//! @file a68g-stack.h
//! @author J. Marcel van der Veer

//! @section Copyright
//!
//! This file is part of Algol68G - an Algol 68 compiler-interpreter.
//! Copyright 2001-2025 J. Marcel van der Veer [algol68g@xs4all.nl].

//! @section License
//!
//! This program 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 of the License, or 
//! (at your option) any later version.
//!
//! This program 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. You should have received a copy of the GNU General Public 
//! License along with this program. If not, see [http://www.gnu.org/licenses/].

//! @section Synopsis
//!
//! Macros for stack checking.

#if !defined (__A68G_STACK_H__)
#define __A68G_STACK_H__

// Macro's for stack checking. Since the stacks grow by small amounts at a time
// (A68 rows are in the heap), we check the stacks only at certain points: where
// A68 recursion may set in, or in the garbage collector. We check whether there
// still is sufficient overhead to make it to the next check.

#define TOO_COMPLEX "program too complex"

#define SYSTEM_STACK_USED (ABS ((int) (A68G (system_stack_offset) - &stack_offset)))
#define LOW_SYSTEM_STACK_ALERT(p) {\
  BYTE_T stack_offset;\
  if (A68G (stack_size) > 0 && SYSTEM_STACK_USED >= A68G (stack_limit)) {\
    if ((p) == NO_NODE) {\
      ABEND (A68G_TRUE, TOO_COMPLEX, ERROR_STACK_OVERFLOW);\
    } else {\
      diagnostic (A68G_RUNTIME_ERROR, (p), ERROR_STACK_OVERFLOW);\
      exit_genie ((p), A68G_RUNTIME_ERROR);\
  }}}

#define LOW_STACK_ALERT(p) {\
  LOW_SYSTEM_STACK_ALERT (p);\
  if ((p) != NO_NODE && (A68G_FP >= A68G (frame_stack_limit) || A68G_SP >= A68G (expr_stack_limit))) { \
    diagnostic (A68G_RUNTIME_ERROR, (p), ERROR_STACK_OVERFLOW);\
    exit_genie ((p), A68G_RUNTIME_ERROR);\
  }}

#endif
