103 lines
3.6 KiB
ArmAsm
103 lines
3.6 KiB
ArmAsm
/*
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* Copyright (c) 2013-2014 Immo Software
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* o Redistributions of source code must retain the above copyright notice, this list
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* of conditions and the following disclaimer.
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*
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* o Redistributions in binary form must reproduce the above copyright notice, this
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* list of conditions and the following disclaimer in the documentation and/or
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* other materials provided with the distribution.
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*
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* o Neither the name of the copyright holder nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "ar_asm_macros.h"
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// EXC_RETURN value to return to Thread mode, while restoring state from PSP.
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_EQU(EXC_RETURN, 0xfffffffd)
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/* specify the section where this code belongs */
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_CODE_SECTION(.text)
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_THUMB
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_IMPORT(ar_kernel_yield_isr)
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_EXPORT(SVC_Handler)
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_EXPORT(PendSV_Handler)
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_FN_BEGIN(PendSV_Handler)
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_FN_DECL(PendSV_Handler)
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_FN_LABEL(SVC_Handler)
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_LABEL(PendSV_Handler)
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_FN_BEGIN_POST
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_FN_CANT_UNWIND
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// Get PSP
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mrs r0, psp
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// Subtract room for the registers we are going to store. We have to pre-subtract
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// and use the incrementing store multiple instruction because the CM0+ doesn't
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// have the decrementing variant.
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subs r0, r0, #32
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// Save registers on the stack. This has to be done in two stages because
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// the stmia instruction cannot access the upper registers on the CM0+.
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stmia r0!, {r4-r7}
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mov r4, r8
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mov r5, r9
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mov r6, r10
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mov r7, r10
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stmia r0!, {r4-r7}
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// Get back to the bottom of the stack before we pass the current SP to the
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// ar_yield call.
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subs r0, r0, #32
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// Invoke scheduler. On return, r0 contains the stack pointer for the new thread.
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ldr r1, =ar_kernel_yield_isr
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blx r1
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// Unstack saved registers.
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adds r0, r0, #16
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ldmia r0!, {r4-r7}
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subs r0, r0, #32
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mov r8, r4
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mov r9, r5
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mov r10, r6
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mov r11, r7
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ldmia r0!, {r4-r7}
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adds r0, r0, #16
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// Update PSP with new stack pointer.
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msr psp, r0
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// Exit handler. Using a bx to the special EXC_RETURN values causes the
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// processor to perform the exception return behavior.
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ldr r0, =EXC_RETURN
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bx r0
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_FN_END(PendSV_Handler)
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_FN_SIZE(PendSV_Handler)
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_ALIGN(4)
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_END
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