maintenance: use modules properly

KindleUnpack/mobi_uncompress.py

@@ -0,0 +1,131 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# vim:ts=4:sw=4:softtabstop=4:smarttab:expandtab
+
+from __future__ import unicode_literals, division, absolute_import, print_function
+
+from .compatibility_utils import PY2, bchr, lmap, bstr
+
+if PY2:
+    range = xrange
+
+import struct
+# note:  struct pack, unpack, unpack_from all require bytestring format
+# data all the way up to at least python 2.7.5, python 3 okay with bytestring
+
+
+class unpackException(Exception):
+    pass
+
+class UncompressedReader:
+
+    def unpack(self, data):
+        return data
+
+class PalmdocReader:
+
+    def unpack(self, i):
+        o, p = b'', 0
+        while p < len(i):
+            # for python 3 must use slice since i[p] returns int while slice returns character
+            c = ord(i[p:p+1])
+            p += 1
+            if (c >= 1 and c <= 8):
+                o += i[p:p+c]
+                p += c
+            elif (c < 128):
+                o += bchr(c)
+            elif (c >= 192):
+                o += b' ' + bchr(c ^ 128)
+            else:
+                if p < len(i):
+                    c = (c << 8) | ord(i[p:p+1])
+                    p += 1
+                    m = (c >> 3) & 0x07ff
+                    n = (c & 7) + 3
+                    if (m > n):
+                        o += o[-m:n-m]
+                    else:
+                        for _ in range(n):
+                            # because of completely ass-backwards decision by python mainters for python 3
+                            # we must use slice for bytes as i[p] returns int while slice returns character
+                            if m == 1:
+                                o += o[-m:]
+                            else:
+                                o += o[-m:-m+1]
+        return o
+
+class HuffcdicReader:
+    q = struct.Struct(b'>Q').unpack_from
+
+    def loadHuff(self, huff):
+        if huff[0:8] != b'HUFF\x00\x00\x00\x18':
+            raise unpackException('invalid huff header')
+        off1, off2 = struct.unpack_from(b'>LL', huff, 8)
+
+        def dict1_unpack(v):
+            codelen, term, maxcode = v&0x1f, v&0x80, v>>8
+            assert codelen != 0
+            if codelen <= 8:
+                assert term
+            maxcode = ((maxcode + 1) << (32 - codelen)) - 1
+            return (codelen, term, maxcode)
+        self.dict1 = lmap(dict1_unpack, struct.unpack_from(b'>256L', huff, off1))
+
+        dict2 = struct.unpack_from(b'>64L', huff, off2)
+        self.mincode, self.maxcode = (), ()
+        for codelen, mincode in enumerate((0,) + dict2[0::2]):
+            self.mincode += (mincode << (32 - codelen), )
+        for codelen, maxcode in enumerate((0,) + dict2[1::2]):
+            self.maxcode += (((maxcode + 1) << (32 - codelen)) - 1, )
+
+        self.dictionary = []
+
+    def loadCdic(self, cdic):
+        if cdic[0:8] != b'CDIC\x00\x00\x00\x10':
+            raise unpackException('invalid cdic header')
+        phrases, bits = struct.unpack_from(b'>LL', cdic, 8)
+        n = min(1<<bits, phrases-len(self.dictionary))
+        h = struct.Struct(b'>H').unpack_from
+        def getslice(off):
+            blen, = h(cdic, 16+off)
+            slice = cdic[18+off:18+off+(blen&0x7fff)]
+            return (slice, blen&0x8000)
+        self.dictionary += lmap(getslice, struct.unpack_from(bstr('>%dH' % n), cdic, 16))
+
+    def unpack(self, data):
+        q = HuffcdicReader.q
+
+        bitsleft = len(data) * 8
+        data += b"\x00\x00\x00\x00\x00\x00\x00\x00"
+        pos = 0
+        x, = q(data, pos)
+        n = 32
+
+        s = b''
+        while True:
+            if n <= 0:
+                pos += 4
+                x, = q(data, pos)
+                n += 32
+            code = (x >> n) & ((1 << 32) - 1)
+
+            codelen, term, maxcode = self.dict1[code >> 24]
+            if not term:
+                while code < self.mincode[codelen]:
+                    codelen += 1
+                maxcode = self.maxcode[codelen]
+
+            n -= codelen
+            bitsleft -= codelen
+            if bitsleft < 0:
+                break
+
+            r = (maxcode - code) >> (32 - codelen)
+            slice, flag = self.dictionary[r]
+            if not flag:
+                self.dictionary[r] = None
+                slice = self.unpack(slice)
+                self.dictionary[r] = (slice, 1)
+            s += slice
+        return s