path: root/src/library.js

// An implementation of a libc for the web. Basically, implementations of
// the various standard C libraries, that can be called from compiled code,
// and work using the actual JavaScript environment.
//
// We search the Library object when there is an external function. If the
// entry in the Library is a function, we insert it. If it is a string, we
// do another lookup in the library (a simple way to write a function once,
// if it can be called by different names). We also allow dependencies,
// using __deps. Initialization code to be run after allocating all
// global constants can be defined by __postset.
//
// Note that the full function name will be '_' + the name in the Library
// object. For convenience, the short name appears here. Note that if you add a
// new function with an '_', it will not be found.

var Library = {
  // stdio.h

  _scanString: function() {
    // Supports %x, %4x, %d.%d
    var str = Pointer_stringify(arguments[0]);
    var stri = 0;
    var fmt = Pointer_stringify(arguments[1]);
    var fmti = 0;
    var args = Array.prototype.slice.call(arguments, 2);
    var argsi = 0;
    var read = 0;
    while (fmti < fmt.length) {
      if (fmt[fmti] === '%') {
        fmti++;
        var max_ = parseInt(fmt[fmti]);
        if (!isNaN(max_)) fmti++;
        var type = fmt[fmti];
        fmti++;
        var curr = 0;
        while ((curr < max_ || isNaN(max_)) && stri+curr < str.length) {
          if ((type === 'd' && parseInt(str[stri+curr]) >= 0) ||
              (type === 'x' && parseInt(str[stri+curr].replace(/[a-fA-F]/, 5)) >= 0)) {
            curr++;
          } else {
            break;
          }
        }
        if (curr === 0) { print("FAIL"); break; }
        var text = str.substr(stri, curr);
        stri += curr;
        var value = type === 'd' ? parseInt(text) : eval('0x' + text);
        {{{ makeSetValue('args[argsi]', '0', 'value', 'i32') }}}
        argsi++;
        read++;
      } else { // not '%'
        if (fmt[fmti] === str[stri]) {
          fmti++;
          stri++;
        } else {
          break;
        }
      }
    }
    return read; // XXX Possibly we should return EOF (-1) sometimes
  },
  sscanf: '_scanString',

  _formatString__deps: ['STDIO'],
  _formatString: function() {
    function isFloatArg(type) {
      return String.fromCharCode(type) in Runtime.set('f', 'e', 'g');
    }
    var cStyle = false;
    var textIndex = arguments[0];
    var argIndex = 1;
    if (textIndex < 0) {
      cStyle = true;
      textIndex = -textIndex;
      argIndex = arguments[1];
    } else