Update of /cvsroot/wisp/wisp/users/dig
In directory sc8-pr-cvs1:/tmp/cvs-serv3871
Modified Files:
bits.py
Log Message:
introduced Bits.__getitem__
Index: bits.py
===================================================================
RCS file: /cvsroot/wisp/wisp/users/dig/bits.py,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -d -r1.1 -r1.2
--- bits.py 26 Apr 2003 17:36:17 -0000 1.1
+++ bits.py 26 Apr 2003 20:56:56 -0000 1.2
@@ -8,23 +8,23 @@
from array import array
from struct import pack, unpack
+from types import SliceType
class Bits (object):
- __slots__ = ['_contents', '_skipped']
+ __slots__ = ['_contents', '_skipped', '_byte_order',
+ 'emit_wyde', 'emit_tetra']
def __init__ (this, byte_order = None):
this._contents = array('c')
if byte_order == None: pass
elif byte_order == '<':
this.emit_wyde = this.emit_lewyde
this.emit_tetra = this.emit_letetra
- this.add_wyde = this.add_lewyde
- this.add_tetra = this.add_letetra
elif byte_order == '>':
this.emit_wyde = this.emit_bewyde
this.emit_tetra = this.emit_betetra
- this.add_wyde = this.add_bewyde
- this.add_tetra = this.add_betetra
else: raise "Unknown byte order", byte_order
+ this._skipped = 0
+ this._byte_order = byte_order
def emit_byte (this, b):
if this._skipped <> 0: raise "Events out of order", this
this._contents.append(chr(b & 0xff))
@@ -51,9 +51,19 @@
datum, = unpack(tpl, this._contents[ofs : ofs + size])
datum += value
datum %= 1L << (size << 3)
- this._contents[ofs : ofs + size] = array('c', pack(tpl, datum))
- def add_lewyde (this, ofs, value): this._add(ofs, value, 2, '<H')
- def add_bewyde (this, ofs, value): this._add(ofs, value, 2, '>H')
- def add_letetra (this, ofs, value): this._add(ofs, value, 4, '<L')
- def add_betetra (this, ofs, value): this._add(ofs, value, 4, '>L')
+ this._contents[ofs : ofs + size] = \
+ array('c', pack(this._byte_order + tpl, datum))
+ def add_wyde (this, ofs, value): this._add(ofs, value, 2, 'H')
+ def add_tetra (this, ofs, value): this._add(ofs, value, 4, 'L')
+ def __getitem__ (this, index):
+ if isinstance(index, SliceType):
+ if index.start == None or index.stop != None or \
+ not index.step in (1, 2, 4):
+ raise 'Bad slice for Bits.__getitem__', index
+ if index.step == 1: return ord(this._contents[index.start])
+ else:
+ data = this._contents[index.start : index.start + index.step]
+ tpl = this._byte_order + {2: 'H', 4: 'L'}[index.step]
+ return unpack(tpl, data)
+ else: return ord(this._contents[index])
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