generic-continuos-ndarray-storage.js

/*

this an approach to be able to use typedarray.set to set continuous parts
of an ndarray:

var store = ndarray(new Store(new Uint8Array(32*32*32*3*3*3)),[32*3,32*3,32*3])
var chunks = {}
for (var x=0;x<3;x++)
for (var y=0;y<3;y++)
for (var z=0;z<3;z++) {
  chunks[x] = chunks[x] || {}
  chunks[x][y] = chunks[x][y] || {}
  chunks[x][y][z] = ndarray(new Uint8Array(32*32*32,[32,32,32]))
  var offset = x*32*32 + y*32 +z
  store.data.set(chunks[x][y][z], offset)
}

*/

var range = 32*32*32
var pow32_2 = 32*32
var stride0 = 3*3
var stride1 = 3
var stride2 = 1

function Store(underlyingStorage) {
  this.data = underlyingStorage
  this.length = underlyingStorage.length
}

Store.prototype.get = function(i) {
  return this.data[calc(i)]
}

Store.prototype.set = function(i, v) {
  this.data[calc(i)] = v
}

function calc(i) {
  var z = i%32
  var y = (i-z)%pow32_2
  var izy = i-z-y
  var x = izy>0 ? izy/pow32_2 : 0
  y = y/32
  var chunk_index = (z/32)|0 * stride0 + (y/32)|0 * stride1 + (x/32)|0 * stride0
  return i%range + (chunk_index*range)
}