From 5b745be4ab95bf047421d7518db91b644da900d8 Mon Sep 17 00:00:00 2001
From: MrHate <gydeng0@gmail.com>
Date: Wed, 7 Oct 2020 00:15:37 +0800
Subject: [PATCH] Add 2's complement negative support

---
 alp/__init__.py   |  1 +
 alp/tc.py         | 25 +++++++++++++++++++++++++
 convertBinary.py  | 11 ++++++++++-
 convertDecimal.py | 11 ++++++++++-
 convertHex.py     | 11 ++++++++++-
 convertOctal.py   | 11 ++++++++++-
 6 files changed, 66 insertions(+), 4 deletions(-)
 create mode 100644 alp/tc.py

diff --git a/alp/__init__.py b/alp/__init__.py
index 4b9b127..d83806e 100755
--- a/alp/__init__.py
+++ b/alp/__init__.py
@@ -1,4 +1,5 @@
 from .core import *
+from .tc import *
 
 try:
     from .item import *
diff --git a/alp/tc.py b/alp/tc.py
new file mode 100644
index 0000000..0055752
--- /dev/null
+++ b/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
+
diff --git a/convertBinary.py b/convertBinary.py
index 8dab6e6..bc3ae3b 100644
--- a/convertBinary.py
+++ b/convertBinary.py
@@ -24,4 +24,13 @@
 h = alp.Item(**hexDic)
 
 itemsList = [d, o, h]
-alp.feedback(itemsList)
\ No newline at end of file
+
+# 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)
diff --git a/convertDecimal.py b/convertDecimal.py
index 282a5f9..3b05c85 100644
--- a/convertDecimal.py
+++ b/convertDecimal.py
@@ -23,4 +23,13 @@
 h = alp.Item(**hexDic)
 
 itemsList = [b, o, h]
-alp.feedback(itemsList)
\ No newline at end of file
+
+# 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)
diff --git a/convertHex.py b/convertHex.py
index ed420d6..8ab7599 100644
--- a/convertHex.py
+++ b/convertHex.py
@@ -23,4 +23,13 @@
 o = alp.Item(**octalDic)
 
 itemsList = [d, b, o]
-alp.feedback(itemsList)
\ No newline at end of file
+
+# 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)
diff --git a/convertOctal.py b/convertOctal.py
index 0d53ee6..5a3c1c7 100644
--- a/convertOctal.py
+++ b/convertOctal.py
@@ -24,4 +24,13 @@
 h = alp.Item(**hexDic)
 
 itemsList = [d, b, h]
-alp.feedback(itemsList)
\ No newline at end of file
+
+# 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)