Add 2's complement negative support

alp/__init__.py

@@ -1,4 +1,5 @@
 from .core import *
+from .tc import *
 
 try:
     from .item import *

alp/tc.py

@@ -0,0 +1,25 @@
+def decimal2negative(n):
+    """
+        We convert a decimal number into a negative based on the 2's complement.
+        As an example for an arbitrary decimal larger than 1:
+
+           0101         (binary for decimal 5)
+        -> 101          (trim the zeros before the most significant bit)
+        -> -(2^2)+2^0   (convert binary into decimal under the 2's complment principle)
+        -> -3           (result)
+    """
+    if (n <= 1):
+        return 0
+
+    nn = n
+    bias = 1
+    msb = 0
+    n = int(n / 2)
+
+    while (n > 0):
+        n = int(n / 2)
+        msb += 1
+        bias *= 2
+
+    return (((1 << msb) - 1) & nn) - bias
+

convertBinary.py

@@ -24,4 +24,13 @@
 h = alp.Item(**hexDic)
 
 itemsList = [d, o, h]
-alp.feedback(itemsList)
+
+# calculate negative number
+tc = alp.decimal2negative(decimal)
+if (tc < 0):
+    # create associative array and create xml from it
+    tcDic = dict(title=str(tc), subtitle="2's complement negative after trimming the zeros before the most significant bit", uid="negative", valid=True, arg=str(tc), icon="icons/decimal.png")
+    t = alp.Item(**tcDic)
+    itemsList += [t]
+
+alp.feedback(itemsList)

convertDecimal.py

@@ -23,4 +23,13 @@
 h = alp.Item(**hexDic)
 
 itemsList = [b, o, h]
-alp.feedback(itemsList)
+
+# calculate negative number
+tc = alp.decimal2negative(int(sys.argv[1]))
+if (tc < 0):
+    # create associative array and create xml from it
+    tcDic = dict(title=str(tc), subtitle="2's complement negative after trimming the zeros before the most significant bit", uid="negative", valid=True, arg=str(tc), icon="icons/decimal.png")
+    t = alp.Item(**tcDic)
+    itemsList += [t]
+
+alp.feedback(itemsList)

convertHex.py

@@ -23,4 +23,13 @@
 o = alp.Item(**octalDic)
 
 itemsList = [d, b, o]
-alp.feedback(itemsList)
+
+# calculate negative number
+tc = alp.decimal2negative(decimal)
+if (tc < 0):
+    # create associative array and create xml from it
+    tcDic = dict(title=str(tc), subtitle="2's complement negative after trimming the zeros before the most significant bit", uid="negative", valid=True, arg=str(tc), icon="icons/decimal.png")
+    t = alp.Item(**tcDic)
+    itemsList += [t]
+
+alp.feedback(itemsList)

convertOctal.py

@@ -24,4 +24,13 @@
 h = alp.Item(**hexDic)
 
 itemsList = [d, b, h]
-alp.feedback(itemsList)
+
+# calculate negative number
+tc = alp.decimal2negative(decimal)
+if (tc < 0):
+    # create associative array and create xml from it
+    tcDic = dict(title=str(tc), subtitle="2's complement negative after trimming the zeros before the most significant bit", uid="negative", valid=True, arg=str(tc), icon="icons/decimal.png")
+    t = alp.Item(**tcDic)
+    itemsList += [t]
+
+alp.feedback(itemsList)