From afbe61a402201a5d23726cde1a83a040d36ee2be Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Wed, 25 Jan 2023 02:54:13 -0800
Subject: [PATCH] distribute rendering to master and slave

---
 main-hosted.cpp |  3 ++-
 main-saturn.cpp | 41 ++++++++++++++++++++++++++++++++++++++++-
 raytracing.cpp  |  8 ++++++--
 raytracing.hpp  |  2 +-
 4 files changed, 49 insertions(+), 5 deletions(-)

diff --git a/main-hosted.cpp b/main-hosted.cpp
index 088b900..56c00e5 100644
--- a/main-hosted.cpp
+++ b/main-hosted.cpp
@@ -50,7 +50,8 @@ void render_ppm(ostream& out)
 
 int main()
 {
-  render(put_pixel);
+  render(0, put_pixel);
+  render(1, put_pixel);
 
   render_ppm(cout);
 }
diff --git a/main-saturn.cpp b/main-saturn.cpp
index 087c93b..0487605 100644
--- a/main-saturn.cpp
+++ b/main-saturn.cpp
@@ -54,6 +54,43 @@ void fill(T * buf, T v, int32_t n) noexcept
   }
 }
 
+extern "C"
+void slave_main(void)
+{
+  render(1, put_pixel);
+
+  while (1) {}
+}
+
+void start_slave()
+{
+  /*
+    Items Common to Command Issue Timing
+    As mentioned above, issuing commands for 300 µs from V-BLANK-IN is
+    prohibited.
+  */
+  while ((smpc.reg.SF & 0x01) == 1);
+
+  smpc.reg.SF = 1;
+  smpc.reg.COMREG = COMREG__SSHOFF;
+
+  while ((smpc.reg.SF & 0x01) == 1);
+
+  /*
+  volatile void (*foo)(uint32_t, void*);
+  foo = *(volatile void (**)(uint32_t, void*))0x6000310;
+  foo(0x94, (void*)&slave_main);
+  */
+  sh2_vec[0x94] = (uint32_t)(&slave_main);
+
+  for (volatile int i = 0; i < 10; i++);
+
+  smpc.reg.SF = 1;
+  smpc.reg.COMREG = COMREG__SSHON;
+
+  while ((smpc.reg.SF & 0x01) == 1);
+}
+
 void main_asdf()
 {
   // DISP: Please make sure to change this bit from 0 to 1 during V blank.
@@ -89,7 +126,9 @@ void main_asdf()
   vdp2.reg.WCTLB = 0;
   vdp2.reg.WCTLC = 0;
 
-  render(put_pixel);
+  start_slave();
+
+  render(0, put_pixel);
 }
 
 extern "C"
diff --git a/raytracing.cpp b/raytracing.cpp
index 6c3ceea..7b324a1 100644
--- a/raytracing.cpp
+++ b/raytracing.cpp
@@ -173,13 +173,17 @@ static vec3 trace_ray
   }
 }
 
-void render(void (&put_pixel) (int32_t x, int32_t y, const vec3& c))
+void render(int half, void (&put_pixel) (int32_t x, int32_t y, const vec3& c))
 {
   using namespace canvas;
 
   vec3 origin = vec3(0, 0, 0);
 
-  for (int x = -(width/2); x < (width/2); x++) {
+  int x_low = half ? 0 : -(width/2);
+  int x_high = half ? (width/2) : 0;
+
+  //for (int x = -(width/2); x < (width/2); x++) {
+  for (int x = x_low; x < x_high; x++) {
     for (int y = -(height/2 + 1); y < (height/2 + 1); y++) {
       vec3 direction = canvas_to_viewport(x, y);
       vec3 color = trace_ray(origin, direction,
diff --git a/raytracing.hpp b/raytracing.hpp
index b8eeb4e..21fa63d 100644
--- a/raytracing.hpp
+++ b/raytracing.hpp
@@ -12,4 +12,4 @@ namespace canvas {
   constexpr int height = (1 << bit_height);
 }
 
-void render(void (&put_pixel) (int32_t x, int32_t y, const vec3& c));
+void render(int half, void (&put_pixel) (int32_t x, int32_t y, const vec3& c));