FreeRTOS-Kernel/portable/Tasking/ARM_CM4F/port_asm.asm

;/*
; * FreeRTOS Kernel <DEVELOPMENT BRANCH>
; * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
; *
; * SPDX-License-Identifier: MIT
; *
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; * this software and associated documentation files (the "Software"), to deal in
; * the Software without restriction, including without limitation the rights to
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; * the Software, and to permit persons to whom the Software is furnished to do so,
; * subject to the following conditions:
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; * copies or substantial portions of the Software.
; *
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; */


    .extern pxCurrentTCB
    .extern vTaskSwitchContext
    .extern ulMaxSyscallInterruptPriorityConst

    .global _vector_14
    .global _lc_ref__vector_pp_14
    .global SVC_Handler
    .global vPortStartFirstTask
    .global vPortEnableVFP
    .global ulPortSetInterruptMask
    .global vPortClearInterruptMask

;-----------------------------------------------------------

    .section .text
    .thumb
    .align 4
_vector_14: .type func

    mrs r0, psp
    isb

    ;Get the location of the current TCB.
    ldr.w   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.
    stmdb r0!, {r4-r11, r14}

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

    stmdb sp!, {r0, r3}
    ldr.w r0, =ulMaxSyscallInterruptPriorityConst
    ldr r0, [r0]
    msr basepri, r0
    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]

    ;Pop the core registers.
    ldmia r0!, {r4-r11, r14}

    ;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

    .size   _vector_14, $-_vector_14
    .endsec

;-----------------------------------------------------------

; This function is an XMC4000 silicon errata workaround.  It will get used when
; the SILICON_BUG_PMC_CM_001 linker macro is defined.
    .section .text
    .thumb
    .align 4
_lc_ref__vector_pp_14: .type func

    mrs r0, psp
    isb

    ;Get the location of the current TCB.
    ldr.w   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.
    stmdb r0!, {r4-r11, r14}

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

    stmdb sp!, {r3}
    ldr.w r0, =ulMaxSyscallInterruptPriorityConst
    ldr r0, [r0]
    msr basepri, r0
    bl vTaskSwitchContext
    mov r0, #0
    msr basepri, r0
    ldmia sp!, {r3}

    ;The first item in pxCurrentTCB is the task top of stack.
    ldr r1, [r3]
    ldr r0, [r1]

    ;Pop the core registers.
    ldmia r0!, {r4-r11, r14}

    ;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
    push { lr }
    pop { pc } ; XMC4000 specific errata workaround.  Do not used "bx lr" here.

    .size   _lc_ref__vector_pp_14, $-_lc_ref__vector_pp_14
    .endsec

;-----------------------------------------------------------

    .section .text
    .thumb
    .align 4
SVC_Handler: .type func
    ;Get the location of the current TCB.
    ldr.w   r3, =pxCurrentTCB
    ldr r1, [r3]
    ldr r0, [r1]
    ;Pop the core registers.
    ldmia r0!, {r4-r11, r14}
    msr psp, r0
    isb
    mov r0, #0
    msr basepri, r0
    bx r14
    .size   SVC_Handler, $-SVC_Handler
    .endsec

;-----------------------------------------------------------

    .section .text
    .thumb
    .align 4
vPortStartFirstTask .type func
    ;Use the NVIC offset register to locate the stack.
    ldr.w r0, =0xE000ED08
    ldr r0, [r0]
    ldr r0, [r0]
    ;Set the msp back to the start of the stack.
    msr msp, r0
    ;Call SVC to start the first task.
    cpsie i
    cpsie f
    dsb
    isb
    svc 0
    .size   vPortStartFirstTask, $-vPortStartFirstTask
    .endsec

;-----------------------------------------------------------

    .section .text
    .thumb
    .align 4
vPortEnableVFP .type func
    ;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
    .size   vPortEnableVFP, $-vPortEnableVFP
    .endsec

;-----------------------------------------------------------

    .section .text
    .thumb
    .align 4
ulPortSetInterruptMask:
    mrs r0, basepri
    ldr.w r1, =ulMaxSyscallInterruptPriorityConst
    ldr r1, [r1]
    msr basepri, r1
    bx r14
    .size   ulPortSetInterruptMask, $-ulPortSetInterruptMask
    .endsec

;-----------------------------------------------------------

    .section .text
    .thumb
    .align 4
vPortClearInterruptMask:
    msr basepri, r0
    bx r14
    .size   vPortClearInterruptMask, $-vPortClearInterruptMask
    .endsec

;-----------------------------------------------------------

    .end