forked from Imagelibrary/littlefs
6e5d314c20
These b*/m* struct tags have a common pattern that would be good to
emphasize in the encoding. The later struct tags get a bit more messy as
they leave space for future possible extensions.
New encoding:
LFSR_TAG_STRUCT 0x03tt v--- --11 -ttt ttrr
LFSR_TAG_DATA 0x0300 v--- --11 ---- ----
LFSR_TAG_BLOCK 0x0304 v--- --11 ---- -1rr
LFSR_TAG_BSHRUB 0x0308 v--- --11 ---- 1---
LFSR_TAG_BTREE 0x030c v--- --11 ---- 11rr
LFSR_TAG_MROOT 0x0310 v--- --11 ---1 --rr
LFSR_TAG_MDIR 0x0314 v--- --11 ---1 -1rr
LFSR_TAG_MSHRUB* 0x0318 v--- --11 ---1 1---
LFSR_TAG_MTREE 0x031c v--- --11 ---1 11rr
LFSR_TAG_DID 0x0320 v--- --11 --1- ----
LFSR_TAG_BRANCH 0x032c v--- --11 --1- 11rr
* Hypothetical
Note that all shrubs currently end with 1---, and all btrees, including
the awkward branch tag, end with 11rr.
This had no impact on code size:
code stack
before: 33564 2816
after: 33564 (+0.0%) 2816 (+0.0%)
313 lines
9.9 KiB
Python
Executable File
313 lines
9.9 KiB
Python
Executable File
#!/usr/bin/env python3
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import io
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import os
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import struct
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import sys
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TAG_NULL = 0x0000
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TAG_CONFIG = 0x0000
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TAG_MAGIC = 0x0003
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TAG_VERSION = 0x0004
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TAG_RCOMPAT = 0x0005
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TAG_WCOMPAT = 0x0006
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TAG_OCOMPAT = 0x0007
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TAG_GEOMETRY = 0x0009
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TAG_NAMELIMIT = 0x000c
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TAG_SIZELIMIT = 0x000d
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TAG_GDELTA = 0x0100
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TAG_GRMDELTA = 0x0100
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TAG_NAME = 0x0200
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TAG_REG = 0x0201
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TAG_DIR = 0x0202
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TAG_ORPHAN = 0x0203
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TAG_BOOKMARK = 0x0204
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TAG_STRUCT = 0x0300
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TAG_DATA = 0x0300
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TAG_BLOCK = 0x0304
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TAG_BSHRUB = 0x0308
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TAG_BTREE = 0x030c
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TAG_MROOT = 0x0311
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TAG_MDIR = 0x0315
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TAG_MTREE = 0x031c
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TAG_DID = 0x0320
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TAG_BRANCH = 0x032c
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TAG_UATTR = 0x0400
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TAG_SATTR = 0x0600
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TAG_SHRUB = 0x1000
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TAG_CKSUM = 0x3000
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TAG_ECKSUM = 0x3100
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TAG_ALT = 0x4000
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TAG_R = 0x2000
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TAG_GT = 0x1000
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# some ways of block geometry representations
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# 512 -> 512
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# 512x16 -> (512, 16)
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# 0x200x10 -> (512, 16)
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def bdgeom(s):
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s = s.strip()
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b = 10
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if s.startswith('0x') or s.startswith('0X'):
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s = s[2:]
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b = 16
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elif s.startswith('0o') or s.startswith('0O'):
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s = s[2:]
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b = 8
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elif s.startswith('0b') or s.startswith('0B'):
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s = s[2:]
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b = 2
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if 'x' in s:
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s, s_ = s.split('x', 1)
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return (int(s, b), int(s_, b))
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else:
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return int(s, b)
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# parse some rbyd addr encodings
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# 0xa -> [0xa]
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# 0xa.c -> [(0xa, 0xc)]
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# 0x{a,b} -> [0xa, 0xb]
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# 0x{a,b}.c -> [(0xa, 0xc), (0xb, 0xc)]
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def rbydaddr(s):
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s = s.strip()
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b = 10
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if s.startswith('0x') or s.startswith('0X'):
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s = s[2:]
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b = 16
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elif s.startswith('0o') or s.startswith('0O'):
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s = s[2:]
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b = 8
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elif s.startswith('0b') or s.startswith('0B'):
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s = s[2:]
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b = 2
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trunk = None
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if '.' in s:
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s, s_ = s.split('.', 1)
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trunk = int(s_, b)
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if s.startswith('{') and '}' in s:
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ss = s[1:s.find('}')].split(',')
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else:
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ss = [s]
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addr = []
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for s in ss:
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if trunk is not None:
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addr.append((int(s, b), trunk))
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else:
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addr.append(int(s, b))
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return addr
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def fromleb128(data):
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word = 0
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for i, b in enumerate(data):
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word |= ((b & 0x7f) << 7*i)
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word &= 0xffffffff
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if not b & 0x80:
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return word, i+1
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return word, len(data)
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def tagrepr(tag, w=None, size=None, off=None):
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if (tag & 0x6fff) == TAG_NULL:
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return '%snull%s%s' % (
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'shrub' if tag & TAG_SHRUB else '',
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' w%d' % w if w else '',
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' %d' % size if size else '')
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elif (tag & 0x6f00) == TAG_CONFIG:
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return '%s%s%s%s' % (
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'shrub' if tag & TAG_SHRUB else '',
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'magic' if (tag & 0xfff) == TAG_MAGIC
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else 'version' if (tag & 0xfff) == TAG_VERSION
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else 'rcompat' if (tag & 0xfff) == TAG_RCOMPAT
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else 'wcompat' if (tag & 0xfff) == TAG_WCOMPAT
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else 'ocompat' if (tag & 0xfff) == TAG_OCOMPAT
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else 'geometry' if (tag & 0xfff) == TAG_GEOMETRY
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else 'sizelimit' if (tag & 0xfff) == TAG_SIZELIMIT
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else 'namelimit' if (tag & 0xfff) == TAG_NAMELIMIT
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else 'config 0x%02x' % (tag & 0xff),
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' w%d' % w if w else '',
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' %s' % size if size is not None else '')
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elif (tag & 0x6f00) == TAG_GDELTA:
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return '%s%s%s%s' % (
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'shrub' if tag & TAG_SHRUB else '',
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'grmdelta' if (tag & 0xfff) == TAG_GRMDELTA
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else 'gdelta 0x%02x' % (tag & 0xff),
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' w%d' % w if w else '',
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' %s' % size if size is not None else '')
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elif (tag & 0x6f00) == TAG_NAME:
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return '%s%s%s%s' % (
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'shrub' if tag & TAG_SHRUB else '',
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'name' if (tag & 0xfff) == TAG_NAME
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else 'reg' if (tag & 0xfff) == TAG_REG
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else 'dir' if (tag & 0xfff) == TAG_DIR
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else 'orphan' if (tag & 0xfff) == TAG_ORPHAN
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else 'bookmark' if (tag & 0xfff) == TAG_BOOKMARK
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else 'name 0x%02x' % (tag & 0xff),
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' w%d' % w if w else '',
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' %s' % size if size is not None else '')
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elif (tag & 0x6f00) == TAG_STRUCT:
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return '%s%s%s%s' % (
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'shrub' if tag & TAG_SHRUB else '',
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'data' if (tag & 0xfff) == TAG_DATA
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else 'block' if (tag & 0xfff) == TAG_BLOCK
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else 'bshrub' if (tag & 0xfff) == TAG_BSHRUB
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else 'btree' if (tag & 0xfff) == TAG_BTREE
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else 'mroot' if (tag & 0xfff) == TAG_MROOT
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else 'mdir' if (tag & 0xfff) == TAG_MDIR
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else 'mtree' if (tag & 0xfff) == TAG_MTREE
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else 'did' if (tag & 0xfff) == TAG_DID
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else 'branch' if (tag & 0xfff) == TAG_BRANCH
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else 'struct 0x%02x' % (tag & 0xff),
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' w%d' % w if w else '',
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' %s' % size if size is not None else '')
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elif (tag & 0x6e00) == TAG_UATTR:
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return '%suattr 0x%02x%s%s' % (
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'shrub' if tag & TAG_SHRUB else '',
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((tag & 0x100) >> 1) | (tag & 0xff),
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' w%d' % w if w else '',
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' %s' % size if size is not None else '')
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elif (tag & 0x6e00) == TAG_SATTR:
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return '%ssattr 0x%02x%s%s' % (
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'shrub' if tag & TAG_SHRUB else '',
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((tag & 0x100) >> 1) | (tag & 0xff),
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' w%d' % w if w else '',
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' %s' % size if size is not None else '')
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elif (tag & 0x7f00) == TAG_CKSUM:
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return 'cksum 0x%02x%s%s' % (
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tag & 0xff,
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' w%d' % w if w else '',
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' %s' % size if size is not None else '')
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elif (tag & 0x7f00) == TAG_ECKSUM:
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return 'ecksum%s%s%s' % (
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' 0x%02x' % (tag & 0xff) if tag & 0xff else '',
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' w%d' % w if w else '',
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' %s' % size if size is not None else '')
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elif tag & TAG_ALT:
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return 'alt%s%s%s%s%s' % (
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'r' if tag & TAG_R else 'b',
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'a' if tag & 0x0fff == 0 and tag & TAG_GT
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else 'n' if tag & 0x0fff == 0
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else 'gt' if tag & TAG_GT
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else 'le',
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' 0x%x' % (tag & 0x0fff) if tag & 0x0fff != 0 else '',
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' w%d' % w if w is not None else '',
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' 0x%x' % (0xffffffff & (off-size))
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if size and off is not None
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else ' -%d' % size if size
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else '')
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else:
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return '0x%04x%s%s' % (
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tag,
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' w%d' % w if w is not None else '',
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' %d' % size if size is not None else '')
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def dbg_tag(data):
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if isinstance(data, int):
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tag = data
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weight = None
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size = None
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else:
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data = data.ljust(2, b'\0')
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tag = (data[0] << 8) | data[1]
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weight, d = fromleb128(data[2:]) if 2 < len(data) else (None, 2)
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size, d_ = fromleb128(data[2+d:]) if d < len(data) else (None, d)
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print(tagrepr(tag, weight, size))
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def main(tags, *,
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block_size=None,
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block_count=None,
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off=None,
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**args):
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# interpret as a sequence of hex bytes
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if args.get('hex'):
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dbg_tag(bytes(int(tag, 16) for tag in tags))
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# interpret as strings
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elif args.get('string'):
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for tag in tags:
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dbg_tag(tag.encode('utf8'))
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# default to interpreting as ints
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elif block_size is None and off is None:
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for tag in tags:
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dbg_tag(int(tag, 0))
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# if either block_size or off provided interpret as a block device
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else:
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disk, *blocks = tags
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blocks = [rbydaddr(block) for block in blocks]
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# is bd geometry specified?
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if isinstance(block_size, tuple):
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block_size, block_count_ = block_size
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if block_count is None:
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block_count = block_count_
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# flatten block, default to block 0
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if not blocks:
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blocks = [[0]]
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blocks = [block for blocks_ in blocks for block in blocks_]
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with open(disk, 'rb') as f:
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# if block_size is omitted, assume the block device is one big block
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if block_size is None:
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f.seek(0, os.SEEK_END)
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block_size = f.tell()
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# blocks may also encode offsets
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blocks, offs = (
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[block[0] if isinstance(block, tuple) else block
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for block in blocks],
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[off if off is not None
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else block[1] if isinstance(block, tuple)
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else None
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for block in blocks])
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# read each tag
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for block, off in zip(blocks, offs):
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f.seek((block * block_size) + (off or 0))
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# read maximum tag size
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data = f.read(2+5+5)
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dbg_tag(data)
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if __name__ == "__main__":
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import argparse
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import sys
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parser = argparse.ArgumentParser(
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description="Decode littlefs tags.",
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allow_abbrev=False)
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parser.add_argument(
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'tags',
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nargs='*',
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help="Tags to decode.")
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parser.add_argument(
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'-x', '--hex',
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action='store_true',
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help="Interpret as a sequence of hex bytes.")
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parser.add_argument(
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'-s', '--string',
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action='store_true',
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help="Interpret as strings.")
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parser.add_argument(
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'-b', '--block-size',
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type=bdgeom,
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help="Block size/geometry in bytes.")
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parser.add_argument(
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'--block-count',
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type=lambda x: int(x, 0),
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help="Block count in blocks.")
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parser.add_argument(
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'--off',
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type=lambda x: int(x, 0),
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help="Use this offset.")
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sys.exit(main(**{k: v
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for k, v in vars(parser.parse_intermixed_args()).items()
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if v is not None}))
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