/*
 * Copyright (c) 2016 Cadence Design Systems, Inc.
 * SPDX-License-Identifier: Apache-2.0
 */

/*******************************************************************************
  Configuration-specific information for Xtensa build. This file must be
  included in FreeRTOSConfig.h to properly set up the config-dependent
  parameters correctly.

  NOTE: To enable thread-safe C library support, XT_USE_THREAD_SAFE_CLIB must
  be defined to be > 0 somewhere above or on the command line.

*******************************************************************************/

#ifndef XTENSA_CONFIG_H
#define XTENSA_CONFIG_H

#ifdef __cplusplus
extern "C" {
#endif

#include <xtensa/hal.h>
#include <xtensa/config/core.h>
#include <xtensa/config/system.h>	/* required for XSHAL_CLIB */

#include "xtensa_context.h"


/*-----------------------------------------------------------------------------
*                                 STACK REQUIREMENTS
*
* This section defines the minimum stack size, and the extra space required to
* be allocated for saving coprocessor state and/or C library state information
* (if thread safety is enabled for the C library). The sizes are in bytes.
*
* Stack sizes for individual tasks should be derived from these minima based on
* the maximum call depth of the task and the maximum level of interrupt nesting.
* A minimum stack size is defined by XT_STACK_MIN_SIZE. This minimum is based
* on the requirement for a task that calls nothing else but can be interrupted.
* This assumes that interrupt handlers do not call more than a few levels deep.
* If this is not true, i.e. one or more interrupt handlers make deep calls then
* the minimum must be increased.
*
* If the Xtensa processor configuration includes coprocessors, then space is 
* allocated to save the coprocessor state on the stack.
*
* If thread safety is enabled for the C runtime library, (XT_USE_THREAD_SAFE_CLIB
* is defined) then space is allocated to save the C library context in the TCB.
* 
* Allocating insufficient stack space is a common source of hard-to-find errors.
* During development, it is best to enable the FreeRTOS stack checking features.
*
* Usage:
* 
* XT_USE_THREAD_SAFE_CLIB -- Define this to a nonzero value to enable thread-safe
*                            use of the C library. This will require extra stack
*                            space to be allocated for tasks that use the C library
*                            reentrant functions. See below for more information.
* 
* NOTE: The Xtensa toolchain supports multiple C libraries and not all of them
* support thread safety. Check your core configuration to see which C library
* was chosen for your system.
* 
* XT_STACK_MIN_SIZE       -- The minimum stack size for any task. It is recommended
*                            that you do not use a stack smaller than this for any
*                            task. In case you want to use stacks smaller than this
*                            size, you must verify that the smaller size(s) will work
*                            under all operating conditions.
*
* XT_STACK_EXTRA          -- The amount of extra stack space to allocate for a task
*                            that does not make C library reentrant calls. Add this
*                            to the amount of stack space required by the task itself.
*
* XT_STACK_EXTRA_CLIB     -- The amount of space to allocate for C library state.
*
-----------------------------------------------------------------------------*/

/* Extra space required for interrupt/exception hooks. */
#ifdef XT_INTEXC_HOOKS
  #ifdef __XTENSA_CALL0_ABI__
    #define STK_INTEXC_EXTRA        0x200
  #else
    #define STK_INTEXC_EXTRA        0x180
  #endif
#else
  #define STK_INTEXC_EXTRA          0
#endif

/* Check C library thread safety support and compute size of C library save area. */
#if XT_USE_THREAD_SAFE_CLIB > 0u
  #if XSHAL_CLIB == XTHAL_CLIB_XCLIB
    #define XT_HAVE_THREAD_SAFE_CLIB        0
    #error Thread-safe operation is not yet supported for the XCLIB C library.
  #elif XSHAL_CLIB == XTHAL_CLIB_NEWLIB
    #define XT_HAVE_THREAD_SAFE_CLIB        1
    #if !defined __ASSEMBLER__
      #include <sys/reent.h>
      #define XT_CLIB_CONTEXT_AREA_SIZE     ((sizeof(struct _reent) + 15) + (-16))
      #define XT_CLIB_GLOBAL_PTR            _impure_ptr
    #endif
  #else
    #define XT_HAVE_THREAD_SAFE_CLIB        0
    #error The selected C runtime library is not thread safe.
  #endif
#else
  #define XT_CLIB_CONTEXT_AREA_SIZE         0
#endif

/*------------------------------------------------------------------------------
  Extra size -- interrupt frame plus coprocessor save area plus hook space.
  NOTE: Make sure XT_INTEXC_HOOKS is undefined unless you really need the hooks.
------------------------------------------------------------------------------*/
#ifdef __XTENSA_CALL0_ABI__
  #define XT_XTRA_SIZE            (XT_STK_FRMSZ + STK_INTEXC_EXTRA + 0x10 + XT_CP_SIZE)
#else
  #define XT_XTRA_SIZE            (XT_STK_FRMSZ + STK_INTEXC_EXTRA + 0x20 + XT_CP_SIZE)
#endif

/*------------------------------------------------------------------------------
  Space allocated for user code -- function calls and local variables.
  NOTE: This number can be adjusted to suit your needs. You must verify that the
  amount of space you reserve is adequate for the worst-case conditions in your
  application.
  NOTE: The windowed ABI requires more stack, since space has to be reserved
  for spilling register windows.
------------------------------------------------------------------------------*/
#ifdef __XTENSA_CALL0_ABI__
  #define XT_USER_SIZE            0x200
#else
  #define XT_USER_SIZE            0x400
#endif

/* Minimum recommended stack size. */
#define XT_STACK_MIN_SIZE         ((XT_XTRA_SIZE + XT_USER_SIZE) / sizeof(unsigned char))

/* OS overhead with and without C library thread context. */
#define XT_STACK_EXTRA              (XT_XTRA_SIZE)
#define XT_STACK_EXTRA_CLIB         (XT_XTRA_SIZE + XT_CLIB_CONTEXT_AREA_SIZE)


#ifdef __cplusplus
}
#endif

#endif /* XTENSA_CONFIG_H */