buffer: bugfix (v2) consolidate the offset and readptr

- It didn't make sense to make the user keep count of the different
  types of read pointers, instead do the relative calculation at the
  lowest level (wraparoundRead)
- Added further tests to prove out that readPtr is being updated
  properly in wraparoundRead)
- Fixed wraparoundRead, as it was relying on the dataInterface->read to
  read until the "end". The "end" was fixed in the bugfix #1 to be the
  end of the queue instead of the mmaped buffer.
- took out addtionalBoundaryCheck from wraparoundRead, as it was no
  longer needed

Tested: Unit tested

Signed-off-by: Brandon Kim <brandonkim@google.com>
Change-Id: I101360223597d197362dc1dbe4a27601da09933f
diff --git a/include/buffer.hpp b/include/buffer.hpp
index 7738339..d86f204 100644
--- a/include/buffer.hpp
+++ b/include/buffer.hpp
@@ -105,39 +105,37 @@
 
     /**
      * Write to the bufferHeader and update the read pointer
-     * @param[in] newReadPtr - read pointer to update to.
-     *  "readPtr"s (including this one) are offset relative to the "Error Log
-     *  Queue region" = (sizeof(CircularBufferHeader) + UE reserved region)
+     * @param[in] newReadPtr - read pointer to update to
      */
     virtual void updateReadPtr(const uint32_t newReadPtr) = 0;
 
     /**
      * Wrapper for the dataInterface->read, performs wraparound read
      *
-     * @param[in] offset - offset relative to the beginning of MMIO space
+     * @param[in] relativeOffset - offset relative the "Error Log
+     *  Queue region" = (sizeof(CircularBufferHeader) + UE reserved region)
      * @param[in] length - bytes to read
-     * @param[in] additionalBoundaryCheck - bytes to add to the boundary check
-     * for added restriction
      * @return the bytes read
      */
-    virtual std::vector<uint8_t>
-        wraparoundRead(const uint32_t offset, const uint32_t length,
-                       const uint32_t additionalBoundaryCheck) = 0;
+    virtual std::vector<uint8_t> wraparoundRead(const uint32_t relativeOffset,
+                                                const uint32_t length) = 0;
     /**
      * Read the entry header from shared buffer
      *
-     * @param[in] offset - offset relative to the beginning of MMIO space
+     * @param[in] relativeOffset - offset relative the "Error Log
+     *  Queue region" = (sizeof(CircularBufferHeader) + UE reserved region)
      * @return the entry header
      */
-    virtual struct QueueEntryHeader readEntryHeader(size_t offset) = 0;
+    virtual struct QueueEntryHeader readEntryHeader(size_t relativeOffset) = 0;
 
     /**
      * Read the queue entry from the error log queue
      *
-     * @param[in] offset - offset relative to the beginning of MMIO space
-     * @return entry header and entry pair read from buffer
+     * @param[in] relativeOffset - offset relative the "Error Log
+     *  Queue region" = (sizeof(CircularBufferHeader) + UE reserved region)
+     * * @return entry header and entry pair read from buffer
      */
-    virtual EntryPair readEntry(size_t offset) = 0;
+    virtual EntryPair readEntry(size_t relativeOffset) = 0;
 };
 
 /**
@@ -156,11 +154,10 @@
     void readBufferHeader() override;
     struct CircularBufferHeader getCachedBufferHeader() const override;
     void updateReadPtr(const uint32_t newReadPtr) override;
-    std::vector<uint8_t>
-        wraparoundRead(const uint32_t offset, const uint32_t length,
-                       const uint32_t additionalBoundaryCheck = 0) override;
-    struct QueueEntryHeader readEntryHeader(size_t offset) override;
-    EntryPair readEntry(size_t offset) override;
+    std::vector<uint8_t> wraparoundRead(const uint32_t relativeOffset,
+                                        const uint32_t length) override;
+    struct QueueEntryHeader readEntryHeader(size_t relativeOffset) override;
+    EntryPair readEntry(size_t relativeOffset) override;
 
   private:
     /** @brief The Error log queue starts after the UE region, which is where
diff --git a/include/data_interface.hpp b/include/data_interface.hpp
index bf91817..8292143 100644
--- a/include/data_interface.hpp
+++ b/include/data_interface.hpp
@@ -18,7 +18,7 @@
     /**
      * Read bytes from shared buffer (blocking call).
      *
-     * @param[in] offset - offset to read from
+     * @param[in] offset - offset to read from relative to MMIO space
      * @param[in] length - number of bytes to read
      * @return the bytes read
      */
@@ -28,7 +28,7 @@
     /**
      * Write bytes to shared buffer.
      *
-     * @param[in] offset - offset to write to
+     * @param[in] offset - offset to write to relative to MMIO space
      * @param[in] bytes - byte vector of data.
      * @return return the byte length written
      */