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Don't actually use LFS_CRC32C_EVENZERO

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This is just 0. Using LFS_CRC32C_EVENZERO could hide the fact that
these can all be replaced with conditional xors if needed.
This commit is contained in:
Christopher Haster
2024-08-20 11:46:12 -05:00
parent c00e0b2af6
commit e492af7e61
1 changed files with 15 additions and 21 deletions
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lfs.c
+15 -21
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@@ -3059,9 +3059,10 @@ static int lfsr_rbyd_fetch(lfs_t *lfs, lfsr_rbyd_t *rbyd,
ecksum = ecksum_;
// revert to canonical checksum and perturb if necessary
cksum_ = cksum ^ ((lfsr_rbyd_isperturb(rbyd))
? LFS_CRC32C_ODDZERO
: LFS_CRC32C_EVENZERO);
cksum_ = cksum
^ ((lfsr_rbyd_isperturb(rbyd))
? LFS_CRC32C_ODDZERO
: 0);
ecksum_ = LFSR_DATA_NULL();
}
}
@@ -3099,9 +3100,10 @@ static int lfsr_rbyd_fetch(lfs_t *lfs, lfsr_rbyd_t *rbyd,
// update canonical checksum, xoring out any perturb
// state, we don't want erased-state affecting our
// canonical checksum
cksum = cksum_ ^ ((lfsr_rbyd_isperturb(rbyd))
? LFS_CRC32C_ODDZERO
: LFS_CRC32C_EVENZERO);
cksum = cksum_
^ ((lfsr_rbyd_isperturb(rbyd))
? LFS_CRC32C_ODDZERO
: 0);
}
// skip data
@@ -3496,9 +3498,7 @@ static int lfsr_bd_ckrbydprefix(lfs_t *lfs,
// revert to canonical checksum and perturb if necessary
perturb = lfsr_tag_p(tag);
cksum__ = cksum_ ^ ((perturb)
? LFS_CRC32C_ODDZERO
: LFS_CRC32C_EVENZERO);
cksum__ = cksum_ ^ ((perturb) ? LFS_CRC32C_ODDZERO : 0);
}
}
@@ -3506,9 +3506,7 @@ static int lfsr_bd_ckrbydprefix(lfs_t *lfs,
if (lfsr_tag_istrunk(tag)) {
// update canonical checksum, xoring out any perturb
// state
cksum_ = cksum__ ^ ((perturb)
? LFS_CRC32C_ODDZERO
: LFS_CRC32C_EVENZERO);
cksum_ = cksum__ ^ ((perturb) ? LFS_CRC32C_ODDZERO : 0);
}
// skip data
@@ -3673,9 +3671,8 @@ static int lfsr_rbyd_appendtag(lfs_t *lfs, lfsr_rbyd_t *rbyd,
// keep track of most recent cksum
lfs->tailck.ckblock = rbyd->blocks[0];
lfs->tailck.ckoff = lfsr_rbyd_eoff(rbyd);
lfs->tailck.cksum = rbyd->cksum ^ ((lfsr_rbyd_isperturb(rbyd))
? LFS_CRC32C_ODDZERO
: LFS_CRC32C_EVENZERO);
lfs->tailck.cksum = rbyd->cksum
^ ((lfsr_rbyd_isperturb(rbyd)) ? LFS_CRC32C_ODDZERO : 0);
#endif
return 0;
@@ -3703,9 +3700,8 @@ static int lfsr_rbyd_appendcat(lfs_t *lfs, lfsr_rbyd_t *rbyd,
// keep track of most recent parity
lfs->tailck.ckblock = rbyd->blocks[0];
lfs->tailck.ckoff = lfsr_rbyd_eoff(rbyd);
lfs->tailck.cksum = rbyd->cksum ^ ((lfsr_rbyd_isperturb(rbyd))
? LFS_CRC32C_ODDZERO
: LFS_CRC32C_EVENZERO);
lfs->tailck.cksum = rbyd->cksum
^ ((lfsr_rbyd_isperturb(rbyd)) ? LFS_CRC32C_ODDZERO : 0);
#endif
return 0;
@@ -4560,9 +4556,7 @@ static int lfsr_rbyd_appendcksum(lfs_t *lfs, lfsr_rbyd_t *rbyd) {
//
// note the odd-parity zero preserves our position in the crc32c
// ring while only changing the parity
cksum_ ^= (lfsr_rbyd_isperturb(rbyd))
? LFS_CRC32C_ODDZERO
: LFS_CRC32C_EVENZERO;
cksum_ ^= (lfsr_rbyd_isperturb(rbyd)) ? LFS_CRC32C_ODDZERO : 0;
lfs_tole32_(cksum_, &cksum_buf[2+1+4]);
// prog, when this lands on disk commit is committed