From 14cd51f7793a9ce07bc435069f57269450141363 Mon Sep 17 00:00:00 2001
From: Stan Shebs <shebs@apple.com>
Date: Fri, 16 Apr 1999 01:35:26 +0000
Subject: Initial revision

---
 gdb/mem-break.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 gdb/mem-break.c

(limited to 'gdb/mem-break.c')

diff --git a/gdb/mem-break.c b/gdb/mem-break.c
new file mode 100644
index 00000000000..b0a1b4f6371
--- /dev/null
+++ b/gdb/mem-break.c
@@ -0,0 +1,124 @@
+/* Simulate breakpoints by patching locations in the target system, for GDB.
+   Copyright 1990, 1991, 1995 Free Software Foundation, Inc.
+   Contributed by Cygnus Support.  Written by John Gilmore.
+
+This file is part of GDB.
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+#include "defs.h"
+
+/* This file is only useful if BREAKPOINT is set.  If not, we punt.  */
+
+#include "symtab.h"
+#include "breakpoint.h"
+#include "inferior.h"
+#include "target.h"
+
+
+/* Use the program counter to determine the contents and size
+   of a breakpoint instruction.  If no target-dependent macro
+   BREAKPOINT_FROM_PC has been defined to implement this function,
+   assume that the breakpoint doesn't depend on the PC, and
+   use the values of the BIG_BREAKPOINT and LITTLE_BREAKPOINT macros.
+   Return a pointer to a string of bytes that encode a breakpoint
+   instruction, stores the length of the string to *lenptr,
+   and optionally adjust the pc to point to the correct memory location
+   for inserting the breakpoint.  */
+
+unsigned char *
+memory_breakpoint_from_pc (pcptr, lenptr)
+     CORE_ADDR *pcptr;
+     int *lenptr;
+{
+  /* {BIG_,LITTLE_}BREAKPOINT is the sequence of bytes we insert for a
+     breakpoint.  On some machines, breakpoints are handled by the
+     target environment and we don't have to worry about them here.  */
+#ifdef BIG_BREAKPOINT
+  if (TARGET_BYTE_ORDER == BIG_ENDIAN)
+    {
+      static unsigned char big_break_insn[] = BIG_BREAKPOINT;
+      *lenptr = sizeof (big_break_insn);
+      return big_break_insn;
+    }
+#endif
+#ifdef LITTLE_BREAKPOINT
+  if (TARGET_BYTE_ORDER != BIG_ENDIAN)
+    {
+      static unsigned char little_break_insn[] = LITTLE_BREAKPOINT;
+      *lenptr = sizeof (little_break_insn);
+      return little_break_insn;
+    }
+#endif
+#ifdef BREAKPOINT
+  {
+    static unsigned char break_insn[] = BREAKPOINT;
+    *lenptr = sizeof (break_insn);
+    return break_insn;
+  }
+#endif
+  *lenptr = 0;
+  return NULL;
+}
+
+
+/* Insert a breakpoint on targets that don't have any better breakpoint
+   support.  We read the contents of the target location and stash it,
+   then overwrite it with a breakpoint instruction.  ADDR is the target
+   location in the target machine.  CONTENTS_CACHE is a pointer to 
+   memory allocated for saving the target contents.  It is guaranteed
+   by the caller to be long enough to save BREAKPOINT_LEN bytes (this
+   is accomplished via BREAKPOINT_MAX).  */
+
+int
+memory_insert_breakpoint (addr, contents_cache)
+     CORE_ADDR addr;
+     char *contents_cache;
+{
+  int val;
+  unsigned char *bp;
+  int bplen;
+
+  /* Determine appropriate breakpoint contents and size for this address.  */
+  bp = BREAKPOINT_FROM_PC (&addr, &bplen);
+  if (bp == NULL)
+    error ("Software breakpoints not implemented for this target.");
+
+  /* Save the memory contents.  */
+  val = target_read_memory (addr, contents_cache, bplen);
+
+  /* Write the breakpoint.  */
+  if (val == 0)
+    val = target_write_memory (addr, (char *)bp, bplen);
+
+  return val;
+}
+
+
+int
+memory_remove_breakpoint (addr, contents_cache)
+     CORE_ADDR addr;
+     char *contents_cache;
+{
+  unsigned char *bp;
+  int bplen;
+
+  /* Determine appropriate breakpoint contents and size for this address.  */
+  bp = BREAKPOINT_FROM_PC (&addr, &bplen);
+  if (bp == NULL)
+    error ("Software breakpoints not implemented for this target.");
+
+  return target_write_memory (addr, contents_cache, bplen);
+}
-- 
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