diff options
Diffstat (limited to 'dos.c')
| -rw-r--r-- | dos.c | 162 |
1 files changed, 162 insertions, 0 deletions
@@ -0,0 +1,162 @@ +
+static char rcsid[] = "$Header: /home/sater/bridge/bigdeal/RCS/dos.c,v 1.9 2000/08/26 14:15:22 sater Exp $";
+
+#include <conio.h>
+#include <time.h>
+#include <ctype.h>
+#include <stdio.h>
+#include "types.h"
+#include "bigdeal.h"
+#include "collect.h"
+
+extern FILE *flog;
+
+/*
+ * Find the best clock to use in this environment
+ * We prefer uclock, since it generates more bits
+ * But it is not ansi, so use clock as an alternative
+ */
+#ifdef UCLOCKS_PER_SEC
+int
+bestclock()
+{
+
+ return (int) uclock();
+}
+#else
+#ifdef CLOCKS_PER_SEC
+int
+bestclock()
+{
+
+ return (int) clock();
+}
+#else
+There is no clock, this program needs it, so do not compile
+#endif
+#endif
+
+#define MAX_INTERVAL_ENTROPY 6
+
+int
+getchtm(int *nbits)
+/*
+ * Read one character from standard input
+ * Time the wait, and use bits for random
+ * MUST be in cbreak mode for this to work
+ */
+{
+ int t1, t2;
+ int tdiff;
+ int c;
+ int shift;
+ int b;
+
+ /*
+ * First get the best clock we have
+ */
+ t1 = bestclock();
+ /*
+ * Now get one character
+ */
+ c = getch();
+ /*
+ * If it is zero, which can happen with getch() under DOS
+ * we have a two character sequence(function key probably)
+ * and we make one character out of it by appending the next
+ */
+ if (c == 0)
+ c = getch() + 256;
+ /*
+ * and get the clock after the keypress
+ */
+ t2 = bestclock();
+ /*
+ * Number of ticks we waited goes to tdiff
+ */
+ tdiff = t2 - t1;
+ /*
+ * Now we are going to believe half the bits we get
+ */
+ for (shift = tdiff, b = 0; shift>2 ; shift >>= 2, b++)
+ ;
+ if (b < MAX_INTERVAL_ENTROPY)
+ *nbits = b;
+ else
+ *nbits = MAX_INTERVAL_ENTROPY;
+ /*
+ * We send all the bits to the collect pool
+ * but do not count the bits yet (parameter 0)
+ * because higher layers might decide not to believe this
+ * character, and its associated timing
+ */
+ collect_more((byte *) &t1, sizeof(t1), 0);
+ collect_more((byte *) &t2, sizeof(t2), 0);
+ if (flog)
+ fprintf(flog, "Collected character %d, timediff %d, timebits %d\n",
+ c, tdiff, *nbits);
+ return c;
+}
+
+void
+os_collect() {
+ time_t t;
+
+ (void) time(&t);
+ /* Trust 6 bits of seconds */
+ collect_more((byte *) &t, sizeof(t), 6);
+}
+
+void
+cbreak()
+{
+
+}
+
+void
+cooked()
+{
+
+}
+
+void
+os_start()
+{
+
+ /*
+ * Start the clock running
+ */
+ (void) bestclock();
+
+}
+
+void
+os_finish()
+{
+
+}
+
+int
+legal_filename_prefix(char *s)
+/*
+ * Legal prefix to make legal name when three letter suffix added
+ */
+{
+
+ if (*s == 0) /* Too short */
+ return 0;
+ if (strlen(s) > 8)
+ return 0;
+ while (*s) {
+ if (!isalnum(*s) && *s != '-' && *s != '_')
+ return 0;
+ s++;
+ }
+ return 1;
+}
+
+char *os_init_file_name()
+{
+
+ return "bigdeal.ini";
+}
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