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-rw-r--r--gdb/defs.h32
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 */