Sindbad~EG File Manager

# Miscellaneous routines for games
# Copyright (C) 2008 Masami Hiramatsu <masami.hiramatsu@gmail.com>
#
# This file is free software and is distributed under the terms of the GNU
# General Public License (GPL); either version 2, or (at your option) any
# later version.

global __GM_rand_seed

function game_srand(seed:long)
{
  __GM_rand_seed = seed
}

function __game_lfsr(val:long) /* pure */
%{
  u64 r = THIS->val;
  r = (r >> 1) ^ ((-(r & 1ULL)) & 0xd800000000000000ULL);
  THIS->__retvalue = r;
%}

function game_rand()
{
  return __GM_rand_seed = __game_lfsr(__GM_rand_seed)
}

function game_urand()
{
  rand = game_rand()
  return rand<0?-rand:rand
}