From 0d04c007825be1d276d9b936b5340db655deaec1 Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Sat, 7 Jan 2023 18:14:59 -0800
Subject: [PATCH] zeroize nbg planes

---
 Makefile |  4 ++--
 main.c   | 14 +++++++++++++-
 sh2.lds  |  2 +-
 type.h   |  6 ++++++
 4 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 2029da1..48d131f 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 AFLAGS = -g -gdwarf-4 --isa=sh2 --big
 CFLAGS += -ffunction-sections -fshort-enums -ffreestanding -nostdlib
-CFLAGS += -Wall -Werror -Wno-error=unused-but-set-variable -g -gdwarf-4 -Og
+CFLAGS += -Wall -Werror -g -gdwarf-4 -Og
 CARCH = -m2 -mb
 
 TARGET = sh2-none-elf-
@@ -56,7 +56,7 @@ main.iso: main.bin sys_ip.bin
 		main.bin
 
 clean:
-	rm -f *.iso *.o *.bin *.elf dts/smpsys.o
+	rm -f *.iso *.o *.bin *.elf
 
 .SUFFIXES:
 .INTERMEDIATE:
diff --git a/main.c b/main.c
index 9550284..fb9ff19 100644
--- a/main.c
+++ b/main.c
@@ -1,6 +1,15 @@
 #include "vdp2.h"
 #include "vdp1.h"
 
+void fill_32(u32 * buf, u32 v, s32 n)
+{
+  while (n > 0) {
+    *buf = v;
+    buf += 1;
+    n -= (sizeof (u32));
+  }
+}
+
 void start(void) {
   //
   // vdp2: enable and set Back Screen color
@@ -48,11 +57,14 @@ void start(void) {
   vdp2.reg.MPABN0 = MPABN0__N0MPB(0) | MPABN0__N0MPA(1); // bits 5~0
   vdp2.reg.MPCDN0 = MPABN0__N0MPB(0) | MPABN0__N0MPA(1); // bits 5~0
 
+  // zeroize NBG0 plane; this should be less than 0x8000 above
+  s32 plane_size = 64 * 64 * 4; // is this correct ?
+  fill_32(&vdp2.vram.u32[(0x4000 / 4)], 0, plane_size);
+
   // Table 4.8  Address value of map designated register by setting
   // (bit 5~0) * 0x4000
   vdp2.vram.u32[(0x4000 / 4)] = PATTERN_NAME_TABLE_2WORD__CHARACTER(1);
 
-
   //
   // vdp1:
   //
diff --git a/sh2.lds b/sh2.lds
index 553599a..ddf7ae9 100644
--- a/sh2.lds
+++ b/sh2.lds
@@ -7,7 +7,7 @@ MEMORY
 }
 SECTIONS
 {
-  . = 0x06003000;
+  . = 0x06010000;
 
   .text ALIGN(2) : SUBALIGN(2)
   {
diff --git a/type.h b/type.h
index 743cf06..1861efa 100644
--- a/type.h
+++ b/type.h
@@ -9,10 +9,16 @@ static_assert((sizeof (reg8)) == 1);
 static_assert((sizeof (reg16)) == 2);
 static_assert((sizeof (reg32)) == 4);
 
+typedef volatile unsigned short u8;
+typedef volatile short s8;
 typedef volatile unsigned short u16;
 typedef volatile short s16;
+typedef volatile unsigned long u32;
+typedef volatile long s32;
 
 static_assert((sizeof (u16)) == 2);
 static_assert((sizeof (s16)) == 2);
+static_assert((sizeof (u32)) == 4);
+static_assert((sizeof (s32)) == 4);
 
 #define REG_UL(U, L) (((U) << 16) | (L))