Extract valid readied spell logic

Source/inv.cpp

@@ -1671,17 +1671,7 @@ void RemoveInvItem(int pnum, int iv)
 
 	CalcPlrScrolls(pnum);
 
-	if (plr[pnum]._pRSplType == RSPLTYPE_SCROLL) {
-		if (plr[pnum]._pRSpell != SPL_INVALID) {
-			if (!(
-			        plr[pnum]._pScrlSpells
-			        & (1ULL << (plr[pnum]._pRSpell - 1)))) {
-				plr[pnum]._pRSpell = SPL_INVALID;
-			}
-
-			force_redraw = 255;
-		}
-	}
+	EnsureValidReadiedSpell(plr[pnum]);
 }
 
 #ifdef HELLFIRE
@@ -1733,15 +1723,7 @@ void RemoveSpdBarItem(int pnum, int iv)
 
 	CalcPlrScrolls(pnum);
 
-	if (plr[pnum]._pRSplType == RSPLTYPE_SCROLL) {
-		if (plr[pnum]._pRSpell != SPL_INVALID) {
-			if (!(
-			        plr[pnum]._pScrlSpells
-			        & (1ULL << (plr[pnum]._pRSpell - 1)))) {
-				plr[pnum]._pRSpell = SPL_INVALID;
-			}
-		}
-	}
+	EnsureValidReadiedSpell(plr[pnum]);
 	force_redraw = 255;
 }
 

Source/items.cpp

@@ -906,13 +906,7 @@ void CalcPlrItemVals(int p, BOOL Loadgfx)
 
 	plr[p]._pISpells = spl;
 
-	// check if the current RSplType is a valid/allowed spell
-	if (plr[p]._pRSplType == RSPLTYPE_CHARGES
-	    && !(spl & (1ULL << (plr[p]._pRSpell - 1)))) {
-		plr[p]._pRSpell = SPL_INVALID;
-		plr[p]._pRSplType = RSPLTYPE_INVALID;
-		force_redraw = 255;
-	}
+	EnsureValidReadiedSpell(plr[p]);
 
 	plr[p]._pISplLvlAdd = spllvladd;
 	plr[p]._pIEnAc = enac;
@@ -1164,13 +1158,7 @@ void CalcPlrScrolls(int p)
 				plr[p]._pScrlSpells |= 1ULL << (plr[p].SpdList[j]._iSpell - 1);
 		}
 	}
-	if (plr[p]._pRSplType == RSPLTYPE_SCROLL) {
-		if (!(plr[p]._pScrlSpells & 1ULL << (plr[p]._pRSpell - 1))) {
-			plr[p]._pRSpell = SPL_INVALID;
-			plr[p]._pRSplType = RSPLTYPE_INVALID;
-			force_redraw = 255;
-		}
-	}
+	EnsureValidReadiedSpell(plr[p]);
 }
 
 void CalcPlrStaff(int p)

Source/player.cpp

@@ -3188,23 +3188,7 @@ BOOL PM_DoSpell(int pnum)
 		    plr[pnum]._pVar4);
 
 		if (!plr[pnum]._pSplFrom) {
-			if (plr[pnum]._pRSplType == RSPLTYPE_SCROLL) {
-				if (!(plr[pnum]._pScrlSpells
-				        & 1ULL << (plr[pnum]._pRSpell - 1))) {
-					plr[pnum]._pRSpell = SPL_INVALID;
-					plr[pnum]._pRSplType = RSPLTYPE_INVALID;
-					force_redraw = 255;
-				}
-			}
-
-			if (plr[pnum]._pRSplType == RSPLTYPE_CHARGES) {
-				if (!(plr[pnum]._pISpells
-				        & 1ULL << (plr[pnum]._pRSpell - 1))) {
-					plr[pnum]._pRSpell = SPL_INVALID;
-					plr[pnum]._pRSplType = RSPLTYPE_INVALID;
-					force_redraw = 255;
-				}
-			}
+			EnsureValidReadiedSpell(plr[pnum]);
 		}
 	}
 

Source/spells.cpp

@@ -93,6 +93,85 @@ void UseMana(int id, int sn)
 	}
 }
 
+/**
+ * @brief Gets a value that represents the specified spellID in 64bit bitmask format.
+ * For example:
+ *  - spell ID  1: 0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.0001
+ *  - spell ID 43: 0000.0000.0000.0000.0000.0100.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000
+ * @param spellId The id of the spell to get a bitmask for.
+ * @return A 64bit bitmask representation for the specified spell.
+ */
+unsigned long long GetSpellBitmask(int spellId)
+{
+	return 1ULL << (spellId - 1);
+}
+
+/**
+ * @brief Gets a value indicating whether the player's current readied spell is a valid spell. Readied spells can be
+ * invalidaded in a few scenarios where the spell comes from items, for example (like dropping the only scroll that
+ * provided the spell).
+ * @param player The player whose readied spell is to be checked.
+ * @return 'true' when the readied spell is currently valid, and 'false' otherwise.
+ */
+bool IsReadiedSpellValid(const PlayerStruct &player)
+{
+	switch (player._pRSplType) {
+	case RSPLTYPE_SKILL:
+	case RSPLTYPE_SPELL:
+	case RSPLTYPE_INVALID:
+		return true;
+
+	case RSPLTYPE_CHARGES:
+		return player._pISpells & GetSpellBitmask(player._pRSpell);
+
+	case RSPLTYPE_SCROLL:
+		return player._pScrlSpells & GetSpellBitmask(player._pRSpell);
+
+	default:
+		return false;
+	}
+}
+
+/**
+ * @brief Clears the current player's readied spell selection.
+ * @note Will force a UI redraw in case the values actually change, so that the new spell reflects on the bottom panel.
+ * @param player The player whose readied spell is to be cleared.
+ */
+void ClearReadiedSpell(PlayerStruct &player)
+{
+	bool needsRedraw = false;
+
+	int &readiedSpell = player._pRSpell;
+	if (readiedSpell != SPL_INVALID) {
+		readiedSpell = SPL_INVALID;
+		needsRedraw = true;
+	}
+
+	char &readiedSpellType = player._pRSplType;
+	if (readiedSpellType != RSPLTYPE_INVALID) {
+		readiedSpellType = RSPLTYPE_INVALID;
+		needsRedraw = true;
+	}
+
+	if (needsRedraw) {
+		force_redraw = 255;
+	}
+}
+
+/**
+ * @brief Ensures the player's current readied spell is a valid selection for the character. If the current selection is
+ * incompatible with the player's items and spell (for example, if the player does not currently have access to the spell),
+ * the selection is cleared.
+ * @note Will force a UI redraw in case the values actually change, so that the new spell reflects on the bottom panel.
+ * @param player The player whose readied spell is to be checked.
+ */
+void EnsureValidReadiedSpell(PlayerStruct &player)
+{
+	if (!IsReadiedSpellValid(player)) {
+		ClearReadiedSpell(player);
+	}
+}
+
 BOOL CheckSpell(int id, int sn, char st, BOOL manaonly)
 {
 	BOOL result;

Source/spells.h

@@ -15,6 +15,7 @@ extern "C" {
 int GetManaAmount(int id, int sn);
 void UseMana(int id, int sn);
 BOOL CheckSpell(int id, int sn, char st, BOOL manaonly);
+void EnsureValidReadiedSpell(PlayerStruct &player);
 void CastSpell(int id, int spl, int sx, int sy, int dx, int dy, int caster, int spllvl);
 void DoResurrect(int pnum, int rid);
 void DoHealOther(int pnum, int rid);