Module for Winbond W25Q SPI flash memory

I've been absent from the Espruino world for some time as my baby daughter was hospitalized with a dangerous virus. She'll be alright.

My Flash module hasn't changed much, but it's working. Only proper documentation is missing. Developers who want to use the module can already do so by simply copying the file to the modules folder of Espruino's project management folder. It can then be used by a simple require call and the WebIDE will fetch it from there.

@Gordon, your assumption is correct: it's only possible to erase a whole sector of 16 pages at once, but not a single page. Erasing simply resets all bits to 1. Writing data can set bits to 0 but not the other way round, and you can start sequential writing anywhere within a page. The data is kept in a buffer and only actually written when the operation is finished by calling finish. When crossing a page boundary, you must call finish and start a new write operation.

I see the benefits of making the module compatible with others. But I don't like those functions that read and write a whole chunk. They could be added for the sake of compatibility, but I would like to also keep the more fine-grain functions for sequential reading/writing (and maybe add those to the other modules if they don't exist). In many cases that's more efficient than allocating a buffer, filling it and then shoveling data from the buffer to the flash in another loop.

The code above looks wrong. I think it should look like this (not tested):

Flash.prototype.getPage = function(address) {
  return {start: address >> 8, size: 256};
}

Flash.prototype.erase16Pages = function(address) {
  var pageNumber = (address >> 8) & 0xFFFFFFF0;
  // ...
}