add dcd.bit.Bitfield and related goodies

dcd/__init__.py

@@ -3,5 +3,6 @@
 
 from . import argv
 from . import aux
+from . import bit
 from . import cfg
 from . import dt

dcd/aux.py

@@ -18,6 +18,20 @@ def flatten_dict(root, glue=" ", prefix=[]):
 
 # ----------------------------------------------------------------
 
+def clamp(A, low, high):
+	"""
+	Clamps integer A to <low; high>
+	"""
+	
+	if A < low:
+		return low
+	elif A > high:
+		return high
+	else:
+		return A
+
+# ----------------------------------------------------------------
+
 import random
 
 PASSPHRASE_VOWELS = "aeiuAEU"
@@ -50,34 +64,6 @@ def hash_password(p, hexdigest=True):
 
 # ----------------------------------------------------------------
 
-def raw_to_hex(raw, separator=" "):
-	"""
-	Converts a bytearray (or bytes) into its textual hexadecimal representation.
-	"""
-	
-	output = []
-	
-	for o in raw:
-		output.append(hex(o)[2:].zfill(2))
-	
-	return separator.join(output)
-
-def hex_to_raw(text, separator=" "):
-	"""
-	Converts a hexadecimal representation of a byte array into a bytearray.
-	"""
-	
-	output = []
-	
-	text = text.replace(separator, "")
-	
-	for i in range(len(text)//2):
-		output.append(int(text[2*i:2*i+2], 16))
-	
-	return bytearray(output)
-
-# ----------------------------------------------------------------
-
 class DeleteOverlay:
 	pass
 

dcd/bit.py

@@ -0,0 +1,58 @@
+#! /usr/bin/env python3
+# encoding: utf-8
+
+# ----------------------------------------------------------------
+
+class Bitfield:
+	def __init__(self):
+		self.value = 0
+		self.length = 0
+	
+	def shift_in(self, value, length):
+		self.value <<= length
+		self.value |= value
+		self.length += length
+		
+	def dump(self, align=True):
+		value = self.value
+		length = self.length
+		
+		pad = (8 - (length % 8)) % 8
+		value <<= pad
+		length += pad
+		
+		Bs = []
+		
+		for i in range(length // 8):
+			Bs.insert(0, value & 0xff)
+			value >>= 8
+		
+		return bytes(Bs)
+
+# ----------------------------------------------------------------
+
+def raw_to_hex(raw, separator=" "):
+	"""
+	Converts a bytearray (or bytes) into its textual hexadecimal representation.
+	"""
+	
+	output = []
+	
+	for o in raw:
+		output.append(hex(o)[2:].zfill(2))
+	
+	return separator.join(output)
+
+def hex_to_raw(text, separator=" "):
+	"""
+	Converts a hexadecimal representation of a byte array into a bytearray.
+	"""
+	
+	output = []
+	
+	text = text.replace(separator, "")
+	
+	for i in range(len(text)//2):
+		output.append(int(text[2*i:2*i+2], 16))
+	
+	return bytearray(output)