1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/libraries/multirand/multirand.c	Sun Oct 25 12:00:00 2009 +0100
     1.3 @@ -0,0 +1,124 @@
     1.4 +#include <lua.h>
     1.5 +#include <lauxlib.h>
     1.6 +#include <dirent.h>
     1.7 +
     1.8 +static FILE *multirand_dev;
     1.9 +
    1.10 +static lua_Integer multirand_range(
    1.11 +  lua_State *L, lua_Integer from, lua_Integer to
    1.12 +) {
    1.13 +  lua_Integer range;
    1.14 +  int bits = 0;
    1.15 +  lua_Integer bit_mask = 0;
    1.16 +  if (to < from) return luaL_error(L, "Assertion failed in C.");
    1.17 +  range = to - from;
    1.18 +  {
    1.19 +    lua_Integer tmp;
    1.20 +    tmp = range;
    1.21 +    while (tmp) {
    1.22 +      bits++;
    1.23 +      bit_mask <<= 1;
    1.24 +      bit_mask |= 1;
    1.25 +      tmp >>= 1;
    1.26 +    }
    1.27 +  }
    1.28 +  while (1) {
    1.29 +    int i;
    1.30 +    lua_Integer rnd = 0;
    1.31 +    for (i = 0; i < (bits + 7) / 8; i++) {
    1.32 +      int b;
    1.33 +      b = getc(multirand_dev);
    1.34 +      if (b == EOF) {
    1.35 +        return luaL_error(L, "I/O error while reading random.");
    1.36 +      }
    1.37 +      rnd = (rnd << 8) | (unsigned char)b;
    1.38 +    }
    1.39 +    rnd &= bit_mask;
    1.40 +    if (rnd <= range) return from + rnd;
    1.41 +  }
    1.42 +}
    1.43 +
    1.44 +static int multirand_integer(lua_State *L) {
    1.45 +  lua_Integer arg1, arg2;
    1.46 +  lua_settop(L, 2);
    1.47 +  arg1 = luaL_checkinteger(L, 1);
    1.48 +  if (lua_toboolean(L, 2)) {
    1.49 +    arg2 = luaL_optinteger(L, 2, 0);
    1.50 +    if (arg1 > arg2) {
    1.51 +      return luaL_error(L,
    1.52 +        "Upper boundary is smaller than lower boundary."
    1.53 +      );
    1.54 +    } else if (arg1 == arg2) {
    1.55 +      lua_pushinteger(L, arg1);
    1.56 +    } else {
    1.57 +      lua_pushinteger(L, multirand_range(L, arg1, arg2));
    1.58 +    }
    1.59 +  } else {
    1.60 +    luaL_argcheck(L, arg1 >= 1, 1, "smaller than 1");
    1.61 +    lua_pushinteger(L, multirand_range(L, 1, arg1));
    1.62 +  }
    1.63 +  return 1;
    1.64 +}
    1.65 +
    1.66 +static int multirand_fraction(lua_State *L) {
    1.67 +  int i, j;
    1.68 +  lua_settop(L, 0);
    1.69 +  lua_Number rnd = 0.0;
    1.70 +  for (i = 0; i < 8; i++) {
    1.71 +    int b;
    1.72 +    unsigned char c;
    1.73 +    b = getc(multirand_dev);
    1.74 +    if (b == EOF) return luaL_error(L, "I/O error while reading random.");
    1.75 +    c = (unsigned char) b;
    1.76 +    for (j = 0; j < 8; j++) {
    1.77 +      rnd /= 2.0;
    1.78 +      if (c & 1) rnd += 0.5;
    1.79 +      c >>= 1;
    1.80 +    }
    1.81 +  }
    1.82 +  lua_pushnumber(L, rnd);
    1.83 +  return 1;
    1.84 +}
    1.85 +
    1.86 +static int multirand_string(lua_State *L) {
    1.87 +  int length;
    1.88 +  const char *charset;
    1.89 +  size_t charset_size;
    1.90 +  luaL_Buffer buf;
    1.91 +  lua_settop(L, 2);
    1.92 +  length = luaL_checkint(L, 1);
    1.93 +  charset = luaL_optlstring(L, 2, "abcdefghijklmnopqrstuvwxyz", &charset_size);
    1.94 +  if (charset_size > 32767) {
    1.95 +    return luaL_error(L, "Set of chars is too big.");
    1.96 +  }
    1.97 +  luaL_buffinit(L, &buf);
    1.98 +  for (; length > 0; length--) {
    1.99 +    luaL_addchar(&buf,
   1.100 +      charset[multirand_range(L, 0, (lua_Integer)charset_size - 1)]
   1.101 +    );
   1.102 +  }
   1.103 +  luaL_pushresult(&buf);
   1.104 +  return 1;
   1.105 +}
   1.106 +
   1.107 +static const struct luaL_Reg multirand_module_functions[] = {
   1.108 +  {"integer",  multirand_integer},
   1.109 +  {"fraction", multirand_fraction},
   1.110 +  {"string",   multirand_string},
   1.111 +  {NULL, NULL}
   1.112 +};
   1.113 +
   1.114 +int luaopen_multirand(lua_State *L) {
   1.115 +  const char *module_name;
   1.116 +  lua_settop(L, 1);
   1.117 +  module_name = lua_tostring(L, 1);
   1.118 +  if (module_name) {
   1.119 +    luaL_register(L, module_name, multirand_module_functions);
   1.120 +  } else {
   1.121 +    luaL_register(L, "multirand", multirand_module_functions);
   1.122 +  }
   1.123 +  lua_replace(L, 1);
   1.124 +  multirand_dev = fopen("/dev/urandom", "r");
   1.125 +  if (!multirand_dev) return luaL_error(L, "Could not open /dev/urandom.");
   1.126 +  return 1;
   1.127 +}