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Added type info to dsize comments

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This is mostly just a lot of leb128s, though we do use be16 for tags and
le32 for cksums and revision counts.

There are several places we use single-byte leb128s, which really are
u8s with the top bit reserved. Still, notating this as leb128 indicates
that the top bit really is reserved, even if you don't need full leb128
encoding/decoding in practice.
This commit is contained in:
Christopher Haster
2024-03-19 15:03:03 -05:00
parent 2564100eaa
commit c71725d627
2 changed files with 65 additions and 65 deletions
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lfs.c
+60 -60
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@@ -978,10 +978,10 @@ static inline void lfsr_tag_trim2(
// support for encoding/decoding tags on disk
// tag encoding:
// .---+---+---+- -+- -+- -+- -+---+- -+- -+- -. tag: 2 bytes
// | tag | weight | size | weight: <=5 bytes
// '---+---+---+- -+- -+- -+- -+---+- -+- -+- -' size: <=4 bytes
// total: <=11 bytes
// .---+---+---+- -+- -+- -+- -+---+- -+- -+- -. tag: 1 be16 2 bytes
// | tag | weight | size | weight: 1 leb128 <=5 bytes
// '---+---+---+- -+- -+- -+- -+---+- -+- -+- -' size: 1 leb128 <=4 bytes
// total: <=11 bytes
#define LFSR_TAG_DSIZE (2+5+4)
static lfs_ssize_t lfsr_bd_readtag(lfs_t *lfs,
@@ -1703,11 +1703,11 @@ static int lfsr_ecksum_validate(lfs_t *lfs, const lfsr_ecksum_t *ecksum,
// erased-state checksum on-disk encoding
// ecksum encoding:
// .---+- -+- -+- -.
// | cksize | cksize: <=4 bytes
// +---+- -+- -+- -+
// | cksum | cksum: 4 bytes
// '---+---+---+---' total: <=8 bytes
// .---+- -+- -+- -. cksize: 1 leb128 <=4 bytes
// | cksize | cksum: 1 le32 4 bytes
// +---+- -+- -+- -+ total: <=8 bytes
// | cksum |
// '---+---+---+---'
//
#define LFSR_ECKSUM_DSIZE (4+4)
@@ -1751,17 +1751,17 @@ static int lfsr_data_readecksum(lfs_t *lfs, lfsr_data_t *data,
// block pointer things
// bptr encoding:
// .---+- -+- -+- -.
// | size | size: <=4 bytes
// +---+- -+- -+- -+- -.
// | block | block: <=5 bytes
// +---+- -+- -+- -+- -'
// | off | off: <=4 bytes
// .---+- -+- -+- -. size: 1 leb128 <=4 bytes
// | size | block: 1 leb128 <=5 bytes
// +---+- -+- -+- -+- -. off: 1 leb128 <=4 bytes
// | block | cksize: 1 leb128 <=4 bytes
// +---+- -+- -+- -+- -' cksum: 1 le32 4 bytes
// | off | total: <=21 bytes
// +---+- -+- -+- -+
// | cksize | cksize: <=4 bytes
// | cksize |
// +---+- -+- -+- -+
// | cksum | cksum: 4 bytes
// '---+---+---+---' total: <=21 bytes
// | cksum |
// '---+---+---+---'
//
#define LFSR_BPTR_DSIZE (4+5+4+4+4)
@@ -3291,24 +3291,24 @@ static int lfsr_rbyd_appendcksum(lfs_t *lfs, lfsr_rbyd_t *rbyd) {
// this gets a bit complicated as we have two types of cksums:
//
// - 9-word cksum with ecksum to check following prog (middle of block):
// .---+---+---+---. ecksum tag: 2 bytes
// | etag | 0 |esz| ecksum weight: 1 byte
// +---+---+---+---+ ecksum size: 1 byte
// | ecksize | ecksum cksize: <=4 bytes
// +---+- -+- -+- -+ ecksum cksum: 4 bytes
// .---+---+---+---. ecksum tag: 1 be16 2 bytes
// | tag | 0 |siz| ecksum weight (0): 1 leb128 1 byte
// +---+---+---+---+ ecksum size: 1 leb128 1 byte
// | ecksize | ecksum cksize: 1 leb128 <=4 bytes
// +---+- -+- -+- -+ ecksum cksum: 1 le32 4 bytes
// | ecksum |
// +---+---+---+---+- -+- -+- -. cksum tag: 2 bytes
// | tag | 0 | size | cksum weight: 1 byte
// +---+---+---+---+- -+- -+- -' cksum size: <=4 bytes
// | cksum | cksum cksum: 4 bytes
// '---+---+---+---' total: <=23 bytes
// +---+---+---+---+- -+- -+- -. cksum tag: 1 be16 2 bytes
// | tag | 0 | size | cksum weight (0): 1 leb128 1 byte
// +---+---+---+---+- -+- -+- -' cksum size: 1 leb128 <=4 bytes
// | cksum | cksum cksum: 1 le32 4 bytes
// '---+---+---+---' total: <=23 bytes
//
// - 4-word cksum with no following prog (end of block):
// .---+---+---+---+- -+- -+- -. cksum tag: 2 bytes
// | tag | 0 | size | cksum weight: 1 byte
// +---+---+---+---+- -+- -+- -' cksum size: <=4 bytes
// | cksum | cksum cksum: 4 bytes
// '---+---+---+---' total: <=11 bytes
// .---+---+---+---+- -+- -+- -. cksum tag: 1 be16 2 bytes
// | tag | 0 | size | cksum weight (0): 1 leb128 1 byte
// +---+---+---+---+- -+- -+- -' cksum size: 1 leb128 <=4 bytes
// | cksum | cksum cksum: 1 le32 4 bytes
// '---+---+---+---' total: <=11 bytes
//
lfs_size_t aligned_eoff = lfs_alignup(
rbyd->eoff + 2+1+1+4+4 + 2+1+4+4,
@@ -3932,13 +3932,13 @@ static inline int lfsr_btree_cmp(
// branch on-disk encoding
// branch encoding:
// .---+- -+- -+- -+- -.
// | block | block: <=5 bytes
// +---+- -+- -+- -+- -'
// | trunk | trunk: <=4 bytes
// .---+- -+- -+- -+- -. block: 1 leb128 <=5 bytes
// | block | trunk: 1 leb128 <=4 bytes
// +---+- -+- -+- -+- -' cksum: 1 le32 4 bytes
// | trunk | total: <=13 bytes
// +---+- -+- -+- -+
// | cksum | cksum: 4 bytes
// '---+---+---+---' total: <=13 bytes
// | cksum |
// '---+---+---+---'
//
#define LFSR_BRANCH_DSIZE (5+4+4)
@@ -4000,15 +4000,15 @@ static int lfsr_data_readbranch(lfs_t *lfs, lfsr_data_t *data,
// btree's weight
// btree encoding:
// .---+- -+- -+- -+- -.
// | weight | weight: <=5 bytes
// +---+- -+- -+- -+- -+
// | block | block: <=5 bytes
// +---+- -+- -+- -+- -'
// | trunk | trunk: <=4 bytes
// .---+- -+- -+- -+- -. weight: 1 leb128 <=5 bytes
// | weight | block: 1 leb128 <=5 bytes
// +---+- -+- -+- -+- -+ trunk: 1 leb128 <=4 bytes
// | block | cksum: 1 le32 4 bytes
// +---+- -+- -+- -+- -' total: <=18 bytes
// | trunk |
// +---+- -+- -+- -+
// | cksum | cksum: 4 bytes
// '---+---+---+---' total: <=18 bytes
// | cksum |
// '---+---+---+---'
//
#define LFSR_BTREE_DSIZE (5+LFSR_BRANCH_DSIZE)
@@ -5061,11 +5061,11 @@ static inline int lfsr_shrub_cmp(
// shrub on-disk encoding
// shrub encoding:
// .---+- -+- -+- -+- -.
// | weight | weight: <=5 bytes
// +---+- -+- -+- -+- -'
// | trunk | trunk: <=4 bytes
// '---+- -+- -+- -' total: <=9 bytes
// .---+- -+- -+- -+- -. weight: 1 leb128 <=5 bytes
// | weight | trunk: 1 leb128 <=4 bytes
// +---+- -+- -+- -+- -' total: <=9 bytes
// | trunk |
// '---+- -+- -+- -'
//
#define LFSR_SHRUB_DSIZE (5+4)
@@ -5261,9 +5261,9 @@ static inline bool lfsr_mptr_ismrootanchor(const lfsr_mptr_t *mptr) {
}
// mptr encoding:
// .---+- -+- -+- -+- -.
// | block x 2 | blocks: <=2x5 bytes
// + + total: <=10 bytes
// .---+- -+- -+- -+- -. blocks: 2 leb128s <=2x5 bytes
// | block x 2 | total: <=10 bytes
// + +
// | |
// '---+- -+- -+- -+- -'
//
@@ -7892,11 +7892,11 @@ typedef struct lfsr_geometry {
} lfsr_geometry_t;
// geometry encoding
// .---+- -+- -+- -.
// | block_size | blocksize: <=4 bytes
// +---+- -+- -+- -+- -.
// | block_count | blockcount: <=5 bytes
// '---+- -+- -+- -+- -' total: <=9 bytes
// .---+- -+- -+- -. block_size: 1 leb128 <=4 bytes
// | block_size | block_count: 1 leb128 <=5 bytes
// +---+- -+- -+- -+- -. total: <=9 bytes
// | block_count |
// '---+- -+- -+- -+- -'
#define LFSR_GEOMETRY_DSIZE (4+5)
#define LFSR_DATA_FROMGEOMETRY(_geometry) \
lfs.h
+5 -5
View File
@@ -371,11 +371,11 @@ typedef struct lfsr_opened {
} lfsr_opened_t;
// grm encoding:
// .---.
// |mod| mode: 1 byte
// +- -+- -+- -+- -+- -.
// ' mid x mod ' mids: <=2x5 bytes
// + + total: <=11 bytes
// .---. mode: 1 leb128 1 byte
// |mod| mids: 2 leb128s <=2x5 bytes
// +- -+- -+- -+- -+- -. total: <=11 bytes
// ' mid x mod '
// + +
// ' '
// '- -+- -+- -+- -+- -'
//