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.
//
// 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

  _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;
      slab = null;
      argIndex = arguments[1];
    } else {
      var _arguments = arguments;
    }
    function getNextArg(type) {
      var ret;
      if (!cStyle) {
        ret = _arguments[argIndex];
        argIndex++;
      } else {
        if (isFloatArg(type)) {
          ret = {{{ makeGetValue(0, 'argIndex', 'double') }}};
        } else {
          ret = {{{ makeGetValue(0, 'argIndex', 'i32') }}};
        }
        argIndex += type === 'l'.charCodeAt(0) ? 8 : 4; // XXX hardcoded native sizes
      }
      return ret;
    }

    var ret = [];
    var curr, next, currArg;
    while(1) {
      curr = {{{ makeGetValue(0, 'textIndex', 'i8') }}};
      if (curr === 0) break;
      next = {{{ makeGetValue(0, 'textIndex+1', 'i8') }}};
      if (curr == '%'.charCodeAt(0)) {
        // Handle very very simply formatting, namely only %.X[f|d|u|etc.]
        var precision = -1;
        if (next == '.'.charCodeAt(0)) {
          textIndex++;
          precision = 0;
          while(1) {
            var precisionChr = {{{ makeGetValue(0, 'textIndex+1', 'i8') }}};
            if (!(precisionChr >= '0'.charCodeAt(0) && precisionChr <= '9'.charCodeAt(0))) break;
            precision *= 10;
            precision += precisionChr - '0'.charCodeAt(0);
            textIndex++;
          }
          next = {{{ makeGetValue(0, 'textIndex+1', 'i8') }}};
        }
        if (next == 'l'.charCodeAt(0)) {
          textIndex++;
          next = {{{ makeGetValue(0, 'textIndex+1', 'i8') }}};
        }
        if (isFloatArg(next)) {
          next = 'f'.charCodeAt(0); // no support for 'e'
        }
        if (['d', 'i', 'u', 'p', 'f'].indexOf(String.fromCharCode(next)) != -1) {
          var currArg;
          var argText;
          currArg = getNextArg(next);
          argText = String(+currArg); // +: boolean=>int
          if (next == 'u'.charCodeAt(0)) {
            argText = String(unSign(currArg, 32));
          } else if (next == 'p'.charCodeAt(0)) {
            argText = '0x' + currArg.toString(16);
          } else {
            argText = String(+currArg); // +: boolean=>int
          }
          if (precision >= 0) {
            if (isFloatArg(next)) {
              var dotIndex = argText.indexOf('.');
              if (dotIndex == -1 && next == 'f'.charCodeAt(0)) {
                dotIndex = argText.length;
                argText += '.';
              }
              argText += '00000000000'; // padding
              argText = argText.substr(0, dotIndex+1+precision);
            } else {
              while (argText.length < precision) {
                argText = '0' + argText;
              }
            }
          }
          argText.split('').forEach(function(chr) {
            ret.push(chr.charCodeAt(0));
          });
          textIndex += 2;
        } else if (next == 's'.charCodeAt(0)) {
          ret = ret.concat(String_copy(getNextArg(next)));
          textIndex += 2;
        } else if (next == 'c'.charCodeAt(0)) {
          ret =