ntsc-beta: Decompile mainLoop

tools/mkrom/main.c

@@ -59,7 +59,11 @@ int main(int argc, char **argv)
 
 	// Compute piracy checksums if requested
 	if (state.piracychecks) {
-		piracy_patch();
+		piracy_patch_checksums();
+	}
+
+	if (state.is_ntscbeta) {
+		piracy_patch_mainloop();
 	}
 
 	// Slice the game segment into chunks and zip each of them to create the

tools/mkrom/mkrom.h

@@ -77,7 +77,8 @@ void pack_lib(void);
 void pack_data(void);
 void pack_game(void);
 
-void piracy_patch(void);
+void piracy_patch_checksums(void);
+void piracy_patch_mainloop(void);
 
 void rarezip(uint8_t *outbuffer, size_t *outlen, uint8_t *inbuffer, size_t inlen, uint32_t magic);
 

tools/mkrom/piracy.c

@@ -160,7 +160,7 @@ static void patch(Algo algo, char *patchfunc, char *sumfunc)
 /**
  * Patch all the piracy functions in the game.
  */
-void piracy_patch(void)
+void piracy_patch_checksums(void)
 {
 	// algorithm, patch function, sum function
 	patch(algo01, "__scHandleTasks", "bootPhase1");
@@ -176,3 +176,50 @@ void piracy_patch(void)
 	patch(algo11, "menuTickTimers", "mtxGetObfuscatedRomBase");
 	patch(algo12, "func0f15c920", "menuTickTimers");
 }
+
+/**
+ * NTSC Beta's original mainLoop function reads from a hardware device and
+ * refuses to run if it doesn't exist. Because of this, the reads must be
+ * patched to allow a ROM to work without this hardware.
+ *
+ * Decomp's target ROM is the patched one, so we apply the patch here.
+ */
+void piracy_patch_mainloop(void)
+{
+	uint32_t start;
+	uint32_t end;
+	uint32_t offset;
+	bool done_first = false;
+
+	if (!map_get_function_rompos("mainLoop", &start, &end)) {
+		return;
+	}
+
+	for (offset = start; offset < end; offset += 4) {
+		uint32_t word = 0;
+		word |= state.rom[offset] << 24;
+		word |= state.rom[offset + 1] << 16;
+		word |= state.rom[offset + 2] << 8;
+		word |= state.rom[offset + 3];
+
+		if (!done_first) {
+			if (word == 0x84820000) { // lh $v0, 0($a0)
+				// Replace with: li $v0, 0x4f4a
+				state.rom[offset + 0] = 0x24;
+				state.rom[offset + 1] = 0x02;
+				state.rom[offset + 2] = 0x4f;
+				state.rom[offset + 3] = 0x4a;
+				done_first = true;
+			}
+		} else {
+			if (word == 0x84820002) { // lh $v0, 2($a0)
+				// Replace with: li $v0, 0x4653
+				state.rom[offset + 0] = 0x24;
+				state.rom[offset + 1] = 0x02;
+				state.rom[offset + 2] = 0x46;
+				state.rom[offset + 3] = 0x53;
+				break;
+			}
+		}
+	}
+}