//***************************************************************************
// libxx/libxx__gnu_unwind_find_exidx.cxx
//
//   Copyright (C) 2015 Gregory Nutt. All rights reserved.
//   Author: Gregory Nutt <gnutt@nuttx.org>
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in
//    the documentation and/or other materials provided with the
//    distribution.
// 3. Neither the name NuttX nor the names of its contributors may be
//    used to endorse or promote products derived from this software
//    without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
// OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
// AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
//***************************************************************************

//***************************************************************************
// Included Files
//***************************************************************************

#include "libxx__gnu_unwind_find_exidx.hxx"

//***************************************************************************
// Pre-processor Definitions
//***************************************************************************

//***************************************************************************
// Private Data
//***************************************************************************

//***************************************************************************
// Operators
//***************************************************************************

//***************************************************************************
// Name:  __gnu_Unwind_Find_exidx
//
// Description:
//    This function is called (if exists) by the gcc generated unwind
//    run-time in order to retrieve an alternative .ARM.exidx Exception
//    index section.
//    This is the case for an ELF module loaded by the elf binary loader.
//    It is needed to support exception handling for loadable ELF modules.
//
//    NOTES:
//
//     1. The section to be searched is chosen by the address of the calling
//        site: if we are in a runtime loaded ELF, the code will be executed
//        in ram ( > 0x20000000 ) otherwise we will  be executing code  from
//        flash (0x08000000) (running nuttx from ram will break this logic)
//
//     2. __exidx_start  and  __exidx_end refers to main nuttx elf image and
//        are defined in its linker script.
//
//     2. __exidx_start_elf  and  __exidx_end_elf refers  to the elf module
//        loaded by the elf binary loader, and are initialized at run-time.
//
//     3. TODO: if nuttx itself is running from ram, this logic will not work
//
//     4. TODO: in order to support multiple elf modules running at the same
//        time, this error logic needs to be extended to store multiple
//        start/end ranges that refers to the loaded binaries.
//
//***************************************************************************

extern "C"
{
  void init_unwind_exidx(Elf32_Addr start, Elf32_Word size)
  {
    __exidx_start_elf = (__EIT_entry *) start;
    __exidx_end_elf   = __exidx_start_elf + size;
  }

  _Unwind_Ptr __gnu_Unwind_Find_exidx (_Unwind_Ptr return_address, int *nrecp)
  {
    if (return_address < 0x20000000)
      {
        *nrecp = &__exidx_end - &__exidx_start;
        return (_Unwind_Ptr) &__exidx_start;
      }
    else
      {
        *nrecp = (__exidx_end_elf - __exidx_start_elf) / sizeof(__EIT_entry);
        return (_Unwind_Ptr) __exidx_start_elf;
      }
  }
}