added simple fake radio driver with ~100ms latency.

fakeradio.c

@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <errno.h>
+
+int main(int argc,char **argv)
+{
+  int left=posix_openpt(O_RDWR|O_NOCTTY);
+  grantpt(left); unlockpt(left);
+  int right=posix_openpt(O_RDWR|O_NOCTTY);
+  grantpt(right); unlockpt(right);
+  fprintf(stdout,"%s\n",ptsname(left));
+  fprintf(stdout,"%s\n",ptsname(right));
+
+  fcntl(left,F_SETFL,fcntl(left, F_GETFL, NULL)|O_NONBLOCK);
+  fcntl(right,F_SETFL,fcntl(right, F_GETFL, NULL)|O_NONBLOCK);
+
+  struct pollfd fds[2];
+  int i;
+  char buffer[8192];
+
+  fds[0].fd=left;
+  fds[0].events=POLLIN;
+  fds[1].fd=right;
+  fds[2].events=POLLIN;
+
+  while(1) {
+    poll(fds,2,1000);
+    for(i=0;i<2;i++) {
+      if (1||fds[i].revents&POLLIN) {
+	int bytes=read(fds[i].fd,buffer,8192);
+	if (bytes>0) {
+	  write(fds[i^1].fd,buffer,bytes);
+	  printf("reading from %d, read %d, errno=%d\n",i,bytes,errno);
+	}       
+	fds[i].revents=0;
+      }
+    }
+    usleep(100000);
+
+  }
+
+  return 0;
+}