'math.randomseed()' returns the seeds it used
A call to 'math.randomseed()' returns the two components of the seed
it set, so that they can be used to set that same seed again.
diff --git a/lmathlib.c b/lmathlib.c
index f6f0b42..1d310b2 100644
--- a/lmathlib.c
+++ b/lmathlib.c
@@ -605,20 +605,24 @@
static void randseed (lua_State *L, RanState *state) {
lua_Unsigned seed1 = (lua_Unsigned)time(NULL);
lua_Unsigned seed2 = (lua_Unsigned)(size_t)L;
+ lua_pushinteger(L, seed1);
+ lua_pushinteger(L, seed2);
setseed(state->s, seed1, seed2);
}
static int math_randomseed (lua_State *L) {
RanState *state = (RanState *)lua_touserdata(L, lua_upvalueindex(1));
- if (lua_isnone(L, 1))
+ if (lua_isnone(L, 1)) {
randseed(L, state);
+ return 2; /* return seeds */
+ }
else {
lua_Integer n1 = luaL_checkinteger(L, 1);
lua_Integer n2 = luaL_optinteger(L, 2, 0);
setseed(state->s, n1, n2);
+ return 0;
}
- return 0;
}
@@ -635,6 +639,7 @@
static void setrandfunc (lua_State *L) {
RanState *state = (RanState *)lua_newuserdatauv(L, sizeof(RanState), 0);
randseed(L, state); /* initialize with a "random" seed */
+ lua_pop(L, 2); /* remove pushed seeds */
luaL_setfuncs(L, randfuncs, 1);
}
diff --git a/manual/manual.of b/manual/manual.of
index 3d2fb4f..7f2596f 100644
--- a/manual/manual.of
+++ b/manual/manual.of
@@ -7798,6 +7798,9 @@
When called with no arguments,
Lua generates a seed with
a weak attempt for randomness.
+In this case,
+the call returns the two seed components that were used.
+
To ensure a required level of randomness to the initial state
(or contrarily, to have a deterministic sequence,
for instance when debugging a program),
diff --git a/testes/all.lua b/testes/all.lua
index 72121e8..bf27f10 100644
--- a/testes/all.lua
+++ b/testes/all.lua
@@ -37,8 +37,6 @@
-- tests should require debug when needed
debug = nil
-require"bwcoercion"
-
if usertests then
T = nil -- no "internal" tests for user tests
@@ -46,7 +44,6 @@
T = rawget(_G, "T") -- avoid problems with 'strict' module
end
-math.randomseed(0)
--[=[
example of a long [comment],
@@ -54,6 +51,14 @@
]=]
+print("\n\tStarting Tests")
+
+do
+ -- set random seed
+ local random_x, random_y = math.randomseed()
+ print(string.format("random seeds: %d, %d", random_x, random_y))
+end
+
print("current path:\n****" .. package.path .. "****\n")
diff --git a/testes/math.lua b/testes/math.lua
index befce12..0c297e7 100644
--- a/testes/math.lua
+++ b/testes/math.lua
@@ -815,7 +815,7 @@
-- low-level!! For the current implementation of random in Lua,
-- the first call after seed 1007 should return 0x7a7040a5a323c9d6
do
- -- all computations assume at most 32-bit integers
+ -- all computations should work with 32-bit integers
local <const> h = 0x7a7040a5 -- higher half
local <const> l = 0xa323c9d6 -- lower half
@@ -840,7 +840,14 @@
assert(rand * 2^floatbits == res)
end
-math.randomseed()
+do
+ -- testing return of 'randomseed'
+ local <const> x, <const> y = math.randomseed()
+ local res = math.random(0)
+ math.randomseed(x, y) -- should repeat the state
+ assert(math.random(0) == res)
+ -- keep the random seed for following tests
+end
do -- test random for floats
local randbits = math.min(floatbits, 64) -- at most 64 random bits
