diff options
author | David Brownell <dbrownell@users.sourceforge.net> | 2009-11-05 21:59:39 -0800 |
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committer | David Brownell <dbrownell@users.sourceforge.net> | 2009-11-05 21:59:39 -0800 |
commit | db116b1ea3c77a3c5850fccbce9e0795faa21dda (patch) | |
tree | 9c9f456f726fe99b098324750b6942bf6c2bd497 /src/target/target.h | |
parent | b7e4c26b9bb10e6e0ebfb07e5d43f0d62526cde2 (diff) |
target: provide container_of()
Provide a cleaner way to handle single inheritance of targets
in C, using the same model Linux does: structs containing other
structs, un-nested via calls to a "container_of()" macro that
are packaged in typesafe inline functions.
Targets already use this containment idiom, but make it much
more complicated because they un-nest using embedded "void *"
pointers ... in chains of up to five per target, which is all
pure needless complication. (Example: arm92x core, arm9tdmi,
arm7_9, armv4_5 ... on top of the base "target" class.)
Applying this scheme consistently simplifies things, and gets
rid of many error-prone untyped pointers. It won't change any
part of the type model though -- it just simplifies things.
(And facilitates more cleanup later on.)
Rule of thumb: where there's an X->arch_info void* pointer,
access to that pointer can and should be removed. It may be
convenient to set up pointers to some of the embedded structs;
and shrink their current "*_common" names (annoyingly long).
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Diffstat (limited to 'src/target/target.h')
-rw-r--r-- | src/target/target.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/src/target/target.h b/src/target/target.h index c971f18b..1bbf40f0 100644 --- a/src/target/target.h +++ b/src/target/target.h @@ -26,6 +26,8 @@ #ifndef TARGET_H #define TARGET_H +#include <stddef.h> + #include "breakpoints.h" #include "algorithm.h" #include "command.h" @@ -34,6 +36,19 @@ struct reg_s; struct trace_s; struct command_context_s; + +/** + * Cast a member of a structure out to the containing structure. + * @param ptr The pointer to the member. + * @param type The type of the container struct this is embedded in. + * @param member The name of the member within the struct. + * + * This is a mechanism which is used throughout the Linux kernel. + */ +#define container_of(ptr, type, member) ({ \ + const typeof( ((type *)0)->member ) *__mptr = (ptr); \ + (type *)( (char *)__mptr - offsetof(type,member) );}) + /* * TARGET_UNKNOWN = 0: we don't know anything about the target yet * TARGET_RUNNING = 1: the target is executing user code |