// Exception handling and frame unwind runtime interface routines.
// Copyright (C) 2011-2024 Free Software Foundation, Inc.

// GCC is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 3, or (at your option) any later
// version.

// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

// extern(C) interface for the ARM EABI and C6X unwinders.
// This corresponds to unwind-arm-common.h

module gcc.unwind.arm_common;

import gcc.config;

static if (GNU_ARM_EABI_Unwinder):

import gcc.builtins;

extern (C):

// Placed outside @nogc in order to not constrain what the callback does.
// ??? Does this really need to be extern(C) alias?
extern(C) alias _Unwind_Exception_Cleanup_Fn
    = void function(_Unwind_Reason_Code, _Unwind_Exception*);

extern(C) alias personality_routine
    = _Unwind_Reason_Code function(_Unwind_State,
                                   _Unwind_Control_Block*,
                                   _Unwind_Context*);

extern(C) alias _Unwind_Stop_Fn
    =_Unwind_Reason_Code function(int, _Unwind_Action,
                                  _Unwind_Exception_Class,
                                  _Unwind_Control_Block*,
                                  _Unwind_Context*, void*);

extern(C) alias _Unwind_Trace_Fn
    = _Unwind_Reason_Code function(_Unwind_Context*, void*);

@nogc:

alias _Unwind_Word = __builtin_machine_uint;
alias _Unwind_Sword = __builtin_machine_int;
alias _Unwind_Ptr = __builtin_pointer_uint;
alias _Unwind_Internal_Ptr =__builtin_pointer_uint;
alias _uw = _Unwind_Word;
alias _uw64 = ulong;
alias _uw16 = ushort;
alias _uw8 = ubyte;

alias _Unwind_Reason_Code = uint;
enum : _Unwind_Reason_Code
{
    _URC_OK = 0,        // operation completed successfully
    _URC_FOREIGN_EXCEPTION_CAUGHT = 1,
    _URC_END_OF_STACK = 5,
    _URC_HANDLER_FOUND = 6,
    _URC_INSTALL_CONTEXT = 7,
    _URC_CONTINUE_UNWIND = 8,
    _URC_FAILURE = 9    // unspecified failure of some kind
}

alias _Unwind_State = int;
enum : _Unwind_State
{
    _US_VIRTUAL_UNWIND_FRAME = 0,
    _US_UNWIND_FRAME_STARTING = 1,
    _US_UNWIND_FRAME_RESUME = 2,
    _US_ACTION_MASK = 3,
    _US_FORCE_UNWIND = 8,
    _US_END_OF_STACK = 16
}

// Provided only for for compatibility with existing code.
alias _Unwind_Action = int;
enum : _Unwind_Action
{
    _UA_SEARCH_PHASE = 1,
    _UA_CLEANUP_PHASE = 2,
    _UA_HANDLER_FRAME = 4,
    _UA_FORCE_UNWIND = 8,
    _UA_END_OF_STACK = 16,
    _URC_NO_REASON = _URC_OK
}

struct _Unwind_Context;
alias _Unwind_EHT_Header = _uw;

struct _Unwind_Control_Block
{
    _Unwind_Exception_Class exception_class = '\0';
    _Unwind_Exception_Cleanup_Fn exception_cleanup;
    // Unwinder cache, private fields for the unwinder's use
    struct _unwinder_cache
    {
        _uw reserved1;  // Forced unwind stop fn, 0 if not forced
        _uw reserved2;  // Personality routine address
        _uw reserved3;  // Saved callsite address
        _uw reserved4;  // Forced unwind stop arg
        _uw reserved5;
    }
    _unwinder_cache unwinder_cache;
    // Propagation barrier cache (valid after phase 1):
    struct _barrier_cache
    {
        _uw sp;
        _uw[5] bitpattern;
    }
    _barrier_cache barrier_cache;
    // Cleanup cache (preserved over cleanup):
    struct _cleanup_cache
    {
        _uw[4] bitpattern;
    }
    _cleanup_cache cleanup_cache;
    // Pr cache (for pr's benefit):
    struct _pr_cache
    {
        _uw fnstart;                // function start address */
        _Unwind_EHT_Header* ehtp;   // pointer to EHT entry header word
        _uw additional;             // additional data
        _uw reserved1;
    }
    _pr_cache pr_cache;
    long[0] _force_alignment;       // Force alignment to 8-byte boundary
}

// Virtual Register Set
alias _Unwind_VRS_RegClass = int;
enum : _Unwind_VRS_RegClass
{
    _UVRSC_CORE = 0,    // integer register
    _UVRSC_VFP = 1,     // vfp
    _UVRSC_FPA = 2,     // fpa
    _UVRSC_WMMXD = 3,   // Intel WMMX data register
    _UVRSC_WMMXC = 4    // Intel WMMX control register
}

alias _Unwind_VRS_DataRepresentation = int;
enum : _Unwind_VRS_DataRepresentation
{
    _UVRSD_UINT32 = 0,
    _UVRSD_VFPX = 1,
    _UVRSD_FPAX = 2,
    _UVRSD_UINT64 = 3,
    _UVRSD_FLOAT = 4,
    _UVRSD_DOUBLE = 5
}

alias _Unwind_VRS_Result = int;
enum : _Unwind_VRS_Result
{
    _UVRSR_OK = 0,
    _UVRSR_NOT_IMPLEMENTED = 1,
    _UVRSR_FAILED = 2
}

// Frame unwinding state.
struct __gnu_unwind_state
{
    _uw data;           // The current word (bytes packed msb first).
    _uw* next;          // Pointer to the next word of data.
    _uw8 bytes_left;    // The number of bytes left in this word.
    _uw8 words_left;    // The number of words pointed to by ptr.
}

_Unwind_VRS_Result _Unwind_VRS_Set(_Unwind_Context*, _Unwind_VRS_RegClass,
                                   _uw, _Unwind_VRS_DataRepresentation,
                                   void*);

_Unwind_VRS_Result _Unwind_VRS_Get(_Unwind_Context*, _Unwind_VRS_RegClass,
                                   _uw, _Unwind_VRS_DataRepresentation,
                                   void*);

_Unwind_VRS_Result _Unwind_VRS_Pop(_Unwind_Context*, _Unwind_VRS_RegClass,
                                   _uw, _Unwind_VRS_DataRepresentation);


// Support functions for the PR.
alias _Unwind_Exception = _Unwind_Control_Block;
alias _Unwind_Exception_Class = char[8];

void* _Unwind_GetLanguageSpecificData(_Unwind_Context*);
_Unwind_Ptr _Unwind_GetRegionStart(_Unwind_Context*);

_Unwind_Ptr _Unwind_GetDataRelBase(_Unwind_Context*);
// This should never be used.
_Unwind_Ptr _Unwind_GetTextRelBase(_Unwind_Context*);

// Interface functions:
_Unwind_Reason_Code _Unwind_RaiseException(_Unwind_Control_Block*);
void _Unwind_Resume(_Unwind_Control_Block*);
_Unwind_Reason_Code _Unwind_Resume_or_Rethrow(_Unwind_Control_Block*);

_Unwind_Reason_Code _Unwind_ForcedUnwind(_Unwind_Control_Block*,
                                         _Unwind_Stop_Fn, void*);

// @@@ Use unwind data to perform a stack backtrace.  The trace callback
// is called for every stack frame in the call chain, but no cleanup
// actions are performed.
_Unwind_Reason_Code _Unwind_Backtrace(_Unwind_Trace_Fn, void*);

_Unwind_Word _Unwind_GetCFA(_Unwind_Context*);
void _Unwind_Complete(_Unwind_Control_Block*);
void _Unwind_DeleteException(_Unwind_Exception*);

_Unwind_Reason_Code __gnu_unwind_frame(_Unwind_Control_Block*,
                                       _Unwind_Context*);
_Unwind_Reason_Code __gnu_unwind_execute(_Unwind_Context*,
                                         __gnu_unwind_state*);

_Unwind_Word _Unwind_GetGR(_Unwind_Context* context, int regno)
{
    _uw val;
    _Unwind_VRS_Get(context, _UVRSC_CORE, regno, _UVRSD_UINT32, &val);
    return val;
}

void _Unwind_SetGR(_Unwind_Context* context, int regno, _Unwind_Word val)
{
    _Unwind_VRS_Set(context, _UVRSC_CORE, regno, _UVRSD_UINT32, &val);
}

// leb128 type numbers have a potentially unlimited size.
// The target of the following definitions of _sleb128_t and _uleb128_t
// is to have efficient data types large enough to hold the leb128 type
// numbers used in the unwind code.
alias _sleb128_t = __builtin_clong;
alias _uleb128_t = __builtin_culong;