From f4e78fd6b8888512a9f45fa7033fb5aaa749c182 Mon Sep 17 00:00:00 2001
From: AZero13 <83477269+SiliconA-Z@users.noreply.github.com>
Date: Sun, 22 Mar 2026 20:04:36 -0400
Subject: [PATCH] Do the syscall in crt0 in UBFIX instead of Main

Harmless in practice but do this before setting up the vector, not after, since it will mess it up.
---
 src/crt0.s |  6 +++++-
 src/main.c | 32 +++-----------------------------
 2 files changed, 8 insertions(+), 30 deletions(-)

diff --git a/src/crt0.s b/src/crt0.s
index a0d8a4b55..ce84f2f96 100644
--- a/src/crt0.s
+++ b/src/crt0.s
@@ -14,6 +14,10 @@ start_vector:
 	mov r0, #PSR_SYS_MODE
 	msr cpsr_cf, r0
 	ldr sp, sp_usr
+	.if MODERN
+	mov r0, #255 @ RESET_ALL
+	svc #1 << 16
+	.endif @ MODERN
 	ldr r1, =INTR_VECTOR
 	adr r0, intr_main
 	str r0, [r1]
@@ -98,7 +102,7 @@ jump_intr:
 	orr r0, r0, #INTR_FLAG_GAMEPAK
 	orr r1, r0, #INTR_FLAG_SERIAL | INTR_FLAG_TIMER3 | INTR_FLAG_VCOUNT | INTR_FLAG_HBLANK
 	and r1, r1, r2
-	strh r1, [r3, #0]
+	strh r1, [r3]
 	mrs r3, cpsr
 	bic r3, r3, #PSR_I_BIT | PSR_F_BIT | PSR_MODE_MASK
 	orr r3, r3, #PSR_SYS_MODE
diff --git a/src/main.c b/src/main.c
index 542b0f5d1..f9444a83b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -102,37 +102,11 @@ void AgbMain()
 #if REVISION >= 0xA
     svc_stubbed();
 #endif
-#if MODERN
-    // Modern compilers are liberal with the stack on entry to this function,
+#if !MODERN
+    // Some compilers, especially modern ones, are liberal with the stack on entry to this function,
     // so RegisterRamReset may crash if it resets IWRAM.
-    RegisterRamReset(RESET_ALL & ~RESET_IWRAM);
-    asm("mov\tr1, #0xC0\n"
-        "\tlsl\tr1, r1, #0x12\n"
-        "\tmov\tr2, #0xFC\n"
-        "\tlsl\tr2, r2, #0x7\n"
-        "\tadd\tr2, r1, r2\n"
-        "\tmov\tr0, #0\n"
-        "\tmov\tr3, r0\n"
-        "\tmov\tr4, r0\n"
-        "\tmov\tr5, r0\n"
-        ".LCU%=:\n"
-        "\tstmia\tr1!, {r0, r3, r4, r5}\n"
-        "\tstmia\tr1!, {r0, r3, r4, r5}\n"
-        "\tstmia\tr1!, {r0, r3, r4, r5}\n"
-        "\tstmia\tr1!, {r0, r3, r4, r5}\n"
-        "\tstmia\tr1!, {r0, r3, r4, r5}\n"
-        "\tstmia\tr1!, {r0, r3, r4, r5}\n"
-        "\tstmia\tr1!, {r0, r3, r4, r5}\n"
-        "\tstmia\tr1!, {r0, r3, r4, r5}\n"
-        "\tcmp\tr1, r2\n"
-        "\tbcc\t.LCU%=\n"
-        :
-        :
-        : "r0", "r1", "r2", "r3", "r4", "r5", "memory"
-    );
-#else
     RegisterRamReset(RESET_ALL);
-#endif //MODERN
+#endif // !MODERN
 
 #if REVISION >= 0xA
     *(vu16 *)BG_PLTT = RGB_BLACK;