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rattrs: Allowed LFS3_RATTR_TAIL as alternate rattr-list terminator

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LFS3_tag_RATTRS, now LFS3_tag_TAIL, is a bit funny in that it only
supports tail-recursive rattrs. The whole point of littlefs is
bounded-RAM after all. And if we know LFS3_tag_TAIL will terminate an
rattr-list, why bother with an additional LFS3_tag_NULL?

Like LFS3_RATTR_NULL, LFS3_RATTR_TAIL sets length=0 to indicate the end
of the rattr-lists.

Saves a bit of code:

                 code          stack          ctx
  before:       35324           2176          660
  after:        35316 (-0.0%)   2176 (+0.0%)  660 (+0.0%)

                 code          stack          ctx
  gbmap before: 38156           2192          772
  gbmap after:  38148 (-0.0%)   2192 (+0.0%)  772 (+0.0%)
This commit is contained in:
Christopher Haster
2025-11-29 21:56:16 -06:00
parent dca915dd95
commit ce6cbc3c77
2 changed files with 8 additions and 8 deletions
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lfs3.c
+7 -7
View File
@@ -1945,6 +1945,9 @@ typedef uint8_t lfs3_count_t;
// null rattr terminates rattr lists
#define LFS3_RATTR_NULL ((lfs3_rattr_t)0)
// alternatively, a tail rattr tail-recurses into another rattr list
#define LFS3_RATTR_TAIL LFS3_RATTR(0, LFS3_tag_TAIL, 0)
// create an attribute list
#define LFS3_RATTRS(...) ((const lfs3_rattr_t[]){__VA_ARGS__})
@@ -8265,9 +8268,7 @@ static int lfs3_mdir_commit___(lfs3_t *lfs3, lfs3_mdir_t *mdir_,
LFS3_ASSERT(!(r > rattrs && lfs3_rattr_isinsert(r)));
// rattr lists can be chained, but only tail-recursively
if (lfs3_rattr_tag(r) == LFS3_tag_RATTRS) {
// must be the last tag
LFS3_ASSERT(!*lfs3_rattr_next(r, NULL));
if (lfs3_rattr_tag(r) == LFS3_tag_TAIL) {
const lfs3_rattr_t *rattrs_
= (const lfs3_rattr_t*)lfs3_rattr_arg(r, 0);
@@ -9285,10 +9286,9 @@ static int lfs3_mdir_commit_(lfs3_t *lfs3, lfs3_mdir_t *mdir,
LFS3_RATTR_ARG(&mtree_),
// were we committing to the mroot? include any -1 rattrs
(mdir->mid <= -1)
? LFS3_RATTR(2, LFS3_tag_RATTRS, 0)
: LFS3_RATTR(2, LFS3_TAG_NULL, 0),
LFS3_RATTR_ARG(rattrs),
LFS3_RATTR_NULL));
? LFS3_RATTR_TAIL
: LFS3_RATTR_NULL,
LFS3_RATTR_ARG(rattrs)));
if (err) {
LFS3_ASSERT(err != LFS3_ERR_RANGE);
goto failed;
lfs3.h
+1 -1
View File
@@ -829,7 +829,7 @@ enum lfs3_tag {
// in-device only tags, these should never get written to disk
LFS3_tag_INTERNAL = 0x0000,
LFS3_tag_RATTRS = 0x0001,
LFS3_tag_TAIL = 0x0001,
LFS3_tag_SHRUBCOMMIT = 0x0002,
LFS3_tag_GRMPUSH = 0x0003,
LFS3_tag_MOVE = 0x0004,