scripts: Added dbgleb128.py and dbgle32.py

These mimic dbgtag.py, but provide debugging for the lower-level integer
primitives in littlefs:

  $ ./scripts/dbgleb128.py -x 2a 80 80 a8 01
  2a             42
  80 80 a8 01    2752512

  $ ./scripts/dbgle32.py -x 2a 00 00 00 00 00 2a 00
  2a 00 00 00    42
  00 00 2a 00    2752512

dbgleb128.py is probably going to be more useful, but I figured we might
as well include both for completeness. Though dbgle32.py is begging to
be generalized.

scripts/dbgle32.py

@@ -0,0 +1,89 @@
+#!/usr/bin/env python3
+
+# prevent local imports
+if __name__ == "__main__":
+    __import__('sys').path.pop(0)
+
+import io
+import os
+import struct
+import sys
+
+
+# open with '-' for stdin/stdout
+def openio(path, mode='r', buffering=-1):
+    import os
+    if path == '-':
+        if 'r' in mode:
+            return os.fdopen(os.dup(sys.stdin.fileno()), mode, buffering)
+        else:
+            return os.fdopen(os.dup(sys.stdout.fileno()), mode, buffering)
+    else:
+        return open(path, mode, buffering)
+
+def fromle32(data):
+    return struct.unpack('<I', data[0:4].ljust(4, b'\0'))[0]
+
+def dbg_le32s(data):
+    lines = []
+    j = 0
+    while j < len(data):
+        word = fromle32(data[j:])
+        lines.append((
+                ' '.join('%02x' % b for b in data[j:j+4]),
+                word))
+        j += 4
+
+    # figure out widths
+    w = [0]
+    for l in lines:
+        w[0] = max(w[0], len(l[0]))
+
+    # then print results
+    for l in lines:
+        print('%-*s    %s' % (
+                w[0], l[0],
+                l[1]))
+
+def main(le32s, *,
+        hex=False,
+        input=None):
+    hex_ = hex; del hex
+
+    # interpret as a sequence of hex bytes
+    if hex_:
+        bytes_ = [b for le32 in le32s for b in le32.split()]
+        dbg_le32s(bytes(int(b, 16) for b in bytes_))
+
+    # parse le32s in a file
+    elif input:
+        with openio(input, 'rb') as f:
+            dbg_le32s(f.read())
+
+    # we don't currently have a default interpretation
+    else:
+        print("error: no -x/--hex or -i/--input?",
+                file=sys.stderr)
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    import argparse
+    import sys
+    parser = argparse.ArgumentParser(
+            description="Decode le32s.",
+            allow_abbrev=False)
+    parser.add_argument(
+            'le32s',
+            nargs='*',
+            help="Le32s to decode.")
+    parser.add_argument(
+            '-x', '--hex',
+            action='store_true',
+            help="Interpret as a sequence of hex bytes.")
+    parser.add_argument(
+            '-i', '--input',
+            help="Read le32s from this file. Can use - for stdin.")
+    sys.exit(main(**{k: v
+            for k, v in vars(parser.parse_intermixed_args()).items()
+            if v is not None}))

scripts/dbgleb128.py

@@ -0,0 +1,95 @@
+#!/usr/bin/env python3
+
+# prevent local imports
+if __name__ == "__main__":
+    __import__('sys').path.pop(0)
+
+import io
+import os
+import struct
+import sys
+
+
+# open with '-' for stdin/stdout
+def openio(path, mode='r', buffering=-1):
+    import os
+    if path == '-':
+        if 'r' in mode:
+            return os.fdopen(os.dup(sys.stdin.fileno()), mode, buffering)
+        else:
+            return os.fdopen(os.dup(sys.stdout.fileno()), mode, buffering)
+    else:
+        return open(path, mode, buffering)
+
+def fromleb128(data):
+    word = 0
+    for i, b in enumerate(data):
+        word |= ((b & 0x7f) << 7*i)
+        word &= 0xffffffff
+        if not b & 0x80:
+            return word, i+1
+    return word, len(data)
+
+def dbg_leb128s(data):
+    lines = []
+    j = 0
+    while j < len(data):
+        word, d = fromleb128(data[j:])
+        lines.append((
+                ' '.join('%02x' % b for b in data[j:j+d]),
+                word))
+        j += d
+
+    # figure out widths
+    w = [0]
+    for l in lines:
+        w[0] = max(w[0], len(l[0]))
+
+    # then print results
+    for l in lines:
+        print('%-*s    %s' % (
+                w[0], l[0],
+                l[1]))
+
+def main(leb128s, *,
+        hex=False,
+        input=None):
+    hex_ = hex; del hex
+
+    # interpret as a sequence of hex bytes
+    if hex_:
+        bytes_ = [b for leb128 in leb128s for b in leb128.split()]
+        dbg_leb128s(bytes(int(b, 16) for b in bytes_))
+
+    # parse leb128s in a file
+    elif input:
+        with openio(input, 'rb') as f:
+            dbg_leb128s(f.read())
+
+    # we don't currently have a default interpretation
+    else:
+        print("error: no -x/--hex or -i/--input?",
+                file=sys.stderr)
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    import argparse
+    import sys
+    parser = argparse.ArgumentParser(
+            description="Decode leb128s.",
+            allow_abbrev=False)
+    parser.add_argument(
+            'leb128s',
+            nargs='*',
+            help="Leb128s to decode.")
+    parser.add_argument(
+            '-x', '--hex',
+            action='store_true',
+            help="Interpret as a sequence of hex bytes.")
+    parser.add_argument(
+            '-i', '--input',
+            help="Read leb128s from this file. Can use - for stdin.")
+    sys.exit(main(**{k: v
+            for k, v in vars(parser.parse_intermixed_args()).items()
+            if v is not None}))