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jbe/bsw@0
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1 #include <lua.h>
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2 #include <lauxlib.h>
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3
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4 static FILE *multirand_dev;
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5
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6 static lua_Integer multirand_range(
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7 lua_State *L, lua_Integer from, lua_Integer to
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8 ) {
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9 lua_Integer range;
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10 int bits = 0;
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11 lua_Integer bit_mask = 0;
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12 if (to < from) return luaL_error(L, "Assertion failed in C.");
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13 range = to - from;
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14 {
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15 lua_Integer tmp;
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16 tmp = range;
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17 while (tmp) {
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18 bits++;
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19 bit_mask <<= 1;
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20 bit_mask |= 1;
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21 tmp >>= 1;
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22 }
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23 }
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24 while (1) {
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25 int i;
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26 lua_Integer rnd = 0;
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27 for (i = 0; i < (bits + 7) / 8; i++) {
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28 int b;
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29 b = getc(multirand_dev);
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30 if (b == EOF) {
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31 return luaL_error(L, "I/O error while reading random.");
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32 }
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33 rnd = (rnd << 8) | (unsigned char)b;
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34 }
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35 rnd &= bit_mask;
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36 if (rnd <= range) return from + rnd;
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37 }
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38 }
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39
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40 static int multirand_integer(lua_State *L) {
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41 lua_Integer arg1, arg2;
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42 lua_settop(L, 2);
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43 arg1 = luaL_checkinteger(L, 1);
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44 if (lua_toboolean(L, 2)) {
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45 arg2 = luaL_checkinteger(L, 2);
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46 if (arg1 > arg2) {
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47 return luaL_error(L,
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48 "Upper boundary is smaller than lower boundary."
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49 );
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50 } else if (arg1 == arg2) {
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51 lua_pushinteger(L, arg1);
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52 } else {
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53 lua_pushinteger(L, multirand_range(L, arg1, arg2));
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54 }
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55 } else {
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56 luaL_argcheck(L, arg1 >= 1, 1, "smaller than 1");
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57 lua_pushinteger(L, multirand_range(L, 1, arg1));
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58 }
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59 return 1;
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60 }
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61
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62 static int multirand_fraction(lua_State *L) {
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63 int i, j;
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64 lua_settop(L, 0);
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65 lua_Number rnd = 0.0;
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66 for (i = 0; i < 8; i++) {
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67 int b;
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68 unsigned char c;
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69 b = getc(multirand_dev);
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70 if (b == EOF) return luaL_error(L, "I/O error while reading random.");
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71 c = (unsigned char) b;
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72 for (j = 0; j < 8; j++) {
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73 rnd /= 2.0;
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74 if (c & 1) rnd += 0.5;
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75 c >>= 1;
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76 }
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77 }
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78 lua_pushnumber(L, rnd);
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79 return 1;
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80 }
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81
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82 static int multirand_string(lua_State *L) {
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83 lua_Integer length;
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84 const char *charset;
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85 size_t charset_size;
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86 luaL_Buffer buf;
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87 lua_settop(L, 2);
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88 length = luaL_checkinteger(L, 1);
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89 charset = luaL_optlstring(L, 2, "abcdefghijklmnopqrstuvwxyz", &charset_size);
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90 if (charset_size > 32767) {
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91 return luaL_error(L, "Set of chars is too big.");
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92 }
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93 luaL_buffinit(L, &buf);
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94 for (; length > 0; length--) {
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95 luaL_addchar(&buf,
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96 charset[multirand_range(L, 0, (lua_Integer)charset_size - 1)]
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97 );
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98 }
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99 luaL_pushresult(&buf);
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100 return 1;
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101 }
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102
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103 static const struct luaL_Reg multirand_module_functions[] = {
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104 {"integer", multirand_integer},
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105 {"fraction", multirand_fraction},
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106 {"string", multirand_string},
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107 {NULL, NULL}
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108 };
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109
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110 int luaopen_multirand(lua_State *L) {
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111 multirand_dev = fopen("/dev/urandom", "r");
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112 if (!multirand_dev) return luaL_error(L, "Could not open /dev/urandom.");
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jbe@64
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113 #if LUA_VERSION_NUM >= 502
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114 lua_newtable(L);
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115 luaL_setfuncs(L, multirand_module_functions, 0);
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116 #else
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117 luaL_register(L, lua_tostring(L, 1), multirand_module_functions);
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118 #endif
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119 return 1;
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120 }
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