From ce0ce9dd8c6162182e5d9d4b1ff91f5b62a03b7e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Markus=20Fr=C3=B6schle?= <mfro@mubf.de>
Date: Mon, 24 Oct 2016 06:25:17 +0000
Subject: [PATCH] fix ST RAM header writes

Newer compilers refuse to dereference NULL pointers. Fix this with
special "no-delete-null-pointer-checks" function attribute
---
 BaS_gcc/BaS_gcc.files |  1 -
 BaS_gcc/sys/BaS.c     | 36 ++++++++++++++++++++++++------------
 2 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/BaS_gcc/BaS_gcc.files b/BaS_gcc/BaS_gcc.files
index 31af8f8..10ad6e5 100644
--- a/BaS_gcc/BaS_gcc.files
+++ b/BaS_gcc/BaS_gcc.files
@@ -568,7 +568,6 @@ Doxyfile
 dump.bdm
 Makefile
 mcf5474.gdb
-svn-commit.tmp
 tos/pci_test/include/bas_printf.h
 tos/pci_test/include/bas_string.h
 tos/pci_test/include/driver_vec.h
diff --git a/BaS_gcc/sys/BaS.c b/BaS_gcc/sys/BaS.c
index 431b6ae..a090b78 100644
--- a/BaS_gcc/sys/BaS.c
+++ b/BaS_gcc/sys/BaS.c
@@ -379,6 +379,29 @@ void init_isr(void)
     }
 }
 
+/* Jump into the OS */
+typedef void void_func(void);
+struct rom_header
+{
+    void *initial_sp;
+    void_func *initial_pc;
+};
+
+/*
+ * fix ST RAM header (address 0x0 and 0x4). FreeMiNT uses these vectors on CTRL-ALT-DEL.
+ *
+ * Beware: Newer compilers refuse to dereference pointers to NULL and abort if the following
+ * attribute isn't set.
+ */
+static inline void fix_stram_header() __attribute__((optimize("no-delete-null-pointer-checks")));
+static inline void fix_stram_header()
+{
+    struct rom_header *bas_header = (struct rom_header *) TARGET_ADDRESS;
+    struct rom_header *stram_header = (struct rom_header *) 0x0;
+
+    *stram_header = *bas_header;
+}
+
 void BaS(void)
 {
     uint8_t *src;
@@ -473,14 +496,6 @@ void BaS(void)
 
     srec_execute("BASFLASH.S19");
 
-    /* Jump into the OS */
-    typedef void void_func(void);
-    struct rom_header
-    {
-        void *initial_sp;
-        void_func *initial_pc;
-    };
-
     xprintf("BaS initialization finished, enable interrupts\r\n");
     init_isr();
 
@@ -542,10 +557,7 @@ void BaS(void)
      * like on original STs (where these values reside in ROM) and uses them on
      * CTRL-ALT-DELETE reboots.
      */
-    struct rom_header *bas_header = (struct rom_header *) TARGET_ADDRESS;
-    struct rom_header *stram_header = (struct rom_header *) 0x0;
-
-    *stram_header = *bas_header;
+    fix_stram_header();
 
     xprintf("call EmuTOS\r\n");
     struct rom_header *os_header = (struct rom_header *) TOS;