From 6ba869691bd38fe7450d54108e32c87de19b4ca6 Mon Sep 17 00:00:00 2001
From: aglab2 <aglab3@gmail.com>
Date: Sun, 5 Sep 2021 16:59:50 +0800
Subject: [PATCH] gIsVC is introduced, VC_HACKS define is removed

---
 Makefile             |  7 -------
 src/audio/heap.c     |  8 +++++---
 src/game/game_init.c | 13 ++++---------
 src/game/vc_check.c  |  7 +++++++
 src/game/vc_check.h  | 20 ++++++++++++++++++++
 5 files changed, 36 insertions(+), 19 deletions(-)
 create mode 100644 src/game/vc_check.c
 create mode 100644 src/game/vc_check.h

diff --git a/Makefile b/Makefile
index 4d4a5393..84330d1b 100644
--- a/Makefile
+++ b/Makefile
@@ -20,9 +20,6 @@ USE_DEBUG := 0
 
 # Build for the N64 (turn this off for ports)
 TARGET_N64 ?= 1
-# Virtual Console hacks. Enabling this makes your hack (hopefully) compatible with the Wii Virtual Console.
-# One of the thing this does is disable the instant input patch, so do NOT use this for your normal z64 release.
-VC_HACKS ?= 0
 
 # CONSOLE - selects the console to target
 #   bb - Targets the iQue Player (codenamed BB)
@@ -39,10 +36,6 @@ else ifeq ($(CONSOLE),bb)
   DEFINES        += BBPLAYER=1
 endif
 
-ifeq ($(VC_HACKS), 1)
-  DEFINES += VC_HACKS=1
-endif
-
 # COMPILER - selects the C compiler to use
 #   gcc - uses the GNU C Compiler
 #   clang - uses clang C/C++ frontend for LLVM
diff --git a/src/audio/heap.c b/src/audio/heap.c
index b63b0664..4b518fc2 100644
--- a/src/audio/heap.c
+++ b/src/audio/heap.c
@@ -11,6 +11,8 @@
 
 #define ALIGN16(val) (((val) + 0xF) & ~0xF)
 
+extern u8 gIsVC;
+
 struct PoolSplit {
     u32 wantSeq;
     u32 wantBank;
@@ -1109,11 +1111,11 @@ s32 audio_shut_down_and_reset_step(void) {
  * Waits until a specified number of audio frames have been created
  */
 void wait_for_audio_frames(s32 frames) {
-#ifdef VC_HACKS
     // VC emulator stubs this function because busy loops are not supported
     // Technically we can put infinite loop that _looks_ like -O0 for emu but this is cleaner
-    return;
-#endif
+    if (gIsVC)
+        return;
+
     gAudioFrameCount = 0;
     // Sound thread will update gAudioFrameCount
     while (gAudioFrameCount < frames) {
diff --git a/src/game/game_init.c b/src/game/game_init.c
index dcde6663..854b7bda 100644
--- a/src/game/game_init.c
+++ b/src/game/game_init.c
@@ -33,6 +33,7 @@
 #include <prevent_bss_reordering.h>
 #include "puppycam2.h"
 #include "debug_box.h"
+#include "vc_check.h"
 
 // First 3 controller slots
 struct Controller gControllers[3];
@@ -48,6 +49,7 @@ OSContStatus gControllerStatuses[4];
 OSContPad gControllerPads[4];
 u8 gControllerBits;
 u8 gIsConsole = TRUE; // Needs to be initialized before audio_reset_session is called
+u8 gIsVC = FALSE;
 u8 gBorderHeight;
 #ifdef CUSTOM_DEBUG
 u8 gCustomDebugMode;
@@ -392,13 +394,9 @@ void render_init(void) {
 
     // Skip incrementing the initial framebuffer index on emulators so that they display immediately as the Gfx task finishes
     // VC probably emulates osViSwapBuffer accurately so instant patch breaks VC compatibility
-#ifndef VC_HACKS
     if (gIsConsole) { // Read RDP Clock Register, has a value of zero on emulators
-#endif
         sRenderingFrameBuffer++;
-#ifndef VC_HACKS
     }
-#endif
     gGlobalTimer++;
 }
 
@@ -421,6 +419,7 @@ void select_gfx_pool(void) {
  * - Selects which framebuffer will be rendered and displayed to next time.
  */
 void display_and_vsync(void) {
+    gIsVC = IS_VC();
     if (IO_READ(DPC_PIPEBUSY_REG) && gIsConsole != 1)
     {
         gIsConsole = 1;
@@ -440,18 +439,14 @@ void display_and_vsync(void) {
     profiler_log_thread5_time(THREAD5_END);
     osRecvMesg(&gGameVblankQueue, &gMainReceivedMesg, OS_MESG_BLOCK);
     // Skip swapping buffers on emulator so that they display immediately as the Gfx task finishes
-#ifndef VC_HACKS
-    if (gIsConsole) { // Read RDP Clock Register, has a value of zero on emulators
-#endif
+    if (gIsConsole || gIsVC) { // Read RDP Clock Register, has a value of zero on emulators
         if (++sRenderedFramebuffer == 3) {
             sRenderedFramebuffer = 0;
         }
         if (++sRenderingFrameBuffer == 3) {
             sRenderingFrameBuffer = 0;
         }
-#ifndef VC_HACKS
     }
-#endif
     gGlobalTimer++;
 }
 
diff --git a/src/game/vc_check.c b/src/game/vc_check.c
new file mode 100644
index 00000000..d5965bec
--- /dev/null
+++ b/src/game/vc_check.c
@@ -0,0 +1,7 @@
+#include "vc_check.h"
+
+// literally return what was passed
+f32 round_double_to_float(f64 v)
+{
+    return v;
+}
diff --git a/src/game/vc_check.h b/src/game/vc_check.h
new file mode 100644
index 00000000..97a913e8
--- /dev/null
+++ b/src/game/vc_check.h
@@ -0,0 +1,20 @@
+#ifndef VC_CHECK_H
+#define VC_CHECK_H
+
+#include "sm64.h"
+
+// This function must not be inlined by the compiler so I move it to a different C file
+f32 round_double_to_float(f64);
+
+/*
+ * This check forces RTZ bug on vc
+ * If console is N64/adequate Emu round-to-nearest (RTN) rounding mode is used
+ * If console is VC round-to-zero (RTZ) mode is used
+ * 
+ * The double value 0.9999999999999999 used is 0x3FEFFFFFFFFFFFFF in binary
+ * Exponent=01111111110, Mantissa=1111111111111111111111111111111111111111111111111111
+ * RTZ will output not 1.0f, RTN will output exactly 1.0f
+ */
+#define IS_VC() (1.0f != round_double_to_float(0.9999999999999999))
+
+#endif