MagnitudeOS/littlefs
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Some small tweaks

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- Moved alt encoding 0x1 => 0x4, which can lead to slightly better
  lookup tables, the perturb bit takes the same place as the color bit,
  which means both can be ignored in readonly operations.

- Dropped lfs_rbyd_fetchmatch, asking each lfs_rbyd_fetch to include NULL
  isn't that bad.

New encoding:

  tags:
  iiii iiiiiii iiiiiTT TTTTTTt ttt0tpv
                   ^--------^------^^^- 16-bit id
                            '------|||- 8-bit type2
                                   '||- 5-bit type1
                                    '|- perturb bit
                                     '- valid bit
  llll lllllll lllllll lllllll lllllll
                                     ^- n-bit length

  alts:
  wwww wwwwwww wwwwwww wwwwwww www1dcv
                                 ^^^-^- 28-bit weight
                                  '|-|- color bit
                                   '-|- direction bit
                                     '- valid bit
  jjjj jjjjjjj jjjjjjj jjjjjjj jjjjjjj
                                     ^- n-bit jump
This commit is contained in:
Christopher Haster
2022-12-21 12:05:17 -06:00
parent 9a0e3fc749
commit 024aaeba56
3 changed files with 45 additions and 47 deletions
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41
scripts/dbgrbyd.py
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@@ -45,15 +45,7 @@ def tagrepr(tag, size, off=None):
type2 = (tag >> 7) & 0xff
id = (tag >> 15) & 0xffff
if type1 & 1:
return 'alt %s %s x%x %s' % (
'r' if type1 & 4 else 'b',
'gt' if type1 & 2 else 'lt',
tag >> 3,
'x%x' % (0xffffffff & (off-size))
if off is not None
else '-%d' % off)
elif type1 == 0x40:
if type1 == 0x40:
return 'create x%02x id%d %d' % (type2, id, size)
elif type1 == 0x48:
return 'delete x%02x id%d %d' % (type2, id, size)
@@ -68,16 +60,24 @@ def tagrepr(tag, size, off=None):
return 'tail x%02x %d' % (type2, size)
elif type1 == 0x10:
return 'gstate x%02x %d' % (type2, size)
elif type1 == 0x02 or type1 == 0x0a:
elif (type1 & 0x7e) == 0x02:
if type2 == 0:
return 'crc%x %d' % (type1 >> 3, size)
else:
return 'crc%x x%02x %d' % (type1 >> 3, type2, size)
elif type1 == 0x12:
elif type1 == 0x0a:
if type2 == 0:
return 'fcrc %d' % (size)
else:
return 'fcrc x%02x %d' % (type2, size)
elif type1 & 0x4:
return 'alt%s%s x%x %s' % (
'r' if type1 & 4 else 'b',
'gt' if type1 & 2 else 'lt',
tag >> 3,
'x%x' % (0xffffffff & (off-size))
if off is not None
else '-%d' % off)
else:
return 'x%02x x%02x id%d %d' % (type1, type2, id, size)
@@ -104,8 +104,8 @@ def main(disk, block_size, block1, block2=None, **args):
crc = crc32c(data[j:j+delta], crc)
j += delta
if not tag & 0x1:
if (tag & 0x37) != 0x2:
if not tag & 0x4:
if (tag & 0x7e) != 0x2:
crc = crc32c(data[j:j+size], crc)
# found a crc?
else:
@@ -131,11 +131,10 @@ def main(disk, block_size, block1, block2=None, **args):
# print contents of the winning metadata block
block, data, rev, off = blocks[i], datas[i], revs[i], offs[i]
print('mdir 0x%x, rev %d, size %d (was 0x%x, %d, %d)' % (
print('mdir 0x%x, rev %d, size %d%s' % (
block, rev, off,
blocks[len(blocks)-1-i],
revs[len(revs)-1-i],
offs[len(offs)-1-i]))
' (was 0x%x, %d, %d)' % (blocks[~i], revs[~i], offs[~i])
if len(blocks) > 1 else ''))
print('%-8s %-22s %s' % (
'off', 'tag',
'data (truncated)'
@@ -158,8 +157,8 @@ def main(disk, block_size, block1, block2=None, **args):
crc = crc32c(data[j:j+delta], crc)
j += delta
if not tag & 0x1:
if (tag & 0x37) != 0x2:
if not tag & 0x4:
if (tag & 0x7e) != 0x2:
crc = crc32c(data[j:j+size], crc)
# found a crc?
else:
@@ -173,7 +172,7 @@ def main(disk, block_size, block1, block2=None, **args):
'%-22s%s' % (
tagrepr(tag, size, j_),
' %s' % next(xxd(data[j_+delta:j_+delta+min(size, 8)], 8), '')
if not tag & 1 and not args.get('no_truncate') else ''),
if not tag & 0x4 and not args.get('no_truncate') else ''),
' (%s)' % ', '.join(notes)
if notes else ''))
@@ -181,7 +180,7 @@ def main(disk, block_size, block1, block2=None, **args):
for o, line in enumerate(xxd(data[j_:j_+delta])):
print('%8s: %s' % ('%04x' % (j_ + o*16), line))
if not tag & 0x1:
if not tag & 0x4:
if args.get('raw') or args.get('no_truncate'):
for o, line in enumerate(xxd(data[j_+delta:j_+delta+size])):
print('%8s: %s' % ('%04x' % (j_+delta + o*16), line))