Markov-chain text generator

// You can install a web browser that supports at least JavaScript 1.0 (1995) to use this tool or you may consider implementing a GemiWeb0 browser with JavaScript0 yourself according to the above specification.
'use strict';

var st = new Object;

// JS1
function strEqual(u, v) {
  return !(u.length - v.length) && !u.indexOf(v);
}

// JS1
function String_substring(th, from, to) {
  if (th.substring) {
    return th.substring(from, to);
  } else {
    var o = '';
    var c;
    if (to > th.length) {
      to = th.length;
    }
    from = from - 1;
    to = to - 1;
    while (to > from) {
      c = th.charAt(from = from + 1);
      o = o + c;
    }
    return o;
  }
}

function removeAfter(s, t) {
  var i = s.indexOf(t);
  if (i >= 0) {
    s = String_substring(s, 0, i + t.length);
  }
  return s;
}

function updateGram(key, next) {
  var o = st.gram[key];
  if (!o) {
    o = new Array;
    st.gram[key] = o;
  }
  o[o.length] = next;
}

function learnGrams(s) {
  if (strEqual(st.inText, s)) {
    return 0;
  }
  st.inText = s;
  st.gram = new Object;
  var i = 0;
  var w;
  var x = '';
  var y = '';
  var z = '';

while (s.length > i) {
    if (!(s.charCodeAt(i) - 32)) {
      while ((s.length > (i = i + 1)) && (!(s.charCodeAt(i) - 32))) {
      }
      if (i >= s.length) {
        return 0;
      }
      i = i - 1;
    }
    w = x;
    x = y;
    y = z;
    z = s.charAt(i);

i = i + 1;
    updateGram(w + x + y + z, i);
    updateGram(x + y + z, i);
    updateGram(y + z, i);
    updateGram(z, i);
  }
}

// JS1
function getRandomBits(n) {
  var x = st.random;
  var i = n + 1;
  while (i = i - 1) {
    x = (((x >> 30) ^ (x >> 27)) & 1) ^ ((x & 1073741823) << 1);
  }
  st.random = x;
  if (n > 31) {
    n = 31;
  }
  return x & ((1 << n) - 1);
}

function getRandom(m) {
  return getRandomBits(8) % m;
}

function generateGrams(len) {
  if (!len) {
    return '';
  }
  var s = st.inText;
  var i = getRandom(s.length);
  var h = '';
  var o;
  var n;
  var w;
  var x = '';
  var y = '';
  var z = '';
  var c;
  var n;
  var word = 0;

len = len + 1;
  while (len = len - 1) {
    w = x;
    x = y;
    y = z;
    if (i >= s.length) {
      i = 0;
    }
    z = s.charAt(i);
    i = i + 1;
    n = z.charCodeAt(0);
    if (!(n - 10)) {
      h = h + '<' + 'br>';
      word = 0;
    } else if (!(n - 32)) {
      h = h + ' ';
      word = 0;
      i = i - 1;

while ((len = len - 1) && !(s.charCodeAt(i = i + 1) - 32)) {
        if (word = !word) {
          h = h + '&' + 'nbsp;';
        } else {
          h = h + ' ';
        }
        if (i >= s.length) {
          i = 0;
        }
      }
      if (!len) {
        len = 1;
      }
      word = 0;
    } else {
      word = word + 1;
      if ((word > 32) || ((word > 13) && ((65 > n) || ((n > 90) && (97 > n)) || ((n > 122) && (127 > n))))) {
        h = h + ' ';
        word = 0;
      }
      c = escapeHtmChar(z);
      h = h + c;
    }

o = st.gram[w + x + y + z];
    if (!o || (!(o.length - 1) && !getRandom(8))) {
      o = st.gram[x + y + z];
      if (!o) {
        o = st.gram[y + z];
        if (!o) {
          o = st.gram[z];
        }
      }
    }
    if (o) {
      i = o[getRandom(o.length)];
    }
  }
  return h;
}

function escapeHtm(s) {
  var h = '';
  var c;
  var i = -1;
  while (s.length > (i = i + 1)) {
    c = escapeHtmChar(s.charAt(i));
    h = h + c;
  }
  return h;
}

function submit() {
  var s = window.f.t.value;
  learnGrams(s);
  var h = generateGrams(2 * s.length);
  h = '<p>' + h;
  if (st.docClosed) {
    s = escapeHtm(s);
    h = '<form name=f action="javascript:app.submit()"><textarea name=t>' +
      s +
      '<' + '/textarea><br><input type=submit name=s value=Shuffle><a target=_blank href="https://bkil.gitlab.io/gemiweb0">bkil.gitlab.io/gemiweb0</a></form>' +
      h;
  }
  writeHtm(h);
}

function init() {
  st.random = (new Date) % 2147483648;
  if (!st.random) {
    st.random = 1;
  }
  getRandomBits(128);

st.inText = '';
  submit();
  st.docClosed = 1;
  var app = new Object;
  app.submit = submit;
  return app;
}

init();

bkil.gitlab.io/gemiweb0