initial drop of phosphor-ipmi-blobs

This implements a majority of the OEM IPMI BLOBS protocol.  The only
piece missing from this is the timed expiration of sessions.

Change-Id: I82c9d17b625c94fc3340edcfabbbf1ffeb5ad7ac
Signed-off-by: Patrick Venture <venture@google.com>

1 files changed, 60 insertions, 0 deletions

diff --git a/crc.hpp b/crc.hpp
new file mode 100644
index 0000000..3793d9a
--- /dev/null
+++ b/crc.hpp
@@ -0,0 +1,60 @@
+#pragma once
+
+#include <cstdint>
+
+namespace blobs
+{
+
+using std::size_t;
+using std::uint16_t;
+using std::uint32_t;
+using std::uint8_t;
+
+constexpr uint16_t crc16Ccitt = 0x1021;
+/* Value from: http://srecord.sourceforge.net/crc16-ccitt.html for
+ * implementation without explicit bit adding.
+ */
+constexpr uint16_t crc16Initial = 0xFFFF;
+
+class CrcInterface
+{
+  public:
+    virtual ~CrcInterface() = default;
+
+    /**
+     * Reset the crc.
+     */
+    virtual void clear() = 0;
+
+    /**
+     * Provide bytes against which to compute the crc.  This method is
+     * meant to be only called once between clear() and get().
+     *
+     * @param[in] bytes - the data against which to compute.
+     * @param[in] length - the number of bytes.
+     */
+    virtual void compute(const uint8_t* bytes, uint32_t length) = 0;
+
+    /**
+     * Read back the current crc value.
+     *
+     * @return the crc16 value.
+     */
+    virtual uint16_t get() const = 0;
+};
+
+class Crc16 : public CrcInterface
+{
+  public:
+    Crc16() : poly(crc16Ccitt), value(crc16Initial){};
+    ~Crc16() = default;
+
+    void clear() override;
+    void compute(const uint8_t* bytes, uint32_t length) override;
+    uint16_t get() const override;
+
+  private:
+    uint16_t poly;
+    uint16_t value;
+};
+} // namespace blobs