More methods for the BigNumber class

pythoncardx/framework/math.py

@@ -1,4 +1,5 @@
 from python.lang import NullPointerException, ArithmeticException
+from pythoncard.framework import Util
 
 def from_bcd(data):
  """
@@ -7,28 +8,36 @@ def from_bcd(data):
  """
  return int(hex(data)[2:])
 
+def to_bcd(data):
+ """
+ >>> to_bcd(59)
+ 0x59
+ """
+ a = data // 10
+ b = data % 10
+ return (a << 4) + b
+
 def from_hex(data):
  """
  >>> from_hex(0x59)
  786
  """
  return data
+to_hex = from_hex
 
 class BigNumber(object):
  FORMAT_BCD = 1
  FORMAT_HEX = 2
 
- def __init__(self, maxBytes):
- if maxBytes <= 0:
+ def __init__(self, maxBytes = None):
+ if maxBytes is not None and maxBytes <= 0:
  raise ArithmeticException()
  self.maxBytes = maxBytes
  self._value = None
 
  def init(self, bArray, bOff, bLen, arrayFormat):
  if bLen == 0:
  raise ArithmeticException()
- if arrayFormat not in (self.FORMAT_BCD, self.FORMAT_HEX):
- raise ArithmeticException()
  if bArray is None:
  raise NullPointerException()
  if arrayFormat == self.FORMAT_BCD:
@@ -40,22 +49,50 @@ def init(self, bArray, bOff, bLen, arrayFormat):
  self._value = 0
  for i in xrange(bLen):
  self._value = self._value << 8
- self._value += bArray[bOff+i]
+ self._value += from_hex(bArray[bOff+i])
+ else:
+ raise ArithmeticException
 
  @staticmethod
  def getMaxBytesSupported():
  # We have to lie there for practical reasons
  return 20
 
  def multiply(self, bArray, bOff, bLen, arrayFormat):
- other = BigNumber(70)
+ other = BigNumber()
  other.init(bArray, bOff, bLen, arrayFormat)
  self._value *= other._value
 
+ def subtract(self, bArray, bOff, bLen, arrayFormat):
+ other = BigNumber()
+ other.init(bArray, bOff, bLen, arrayFormat)
+ self._value -= other._value
+
  def compareTo(self, operand):
  if self._value == operand._value:
  return 0
  elif self._value > operand._value:
  return 1
  else:
  return -1
+
+ def toBytes(self, outBuf, bOff, numBytes, arrayFormat):
+ array = []
+ if arrayFormat == self.FORMAT_BCD:
+ value = self._value
+ while value > 100:
+ array.append(to_bcd(value % 100))
+ value = value // 100
+ elif arrayFormat == self.FORMAT_HEX:
+ value = self._value
+ while value > 0xff:
+ array.append(to_hex(value % 0xff))
+ value = value // 0xff
+ else:
+ raise ArithmeticException
+ if numBytes < len(array):
+ raise ArithmeticException
+ array.extend([0 for i in range(numBytes - len(array))])
+ array.reverse()
+ Util.arrayCopy(array, 0, outBuf, bOff, numBytes)
+