Data update

Task/Straddling-checkerboard/FreeBASIC/straddling-checkerboard.basic

@@ -0,0 +1,86 @@
+Function Encipher(bd As String, pt As String) As String
+    Dim As String enc(256), row(3), r2d, r3d, d, num, ct
+    Dim As Integer i = 1, j, col
+
+    For j = 0 To 3
+        row(j) = Mid(bd, i, Instr(i, bd, Chr(10)) - i)
+        i = Instr(i, bd, Chr(10)) + 1
+    Next j
+    r2d = Mid(row(2), 1, 1)
+    r3d = Mid(row(3), 1, 1)
+    For col = 1 To 10
+        d = Mid(row(0), col+1, 1)
+        enc(Asc(Mid(row(1), col+1, 1))) = d
+        enc(Asc(Mid(row(2), col+1, 1))) = r2d + d
+        enc(Asc(Mid(row(3), col+1, 1))) = r3d + d
+    Next col
+    num = enc(Asc("/"))
+    enc(Asc("/")) = ""
+    enc(Asc(" ")) = ""
+    ct = ""
+    For i = 0 To Len(pt)-1
+        j = Asc(Mid(pt, i+1, 1))
+        If j <= Asc("9") And j >= Asc("0") Then
+            ct += num + Chr(j)
+        Else
+            If j <= Asc("z") And j >= Asc("a") Then
+                j -= Asc("a") - Asc("A")
+            End If
+            ct += enc(j)
+        End If
+    Next i
+    Return ct
+End Function
+
+Function Decipher(bd As String, ct As String) As String
+    Dim As String row(3), pt, b
+    Dim As Integer i = 1, j, cx(10), r2d, r3d, r, d
+
+    For j = 0 To 3
+        row(j) = Mid(bd, i, Instr(i, bd, Chr(10)) - i)
+        i = Instr(i, bd, Chr(10)) + 1
+    Next j
+
+    For i = 1 To 10
+        cx(Asc(Mid(row(0), i+1, 1)) - Asc("0")) = i
+    Next i
+    r2d = Asc(Mid(row(2), 1, 1)) - Asc("0")
+    r3d = Asc(Mid(row(3), 1, 1)) - Asc("0")
+    pt = ""
+    i = 0
+    While i < Len(ct)
+        d = Asc(Mid(ct, i+1, 1)) - Asc("0")
+        If d = r2d Then
+            r = 2
+        Elseif d = r3d Then
+            r = 3
+        Else
+            pt += Mid(row(1), cx(d)+1, 1)
+            i += 1
+            Continue While
+        End If
+        i += 1
+        b = Mid(row(r), cx(Asc(Mid(ct, i+1, 1)) - Asc("0"))+1, 1)
+        If b = "/" Then
+            i += 1
+            pt += Mid(ct, i+1, 1)
+        Else
+            pt += b
+        End If
+        i += 1
+    Wend
+    Return pt
+End Function
+
+Dim As String key = _
+" 8752390146" + Chr(10) + _
+" ET AON RIS" + Chr(10) + _
+"5BC/FGHJKLM" + Chr(10) + _
+"0PQD.VWXYZU"
+Dim p As String = "you have put on 7.5 pounds since I saw you."
+Print p
+Dim c As String = Encipher(key, p)
+Print c
+Print Decipher(key, c)
+
+Sleep