bitutils.py: harden shifts, add multibit XOR operation and sum function with right alignment

src/bitutils.py

@@ -20,13 +20,13 @@ al = align_binary_to_left
 
 
 def shift_left(rg, fill_bit = 0):
-    return rg[1:] + fill_bit
+    return rg[1:] + str(fill_bit)
 
 l = shift_left
 
 
 def shift_right(rg, fill_bit = 0):
-    return fill_bit + rg[:-1]
+    return str(fill_bit) + rg[:-1]
 
 r = shift_right
 
@@ -37,14 +37,20 @@ def sum_supplementary_codes(x, y, size):
 sum = sum_supplementary_codes
 
 
-def sum_supplementary_codes_with_overspill(x, y, size):
+def sum_supplementary_codes_right_align(x, y, size):
+    return ar(bin(int("0b"+x, 2) + int("0b"+y, 2))[2:], size)
+
+rsum = sum_supplementary_codes_right_align
+
+
+def sum_supplementary_codes_with_overflow(x, y, size):
     result = bin(int("0b"+x, 2) + int("0b"+y, 2))[2:]
     if len(result) > size:
         return al(result, size), '1'
     else:
         return al(result, size), '0'
 
-sump = sum_supplementary_codes_with_overspill
+sump = sum_supplementary_codes_with_overflow
 
 
 def invert_bit(b):
@@ -57,3 +63,15 @@ def invert_bit(b):
         exit(1)
 
 inv = invert_bit
+
+
+def xor(x, y):
+    if len(x) == len(y):
+        result = ''
+        for i in zip(x, y):
+            if x != y:
+                result += '1'
+            else:
+                result += '0'
+
+    return result

src/mult-test.py

@@ -24,4 +24,4 @@ for x in range(top_value):
 if len(errors) == 0:
     print("Testing finished, no miscalculations detected.\nIt's safe to use!")
 else:
-    print("Testing failed with {len(errors)} errors.")
+    print(f"Testing failed with {len(errors)} errors.")

src/multiply.py

@@ -1,3 +1,9 @@
+import bitutils as bu
+
+# this needs to be replaced at some point, because:
+# - it uses old notation for align operation, which contradicts with
+#   modern instruction sets, thus making it easily confusable with
+#   the bu.al() operation which aligns bits to the left
 def align_binary_to_right(value, size):
     if "b" in value:
         result = value.split("b")[1]
@@ -15,19 +21,62 @@ def multiply(n, x, y, method):
     - get just the end result of binary multiplication;
 
     it takes 4 arguments:
-    n - (int) base register bit depth
+    n - (int) base register bit length
     x - (int) value for X operand
     y - (int) value for Y operand
     method - (int) which method to use to perform multiplication
 
     it returns 2 items:
-    - (list) table with step-by-step operations and descriptions
-    - (str)  binary representation of the result
+    - (list) table with step-by-step operations and descriptions (table format
+             depends on the chosen method)
+    - (str)  binary representation of the result (method-independant)
 
-    Methods fully supported: №4
+    Methods fully supported:
+    - №2 (passed mult-test.py with 10 bits)
+    - №4 (passed mult-test.py with 12 bits)
     '''
 
-    if method == 4:
+    if method == 2:
+        # every table line has registers like so: RG1, RG3, RG2
+        data_table = [[["0", "0"*(2*n), "0"*n + bu.ar(bin(y)[2:], n), bu.ar(bin(x)[2:], n), "-"]]*2]
+
+        # iteration number
+        i = 0
+
+        while int('0b' + data_table[-1][-1][3], 2) != 0:
+            data_table.append([])
+            i += 1
+
+            if data_table[-2][-1][3][-1] == "1":
+                data_table[-1].append([
+                    i,
+                    #al(bin(int("0b"+data_table[-2][-1][1], 2) + int("0b"+data_table[-2][-1][2], 2))[-(2*n+1):], 2*n+1), # RG1 + RG3
+                    bu.rsum(data_table[-2][-1][1], data_table[-2][-1][2], 2*n),
+                    data_table[-2][-1][2],
+                    data_table[-2][-1][3],
+                    "RG1+RG3"
+                ])
+
+                data_table[-1].append([
+                    i,
+                    data_table[-1][-1][1],
+                    bu.l(data_table[-1][-1][2]), # l(RG3).0
+                    bu.r(data_table[-1][-1][3]), # 0.r(RG2)
+                    "0.r(RG2), l(RG3).0"
+                ])
+
+            else:
+                data_table[-1].append([
+                    i,
+                    data_table[-2][-1][1],
+                    bu.l(data_table[-2][-1][2]), # l(RG3).0
+                    bu.r(data_table[-2][-1][3]), # 0.r(RG2)
+                    "0.r(RG2), l(RG3).0"
+                ])
+
+        return data_table, data_table[-1][-1][1]
+
+    elif method == 4:
         # every table line has registers like so: RG1, RG3, RG2
         data_table = [[["0", "0"*(2*n+1), "0" + al(bin(y)[2:], n) + "0"*n, al(bin(x)[2:], n), "-"]]*2]
 
@@ -66,6 +115,19 @@ def multiply(n, x, y, method):
 
         return data_table, data_table[-1][-1][1][:-1]
 
+def table_to_text(dt):
+    from lib.prettytable import PrettyTable
+    pt = PrettyTable()
+    pt.field_names = ["Iteration", "RG1", "RG3", "RG2", "Operations"]
+
+    for i in dt:
+        for j in range(len(i)):
+            if j+1 == len(i):
+                pt.add_row(i[j], divider = True)
+            else:
+                pt.add_row(i[j])
+
+    return pt.get_string()
 
 if __name__ == "__main__":
     # a fully functional reference
@@ -86,7 +148,8 @@ if __name__ == "__main__":
     method = int(input("Method: "))
 
     dt, result = multiply(n, x, y, method)
-
+    
+    '''
     from lib.prettytable import PrettyTable
     pt = PrettyTable()
     pt.field_names = ["Iteration", "RG1", "RG3", "RG2", "Operations"]
@@ -99,4 +162,6 @@ if __name__ == "__main__":
                 pt.add_row(i[j])
 
     print(pt)
+    '''
+    print(table_to_text(dt))
     print(f"Result: {result}")