Data commit

Task/CRC-32/FreeBASIC/crc-32.basic

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+' version 18-03-2017
+' compile with: fbc -s console
+
+Function crc32(buf As String) As UInteger<32>
+
+    Static As UInteger<32> table(256)
+    Static As UInteger<32> have_table
+    Dim As UInteger<32> crc, k
+    Dim As ULong i, j
+
+    If have_table = 0 Then
+        For i = 0 To 255
+            k = i
+            For j = 0 To 7
+                If (k And 1) Then
+                    k Shr= 1
+                    k Xor= &Hedb88320
+                Else
+                    k Shr= 1
+                End If
+                table(i) = k
+            Next
+        Next
+        have_table = 1
+    End If
+
+    crc = Not crc ' crc = &Hffffffff
+
+    For i = 0 To Len(buf) -1
+        crc = (crc Shr 8) Xor table((crc And &hff) Xor buf[i])
+    Next
+
+    Return Not crc
+
+End Function
+
+' ------=< MAIN >=------
+
+Dim As String l = "The quick brown fox jumps over the lazy dog"
+Dim As UInteger<32> crc
+
+Print "input = "; l
+print
+Print "The CRC-32 checksum = "; Hex(crc32(l), 8)
+
+' empty keyboard buffer
+While Inkey <> "" : Wend
+Print : Print "hit any key to end program"
+Sleep
+End