From a675f1613f8b0c375eb3cbbe7ae35a9d3de1c303 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Beno=C3=AEt=20Allard?= <benoit.allard@gmx.de>
Date: Thu, 22 Sep 2011 23:33:03 +0200
Subject: [PATCH] More methods for the BigNumber class

---
 pythoncardx/framework/math.py | 49 ++++++++++++++++++++++++++++++-----
 1 file changed, 43 insertions(+), 6 deletions(-)

diff --git a/pythoncardx/framework/math.py b/pythoncardx/framework/math.py
index 57d6bc5..4423722 100644
--- a/pythoncardx/framework/math.py
+++ b/pythoncardx/framework/math.py
@@ -1,4 +1,5 @@
 from python.lang import NullPointerException, ArithmeticException
+from pythoncard.framework import Util
 
 def from_bcd(data):
     """
@@ -7,19 +8,29 @@ 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
@@ -27,8 +38,6 @@ def __init__(self, maxBytes):
     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:
@@ -40,7 +49,9 @@ 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():
@@ -48,10 +59,15 @@ def getMaxBytesSupported():
         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
@@ -59,3 +75,24 @@ def compareTo(self, operand):
             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)
+