1 files changed, 9 insertions, 0 deletions
diff --git a/csim/sim.c b/csim/sim.c
index 1dd2791..4451d0e 100644
--- a/csim/sim.c
+++ b/csim/sim.c
@@ -74,6 +74,13 @@ void read_inputs(t_machine *m, FILE *stream) {
     t_id var;
     t_program *p = m->prog;
 
+    int magic;
+    fscanf(stream, " %x", &magic);
+    if (magic != 0xFEED) {
+        fprintf(stderr, "(simulator) Protocol error.\n");
+        exit(1);
+    }
+
     if (p->n_inputs == 0) return;       // nothing to do
 
     for (i = 0; i < p->n_inputs; i++) {
@@ -213,6 +220,8 @@ void write_outputs(t_machine *m, FILE *stream) {
     t_value v, mask;
     t_program *p = m->prog;
 
+    fprintf(stream, "FED\n");
+
     for (i = 0; i < p->n_outputs; i++) {
         var = p->outputs[i];
         fprintf(stream, "%s\t", p->vars[var].name);