From 4993be4c086b2a81dbf5af5a2c687cf2f0c93d21 Mon Sep 17 00:00:00 2001
From: "Eric S. Raymond" <esr@thyrsus.com>
Date: Wed, 14 Jun 2017 13:00:28 -0400
Subject: [PATCH] Include LCG state in game saves.

---
 advent.h   | 7 +------
 main.c     | 7 +++----
 misc.c     | 8 ++++----
 notes.adoc | 1 -
 4 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/advent.h b/advent.h
index ee8e3fa..4717fe7 100644
--- a/advent.h
+++ b/advent.h
@@ -14,15 +14,11 @@
 #define INTRANSITIVE	-1		/* illegal object number */
 #define SPECIALBASE	300		/* base umber of special rooms */
 
-typedef struct lcg_state
-{
-  unsigned long a, c, m, x;
-} lcg_state;
-
 typedef long token_t;	/* word token - someday this will be char[TOKLEN+1] */
 typedef long vocab_t;	/* index into a vocabulary array */
 
 struct game_t {
+    unsigned long lcg_a, lcg_c, lcg_m, lcg_x;
     long abbnum;
     long blklin;
     long bonus;
@@ -81,7 +77,6 @@ extern const char ascii_to_advent[];
 extern const char advent_to_ascii[];
 extern FILE *logfp;
 extern bool oldstyle, editline, prompt;
-extern lcg_state lcgstate;
 
 /* b is not needed for POSIX but harmless */
 #define READ_MODE "rb"
diff --git a/main.c b/main.c
index 90f6003..6ba8897 100644
--- a/main.c
+++ b/main.c
@@ -46,7 +46,6 @@ FILE  *logfp;
 bool oldstyle = false;
 bool editline = true;
 bool prompt = true;
-lcg_state lcgstate;
 
 extern void initialise();
 extern void score(long);
@@ -114,9 +113,9 @@ int main(int argc, char *argv[])
 
     /* Initialize our LCG PRNG with parameters tested against
      * Knuth vol. 2. by the original authors */
-    lcgstate.a = 1093;
-    lcgstate.c = 221587;
-    lcgstate.m = 1048576;
+    game.lcg_a = 1093;
+    game.lcg_c = 221587;
+    game.lcg_m = 1048576;
     srand(time(NULL));
     long seedval = (long)rand();
     set_seed(seedval);
diff --git a/misc.c b/misc.c
index 6f33146..6ca1f87 100644
--- a/misc.c
+++ b/misc.c
@@ -460,21 +460,21 @@ bool TSTBIT(long mask, int bit)
 void set_seed(long seedval)
 /* Set the LCG seed */
 {
-    lcgstate.x = (unsigned long) seedval % lcgstate.m;
+    game.lcg_x = (unsigned long) seedval % game.lcg_m;
 }
 
 unsigned long get_next_lcg_value(void)
 /* Return the LCG's current value, and then iterate it. */
 {
-    unsigned long old_x = lcgstate.x;
-    lcgstate.x = (lcgstate.a * lcgstate.x + lcgstate.c) % lcgstate.m;
+    unsigned long old_x = game.lcg_x;
+    game.lcg_x = (game.lcg_a * game.lcg_x + game.lcg_c) % game.lcg_m;
     return old_x;
 }
 
 long randrange(long range)
 /* Return a random integer from [0, range). */
 {
-    return range * get_next_lcg_value() / lcgstate.m;
+    return range * get_next_lcg_value() / game.lcg_m;
 }
 
 long RNDVOC(long second, long force)
diff --git a/notes.adoc b/notes.adoc
index 07602ec..475ca94 100644
--- a/notes.adoc
+++ b/notes.adoc
@@ -111,7 +111,6 @@ ways:
   We don't need whatever minor performance gains this might collect,
   and the choice to refrain will make forward translation into future
   languages easier.
-
 * There are a few gotos left that resist restructuring; all of these
   are in the principal command interpreter function implementing its
   state machine.
-- 
2.31.1