Changes frame length to mean bytes of samples in frame

I misunderstood the meaning of the frame header's "length" field: I
thought that it meant the number of samples in the frame. It actually
means the number of bytes of samples in the frame. This CL fixes that
mistake.

BUG=542837

Review URL: https://codereview.chromium.org/1579753002

Cr-Commit-Position: refs/heads/master@{#368863}

3 files changed, 14 insertions, 20 deletions

diff --git a/tools/battor_agent/battor_agent.cc b/tools/battor_agent/battor_agent.cc
index a613566..077aa7f 100644
--- a/tools/battor_agent/battor_agent.cc
+++ b/tools/battor_agent/battor_agent.cc
@@ -71,18 +71,12 @@ bool ParseSampleFrame(BattOrMessageType type,
   memcpy(frame_header, frame_ptr, sizeof(BattOrFrameHeader));
   frame_ptr += sizeof(BattOrFrameHeader);
 
-  // The remaining bytes in the frame contain an array of raw samples.
-  // Therefore, the number of samples in the frame should correspond to number
-  // of total bytes remaining in the frame.
-  uint8_t samples_in_frame =
-      (msg.size() - sizeof(BattOrFrameHeader)) / sizeof(RawBattOrSample);
-
-  if (samples_in_frame != frame_header->length)
+  size_t remaining_bytes = msg.size() - sizeof(BattOrFrameHeader);
+  if (remaining_bytes != frame_header->length)
     return false;
 
-  samples->resize(samples_in_frame);
-  memcpy(samples->data(), frame_ptr,
-         samples_in_frame * sizeof(RawBattOrSample));
+  samples->resize(remaining_bytes / sizeof(RawBattOrSample));
+  memcpy(samples->data(), frame_ptr, remaining_bytes);
 
   return true;
 }
diff --git a/tools/battor_agent/battor_agent_unittest.cc b/tools/battor_agent/battor_agent_unittest.cc
index 15b7205..f7bf70e 100644
--- a/tools/battor_agent/battor_agent_unittest.cc
+++ b/tools/battor_agent/battor_agent_unittest.cc
@@ -429,7 +429,7 @@ TEST_F(BattOrAgentTest, StopTracing) {
   RunStopTracingTo(BattOrAgentState::SAMPLES_REQUEST_SENT);
 
   // Send the calibration frame.
-  BattOrFrameHeader cal_frame_header{0, 2};
+  BattOrFrameHeader cal_frame_header{0, 2 * sizeof(RawBattOrSample)};
   RawBattOrSample cal_frame[] = {
       RawBattOrSample{1, 1}, RawBattOrSample{2, 2},
   };
@@ -437,20 +437,20 @@ TEST_F(BattOrAgentTest, StopTracing) {
                             CreateFrame(cal_frame_header, cal_frame, 2));
 
   // Send the two real data frames.
-  BattOrFrameHeader frame_header1{0, 3};
+  BattOrFrameHeader frame_header1{0, 3 * sizeof(RawBattOrSample)};
   RawBattOrSample frame1[] = {
       RawBattOrSample{1, 1}, RawBattOrSample{2, 2}, RawBattOrSample{3, 3},
   };
   GetAgent()->OnMessageRead(true, BATTOR_MESSAGE_TYPE_SAMPLES,
                             CreateFrame(frame_header1, frame1, 3));
 
-  BattOrFrameHeader frame_header2{0, 1};
+  BattOrFrameHeader frame_header2{0, 1 * sizeof(RawBattOrSample)};
   RawBattOrSample frame2[] = {RawBattOrSample{1, 1}};
   GetAgent()->OnMessageRead(true, BATTOR_MESSAGE_TYPE_SAMPLES,
                             CreateFrame(frame_header2, frame2, 1));
 
   // Send an empty last frame to indicate that we're done.
-  BattOrFrameHeader frame_header3{0, 0};
+  BattOrFrameHeader frame_header3{0, 0 * sizeof(RawBattOrSample)};
   RawBattOrSample frame3[] = {};
   GetAgent()->OnMessageRead(true, BATTOR_MESSAGE_TYPE_SAMPLES,
                             CreateFrame(frame_header3, frame3, 0));
@@ -531,7 +531,7 @@ TEST_F(BattOrAgentTest, StopTracingFailsIfCalibrationFrameHasWrongLength) {
 
   // Send a calibration frame with a mismatch between the frame length in the
   // header and the actual frame length.
-  BattOrFrameHeader cal_frame_header{0, 1};
+  BattOrFrameHeader cal_frame_header{0, 1 * sizeof(RawBattOrSample)};
   RawBattOrSample cal_frame[] = {
       RawBattOrSample{1, 1}, RawBattOrSample{2, 2},
   };
@@ -545,7 +545,7 @@ TEST_F(BattOrAgentTest, StopTracingFailsIfCalibrationFrameHasWrongLength) {
 TEST_F(BattOrAgentTest, StopTracingFailsIfDataFrameHasWrongLength) {
   RunStopTracingTo(BattOrAgentState::SAMPLES_REQUEST_SENT);
 
-  BattOrFrameHeader cal_frame_header{0, 1};
+  BattOrFrameHeader cal_frame_header{0, 1 * sizeof(RawBattOrSample)};
   RawBattOrSample cal_frame[] = {
       RawBattOrSample{1, 1},
   };
@@ -554,7 +554,7 @@ TEST_F(BattOrAgentTest, StopTracingFailsIfDataFrameHasWrongLength) {
 
   // Send a data frame with a mismatch between the frame length in the
   // header and the actual frame length.
-  BattOrFrameHeader frame_header{0, 2};
+  BattOrFrameHeader frame_header{0, 2 * sizeof(RawBattOrSample)};
   RawBattOrSample frame[] = {RawBattOrSample{1, 1}};
   GetAgent()->OnMessageRead(true, BATTOR_MESSAGE_TYPE_SAMPLES,
                             CreateFrame(frame_header, frame, 1));
@@ -567,7 +567,7 @@ TEST_F(BattOrAgentTest, StopTracingFailsIfDataFrameHasWrongLength) {
 TEST_F(BattOrAgentTest, StopTracingFailsIfCalibrationFrameMissingByte) {
   RunStopTracingTo(BattOrAgentState::SAMPLES_REQUEST_SENT);
 
-  BattOrFrameHeader cal_frame_header{0, 2};
+  BattOrFrameHeader cal_frame_header{0, 2 * sizeof(RawBattOrSample)};
   RawBattOrSample cal_frame[] = {
       RawBattOrSample{1, 1}, RawBattOrSample{2, 2},
   };
@@ -587,7 +587,7 @@ TEST_F(BattOrAgentTest, StopTracingFailsIfCalibrationFrameMissingByte) {
 TEST_F(BattOrAgentTest, StopTracingFailsIfDataFrameMissingByte) {
   RunStopTracingTo(BattOrAgentState::SAMPLES_REQUEST_SENT);
 
-  BattOrFrameHeader cal_frame_header{0, 1};
+  BattOrFrameHeader cal_frame_header{0, 1 * sizeof(RawBattOrSample)};
   RawBattOrSample cal_frame[] = {
       RawBattOrSample{1, 1},
   };
diff --git a/tools/battor_agent/battor_protocol_types.h b/tools/battor_agent/battor_protocol_types.h
index 292c6d9..48a96a6 100644
--- a/tools/battor_agent/battor_protocol_types.h
+++ b/tools/battor_agent/battor_protocol_types.h
@@ -115,7 +115,7 @@ struct BattOrEEPROM {
 struct BattOrFrameHeader {
   // The number of frames that have preceded this one.
   uint32_t sequence_no;
-  // The number of samples in this frame.
+  // The number of bytes of raw samples in this frame.
   uint16_t length;
 };