From e5ebc7679e8b864dee30e7651867fceacbf069b1 Mon Sep 17 00:00:00 2001
From: Abaresk <abaresk01@gmail.com>
Date: Tue, 9 Jan 2024 12:40:58 -0500
Subject: [PATCH] Print r0 to terminal on 'swi 0xFC'

---
 src/ARMInterpreter.cpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/ARMInterpreter.cpp b/src/ARMInterpreter.cpp
index ff73e230..f58b1f4c 100644
--- a/src/ARMInterpreter.cpp
+++ b/src/ARMInterpreter.cpp
@@ -278,6 +278,20 @@ void A_SVC(ARM* cpu)
 
 void T_SVC(ARM* cpu)
 {
+    // Print from game. Execute `svc 0xFC` with the null-terminated string address in `r0`.
+    if ((cpu->CurInstr & 0xFF) == 0xFC)
+    {
+        u32 addr = cpu->R[0];
+        for (;;)
+        {
+            u32 c;
+            cpu->DataRead8(addr++, &c);
+            if (!c) break;
+            printf("%c", c);
+        }
+        return;
+    }
+
     u32 oldcpsr = cpu->CPSR;
     cpu->CPSR &= ~0xBF;
     cpu->CPSR |= 0x93;