/*
 * FreeRTOS Kernel <DEVELOPMENT BRANCH>
 * Copyright (C) 2021 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * https://www.FreeRTOS.org
 * https://github.com/FreeRTOS
 *
 */
/* Including FreeRTOSConfig.h here will cause build errors if the header file
contains code not understood by the assembler - for example the 'extern' keyword.
To avoid errors place any such code inside a #ifdef __ICCARM__/#endif block so
the code is included in C files but excluded by the preprocessor in assembly
files (__ICCARM__ is defined by the IAR C compiler but not by the IAR assembler. */
#include <FreeRTOSConfig.h>

    RSEG    CODE:CODE(2)
    thumb

    EXTERN pxCurrentTCB
    EXTERN vTaskSwitchContext
    EXTERN vPortSVCHandler_C

    PUBLIC xPortPendSVHandler
    PUBLIC vPortSVCHandler
    PUBLIC vPortStartFirstTask
    PUBLIC vPortEnableVFP
    PUBLIC vPortRestoreContextOfFirstTask
    PUBLIC xIsPrivileged
    PUBLIC vResetPrivilege

/*-----------------------------------------------------------*/

xPortPendSVHandler:
    mrs r0, psp
    isb
    /* Get the location of the current TCB. */
    ldr r3, =pxCurrentTCB
    ldr r2, [r3]

    /* Is the task using the FPU context?  If so, push high vfp registers. */
    tst r14, #0x10
    it eq
    vstmdbeq r0!, {s16-s31}

    /* Save the core registers. */
    mrs r1, control
    stmdb r0!, {r1, r4-r11, r14}

    /* Save the new top of stack into the first member of the TCB. */
    str r0, [r2]

    stmdb sp!, {r0, r3}
    mov r0, #configMAX_SYSCALL_INTERRUPT_PRIORITY
    #if ( configENABLE_ERRATA_837070_WORKAROUND == 1 )
        cpsid i /* ARM Cortex-M7 r0p1 Errata 837070 workaround. */
    #endif
    msr basepri, r0
    dsb
    isb
    #if ( configENABLE_ERRATA_837070_WORKAROUND == 1 )
        cpsie i /* ARM Cortex-M7 r0p1 Errata 837070 workaround. */
    #endif
    bl vTaskSwitchContext
    mov r0, #0
    msr basepri, r0
    ldmia sp!, {r0, r3}

    /* The first item in pxCurrentTCB is the task top of stack. */
    ldr r1, [r3]
    ldr r0, [r1]
    /* Move onto the second item in the TCB... */
    add r1, r1, #4

    dmb                 /* Complete outstanding transfers before disabling MPU. */
    ldr r2, =0xe000ed94 /* MPU_CTRL register. */
    ldr r3, [r2]        /* Read the value of MPU_CTRL. */
    bic r3, r3, #1      /* r3 = r3 & ~1 i.e. Clear the bit 0 in r3. */
    str r3, [r2]        /* Disable MPU. */

    /* Region Base Address register. */
    ldr r2, =0xe000ed9c
    /* Read 4 sets of MPU registers [MPU Region # 4 - 7]. */
    ldmia r1!, {r4-r11}
    /* Write 4 sets of MPU registers [MPU Region # 4 - 7]. */
    stmia r2, {r4-r11}

    #ifdef configTOTAL_MPU_REGIONS
        #if ( configTOTAL_MPU_REGIONS == 16 )
            /* Read 4 sets of MPU registers [MPU Region # 8 - 11]. */
            ldmia r1!, {r4-r11}
            /* Write 4 sets of MPU registers. [MPU Region # 8 - 11]. */
            stmia r2, {r4-r11}
            /* Read 4 sets of MPU registers [MPU Region # 12 - 15]. */
            ldmia r1!, {r4-r11}
            /* Write 4 sets of MPU registers. [MPU Region # 12 - 15]. */
            stmia r2, {r4-r11}
        #endif /* configTOTAL_MPU_REGIONS == 16. */
    #endif /* configTOTAL_MPU_REGIONS */

    ldr r2, =0xe000ed94 /* MPU_CTRL register. */
    ldr r3, [r2]        /* Read the value of MPU_CTRL. */
    orr r3, r3, #1      /* r3 = r3 | 1 i.e. Set the bit 0 in r3. */
    str r3, [r2]        /* Enable MPU. */
    dsb                 /* Force memory writes before continuing. */

    /* Pop the registers that are not automatically saved on exception entry. */
    ldmia r0!, {r3-r11, r14}
    msr control, r3

    /* Is the task using the FPU context?  If so, pop the high vfp registers
    too. */
    tst r14, #0x10
    it eq
    vldmiaeq r0!, {s16-s31}

    msr psp, r0
    isb

    bx r14


/*-----------------------------------------------------------*/

vPortSVCHandler:
    #ifndef USE_PROCESS_STACK   /* Code should not be required if a main() is using the process stack. */
        tst lr, #4
        ite eq
        mrseq r0, msp
        mrsne r0, psp
    #else
        mrs r0, psp
    #endif
        b vPortSVCHandler_C

/*-----------------------------------------------------------*/

vPortStartFirstTask:
    /* Use the NVIC offset register to locate the stack. */
    ldr r0, =0xE000ED08
    ldr r0, [r0]
    ldr r0, [r0]
    /* Set the msp back to the start of the stack. */
    msr msp, r0
    /* Clear the bit that indicates the FPU is in use in case the FPU was used
    before the scheduler was started - which would otherwise result in the
    unnecessary leaving of space in the SVC stack for lazy saving of FPU
    registers. */
    mov r0, #0
    msr control, r0
    /* Call SVC to start the first task. */
    cpsie i
    cpsie f
    dsb
    isb
    svc 0

/*-----------------------------------------------------------*/

vPortRestoreContextOfFirstTask:
    /* Use the NVIC offset register to locate the stack. */
    ldr r0, =0xE000ED08
    ldr r0, [r0]
    ldr r0, [r0]
    /* Set the msp back to the start of the stack. */
    msr msp, r0
    /* Restore the context. */
    ldr r3, =pxCurrentTCB
    ldr r1, [r3]
    /* The first item in the TCB is the task top of stack. */
    ldr r0, [r1]
    /* Move onto the second item in the TCB... */
    add r1, r1, #4

    dmb                 /* Complete outstanding transfers before disabling MPU. */
    ldr r2, =0xe000ed94 /* MPU_CTRL register. */
    ldr r3, [r2]        /* Read the value of MPU_CTRL. */
    bic r3, r3, #1      /* r3 = r3 & ~1 i.e. Clear the bit 0 in r3. */
    str r3, [r2]        /* Disable MPU. */

    /* Region Base Address register. */
    ldr r2, =0xe000ed9c
    /* Read 4 sets of MPU registers [MPU Region # 4 - 7]. */
    ldmia r1!, {r4-r11}
    /* Write 4 sets of MPU registers [MPU Region # 4 - 7]. */
    stmia r2, {r4-r11}

    #ifdef configTOTAL_MPU_REGIONS
        #if ( configTOTAL_MPU_REGIONS == 16 )
            /* Read 4 sets of MPU registers [MPU Region # 8 - 11]. */
            ldmia r1!, {r4-r11}
            /* Write 4 sets of MPU registers. [MPU Region # 8 - 11]. */
            stmia r2, {r4-r11}
            /* Read 4 sets of MPU registers [MPU Region # 12 - 15]. */
            ldmia r1!, {r4-r11}
            /* Write 4 sets of MPU registers. [MPU Region # 12 - 15]. */
            stmia r2, {r4-r11}
        #endif /* configTOTAL_MPU_REGIONS == 16. */
    #endif /* configTOTAL_MPU_REGIONS */

    ldr r2, =0xe000ed94 /* MPU_CTRL register. */
    ldr r3, [r2]        /* Read the value of MPU_CTRL. */
    orr r3, r3, #1      /* r3 = r3 | 1 i.e. Set the bit 0 in r3. */
    str r3, [r2]        /* Enable MPU. */
    dsb                 /* Force memory writes before continuing. */

    /* Pop the registers that are not automatically saved on exception entry. */
    ldmia r0!, {r3-r11, r14}
    msr control, r3
    /* Restore the task stack pointer. */
    msr psp, r0
    mov r0, #0
    msr basepri, r0
    bx r14

/*-----------------------------------------------------------*/

vPortEnableVFP:
    /* The FPU enable bits are in the CPACR. */
    ldr.w r0, =0xE000ED88
    ldr r1, [r0]

    /* Enable CP10 and CP11 coprocessors, then save back. */
    orr r1, r1, #( 0xf << 20 )
    str r1, [r0]
    bx  r14

/*-----------------------------------------------------------*/

xIsPrivileged:
    mrs r0, control     /* r0 = CONTROL. */
    tst r0, #1          /* Perform r0 & 1 (bitwise AND) and update the conditions flag. */
    ite ne
    movne r0, #0        /* CONTROL[0]!=0. Return false to indicate that the processor is not privileged. */
    moveq r0, #1        /* CONTROL[0]==0. Return true to indicate that the processor is privileged. */
    bx lr               /* Return. */
/*-----------------------------------------------------------*/

vResetPrivilege:
    mrs r0, control     /* r0 = CONTROL. */
    orr r0, r0, #1      /* r0 = r0 | 1. */
    msr control, r0     /* CONTROL = r0. */
    bx lr               /* Return to the caller. */
/*-----------------------------------------------------------*/

    END