decompile other_random

5 files changed, 29 insertions, 50 deletions

diff --git a/asm/other_random.s b/asm/other_random.s
deleted file mode 100644
index 751fc20..0000000
--- a/asm/other_random.s
+++ /dev/null
@@ -1,48 +0,0 @@
-	.include "constants/gba_constants.inc"
-	.include "asm/macros.inc"
-
-	.syntax unified
-
-	.text
-
-	thumb_func_start OtherRandom
-OtherRandom:
-	ldr r1, _08004514
-	ldrh r2, [r1]
-	movs r0, 0x6D
-	muls r0, r2
-	ldr r2, _08004518
-	adds r0, r2
-	strh r0, [r1]
-	ldrh r0, [r1]
-	bx lr
-	.align 2, 0
-_08004514: .4byte gUnknown_203B070
-_08004518: .4byte 0x000003fd
-	thumb_func_end OtherRandom
-
-	thumb_func_start OtherRandomCapped
-OtherRandomCapped:
-	push {r4,lr}
-	adds r4, r0, 0
-	bl OtherRandom
-	muls r0, r4
-	asrs r0, 16
-	pop {r4}
-	pop {r1}
-	bx r1
-	thumb_func_end OtherRandomCapped
-
-	thumb_func_start OtherRandomRange
-OtherRandomRange:
-	push {r4,lr}
-	adds r4, r0, 0
-	subs r0, r1, r4
-	bl OtherRandomCapped
-	adds r0, r4
-	pop {r4}
-	pop {r1}
-	bx r1
-	thumb_func_end OtherRandomRange
-
-	.align 2, 0 @ Don't pad with nop.
diff --git a/include/other_random.h b/include/other_random.h
new file mode 100644
index 0000000..83a1b60
--- /dev/null
+++ b/include/other_random.h
@@ -0,0 +1,7 @@
+#ifndef GUARD_OTHER_RANDOM_H
+#define GUARD_OTHER_RANDOM_H
+
+s32 OtherRandomCapped(s32 cap);
+s32 OtherRandomRange(s32 a, s32 b);
+
+#endif // GUARD_OTHER_RANDOM_H
diff --git a/ld_script.txt b/ld_script.txt
index 1eb1602..07163b1 100644
--- a/ld_script.txt
+++ b/ld_script.txt
@@ -37,7 +37,7 @@ SECTIONS {
         asm/code.o(.text);
         asm/memory.o(.text);
         asm/code_80035F0.o(.text);
-        asm/other_random.o(.text);
+        src/other_random.o(.text);
         asm/util.o(.text);
         asm/bg_palette_buffer.o(.text);
         asm/code_80047E8.o(.text);
diff --git a/src/other_random.c b/src/other_random.c
new file mode 100644
index 0000000..847530e
--- /dev/null
+++ b/src/other_random.c
@@ -0,0 +1,20 @@
+#include "global.h"
+#include "other_random.h"
+
+extern u16 gOtherRngState;
+
+static s32 OtherRandom16(void)
+{
+    gOtherRngState = 109 * gOtherRngState + 1021;
+    return gOtherRngState;
+}
+
+s32 OtherRandomCapped(s32 cap)
+{
+    return (OtherRandom16() * cap) >> 16;
+}
+
+s32 OtherRandomRange(s32 a, s32 b)
+{
+    return OtherRandomCapped(b - a) + a;
+}
diff --git a/sym_ewram2.txt b/sym_ewram2.txt
index 2785f4e..9c9ec5b 100644
--- a/sym_ewram2.txt
+++ b/sym_ewram2.txt
@@ -73,7 +73,7 @@ gUnknown_203B03C: @ 203B03C
 gUnknown_203B040: @ 203B040
 	.space 0x30
 
-gUnknown_203B070: @ 203B070
+gOtherRngState: @ 203B070
 	.space 0x4
 
 gUnknown_203B074: @ 203B074