/*
*********************************************************************************************************
*                                              uC/OS-II
*                                        The Real-Time Kernel
*
*                    Copyright 1992-2021 Silicon Laboratories Inc. www.silabs.com
*
*                                 SPDX-License-Identifier: APACHE-2.0
*
*               This software is subject to an open source license and is distributed by
*                Silicon Laboratories Inc. pursuant to the terms of the Apache License,
*                    Version 2.0 available at www.apache.org/licenses/LICENSE-2.0.
*
*********************************************************************************************************
*/

/*
*********************************************************************************************************
*
*                                             ARMv6-M Port
*
* Filename  : os_cpu.h
* Version   : V2.93.01
*********************************************************************************************************
* For       : ARMv6-M Cortex-M0 or Cortex-M0+
* Mode      : Thumb2
* Toolchain : ARM C Compiler
**********************************************************************************************************
* Note(s)   : (1) This port supports the ARM Cortex-M0 and Cortex-M0+ architectures.
**********************************************************************************************************
*/

#ifndef  OS_CPU_H
#define  OS_CPU_H

#ifdef   OS_CPU_GLOBALS
#define  OS_CPU_EXT
#else
#define  OS_CPU_EXT  extern
#endif


/*
*********************************************************************************************************
*                                     EXTERNAL C LANGUAGE LINKAGE
*
* Note(s) : (1) C++ compilers MUST 'extern'ally declare ALL C function prototypes & variable/object
*               declarations for correct C language linkage.
*********************************************************************************************************
*/

#ifdef __cplusplus
extern  "C" {                                    /* See Note #1.                                       */
#endif


/*
*********************************************************************************************************
*                                               DEFINES
*********************************************************************************************************
*/

#ifndef  OS_CPU_EXCEPT_STK_SIZE
#define  OS_CPU_EXCEPT_STK_SIZE    128u          /* Default exception stack size is 128 OS_STK entries */
#endif


/*
*********************************************************************************************************
*                              OS TICK INTERRUPT PRIORITY CONFIGURATION
*
* Note(s) : (1) For systems that don't need any high, real-time priority interrupts; the tick interrupt
*               should be configured as the highest priority interrupt but won't adversely affect system
*               operations.
*
*           (2) For systems that need one or more high, real-time interrupts; these should be configured
*               higher than the tick interrupt which MAY delay execution of the tick interrupt.
*
*               (a) If the higher priority interrupts do NOT continually consume CPU cycles but only
*                   occasionally delay tick interrupts, then the real-time interrupts can successfully
*                   handle their intermittent/periodic events with the system not losing tick interrupts
*                   but only increasing the jitter.
*
*               (b) If the higher priority interrupts consume enough CPU cycles to continually delay the
*                   tick interrupt, then the CPU/system is most likely over-burdened & can't be expected
*                   to handle all its interrupts/tasks. The system time reference gets compromised as a
*                   result of losing tick interrupts.
*********************************************************************************************************
*/

#ifndef  OS_CPU_CFG_SYSTICK_PRIO
#define  OS_CPU_CFG_SYSTICK_PRIO           0u
#endif

/*
*********************************************************************************************************
*                                              DATA TYPES
*                                         (Compiler Specific)
*********************************************************************************************************
*/

typedef unsigned char  BOOLEAN;
typedef unsigned char  INT8U;                    /* Unsigned  8 bit quantity                           */
typedef signed   char  INT8S;                    /* Signed    8 bit quantity                           */
typedef unsigned short INT16U;                   /* Unsigned 16 bit quantity                           */
typedef signed   short INT16S;                   /* Signed   16 bit quantity                           */
typedef unsigned int   INT32U;                   /* Unsigned 32 bit quantity                           */
typedef signed   int   INT32S;                   /* Signed   32 bit quantity                           */
typedef float          FP32;                     /* Single precision floating point                    */
typedef double         FP64;                     /* Double precision floating point                    */

typedef unsigned int   OS_STK;                   /* Each stack entry is 32-bit wide                    */
typedef unsigned int   OS_CPU_SR;                /* Define size of CPU status register (PSR = 32 bits) */


/*
*********************************************************************************************************
*                                              Cortex-M0
*                                      Critical Section Management
*
* Method #1:  Disable/Enable interrupts using simple instructions.  After critical section, interrupts
*             will be enabled even if they were disabled before entering the critical section.
*             NOT IMPLEMENTED
*
* Method #2:  Disable/Enable interrupts by preserving the state of interrupts.  In other words, if
*             interrupts were disabled before entering the critical section, they will be disabled when
*             leaving the critical section.
*             NOT IMPLEMENTED
*
* Method #3:  Disable/Enable interrupts by preserving the state of interrupts.  Generally speaking you
*             would store the state of the interrupt disable flag in the local variable 'cpu_sr' and then
*             disable interrupts.  'cpu_sr' is allocated in all of uC/OS-II's functions that need to
*             disable interrupts.  You would restore the interrupt disable state by copying back 'cpu_sr'
*             into the CPU's status register.
*********************************************************************************************************
*/

#define  OS_CRITICAL_METHOD   3u

#if OS_CRITICAL_METHOD == 3u
#define  OS_ENTER_CRITICAL()  do { cpu_sr = OS_CPU_SR_Save();} while (0)
#define  OS_EXIT_CRITICAL()   do { OS_CPU_SR_Restore(cpu_sr);} while (0)
#endif


/*
*********************************************************************************************************
*                                        Cortex-M0 Miscellaneous
*********************************************************************************************************
*/

#define  OS_STK_GROWTH        1u                  /* Stack grows from HIGH to LOW memory on ARM        */

#define  OS_TASK_SW()         OSCtxSw()


/*
*********************************************************************************************************
*                                          GLOBAL VARIABLES
*********************************************************************************************************
*/

OS_CPU_EXT  OS_STK   OS_CPU_ExceptStk[OS_CPU_EXCEPT_STK_SIZE];
OS_CPU_EXT  OS_STK  *OS_CPU_ExceptStkBase;


/*
*********************************************************************************************************
*                                         FUNCTION PROTOTYPES
*********************************************************************************************************
*/

#if OS_CRITICAL_METHOD == 3u                      /* See OS_CPU_A.ASM                                  */
OS_CPU_SR  OS_CPU_SR_Save         (void);
void       OS_CPU_SR_Restore      (OS_CPU_SR  cpu_sr);
#endif

void       OSCtxSw                (void);
void       OSIntCtxSw             (void);
void       OSStartHighRdy         (void);

                                                  /* See OS_CPU_C.C                                    */
void       OS_CPU_SysTickInit     (INT32U  cnts);
void       OS_CPU_SysTickInitFreq (INT32U  cpu_freq);

void       OS_CPU_SysTickHandler  (void);
void       OS_CPU_PendSVHandler   (void);


/*
*********************************************************************************************************
*                                   EXTERNAL C LANGUAGE LINKAGE END
*********************************************************************************************************
*/

#ifdef __cplusplus
}                                                 /* End of 'extern'al C lang linkage.                 */
#endif


/*
*********************************************************************************************************
*                                             MODULE END
*********************************************************************************************************
*/

#endif
