* dwarf-frame.c: Add and fix some comments.

2 files changed, 17 insertions, 1 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 568600fdf3a..421a6068d3c 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,7 @@
 2003-05-17  Mark Kettenis  <kettenis@gnu.org>
 
+	* dwarf-frame.c: Add and fix some comments.
+
 	* i386-tdep.c (i386_frame_cache, i386_sigtramp_frame_cache,
 	i386_extract_struct_value_address, i386_svr4_sigcontext_addr): Use
 	extract_unsigned_integer instead of extract_address.
diff --git a/gdb/dwarf-frame.c b/gdb/dwarf-frame.c
index 6279171c7ee..a1d963491fa 100644
--- a/gdb/dwarf-frame.c
+++ b/gdb/dwarf-frame.c
@@ -796,6 +796,20 @@ read_initial_length (bfd *abfd, char *buf, unsigned int *bytes_read_ptr)
 
 /* Pointer encoding helper functions.  */
 
+/* GCC supports exception handling based on DWARF2 CFI.  However, for
+   technical reasons, it encodes addresses in its FDE's in a different
+   way.  Several "pointer encodings" are supported.  The encoding
+   that's used for a particular FDE is determined by the 'R'
+   augmentation in the associated CIE.  The argument of this
+   augmentation is a single byte.  
+
+   The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a
+   LEB128.  This is encoded in bits 0, 1 and 2.  Bit 3 encodes whether
+   the address is signed or unsigned.  Bits 4, 5 and 6 encode how the
+   address should be interpreted (absolute, relative to the current
+   position in the FDE, ...).  Bit 7, indicates that the address
+   should be dereferenced.  */
+
 static unsigned char
 encoding_for_size (unsigned int size)
 {
@@ -958,7 +972,7 @@ add_fde (struct comp_unit *unit, struct dwarf_fde *fde)
 #define DW64_CIE_ID ~0
 #endif
 
-/* Read and the CIE or FDE in BUF and decode it.  */
+/* Read a CIE or FDE in BUF and decode it.  */
 
 static char *
 decode_frame_entry (struct comp_unit *unit, char *buf, int eh_frame_p)