From 4ac824191762cec6f4697cd2e8855b3698ad3ce1 Mon Sep 17 00:00:00 2001
From: Michael Meyer <me@entrez.cc>
Date: Wed, 20 Dec 2023 13:33:40 -0500
Subject: [PATCH] Use a macro for all foo_RES to MR_foo conversions

This makes it easier to understand what is happening in each of those
places, and also much easier to find the places that conversion between
hero and monster resistances happens (since you can now just grep for
"res_to_mr").  I think I got all the instances where the macro should be
used but I'm not 100% sure since there wasn't a single unique term to
search for to find them all.

I replaced the modifications to give_u_to_m_resistances made in the
previous commit, so that it now uses the same macro as other
conversions, since otherwise it would be much harder to find the
complete list of places where conversions between hero and monster
properties happen.
---
 include/monflag.h |  3 +++
 include/prop.h    |  5 ++++-
 src/mon.c         |  7 +------
 src/mondata.c     | 20 +++++++-------------
 src/worn.c        |  9 ++-------
 5 files changed, 17 insertions(+), 27 deletions(-)

diff --git a/include/monflag.h b/include/monflag.h
index d04e84227..e5d4f4ece 100644
--- a/include/monflag.h
+++ b/include/monflag.h
@@ -67,6 +67,9 @@ enum ms_sounds {
 #define MR_POISON       0x20 /* resists poison */
 #define MR_ACID         0x40 /* resists acid */
 #define MR_STONE        0x80 /* resists petrification */
+/* NB: the above resistances correspond to the first 8 hero properties in
+   prop_types (FIRE_RES through STONE_RES), which can be converted to their
+   MR_foo equivalents with the macro res_to_mr() defined in prop.h */
 /* other resistances: magic, sickness */
 /* other conveyances: teleport, teleport control, telepathy */
 
diff --git a/include/prop.h b/include/prop.h
index 57f07b998..9824d892b 100644
--- a/include/prop.h
+++ b/include/prop.h
@@ -20,7 +20,10 @@ enum prop_types {
     POISON_RES        =  6,
     ACID_RES          =  7,
     STONE_RES         =  8,
-    /* note: for the first eight properties, MR_xxx == (1 << (xxx_RES - 1)) */
+    /* note: the first eight properties above are equivalent to MR_xxx bits
+     * MR_FIRE through MR_STONE, and can be directly converted to them: */
+#define res_to_mr(r) \
+    ((FIRE_RES <= (r) && (r) <= STONE_RES) ? (uchar) (1 << ((r) - 1)) : 0x00)
     DRAIN_RES         =  9,
     SICK_RES          = 10,
     INVULNERABLE      = 11,
diff --git a/src/mon.c b/src/mon.c
index f4666b151..c4ad04027 100644
--- a/src/mon.c
+++ b/src/mon.c
@@ -1682,33 +1682,28 @@ mon_give_prop(struct monst *mtmp, int prop)
        control or whatever, ignore it. */
     switch (prop) {
     case FIRE_RES:
-        intrinsic = MR_FIRE;
         msg = "%s shivers slightly.";
         break;
     case COLD_RES:
-        intrinsic = MR_COLD;
         msg = "%s looks quite warm.";
         break;
     case SLEEP_RES:
-        intrinsic = MR_SLEEP;
         msg = "%s looks wide awake.";
         break;
     case DISINT_RES:
-        intrinsic = MR_DISINT;
         msg = "%s looks very firm.";
         break;
     case SHOCK_RES:
-        intrinsic = MR_ELEC;
         msg = "%s crackles with static electricity.";
         break;
     case POISON_RES:
-        intrinsic = MR_POISON;
         msg = "%s looks healthy.";
         break;
     default:
         return; /* can't give it */
         break;
     }
+    intrinsic = res_to_mr(prop);
 
     /* Don't give message if it already had this property intrinsically, but
        still do grant the intrinsic if it only had it from mresists.
diff --git a/src/mondata.c b/src/mondata.c
index bcc6cc6ec..58c29f63f 100644
--- a/src/mondata.c
+++ b/src/mondata.c
@@ -1498,20 +1498,14 @@ monstunseesu(unsigned long seenres)
 void
 give_u_to_m_resistances(struct monst *mtmp)
 {
-    const struct {
-        int u;
-        unsigned short m;
-    } u_to_m_res[] = {
-        { FIRE_RES, MR_FIRE }, { COLD_RES, MR_COLD },
-        { SLEEP_RES, MR_SLEEP }, { DISINT_RES, MR_DISINT },
-        { SHOCK_RES, MR_ELEC }, { POISON_RES, MR_POISON },
-        { ACID_RES, MR_ACID }, { STONE_RES, MR_STONE },
-    };
-    int i;
+    int intr;
 
-    for (i = 0; i < SIZE(u_to_m_res); i++) {
-        if ((u.uprops[u_to_m_res[i].u].intrinsic & INTRINSIC) != 0L) {
-            mtmp->mintrinsics |= u_to_m_res[i].m;
+    /* convert the hero's current set of intrinsics to their monster
+       equivalents -- FIRE_RES to MR_FIRE, COLD_RES to MR_COLD, etc -- and
+       add each to the mintrinsics field for the given monster */
+    for (intr = FIRE_RES; intr <= STONE_RES; intr++) {
+        if ((u.uprops[intr].intrinsic & INTRINSIC) != 0L) {
+            mtmp->mintrinsics |= (unsigned short) res_to_mr(intr);
         }
     }
 }
diff --git a/src/worn.c b/src/worn.c
index 6b5026f04..b8593b214 100644
--- a/src/worn.c
+++ b/src/worn.c
@@ -550,12 +550,7 @@ update_mon_extrinsics(
         case JUMPING:
             break;
         default:
-            /* 1 through 8 correspond to MR_xxx mask values */
-            if (which >= 1 && which <= 8) {
-                /* FIRE,COLD,SLEEP,DISINT,SHOCK,POISON,ACID,STONE */
-                mask = (uchar) (1 << (which - 1));
-                mon->mextrinsics |= (unsigned short) mask;
-            }
+            mon->mextrinsics |= (unsigned short) res_to_mr(which);
             break;
         }
     } else { /* off */
@@ -592,7 +587,7 @@ update_mon_extrinsics(
              * only one pass but a worn alchemy smock will be an
              * alternate source for either of those two resistances.
              */
-            mask = (uchar) (1 << (which - 1));
+            mask = res_to_mr(which);
             for (otmp = mon->minvent; otmp; otmp = otmp->nobj) {
                 if (otmp == obj || !otmp->owornmask)
                     continue;