Actually pre-sort by speed for better PRNG usage

sim/battle-actions.ts

@@ -169,38 +169,43 @@ export class BattleActions {
 		return true;
 	}
 	runSwitch(pokemon: Pokemon) {
-		if (this.battle.gen >= 5) {
+		const battle = this.battle;
+		if (battle.gen >= 5) {
 			const switchersIn = [pokemon];
-			for (let a = this.battle.queue.peek(); a?.choice === 'runSwitch'; a = this.battle.queue.peek()) {
-				const nextSwitch = this.battle.queue.shift();
+			for (let a = battle.queue.peek(); a?.choice === 'runSwitch'; a = battle.queue.peek()) {
+				const nextSwitch = battle.queue.shift();
 				switchersIn.push(nextSwitch!.pokemon!);
 			}
-			this.battle.prng.shuffle(this.battle.speedTieResolution);
-			this.battle.fieldEvent('SwitchIn', switchersIn);
+			const allActive = battle.getAllActive(true);
+			battle.speedSort(allActive);
+			battle.speedOrder = allActive.map((a) => a.side.n * battle.sides.length + a.position);
+			battle.fieldEvent('SwitchIn', switchersIn);
 
-			if (!pokemon.hp) return false;
-			pokemon.isStarted = true;
-			pokemon.draggedIn = null;
+			for (const poke of allActive) {
+				if (!poke.hp) continue;
+				poke.isStarted = true;
+				poke.draggedIn = null;
+			}
 			return true;
 		}
-		this.battle.runEvent('EntryHazard', pokemon);
+		battle.runEvent('EntryHazard', pokemon);
 
-		this.battle.runEvent('SwitchIn', pokemon);
+		battle.runEvent('SwitchIn', pokemon);
 
-		if (this.battle.gen <= 2) {
+		if (battle.gen <= 2) {
 			// pokemon.lastMove is reset for all Pokemon on the field after a switch. This affects Mirror Move.
-			for (const poke of this.battle.getAllActive()) poke.lastMove = null;
-			if (!pokemon.side.faintedThisTurn && pokemon.draggedIn !== this.battle.turn) {
-				this.battle.runEvent('AfterSwitchInSelf', pokemon);
+			for (const poke of battle.getAllActive()) poke.lastMove = null;
+			if (!pokemon.side.faintedThisTurn && pokemon.draggedIn !== battle.turn) {
+				battle.runEvent('AfterSwitchInSelf', pokemon);
 			}
 		}
 		if (!pokemon.hp) return false;
 		pokemon.isStarted = true;
 		if (!pokemon.fainted) {
-			this.battle.singleEvent('Start', pokemon.getAbility(), pokemon.abilityState, pokemon);
-			this.battle.singleEvent('Start', pokemon.getItem(), pokemon.itemState, pokemon);
+			battle.singleEvent('Start', pokemon.getAbility(), pokemon.abilityState, pokemon);
+			battle.singleEvent('Start', pokemon.getItem(), pokemon.itemState, pokemon);
 		}
-		if (this.battle.gen === 4) {
+		if (battle.gen === 4) {
 			for (const foeActive of pokemon.foes()) {
 				foeActive.removeVolatile('substitutebroken');
 			}

sim/battle.ts

@@ -174,7 +174,7 @@ export class Battle {
 	lastDamage: number;
 	effectOrder: number;
 	quickClawRoll: boolean;
-	speedTieResolution: number[];
+	speedOrder: number[];
 
 	teamGenerator: ReturnType<typeof Teams.getGenerator> | null;
 
@@ -262,9 +262,9 @@ export class Battle {
 		this.lastDamage = 0;
 		this.effectOrder = 0;
 		this.quickClawRoll = false;
-		this.speedTieResolution = [];
+		this.speedOrder = [];
 		for (let i = 0; i < this.activePerHalf * 2; i++) {
-			this.speedTieResolution.push(i / (this.activePerHalf * 2));
+			this.speedOrder.push(i);
 		}
 
 		this.teamGenerator = null;
@@ -954,14 +954,14 @@ export class Battle {
 			}
 		}
 		if (handler.effectHolder && (handler.effectHolder as Pokemon).getStat) {
-			handler.speed = (handler.effectHolder as Pokemon).speed;
+			const pokemon = (handler.effectHolder as Pokemon);
+			handler.speed = pokemon.speed;
 			if (callbackName.endsWith('SwitchIn')) {
 				// Pokemon speeds including ties are resolved before all onSwitchIn handlers and aren't re-sorted in-between
-				// so we add a fractional speed to each Pokemon's respective event handlers by using their unique field position
-				// to index a randomly shuffled array of sequential numbers
-				const allSlots = 'abcdef';
-				const speedTieIndex = allSlots.indexOf((handler.effectHolder as Pokemon).getSlot().charAt(2));
-				handler.speed += this.speedTieResolution[speedTieIndex];
+				// so we subtract a fractional speed to each Pokemon's respective event handlers by using the index of their
+				// unique field position in a pre-sorted-by-speed array
+				const fieldPositionValue = pokemon.side.n * this.sides.length + pokemon.position;
+				handler.speed -= this.speedOrder.indexOf(fieldPositionValue) / (this.activePerHalf * 2);
 			}
 		}
 		return handler;
@@ -1248,11 +1248,11 @@ export class Battle {
 		return pokemonList;
 	}
 
-	getAllActive() {
+	getAllActive(includeFainted?: boolean) {
 		const pokemonList: Pokemon[] = [];
 		for (const side of this.sides) {
 			for (const pokemon of side.active) {
-				if (pokemon && !pokemon.fainted) {
+				if (pokemon && (includeFainted || !pokemon.fainted)) {
 					pokemonList.push(pokemon);
 				}
 			}

test/sim/abilities/pastelveil.js

@@ -29,7 +29,7 @@ describe('Pastel Veil', function () {
 			{species: 'wynaut', moves: ['sleeptalk']},
 			{species: 'wynaut', moves: ['sleeptalk']},
 		], [
-			{species: 'croagunk', moves: ['skillswap', 'sleeptalk']},
+			{species: 'croagunk', moves: ['sleeptalk', 'skillswap']},
 			{species: 'wynaut', ability: 'compoundeyes', moves: ['poisongas']},
 		]]);
 		battle.makeChoices('auto', 'move skillswap 1, move poisongas');