58 lines
1.5 KiB
ArmAsm
58 lines
1.5 KiB
ArmAsm
/* See the end of this file for copyright, license, and warranty information. */
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.include "asm.S"
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.text
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.extern sched_process_switch
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/* void handle_pend_sv(void); */
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func_begin handle_pend_sv
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/*
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* Some registers have already been saved by hardware at this point,
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* we only need to take care of r4-r11 and lr (the latter of which is
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* required because lr is overwritten when entering the irq).
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* The stuff we push onto the stack manually looks about like this:
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*
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* <<< stack grow direction (decreasing addresses) <<<
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* r4 r5 r6 r7 r8 r9 r10 r11 lr
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*/
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push {r4-r11,lr}
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/*
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* Now that our stack is completely saved, we can proceed to call the
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* Kernel's scheduler. This updates `_current_process` to the process
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* we want to execute next.
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*/
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/* TODO: Implement banked stack pointer */
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mov r0, sp
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bl sched_process_switch /* sp = sched_process_switch(sp); */
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mov sp, r0
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/*
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* The new stack pointer contains the state of the new process, so we
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* load it into our registers using the same procedure as above,
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* just in reverse order.
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*/
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pop {r4-r11,lr}
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clrex
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bx lr
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func_end handle_pend_sv
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/*
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* This file is part of Ardix.
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* Copyright (c) 2020, 2021 Felix Kopp <owo@fef.moe>.
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*
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* Ardix is non-violent software: you may only use, redistribute,
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* and/or modify it under the terms of the CNPLv6+ as found in
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* the LICENSE file in the source code root directory or at
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* <https://git.pixie.town/thufie/CNPL>.
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*
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* Ardix comes with ABSOLUTELY NO WARRANTY, to the extent
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* permitted by applicable law. See the CNPLv6+ for details.
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*/
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