Merge branch 'main' into bitstreams

asm/include/overlay_29_022EAA20.inc

@@ -1,3 +0,0 @@
-#pragma once
-.public DUNGEON_PRNG_STATE
-.public DUNGEON_PRNG_STATE_SECONDARY_VALUES

asm/overlay_29_022EAA20.s

@@ -1,42 +0,0 @@
-	.include "asm/macros.inc"
-	.include "overlay_29_022EAA20.inc"
-
-	.text
-
-; https://decomp.me/scratch/UiD3J
-	arm_func_start DungeonRand16Bit
-DungeonRand16Bit: ; 0x022EAA20
-	stmdb sp!, {r3, lr}
-	ldr r1, _022EAA88 ; =DUNGEON_PRNG_STATE
-	ldrb r0, [r1]
-	cmp r0, #0
-	ldr r0, _022EAA8C ; =0x5D588B65
-	beq _022EAA5C
-	ldr lr, [r1, #0x10]
-	ldr r3, _022EAA90 ; =DUNGEON_PRNG_STATE_SECONDARY_VALUES
-	ldr r1, _022EAA94 ; =0x00269EC3
-	ldr r2, [r3, lr, lsl #2]
-	umull ip, r0, r2, r0
-	adds r1, ip, r1
-	mov r0, r1, lsl #0x10
-	str r1, [r3, lr, lsl #2]
-	b _022EAA80
-_022EAA5C:
-	ldr r2, [r1, #4]
-	add r2, r2, #1
-	str r2, [r1, #4]
-	ldr r2, [r1, #0xc]
-	mul r0, r2, r0
-	add r2, r0, #1
-	mov r0, r2, lsr #0x10
-	mov r0, r0, lsl #0x10
-	str r2, [r1, #0xc]
-_022EAA80:
-	mov r0, r0, lsr #0x10
-	ldmia sp!, {r3, pc}
-	.align 2, 0
-_022EAA88: .word DUNGEON_PRNG_STATE
-_022EAA8C: .word 0x5D588B65
-_022EAA90: .word DUNGEON_PRNG_STATE_SECONDARY_VALUES
-_022EAA94: .word 0x00269EC3
-	arm_func_end DungeonRand16Bit

include/dg_random.h

@@ -3,6 +3,16 @@
 
 #include "util.h"
 
+typedef struct prng_state {
+    bool8 use_secondary;
+    u32 seq_num_primary;
+    u32 preseed;
+    u32 last_value_primary;
+    s32 idx_secondary;
+} prng_state;
+
+void InitDungeonRng(u32 seed);
+u16 DungeonRand16Bit(void);
 // Compute a pseudorandom integer under a given maximum value using the dungeon PRNG.
 // pseudorandom integer on the interval [0, end - 1]
 s32 DungeonRandInt(s32 end);

include/overlay_29_022EA9EC.h

@@ -1,6 +0,0 @@
-#ifndef PMDSKY_OVERLAY_29_022EA9EC_H
-#define PMDSKY_OVERLAY_29_022EA9EC_H
-
-void InitDungeonRng(u32 seed);
-
-#endif //PMDSKY_OVERLAY_29_022EA9EC_H

main.lsf

@@ -481,8 +481,6 @@ Overlay OVY_29
 	Object asm/overlay_29_022E9488.o
 	Object src/dg_uty.o
 	Object asm/overlay_29_022E9618.o
-	Object src/overlay_29_022EA9EC.o
-	Object asm/overlay_29_022EAA20.o
 	Object src/dg_random.o
 	Object asm/overlay_29_022EAB50.o
 	Object src/dungeon_action.o

src/dg_random.c

@@ -1,8 +1,45 @@
 #include "dg_random.h"
 
-// file starts at 0x022ea968
+extern prng_state DUNGEON_PRNG_STATE;
+extern u32 DUNGEON_PRNG_STATE_SECONDARY_VALUES[];
+#define DUNGEON_PRNG_LCG_MULTIPLIER 0x5d588b65
+#define DUNGEON_PRNG_LCG_INCREMENT_SECONDARY 0x00269ec3
 
-extern s16 DungeonRand16Bit(void);
+void InitDungeonRng(u32 seed) {
+    DUNGEON_PRNG_STATE.last_value_primary = seed|1;
+    s32 scratch_0 = 0;
+    DUNGEON_PRNG_STATE.seq_num_primary = scratch_0;
+    do {
+        DUNGEON_PRNG_STATE_SECONDARY_VALUES[scratch_0]=seed;
+        scratch_0++;
+    } while (scratch_0<5);
+}
+
+u16 DungeonRand16Bit(void) {
+    u32 mult = DUNGEON_PRNG_LCG_MULTIPLIER;
+
+    if (DUNGEON_PRNG_STATE.use_secondary) {
+        u32 increment = DUNGEON_PRNG_LCG_INCREMENT_SECONDARY;
+        s32 idx = DUNGEON_PRNG_STATE.idx_secondary;
+        u32 val = DUNGEON_PRNG_STATE_SECONDARY_VALUES[idx];
+        
+        u64 temp = (u64)val * mult;
+        temp += increment; 
+        
+        u32 result = (u32)temp;
+        DUNGEON_PRNG_STATE_SECONDARY_VALUES[idx] = result;
+        
+        return (u16)result;
+    } else {
+        // Accessing the global directly often changes register allocation
+        DUNGEON_PRNG_STATE.seq_num_primary++;
+        
+        u32 result = (DUNGEON_PRNG_STATE.last_value_primary * mult) + 1;
+        DUNGEON_PRNG_STATE.last_value_primary = result;
+        
+        return (u16)(result >> 16);
+    }
+}
 
 s32 DungeonRandInt(s32 end)
 {

src/overlay_29_022EA9EC.c

@@ -1,14 +0,0 @@
-#include "overlay_29_022EA9EC.h"
-
-extern u32 DUNGEON_PRNG_STATE[];
-extern u32 DUNGEON_PRNG_STATE_SECONDARY_VALUES[];
-
-void InitDungeonRng(u32 seed) {
-    DUNGEON_PRNG_STATE[3] = seed|1;
-    s32 scratch_0 = 0;
-    DUNGEON_PRNG_STATE[1] = scratch_0;
-    do {
-        DUNGEON_PRNG_STATE_SECONDARY_VALUES[scratch_0]=seed;
-        scratch_0++;
-    } while (scratch_0<5);
-}