Remove srand() and rnd() functions.

It’s a bit sad but since these functions have a state that is not directly
accessible to the VM, I am faced with the choice of either exposing that
state and patching Lua even more, or implement these functions in the VM
rather than in Lua.

Author: samhocevar

lpico8lib.c

@@ -1,7 +1,7 @@
 //
 //  ZEPTO-8 — Fantasy console emulator
 //
-//  Copyright © 2016—2017 Sam Hocevar <[email protected]>
+//  Copyright © 2016—2020 Sam Hocevar <[email protected]>
 //
 //  This program is free software. It comes without any warranty, to
 //  the extent permitted by applicable law. You can redistribute it
@@ -24,7 +24,6 @@
 #include "lauxlib.h"
 #include "llimits.h"
 #include "lobject.h"
-#include "lstate.h"
 
 #define TAU 6.2831853071795864769252867665590057683936
 
@@ -198,27 +197,6 @@ static int pico8_ord(lua_State *l) {
     return 1;
 }
 
-static void update_prng(global_State *g) {
-    g->prngseed2 = g->prngseed1 + ((g->prngseed2 >> 16) | (g->prngseed2 << 16));
-    g->prngseed1 += g->prngseed2;
-}
-
-static int pico8_srand(lua_State *L) {
-    uint32_t seed = lua_tonumber(L, 1).bits();
-    G(L)->prngseed1 = seed ? seed : 0xdeadbeef;
-    G(L)->prngseed2 = G(L)->prngseed1 ^ 0xbead29ba;
-    for (int i = 0; i < 32; ++i)
-        update_prng(G(L));
-    return 0;
-}
-
-static int pico8_rnd(lua_State *L) {
-    uint32_t range = lua_isnone(L, 1) ? 0x10000 : lua_tonumber(L, 1).bits();
-    update_prng(G(L));
-    lua_pushnumber(L, lua_Number::frombits(range ? G(L)->prngseed2 % range : 0));
-    return 1;
-}
-
 static const luaL_Reg pico8lib[] = {
   {"max",   pico8_max},
   {"min",   pico8_min},
@@ -244,8 +222,6 @@ static const luaL_Reg pico8lib[] = {
   {"tonum", pico8_tonum},
   {"chr",   pico8_chr},
   {"ord",   pico8_ord},
-  {"srand", pico8_srand},
-  {"rnd",   pico8_rnd},
   {NULL, NULL}
 };
 

lstate.c

@@ -281,7 +281,6 @@ LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
   g->ud = ud;
   g->mainthread = L;
   g->seed = makeseed(L);
-  g->prngseed1 = g->prngseed2 = g->seed;
   g->uvhead.u.l.prev = &g->uvhead;
   g->uvhead.u.l.next = &g->uvhead;
   g->gcrunning = 0;  /* no GC while building state */

lstate.h

@@ -119,7 +119,6 @@ typedef struct global_State {
   stringtable strt;  /* hash table for strings */
   TValue l_registry;
   unsigned int seed;  /* randomized seed for hashes */
-  uint32_t prngseed1, prngseed2;  /* randomized seed for PRNG */
   lu_byte currentwhite;
   lu_byte gcstate;  /* state of garbage collector */
   lu_byte gckind;  /* kind of GC running */