From c8e84be5d234551bd13ac01fd3abddcb79994f90 Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Mon, 15 Apr 2024 18:22:28 +0800
Subject: [PATCH] common.lds: define vbr alignment

This also creates an example of a VBR+0x100 function in interrupt.cpp
---
 common.lds            |  9 +++++
 example/example.mk    |  1 +
 example/illslot.s     |  6 +++
 example/interrupt.cpp | 93 ++++++++++++++++++++++++++++++++++++++++++-
 sh7091/vbr.hpp        | 17 ++++++++
 symbols.lds           |  4 ++
 6 files changed, 128 insertions(+), 2 deletions(-)
 create mode 100644 example/illslot.s
 create mode 100644 sh7091/vbr.hpp

diff --git a/common.lds b/common.lds
index 0f36d99..37ff231 100644
--- a/common.lds
+++ b/common.lds
@@ -41,6 +41,15 @@ SECTIONS
     *(COMMON)
   } > p1ram
 
+  .text.vbr ALIGN(4) : SUBALIGN(4)
+  {
+    KEEP(*(.vbr.100))
+    . = ALIGN(0x300);
+    KEEP(*(.vbr.400))
+    . = ALIGN(0x200);
+    KEEP(*(.vbr.600))
+  } > p1ram
+
   INCLUDE "debug.lds"
 }
 
diff --git a/example/example.mk b/example/example.mk
index 3dd3627..4f02d54 100644
--- a/example/example.mk
+++ b/example/example.mk
@@ -329,6 +329,7 @@ example/serial_transfer.elf: $(START_OBJ) $(SERIAL_TRANSFER_OBJ)
 
 INTERRUPT_OBJ = \
 	example/interrupt.o \
+	example/illslot.o \
 	sh7091/serial.o
 
 example/interrupt.elf: LDSCRIPT = $(LIB)/alt.lds
diff --git a/example/illslot.s b/example/illslot.s
new file mode 100644
index 0000000..76deb3c
--- /dev/null
+++ b/example/illslot.s
@@ -0,0 +1,6 @@
+	.global _illslot
+_illslot:
+	rts
+	mova	test,r0
+
+test:	.long 0x12345678
diff --git a/example/interrupt.cpp b/example/interrupt.cpp
index ca2756b..3116687 100644
--- a/example/interrupt.cpp
+++ b/example/interrupt.cpp
@@ -4,14 +4,103 @@
 
 #include "sh7091/sh7091.hpp"
 #include "sh7091/sh7091_bits.hpp"
+#include "sh7091/vbr.hpp"
+#include "systembus.hpp"
 
+void vbr100()
+{
+  serial::string("vbr100\n");
+  serial::string("expevt ");
+  serial::integer(sh7091.CCN.EXPEVT);
+  serial::string("intevt ");
+  serial::integer(sh7091.CCN.INTEVT);
+  uint32_t spc;
+  uint32_t ssr;
+  asm volatile ("stc spc,%0"
+		: "=r" (spc)
+		);
+  asm volatile ("stc ssr,%0"
+		: "=r" (ssr)
+		);
+
+  serial::string("spc ");
+  serial::integer(spc);
+  serial::string("ssr ");
+  serial::integer(ssr);
+  while (1);
+}
+
+void vbr400()
+{
+  serial::string("vbr400");
+  while (1);
+}
+
+void vbr600()
+{
+  serial::string("vbr600");
+  while (1);
+}
+
+extern "C" uint32_t * illslot(void);
 void main()
 {
-  uint32_t vbr;
+  uint32_t vbr = reinterpret_cast<uint32_t>(&__vbr_link_start) - 0x100;
 
-  asm ("stc vbr,%0" : "=r" (vbr));
+  system.IML2NRM = 0;
+  system.IML2ERR = 0;
+  system.IML2EXT = 0;
+
+  system.IML4NRM = 0;
+  system.IML4ERR = 0;
+  system.IML4EXT = 0;
+
+  system.IML6NRM = 0;
+  system.IML6ERR = 0;
+  system.IML6EXT = 0;
+
+  sh7091.CCN.INTEVT = 0;
+  sh7091.CCN.EXPEVT = 0;
+
+  uint32_t zero = 0;
+  asm volatile ("ldc %0,spc"
+		:
+		: "r" (zero));
+
+  asm volatile ("ldc %0,ssr"
+		:
+		: "r" (zero));
+
+  asm volatile ("ldc %0,vbr"
+		:
+		: "r" (vbr));
+
+
+  uint32_t sr;
+  asm volatile ("stc sr,%0"
+		: "=r" (sr));
+
+  serial::string("sr ");
+  serial::integer<uint32_t>(sr);
+
+  sr = sr & (~(1 << 28)); // BL
+
+  asm volatile ("ldc %0, sr"
+		:
+		: "r" (sr));
+
+  /*
+  uint32_t vbr2;
+  asm volatile ("stc vbr,%0"
+		: "=r" (vbr2));
+  */
 
   serial::integer<uint32_t>(vbr);
+  //serial::integer<uint32_t>(vbr2);
+  serial::integer<uint32_t>(reinterpret_cast<uint32_t>(&vbr100));
+
+  uint32_t * test = illslot();
+  serial::integer<uint32_t>(*test);
 
   while (1);
 }
diff --git a/sh7091/vbr.hpp b/sh7091/vbr.hpp
new file mode 100644
index 0000000..fd348ef
--- /dev/null
+++ b/sh7091/vbr.hpp
@@ -0,0 +1,17 @@
+#pragma once
+
+#include <cstdint>
+
+__attribute__((section(".vbr.100")))
+__attribute__((interrupt_handler))
+void vbr100();
+
+__attribute__((section(".vbr.400")))
+__attribute__((interrupt_handler))
+void vbr400();
+
+__attribute__((section(".vbr.600")))
+__attribute__((interrupt_handler))
+void vbr600();
+
+extern uint32_t __vbr_link_start __asm("__vbr_link_start");
diff --git a/symbols.lds b/symbols.lds
index 36d00f8..74c01e4 100644
--- a/symbols.lds
+++ b/symbols.lds
@@ -18,3 +18,7 @@ __ctors_link_end = ADDR(.ctors) + SIZEOF(.ctors);
 
 __bss_link_start = ADDR(.bss);
 __bss_link_end = ADDR(.bss) + SIZEOF(.bss);
+
+__vbr_link_start = ADDR(.text.vbr);
+__vbr_link_end = ADDR(.text.vbr) + SIZEOF(.text.vbr);
+__vbr_load_end = LOADADDR(.text.vbr);