Add software for Golay(24,12) lookup table.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6414 ab8295b8-cf94-4d9e-aec4-7959e3be5d79

lib/golay24_table.c

@@ -0,0 +1,28 @@
+void golay24_table_(int cw[])
+{
+  // Compute arnd return the table of 4096 codewords for the Golay (24,12) code.
+
+  // Array y contains the twelve rows (columns) of the parity-check matrix
+  int y[12] = { 0x7ff, 0xee2, 0xdc5, 0xb8b, 0xf16, 0xe2d,
+		0xc5b, 0x8b7, 0x96e, 0xadc, 0xdb8, 0xb71 };
+
+  int c[2];          /* Codeword composed of 12-bit info and 12-bit parity */
+
+
+  int i,j,k;
+  int aux;
+  int weight(int vector); 
+
+  for(k=0; k<4096; k++) {
+    c[0] = k;
+    c[1] = 0;
+    for (i=0; i<12; i++) {
+      aux = 0;
+      for (j=0; j<12; j++) {
+	aux = aux ^ ((c[0] & y[i]) >> j & 1);
+      }
+      c[1] = (c[1] << 1) ^ aux;
+    }
+    cw[k]=4096*c[0] + c[1];
+  }
+}