trace-itm.cpp

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/*
 * This file is part of the µOS++ project (https://micro-os-plus.github.io/).
 * Copyright (c) 2015-2025 Liviu Ionescu. All rights reserved.
 *
 * Permission to use, copy, modify, and/or distribute this software
 * for any purpose is hereby granted, under the terms of the MIT license.
 *
 * If a copy of the license was not distributed with this file, it can
 * be obtained from https://opensource.org/licenses/mit.
 */
 
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wempty-translation-unit"
#endif
 
// ----------------------------------------------------------------------------
 
#if defined(__ARM_EABI__)
 
// ----------------------------------------------------------------------------
 
#if defined(TRACE)
 
#if defined(OS_USE_OS_APP_CONFIG_H)
#include <cmsis-plus/os-app-config.h>
#endif
 
#if defined(OS_USE_TRACE_ITM)
 
#include <cmsis-plus/diag/trace.h>
 
// TODO: Find a better way to include the ITM definitions (including
// the entire vendor header is averkill).
#include <cmsis_device.h>
 
// ----------------------------------------------------------------------------
 
namespace os
{
  namespace trace
  {
    // ------------------------------------------------------------------------
 
    void
    initialize (void)
    {
      // For ITM no inits required.
      // The debug registers are set the JTAG software.
    }
 
    // ------------------------------------------------------------------------
 
#if defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)
 
    // ITM is the ARM standard mechanism, running over SWD/SWO on Cortex-M3/M4
    // devices, and is the recommended setting, if available.
    //
    // The JLink probe and the GDB server fully support SWD/SWO
    // and the JLink Debugging plug-in enables it by default.
    // The current OpenOCD does not include support to parse the SWO stream,
    // so this configuration will not work on OpenOCD (will not crash, but
    // nothing will be displayed in the output console).
 
#if !defined(OS_INTEGER_TRACE_ITM_STIMULUS_PORT)
#define OS_INTEGER_TRACE_ITM_STIMULUS_PORT (0)
#endif
 
    ssize_t
    write (const void* buf, std::size_t nbyte)
    {
      if (buf == nullptr || nbyte == 0)
        {
          return 0;
        }
 
      const char* cbuf = (const char*)buf;
 
      for (size_t i = 0; i < nbyte; i++)
        {
          // Check if ITM or the stimulus port are not enabled.
          if (((ITM->TCR & ITM_TCR_ITMENA_Msk) == 0)
              || ((ITM->TER & (1UL << OS_INTEGER_TRACE_ITM_STIMULUS_PORT))
                  == 0))
            {
              // Return the number of sent characters (may be 0).
              return (ssize_t)i;
            }
 
          // Wait until STIMx is ready...
          while (ITM->PORT[OS_INTEGER_TRACE_ITM_STIMULUS_PORT].u32 == 0)
            ;
          // then send data, one byte at a time
          ITM->PORT[OS_INTEGER_TRACE_ITM_STIMULUS_PORT].u8
              = (uint8_t)(*cbuf++);
        }
 
      // All characters successfully sent.
      return (ssize_t)nbyte;
    }
 
#else
 
#error "ITM available only on ARCH 7M"
 
#endif /* defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__) */
 
  } /* namespace trace */
} /* namespace os */
 
#endif /* defined(OS_USE_TRACE_ITM) */
#endif /* defined(TRACE) */
 
// ----------------------------------------------------------------------------
 
#endif /* defined(__ARM_EABI__) */