Add COBS implementation of ZCM serial transport

.clang-format

@@ -0,0 +1,23 @@
+BasedOnStyle: Google
+AllowShortBlocksOnASingleLine: true
+AllowShortIfStatementsOnASingleLine: true
+ColumnLimit: 80
+DerivePointerAlignment: false
+PointerAlignment: Left
+IndentWidth: 4
+TabWidth: 4
+UseTab: Never
+BreakBeforeBraces: Stroustrup
+IncludeBlocks: Regroup
+IncludeCategories:
+  - Regex:           '^"(llvm|llvm-c|clang|clang-c)/'
+    Priority:        2
+    SortPriority:    2
+    CaseSensitive:   true
+  - Regex:           '^((<|")(gtest|gmock|isl|json)/)'
+    Priority:        3
+  - Regex:           '<[[:alnum:].]+>'
+    Priority:        4
+  - Regex:           '.*'
+    Priority:        1
+    SortPriority:    0

.gitignore

@@ -8,3 +8,4 @@ build/
 .lock*
 .waf*
 deps/
+.vscode/

examples/cpp/transport/SerialCobsTransportTest.cpp

@@ -0,0 +1,94 @@
+#include "types/example_t.hpp"
+#include "zcm/transport/cobs_serial/generic_serial_cobs_transport.h"
+#include "zcm/zcm-cpp.hpp"
+#include <sys/time.h>
+
+#include <cassert>
+#include <iostream>
+#include <queue>
+
+using namespace std;
+using namespace zcm;
+
+#define PUBLISH_DT (1e6) / (5)
+#define MIN(A, B) ((A) < (B)) ? (A) : (B)
+#define MAX_FIFO 12
+
+queue<uint8_t> fifo;
+
+static size_t get(uint8_t* data, size_t nData, void* usr)
+{
+    size_t n = MIN(MAX_FIFO, nData);
+    n = MIN(fifo.size(), n);
+
+    for (size_t i = 0; i < n; ++i) {
+        data[i] = fifo.front();
+        fifo.pop();
+    }
+
+    return n;
+}
+
+static size_t put(const uint8_t* data, size_t nData, void* usr)
+{
+    size_t n = MIN(MAX_FIFO - fifo.size(), nData);
+    // cout << "Put " << n << " bytes" << endl;
+
+    for (size_t i = 0; i < n; ++i) fifo.push(data[i]);
+
+    return n;
+}
+
+static uint64_t utime(void* usr)
+{
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    return (uint64_t)tv.tv_sec * 1000000 + tv.tv_usec;
+}
+
+class Handler {
+    int64_t lastHost = 0;
+
+   public:
+    void handle(const ReceiveBuffer* rbuf, const string& chan,
+                const example_t* msg)
+    {
+        cout << "Message received" << endl;
+
+        if (msg->timestamp <= lastHost || rbuf->recv_utime < lastHost) {
+            assert("ERROR: utime mismatch. This should never happen");
+        }
+        lastHost = msg->timestamp;
+    }
+};
+
+int main(int argc, const char* argv[])
+{
+    ZCM zcmLocal(zcm_trans_generic_serial_cobs_create(&get, &put, NULL, &utime,
+                                                      NULL, 1024, 1024 * 5));
+
+    example_t example = {};
+    example.num_ranges = 1;
+    example.ranges.resize(1);
+    example.ranges.at(0) = 1;
+
+    Handler handler;
+    auto sub = zcmLocal.subscribe("EXAMPLE", &Handler::handle, &handler);
+
+    uint64_t nextPublish = 0;
+    while (true) {
+        uint64_t now = utime(NULL);
+        if (now > nextPublish) {
+            cout << "Publishing" << endl;
+            example.timestamp = now;
+            zcmLocal.publish("EXAMPLE", &example);
+            nextPublish = now + PUBLISH_DT;
+        }
+
+        zcmLocal.handleNonblock();
+    }
+
+    zcmLocal.unsubscribe(sub);
+
+    return 0;
+}

examples/cpp/transport/wscript

@@ -5,3 +5,7 @@ def build(ctx):
     ctx.program(target = 'generic-serial',
                 use = 'default zcm examplezcmtypes_cpp',
                 source = 'SerialTransportTest.cpp')
+
+    ctx.program(target = 'generic-cobs-serial',
+                use = 'default zcm examplezcmtypes_cpp',
+                source = 'SerialCobsTransportTest.cpp')