Add Peek() to SEGGER RTT.

henrygab · Jan 13, 2020 · 75145eb · 75145eb
1 parent d5b77b0
commit 75145eb
Show file tree

Hide file tree

Showing 2 changed files with 42 additions and 0 deletions.
diff --git a/cores/nRF5/sysview/SEGGER/SEGGER_RTT.c b/cores/nRF5/sysview/SEGGER/SEGGER_RTT.c
@@ -600,6 +600,46 @@ unsigned SEGGER_RTT_ReadUpBufferNoLock(unsigned BufferIndex, void* pData, unsign
   return NumBytesRead;
 }
 
+/*********************************************************************
+*
+*       SEGGER_RTT_Peek
+*
+*  Function description
+*    Reads one character from the SEGGER RTT buffer.
+*    Host has previously stored data there.
+*
+*  Return value
+*    <  0 -   No character available (buffer empty).
+*    >= 0 -   Character which is next in the buffer.
+*
+*  Notes
+*    (1) This function is only specified for accesses to RTT buffer 0.
+*/
+int SEGGER_RTT_Peek(void) {
+  char      c;
+  int       r;
+  unsigned  RdOff;
+  unsigned  WrOff;
+  SEGGER_RTT_BUFFER_DOWN* pRing;
+
+  SEGGER_RTT_LOCK();
+  INIT();
+  pRing = &_SEGGER_RTT.aDown[0]; // Note (1)  This function is only specified for accesses to RTT buffer 0.
+  RdOff = pRing->RdOff;
+  WrOff = pRing->WrOff;
+
+  /* WrOff == RdOff: Buffer is empty */
+  if (WrOff == RdOff) { // Buffer is empty when these are equal
+    r = -1;
+  } else {
+    c = *(pRing->pBuffer + RdOff);
+    r = (int)(unsigned char)c;
+  }
+  SEGGER_RTT_UNLOCK();
+  return r;
+}
+
+
 /*********************************************************************
 *
 *       SEGGER_RTT_ReadNoLock()

diff --git a/cores/nRF5/sysview/SEGGER/SEGGER_RTT.h b/cores/nRF5/sysview/SEGGER/SEGGER_RTT.h
@@ -201,6 +201,7 @@ unsigned     SEGGER_RTT_HasDataUp               (unsigned BufferIndex);
 void         SEGGER_RTT_Init                    (void);
 unsigned     SEGGER_RTT_Read                    (unsigned BufferIndex,       void* pBuffer, unsigned BufferSize);
 unsigned     SEGGER_RTT_ReadNoLock              (unsigned BufferIndex,       void* pData,   unsigned BufferSize);
+int          SEGGER_RTT_Peek                    (void);
 int          SEGGER_RTT_SetNameDownBuffer       (unsigned BufferIndex, const char* sName);
 int          SEGGER_RTT_SetNameUpBuffer         (unsigned BufferIndex, const char* sName);
 int          SEGGER_RTT_SetFlagsDownBuffer      (unsigned BufferIndex, unsigned Flags);
@@ -216,6 +217,7 @@ unsigned     SEGGER_RTT_PutCharSkip             (unsigned BufferIndex, char c);
 unsigned     SEGGER_RTT_PutCharSkipNoLock       (unsigned BufferIndex, char c);
 unsigned     SEGGER_RTT_GetAvailWriteSpace      (unsigned BufferIndex);
 unsigned     SEGGER_RTT_GetBytesInBuffer        (unsigned BufferIndex);
+
 //
 // Function macro for performance optimization
 //