint32(ptr,CRCAdler32[2],false) // zlib Adler32
+ ptr += 4
+ //
+ // set IDAT length
+ //
+ view.setUint32(LengthPtr,ptr-DataStart,false)
+ //
+ // IDAT CRC
+ //
+ view.setUint32(ptr,CRC32(arr,CRCstart,ptr),false)
+ ptr += 4
+ //
+ // IEND length
+ //
+ view.setUint32(ptr,0,false)
+ ptr += 4
+ //
+ // IEND type
+ //
+ CRCstart = ptr
+ arr.set([73,69,78,68],ptr)
+ ptr += 4
+ //
+ // no IEND data
+ //
+ // IHDR CRC
+ //
+ view.setUint32(ptr,CRC32(arr,CRCstart,ptr),false)
+ ptr += 4
+ //
+ // return
+ //
+ return arr
+ }