Initial commit

src/helpers/SimpleSeenTable.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include <Packet.h>
+#include <string.h>
+
+#define MAX_PACKET_HASHES  64
+
+class SimpleSeenTable {
+  uint8_t _hashes[MAX_PACKET_HASHES*MAX_HASH_SIZE];
+  int _next_idx;
+
+public:
+  SimpleSeenTable() { 
+    memset(_hashes, 0, sizeof(_hashes));
+    _next_idx = 0;
+  }
+
+  bool hasSeenPacket(const mesh::Packet* packet) {
+    uint8_t hash[MAX_HASH_SIZE];
+    packet->calculatePacketHash(hash);
+
+    const uint8_t* sp = _hashes;
+    for (int i = 0; i < MAX_PACKET_HASHES; i++, sp += MAX_HASH_SIZE) {
+      if (memcmp(hash, sp, MAX_HASH_SIZE) == 0) return true;
+    }
+
+    memcpy(&_hashes[_next_idx*MAX_HASH_SIZE], hash, MAX_HASH_SIZE);
+    _next_idx = (_next_idx + 1) % MAX_PACKET_HASHES;  // cyclic table
+
+    return false;
+  }
+
+};