/*----------------------------------------------------------------------------
 *      RL-ARM - RTX
 *----------------------------------------------------------------------------
 *      Name:    HAL_CM0.C
 *      Purpose: Hardware Abstraction Layer for Cortex-M0
 *      Rev.:    V4.60
 *----------------------------------------------------------------------------
 *
 * Copyright (c) 1999-2009 KEIL, 2009-2012 ARM Germany GmbH
 * All rights reserved.
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *  - Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  - 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.
 *  - Neither the name of ARM  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 COPYRIGHT HOLDERS AND 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.
 *---------------------------------------------------------------------------*/

#include "rt_TypeDef.h"
#include "RTX_Config.h"
#include "rt_System.h"
#include "rt_HAL_CM.h"
#include "rt_Task.h"
#include "rt_MemBox.h"


/*----------------------------------------------------------------------------
 *      Functions
 *---------------------------------------------------------------------------*/


/*--------------------------- rt_set_PSP ------------------------------------*/

__asm void rt_set_PSP (U32 stack) {
        MSR     PSP,R0
        BX      LR
}


/*--------------------------- rt_get_PSP ------------------------------------*/

__asm U32 rt_get_PSP (void) {
        MRS     R0,PSP
        BX      LR
}


/*--------------------------- os_set_env ------------------------------------*/

__asm void os_set_env (void) {
   /* Switch to Unprivileged/Privileged Thread mode, use PSP. */
        MOV     R0,SP                   ; PSP = MSP
        MSR     PSP,R0
        LDR     R0,=__cpp(&os_flags)
        LDRB    R0,[R0]
        LSLS    R0,#31
        BNE     PrivilegedE
        MOVS    R0,#0x03                ; Unprivileged Thread mode, use PSP
        MSR     CONTROL,R0
        BX      LR
PrivilegedE
        MOVS    R0,#0x02                ; Privileged Thread mode, use PSP
        MSR     CONTROL,R0
        BX      LR

        ALIGN
}


/*--------------------------- _alloc_box ------------------------------------*/

__asm void *_alloc_box (void *box_mem) {
   /* Function wrapper for Unprivileged/Privileged mode. */
        LDR     R3,=__cpp(rt_alloc_box)
        MOV     R12,R3
        MRS     R3,IPSR
        LSLS    R3,#24
        BNE     PrivilegedA
        MRS     R3,CONTROL
        LSLS    R3,#31
        BEQ     PrivilegedA
        SVC     0
        BX      LR
PrivilegedA
        BX      R12

        ALIGN
}


/*--------------------------- _free_box -------------------------------------*/

__asm int _free_box (void *box_mem, void *box) {
   /* Function wrapper for Unprivileged/Privileged mode. */
        LDR     R3,=__cpp(rt_free_box)
        MOV     R12,R3
        MRS     R3,IPSR
        LSLS    R3,#24
        BNE     PrivilegedF
        MRS     R3,CONTROL
        LSLS    R3,#31
        BEQ     PrivilegedF
        SVC     0
        BX      LR
PrivilegedF
        BX      R12

        ALIGN
}


/*-------------------------- SVC_Handler ------------------------------------*/

__asm void SVC_Handler (void) {
        PRESERVE8

        IMPORT  SVC_Count
        IMPORT  SVC_Table
        IMPORT  rt_stk_check

        MRS     R0,PSP                  ; Read PSP
        LDR     R1,[R0,#24]             ; Read Saved PC from Stack
        SUBS    R1,R1,#2                ; Point to SVC Instruction
        LDRB    R1,[R1]                 ; Load SVC Number
        CMP     R1,#0
        BNE     SVC_User                ; User SVC Number > 0

        MOV     LR,R4
        LDMIA   R0,{R0-R3,R4}           ; Read R0-R3,R12 from stack
        MOV     R12,R4
        MOV     R4,LR
        BLX     R12                     ; Call SVC Function 

        MRS     R3,PSP                  ; Read PSP
        STMIA   R3!,{R0-R2}             ; Store return values

        LDR     R3,=__cpp(&os_tsk)
        LDMIA   R3!,{R1,R2}             ; os_tsk.run, os_tsk.new
        CMP     R1,R2
        BEQ     SVC_Exit                ; no task switch

        SUBS    R3,#8
        CMP     R1,#0                   ; Runtask deleted?
        BEQ     SVC_Next

        MRS     R0,PSP                  ; Read PSP
        SUBS    R0,R0,#32               ; Adjust Start Address
        STR     R0,[R1,#TCB_TSTACK]     ; Update os_tsk.run->tsk_stack       
        STMIA   R0!,{R4-R7}             ; Save old context (R4-R7)
        MOV     R4,R8
        MOV     R5,R9
        MOV     R6,R10
        MOV     R7,R11
        STMIA   R0!,{R4-R7}             ; Save old context (R8-R11)
        
        PUSH    {R2,R3}
        BL      rt_stk_check            ; Check for Stack overflow
        POP     {R2,R3}

SVC_Next
        STR     R2,[R3]                 ; os_tsk.run = os_tsk.new

        LDR     R0,[R2,#TCB_TSTACK]     ; os_tsk.new->tsk_stack
        ADDS    R0,R0,#16               ; Adjust Start Address
        LDMIA   R0!,{R4-R7}             ; Restore new Context (R8-R11)
        MOV     R8,R4
        MOV     R9,R5
        MOV     R10,R6
        MOV     R11,R7
        MSR     PSP,R0                  ; Write PSP
        SUBS    R0,R0,#32               ; Adjust Start Address
        LDMIA   R0!,{R4-R7}             ; Restore new Context (R4-R7)

SVC_Exit
        MOVS    R0,#:NOT:0xFFFFFFFD     ; Set EXC_RETURN value
        MVNS    R0,R0
        BX      R0                      ; RETI to Thread Mode, use PSP

        /*------------------- User SVC ------------------------------*/

SVC_User
        PUSH    {R4,LR}                 ; Save Registers
        LDR     R2,=SVC_Count
        LDR     R2,[R2]
        CMP     R1,R2
        BHI     SVC_Done                ; Overflow

        LDR     R4,=SVC_Table-4
        LSLS    R1,R1,#2
        LDR     R4,[R4,R1]              ; Load SVC Function Address
        MOV     LR,R4

        LDMIA   R0,{R0-R3,R4}           ; Read R0-R3,R12 from stack
        MOV     R12,R4
        BLX     LR                      ; Call SVC Function

        MRS     R4,PSP                  ; Read PSP
        STMIA   R4!,{R0-R3}             ; Function return values
SVC_Done
        POP     {R4,PC}                 ; RETI

        ALIGN
}


/*-------------------------- PendSV_Handler ---------------------------------*/

__asm void PendSV_Handler (void) {
        PRESERVE8

        BL      __cpp(rt_pop_req)

Sys_Switch
        LDR     R3,=__cpp(&os_tsk)
        LDMIA   R3!,{R1,R2}             ; os_tsk.run, os_tsk.new
        CMP     R1,R2
        BEQ     Sys_Exit                ; no task switch

        SUBS    R3,#8

        MRS     R0,PSP                  ; Read PSP
        SUBS    R0,R0,#32               ; Adjust Start Address
        STR     R0,[R1,#TCB_TSTACK]     ; Update os_tsk.run->tsk_stack
        STMIA   R0!,{R4-R7}             ; Save old context (R4-R7)
        MOV     R4,R8
        MOV     R5,R9
        MOV     R6,R10
        MOV     R7,R11
        STMIA   R0!,{R4-R7}             ; Save old context (R8-R11)
        
        PUSH    {R2,R3}
        BL      rt_stk_check            ; Check for Stack overflow
        POP     {R2,R3}

        STR     R2,[R3]                 ; os_tsk.run = os_tsk.new

        LDR     R0,[R2,#TCB_TSTACK]     ; os_tsk.new->tsk_stack
        ADDS    R0,R0,#16               ; Adjust Start Address
        LDMIA   R0!,{R4-R7}             ; Restore new Context (R8-R11)
        MOV     R8,R4
        MOV     R9,R5
        MOV     R10,R6
        MOV     R11,R7
        MSR     PSP,R0                  ; Write PSP
        SUBS    R0,R0,#32               ; Adjust Start Address
        LDMIA   R0!,{R4-R7}             ; Restore new Context (R4-R7)

Sys_Exit
        MOVS    R0,#:NOT:0xFFFFFFFD     ; Set EXC_RETURN value
        MVNS    R0,R0
        BX      R0                      ; RETI to Thread Mode, use PSP

        ALIGN
}


/*-------------------------- SysTick_Handler --------------------------------*/

__asm void SysTick_Handler (void) {
        PRESERVE8

        BL      __cpp(rt_systick)
        B       Sys_Switch

        ALIGN
}


/*-------------------------- OS_Tick_Handler --------------------------------*/

__asm void OS_Tick_Handler (void) {
        PRESERVE8

        BL      __cpp(os_tick_irqack)
        BL      __cpp(rt_systick)
        B       Sys_Switch

        ALIGN
}


/*----------------------------------------------------------------------------
 * end of file
 *---------------------------------------------------------------------------*/

