--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Meerwald/gen_cox_sig.c	Sun Aug 12 13:14:34 2007 +0200
@@ -0,0 +1,158 @@
+#include "wm.h"
+
+char *progname;
+
+void usage(void) {
+  fprintf(stderr, "usage: %s [-a n] [-d n] [-m n] [-n n] [-o file] [-s file] [-S n]\n\n", progname);
+  fprintf(stderr, "\t-a n\t\talpha factor (default 0.3)\n");
+  fprintf(stderr, "\t-d n\t\tdeviation (default 1.0)\n");
+  fprintf(stderr, "\t-h\t\tprint usage\n");
+  fprintf(stderr, "\t-m n \t\tmean value (default 0.0)\n");
+  fprintf(stderr, "\t-n n\t\twatermark length (default 100)\n");
+  fprintf(stderr, "\t-o file\t\toutput file\n");
+  fprintf(stderr, "\t-s file\t\tuse signature file's embedding information\n");
+  fprintf(stderr, "\t-S n\t\tseed\n");
+  exit(0);
+}
+
+int main(int argc, char *argv[]) {
+  FILE *out = stdout;
+  FILE *sig = NULL;
+
+  char output_name[MAXPATHLEN] = "(stdout)";
+  char signature_name[MAXPATHLEN];
+
+  int c;
+  int i;
+  int n = 100;
+  int s = 0;
+  double a = 0.3;
+  double m = 0.0;
+  double d = 1.0;
+
+  progname = argv[0];
+
+  while ((c = getopt(argc, argv, "a:d:h?m:n:o:s:S:")) != EOF) {
+    switch (c) {
+      case 'a':
+        a = atof(optarg);
+        if (a <= 0.0) {
+          fprintf(stderr, "%s: alpha factor %f out of range\n", progname, a);
+          exit(1);
+        }
+        break;
+      case 'd':
+        d = atof(optarg);
+        if (d <= 0.0) {
+          fprintf(stderr, "%s: deviation %f out of range\n", progname, d);
+          exit(1);
+        }
+        break;
+      case 'h':
+      case '?':
+        usage();
+        break;
+      case 'm':
+        m = atof(optarg);
+        break;
+      case 'n':
+        n = atoi(optarg);
+        if (n < 1 || n > 32000) {
+          fprintf(stderr, "%s: watermark length %d out of range\n", progname, n);
+          exit(1);
+        }
+        break;
+      case 'o':
+        if ((out = fopen(optarg, "w")) == NULL) {
+          fprintf(stderr, "%s: unable to open output file %s\n", progname, optarg);
+          exit(1);
+        }
+        strcpy(output_name, optarg);
+        break;
+      case 's':
+        if ((sig = fopen(optarg, "r")) == NULL) {
+          fprintf(stderr, "%s: unable to open signature file %s\n", progname, optarg);
+          exit(1);
+        }
+        strcpy(signature_name, optarg);
+        break;      
+      case 'S':
+        s = atoi(optarg);
+        break;
+    }
+  }
+
+  argc -= optind;
+  argv += optind;
+
+  if (argc > 0) {
+    usage();
+    exit(1);
+  }
+
+    if (sig) {
+    char line[32];
+    fgets(line, sizeof(line), sig);
+    if (strspn(line, "CXSG") >= 4) {
+      if (n == 0)
+        fscanf(sig, "%d\n", &n);
+      else
+        fscanf(sig, "%*d\n");
+      if (a == 0.0)
+        fscanf(sig, "%lf\n", &a);
+      else
+        fscanf(sig, "%*lf\n");
+      if (m == 0.0)
+        fscanf(sig, "%lf\n", &m);
+      else
+        fscanf(sig, "%*lf\n");
+      if (d == 0.0)
+        fscanf(sig, "%lf\n", &d);
+      else
+        fscanf(sig, "%*lf\n");
+    }
+    else {
+      fprintf(stderr, "%s: invalid signature file %s\n", progname, signature_name);
+      exit(1);
+    }
+    close(sig);
+  }
+
+  if (s)
+    srandom(s);
+  else
+    srandom(time(NULL) * getpid());
+
+  fprintf(out, "CXSG\n");
+  fprintf(out, "%d\n", n);
+  fprintf(out, "%f\n", a);
+  fprintf(out, "%f\n", m);
+  fprintf(out, "%f\n", d);
+
+  n >>= 1;
+  while (n > 0) {
+    double x;
+    double x1, x2;
+
+    /*
+     * Algorithm P (Polar method for normal deviates),
+     * Knuth, D., "The Art of Computer Programming", Vol. 2, 3rd Edition, p. 122
+     */
+    do {
+      x1 = 2.0 * ((random() & RAND_MAX) / ((double) RAND_MAX + 1.0)) - 1.0;
+      x2 = 2.0 * ((random() & RAND_MAX) / ((double) RAND_MAX + 1.0)) - 1.0;
+      x = x1 * x1 + x2 * x2;
+    } while (x >= 1.0);
+    x1 *= sqrt((-2.0) * log(x) / x);
+    x2 *= sqrt((-2.0) * log(x) / x);
+
+    fprintf(out, "%f\n", m + d * x1);
+    fprintf(out, "%f\n", m + d * x2);
+
+    n--;
+  }
+
+  fclose(out);
+
+  exit(0);
+}