HidController: reorganize polling loop code

1 files changed, 21 insertions, 22 deletions

diff --git a/src/controllers/hid/hidcontroller.cpp b/src/controllers/hid/hidcontroller.cpp
index 3fd227357b..9a5506e895 100644
--- a/src/controllers/hid/hidcontroller.cpp
+++ b/src/controllers/hid/hidcontroller.cpp
@@ -248,41 +248,40 @@ int HidController::close() {
 bool HidController::poll() {
     Trace hidRead("HidController poll");
 
-    int result = 1;
     // This loop risks becoming a high priority endless loop in case processing
     // the mapping JS code takes longer than the controller polling rate.
     // This could stall other low priority tasks.
     // There is no safety net for this because it has not been demonstrated to be
     // a problem in practice.
-    while (result > 0) {
+    while (true) {
         // Rotate between two buffers so the memcmp below does not require deep copying to another buffer.
         unsigned char* pPreviousBuffer = m_pPollData[m_iPollingBufferIndex];
         m_iPollingBufferIndex = (m_iPollingBufferIndex + 1) % kNumBuffers;
         unsigned char* pCurrentBuffer = m_pPollData[m_iPollingBufferIndex];
 
-        result = hid_read(m_pHidDevice, pCurrentBuffer, kBufferSize);
-        if (result == -1) {
+        int bytesRead = hid_read(m_pHidDevice, pCurrentBuffer, kBufferSize);
+        if (bytesRead == -1) {
             return false;
-        } else if (result > 0) {
-            Trace process("HidController process packet");
-            // Some controllers such as the Gemini GMX continuously send input packets even if it
-            // is identical to the previous packet. If this loop processed all those redundant
-            // packets, it would be a big performance problem to run JS code for every packet and
-            // would be unnecessary.
-            // This assumes that the redundant packets all use the same report ID. In practice we
-            // have not encountered any controllers that send redundant packets with different report
-            // IDs. If any such devices exist, this may be changed to use a separate buffer to store
-            // the last packet for each report ID.
-            if (memcmp(pCurrentBuffer, pPreviousBuffer, kBufferSize) == 0) {
-                continue;
-            }
-            auto incomingData = QByteArray::fromRawData(
-                    reinterpret_cast<char*>(pCurrentBuffer), result);
-            receive(incomingData, mixxx::Time::elapsed());
+        } else if (bytesRead == 0) {
+            return true;
         }
-    }
 
-    return true;
+        Trace process("HidController process packet");
+        // Some controllers such as the Gemini GMX continuously send input packets even if it
+        // is identical to the previous packet. If this loop processed all those redundant
+        // packets, it would be a big performance problem to run JS code for every packet and
+        // would be unnecessary.
+        // This assumes that the redundant packets all use the same report ID. In practice we
+        // have not encountered any controllers that send redundant packets with different report
+        // IDs. If any such devices exist, this may be changed to use a separate buffer to store
+        // the last packet for each report ID.
+        if (memcmp(pCurrentBuffer, pPreviousBuffer, kBufferSize) == 0) {
+            continue;
+        }
+        auto incomingData = QByteArray::fromRawData(
+                reinterpret_cast<char*>(pCurrentBuffer), bytesRead);
+        receive(incomingData, mixxx::Time::elapsed());
+    }
 }
 
 bool HidController::isPolling() const {