2001-12-17 Fernando Nasser <fnasser@redhat.com>

	From Richard Earnshaw <rearnsha@arm.com>:
	* arm-tdep.c (arm_software_single_step): New function. Implements
	software single-stepping for ARM targets.
	(arm_get_next_pc, thumb_get_next_pc, bitcount, shifted_reg_val): Only
	needed for software single-stepping.
	* config/arm/tm-arm.h: Activate SOFTWARE_SINGLE_STEP_P.

3 files changed, 55 insertions, 8 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index f8cbdc6..078f352 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,11 +1,20 @@
 2001-12-17  Fernando Nasser  <fnasser@redhat.com>
 
 	From Richard Earnshaw <rearnsha@arm.com>:
-        * config/arm/nbsd.mh, config/arm/nbsd.mt, config/arm/tm-nbsd.h,
-        config/arm/nm-nbsd.h, config/arm/xm-nbsd.h: New files.
-        * armbsd-nat.c: New file.
-        * Makefile.in: Build it.
-        * configure.host, configure.tgt: Support NetBSD/arm.
+	* arm-tdep.c (arm_software_single_step): New function. Implements
+	software single-stepping for ARM targets.
+	(arm_get_next_pc, thumb_get_next_pc, bitcount, shifted_reg_val): Only
+	needed for software single-stepping.
+	* config/arm/tm-arm.h: Activate SOFTWARE_SINGLE_STEP_P.
+
+2001-12-17  Fernando Nasser  <fnasser@redhat.com>
+
+	From Richard Earnshaw <rearnsha@arm.com>:
+	* config/arm/nbsd.mh, config/arm/nbsd.mt, config/arm/tm-nbsd.h,
+	config/arm/nm-nbsd.h, config/arm/xm-nbsd.h: New files.
+	* armbsd-nat.c: New file.
+	* Makefile.in: Build it.
+	* configure.host, configure.tgt: Support NetBSD/arm.
 
 2001-12-17  Corinna Vinschen  <vinschen@redhat.com>
 
diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index afcc7f0..bec9c80 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -1532,6 +1532,8 @@ condition_true (unsigned long cond, unsigned long status_reg)
   return 1;
 }
 
+#if SOFTWARE_SINGLE_STEP_P
+/* Support routines for single stepping.  Calculate the next PC value.  */
 #define submask(x) ((1L << ((x) + 1)) - 1)
 #define bit(obj,st) (((obj) >> (st)) & 1)
 #define bits(obj,st,fn) (((obj) >> (st)) & submask ((fn) - (st)))
@@ -1866,6 +1868,32 @@ arm_get_next_pc (CORE_ADDR pc)
   return nextpc;
 }
 
+/* single_step() is called just before we want to resume the inferior,
+   if we want to single-step it but there is no hardware or kernel
+   single-step support.  We find the target of the coming instruction
+   and breakpoint it.
+
+   single_step is also called just after the inferior stops.  If we had
+   set up a simulated single-step, we undo our damage.  */
+
+void
+arm_software_single_step (ignore, insert_bpt)
+     int ignore; /* Signal, not needed */
+     int insert_bpt;
+{
+  static int next_pc; /* State between setting and unsetting. */
+  static char break_mem[BREAKPOINT_MAX]; /* Temporary storage for mem@bpt */
+
+  if (insert_bpt)
+    {
+      next_pc = arm_get_next_pc (read_register (PC_REGNUM));
+      target_insert_breakpoint (next_pc, &break_mem);
+    }
+  else
+    target_remove_breakpoint (next_pc, &break_mem);
+}
+#endif /* SOFTWARE_SINGLE_STEP_P */
+
 #include "bfd-in2.h"
 #include "libcoff.h"
 
diff --git a/gdb/config/arm/tm-arm.h b/gdb/config/arm/tm-arm.h
index 3c15350..c9b91c9 100644
--- a/gdb/config/arm/tm-arm.h
+++ b/gdb/config/arm/tm-arm.h
@@ -96,9 +96,9 @@ extern CORE_ADDR arm_saved_pc_after_call (struct frame_info *);
    Even this may only true if the condition predicate is true. The
    following use a condition predicate of ALWAYS so it is always TRUE.
    
-   There are other ways of forcing a breakpoint.  ARM Linux, RisciX,
-   and I suspect NetBSD will all use a software interrupt rather than
-   an undefined instruction to force a trap.  This can be handled by
+   There are other ways of forcing a breakpoint.  ARM Linux, RISC iX,
+   and NetBSD will all use a software interrupt rather than an
+   undefined instruction to force a trap.  This can be handled by
    redefining some or all of the following in a target dependent
    fashion.  */
 
@@ -451,6 +451,16 @@ void arm_fix_call_dummy (char *dummy, CORE_ADDR pc, CORE_ADDR fun,
 			 int nargs, struct value ** args,
 			 struct type * type, int gcc_p);
 
+/* Most ARMs don't have single stepping capability, so provide a 
+   single-stepping mechanism by default */
+#ifndef SOFTWARE_SINGLE_STEP_P
+#define SOFTWARE_SINGLE_STEP_P 1
+#endif
+#if SOFTWARE_SINGLE_STEP_P
+#define SOFTWARE_SINGLE_STEP(sig,bpt) arm_software_single_step((sig), (bpt))
+void arm_software_single_step PARAMS((int, int));
+#endif
+
 CORE_ADDR arm_get_next_pc (CORE_ADDR pc);
 
 /* Macros for setting and testing a bit in a minimal symbol that marks