Wrote license header prefixing tool and added some new code.

1 files changed, 51 insertions, 0 deletions

diff --git a/lskdecode.c b/lskdecode.c
new file mode 100644
index 0000000..96ab023
--- /dev/null
+++ b/lskdecode.c
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2014  Tomasz Kramkowski <tk@the-tk.com>
+ *
+ * This program is free software. It is licensed under version 3 of the
+ * GNU General Public License.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see [http://www.gnu.org/licenses/].
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+
+int main(int argc, char **argv)
+{
+	unsigned char subst[4][256];
+	unsigned char lastval[] = {249, 20, 174, 199};
+
+	/* Generate substitution tables. */
+	for (int i = 0; i < 256; i++) {
+		for (int ii = 0; ii < 4; ii++)
+			subst[ii][i] = lastval[ii];
+
+		if (i % 8 == 7) lastval[0] -= 13;
+		else lastval[0] += i & 1 ? 3 : -1;
+
+		if (i % 8 == 7) lastval[1] += 9;
+		else if ((i + 4) % 8 == 7) lastval[1] -=7;
+		else lastval[1] += 1;
+
+		if (i % 16 == 15) lastval[2] += 29;
+		else lastval[2] += i & 1 ? -3 : 1;
+
+		if (i % 8 == 7) lastval[3] += 15;
+		else lastval[3] -= 1;
+	}
+
+	/* decode */
+	int c;
+	int pos = argc > 1 ? strtol(argv[1], NULL, 10) : 0;
+	while ((c = getchar()) != EOF) {
+		for (int i = 0; i < 256; i++)
+			if (subst[pos%4][i] == c) {
+				if (isascii(i)) putchar(i);
+				break;
+			}
+		pos++;
+	}
+
+	return 0;
+}