system: disable BIOS hooks by default

premake5.lua

@@ -21,6 +21,13 @@ newoption {
 filter "options:enable-io-log"
 	defines "ENABLE_IO_LOG"
 
+newoption {
+	trigger = "enable-bios-hooks",
+	description = "Enable BIOS hooks/log",
+}
+filter "options:enable-bios-hooks"
+	defines "ENABLE_BIOS_HOOKS"
+
 newoption {
 	trigger = "asan",
 	description = "Build with Address Sanitizer enabled"

src/cpu/cpu.cpp

@@ -78,9 +78,10 @@ INLINE uint32_t CPU::fetchInstruction(uint32_t address) {
 
 bool CPU::executeInstructions(int count) {
     for (int i = 0; i < count; i++) {
-        // HACK: BIOS hooks
+#ifdef ENABLE_BIOS_HOOKS
         uint32_t maskedPc = PC & 0x1fff'ffff;
         if (maskedPc == 0xa0 || maskedPc == 0xb0 || maskedPc == 0xc0) sys->handleBiosFunction();
+#endif
 
         saveStateForException();
         checkForInterrupts();

src/system.h

@@ -33,6 +33,14 @@
  * Enables IO access buffer log
  */
 
+/**
+ * #define ENABLE_BIOS_HOOKS
+ * Switch --enable-bios-hooks
+ * Default: false
+ *
+ * Enables BIOS syscall hooking/logging
+ */
+
 namespace bios {
 struct Function;
 }