Factor out common fortress fire code into fort_fire()

This takes care of a number of bugs / inconsistencies:

* sb() fired support even when there were not enough mil.

* Shell resupply bugs: multifire() and quiet_bigdef() resupplied
  shells before checking all other requirements and could thus get
  more shells than actually needed.

Rename landgun() to fortgun() for consistency.

include/prototypes.h

@@ -459,7 +459,7 @@ extern int lnd_postread(int, void *);
 extern int lnd_prewrite(int, void *);
 /* landgun.c */
 extern double seagun(int, int);
-extern double landgun(int, int);
+extern double fortgun(int, int);
 extern double landunitgun(int, int, int, int, int);
 extern double effrange(int, double);
 extern double torprange(struct shpstr *);

include/sect.h

@@ -214,4 +214,6 @@ struct sctintrins {
 
 extern struct sctintrins intrchr[INT_DEF + 2];
 
+extern int fort_fire(struct sctstr *);
+
 #endif

src/lib/commands/mfir.c

@@ -419,25 +419,20 @@ multifire(void)
 		}
 	    }
 	    attacker = targ_land;
-	    if ((gun = fsect.sct_item[I_GUN]) == 0) {
+	    if (fsect.sct_item[I_GUN] == 0) {
 		pr("Insufficient arms.\n");
 		continue;
 	    }
-	    shell = fsect.sct_item[I_SHELL];
-	    if (shell <= 0)
-		shell += supply_commod(fsect.sct_own,
-				       fsect.sct_x, fsect.sct_y,
-				       I_SHELL, 1);
-	    if (shell <= 0) {
-		pr("Klick!     ...\n");
-		continue;
-	    }
 	    if (fsect.sct_item[I_MILIT] < 5) {
 		pr("Not enough military for firing crew.\n");
 		continue;
 	    }
-	    if (gun > 7)
+	    dam = fort_fire(&fsect);
-		gun = 7;
+	    putsect(&fsect);
+	    if (dam < 0) {
+		pr("Klick!     ...\n");
+		continue;
+	    }
 	    range = fortrange(&fsect);
 	    range2 = roundrange(range);
 	    pr("range is %d.00 (%.2f)\n", range2, range);
@@ -445,11 +440,6 @@ multifire(void)
 		/* Don't tell it's a sub */
 		range2 = -1;
 	    }
-	    guneff = landgun((int)fsect.sct_effic, gun);
-	    dam = (int)guneff;
-	    shell--;
-	    fsect.sct_item[I_SHELL] = shell;
-	    putsect(&fsect);
 	}
 	trange = mapdist(x, y, fx, fy);
 	if (trange > range2) {
@@ -904,14 +894,9 @@ quiet_bigdef(int attacker, struct emp_qelem *list, natid own, natid aown,
 	    if (roundrange(erange) < ns.curdist)
 		continue;
 
-	    gun = firing.sct_item[I_GUN];
+	    dam2 = fort_fire(&firing);
-	    shell = firing.sct_item[I_SHELL];
+	    /* no putsect(&firing) because ammo is charged in use_ammo() */
-
+	    if (dam2 < 0)
-	    if (shell < 1)
-		shell += supply_commod(firing.sct_own,
-				       firing.sct_x, firing.sct_y,
-				       I_SHELL, 1);
-	    if (gun == 0 || firing.sct_item[I_MILIT] < 5 || shell == 0)
 		continue;
 	    (*nfiring)++;
 	    fp = malloc(sizeof(struct flist));
@@ -921,9 +906,7 @@ quiet_bigdef(int attacker, struct emp_qelem *list, natid own, natid aown,
 	    fp->type = targ_land;
 	    add_to_fired_queue(&fp->queue, list);
 	    nreport(firing.sct_own, N_FIRE_BACK, player->cnum, 1);
-	    if (gun > 7)
+	    dam += dam2;
-		gun = 7;
-	    dam += landgun((int)firing.sct_effic, gun);
 	}
     }
 

src/lib/commands/sabo.c

@@ -83,7 +83,7 @@ sabo(void)
 	    continue;
 	}
 
-	dam = landgun(3 * land.lnd_effic, 7);
+	dam = fortgun(3 * land.lnd_effic, 7);
 	if (sect.sct_item[I_SHELL] > 20)
 	    dam += seagun(land.lnd_effic,
 			  random() % (sect.sct_item[I_SHELL] / 10));

src/lib/subs/fortdef.c

@@ -181,9 +181,7 @@ sb(natid att, natid def, struct sctstr *sp, coord tx, coord ty, int noisy,
 {
     int damage;
     natid own;
-    int shell;
+    int range, range2;
-    int range;
-    int range2, gun;
 
     own = sp->sct_own;
     if (own == 0)
@@ -194,18 +192,10 @@ sb(natid att, natid def, struct sctstr *sp, coord tx, coord ty, int noisy,
     range2 = mapdist(sp->sct_x, sp->sct_y, tx, ty);
     if (range < range2)
 	return 0;
-    gun = sp->sct_item[I_GUN];
+    damage = fort_fire(sp);
-    if (gun == 0)
-	return 0;
-    shell = sp->sct_item[I_SHELL];
-    if (shell <= 0)
-	shell += supply_commod(sp->sct_own, sp->sct_x, sp->sct_y,
-			       I_SHELL, 1);
-    if (shell <= 0)
-	return 0;
-    sp->sct_item[I_SHELL] = shell - 1;
     putsect(sp);
-    damage = landgun((int)sp->sct_effic, gun);
+    if (damage < 0)
+	return 0;
     if (sp->sct_own != def)
 	wu(0, sp->sct_own,
 	   "%s fired on %s in %s in defense of %s, doing %d damage!\n",

src/lib/subs/landgun.c

@@ -41,7 +41,7 @@
 #include "ship.h"
 
 double
-landgun(int effic, int guns)
+fortgun(int effic, int guns)
 {
     double d;
     double g = MIN(guns, 7);
@@ -77,6 +77,30 @@ landunitgun(int effic, int shots, int guns, int ammo, int shells)
     return d;
 }
 
+/*
+ * Fire from fortress SP.
+ * Use ammo, resupply if necessary.
+ * Return damage if the fortress fires, else -1.
+ */
+int
+fort_fire(struct sctstr *sp)
+{
+    int guns = sp->sct_item[I_GUN];
+    int shells;
+
+    if (sp->sct_type != SCT_FORTR || sp->sct_effic < FORTEFF)
+	return -1;
+    if (sp->sct_item[I_MILIT] < 5 || guns == 0)
+	return -1;
+    shells = sp->sct_item[I_SHELL];
+    shells += supply_commod(sp->sct_own, sp->sct_x, sp->sct_y,
+			    I_SHELL, 1 - shells);
+    if (shells == 0)
+	return -1;
+    sp->sct_item[I_SHELL] = shells - 1;
+    return (int)fortgun(sp->sct_effic, guns);
+}
+
 /*
  * Return effective firing range for range factor RNG at tech TLEV.
  */

src/lib/subs/lndsub.c

@@ -846,28 +846,14 @@ lnd_fort_interdiction(struct emp_qelem *list,
 	    continue;
 	if (getrel(getnatp(fsect.sct_own), victim) >= NEUTRAL)
 	    continue;
-	gun = fsect.sct_item[I_GUN];
-	if (gun < 1)
-	    continue;
 	range = roundrange(fortrange(&fsect));
 	trange = mapdist(newx, newy, fsect.sct_x, fsect.sct_y);
 	if (trange > range)
 	    continue;
-	if (fsect.sct_item[I_MILIT] < 5)
+	dam = fort_fire(&fsect);
-	    continue;
-	shell = fsect.sct_item[I_SHELL];
-	if (shell < 1)
-	    shell += supply_commod(fsect.sct_own, fsect.sct_x, fsect.sct_y,
-				   I_SHELL, 1);
-	if (shell < 1)
-	    continue;
-	shell--;
-	fsect.sct_item[I_SHELL] = shell;
 	putsect(&fsect);
-	if (gun > 7)
+	if (dam < 0)
-	    gun = 7;
+	    continue;
-	guneff = landgun((int)fsect.sct_effic, gun);
-	dam = (int)guneff;
 	totdam += dam;
 	mpr(victim, "Incoming fire does %d damage!\n", dam);
 	wu(0, fsect.sct_own,

src/lib/subs/shpsub.c

@@ -587,8 +587,6 @@ shp_fort_interdiction(struct emp_qelem *list, coord newx, coord newy,
     struct nstr_sect ns;
     struct sctstr fsect;
     int trange, range;
-    double guneff;
-    int shell, gun;
     int dam;
     int totdam = 0;
     signed char notified[MAXNOC];
@@ -625,28 +623,14 @@ shp_fort_interdiction(struct emp_qelem *list, coord newx, coord newy,
     while (nxtsct(&ns, &fsect)) {
 	if (!notified[fsect.sct_own])
 	    continue;
-	gun = fsect.sct_item[I_GUN];
-	if (gun < 1)
-	    continue;
 	range = roundrange(fortrange(&fsect));
 	trange = mapdist(newx, newy, fsect.sct_x, fsect.sct_y);
 	if (trange > range)
 	    continue;
-	if (fsect.sct_item[I_MILIT] < 5)
+	dam = fort_fire(&fsect);
-	    continue;
-	shell = fsect.sct_item[I_SHELL];
-	if (shell < 1)
-	    shell += supply_commod(fsect.sct_own, fsect.sct_x, fsect.sct_y,
-				   I_SHELL, 1);
-	if (shell < 1)
-	    continue;
-	shell--;
-	fsect.sct_item[I_SHELL] = shell;
 	putsect(&fsect);
-	if (gun > 7)
+	if (dam < 0)
-	    gun = 7;
+	    continue;
-	guneff = landgun((int)fsect.sct_effic, gun);
-	dam = (int)guneff;
 	totdam += dam;
 	mpr(victim, "Incoming fire does %d damage!\n", dam);
 /*