2003-09-19 Andrew Cagney <cagney@redhat.com>

	* utils.c (align_up, align_down): New functions.
	* defs.h (align_up, align_down): Declare.
	* ppc-sysv-tdep.c (align_up, align_down): Delete functions.
	* s390-tdep.c: Replace "round_up" and "round_down" with "align_up"
	and "align_down".
	(round_up, round_down): Delete functions.
	* mips-tdep.c: Replace ROUND_UP and ROUND_DOWN with "align_up" and
	"align_down".
	(ROUND_DOWN, ROUND_UP): Delete macros.
	(mips_dump_tdep): Do not print "ROUND_UP" or "ROUND_DOWN".
	* h8300-tdep.c: Replace "round_up" and "round_down" with
	"align_up" and "align_down".
	(round_up, round_down): Delete macros.
	* frv-tdep.c: Replace ROUND_UP and ROUND_DOWN with "align_up" and
	"align_down".
	(ROUND_UP, ROUND_DOWN): Delete macros.

1 files changed, 32 insertions, 0 deletions

diff --git a/gdb/defs.h b/gdb/defs.h
index 842f4d8..696ee5b 100644
--- a/gdb/defs.h
+++ b/gdb/defs.h
@@ -1264,4 +1264,36 @@ extern int use_windows;
 #define ISATTY(FP)	(isatty (fileno (FP)))
 #endif
 
+/* Ensure that V is aligned to an N byte boundary (B's assumed to be a
+   power of 2).  Round up/down when necessary.  Examples of correct
+   use include:
+
+   addr = align_up (addr, 8); -- VALUE needs 8 byte alignment
+   write_memory (addr, value, len);
+   addr += len;
+
+   and:
+
+   sp = align_down (sp - len, 16); -- Keep SP 16 byte aligned
+   write_memory (sp, value, len);
+
+   Note that uses such as:
+
+   write_memory (addr, value, len);
+   addr += align_up (len, 8);
+
+   and:
+
+   sp -= align_up (len, 8);
+   write_memory (sp, value, len);
+
+   are typically not correct as they don't ensure that the address (SP
+   or ADDR) is correctly aligned (relying on previous alignment to
+   keep things right).  This is also why the methods are called
+   "align_..." instead of "round_..." as the latter reads better with
+   this incorrect coding style.  */
+
+extern ULONGEST align_up (ULONGEST v, int n);
+extern ULONGEST align_down (ULONGEST v, int n);
+
 #endif /* #ifndef DEFS_H */