diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..65c4898
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,27 @@
+#include "monitor.h"
+#include <stdio.h>
+
+static void emit(monitor_t *monitor, uint8_t *frame) {
+    unsigned crc = 0;
+    for (int i = 0; i < 7; ++i) {
+        crc ^= frame[i];
+        for (int bit = 0; bit < 8; ++bit)
+            crc = (crc & 0x80u) ? ((crc << 1) ^ 7u) & 255u : (crc << 1) & 255u;
+    }
+    frame[7] = (uint8_t)crc;
+    printf("seq=%u status=%s\n", (unsigned)((frame[1] << 8) | frame[2]),
+           frame_result_name(monitor_accept(monitor, frame, 8)));
+}
+
+int main(void) {
+    monitor_t monitor;
+    monitor_init(&monitor);
+    uint8_t frame[8] = {1, 0, 1, 0, 25, 46, 224, 0};
+    emit(&monitor, frame);
+    frame[2] = 3;
+    emit(&monitor, frame);
+    emit(&monitor, frame);
+    printf("accepted=%u rejected=%u lost=%u duplicate=%u\n",
+           monitor.accepted, monitor.rejected, monitor.lost, monitor.duplicate);
+    return 0;
+}