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[fiber] Add cooperative, stackful fibers
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16 files changed

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‎repo.lb

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@@ -274,6 +274,10 @@ def init(repo):
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description=descr_target,
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enumeration=devices))
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# Invisible option guarding the Fiber API until it is ready
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repo.add_option(BooleanOption(name="__fibers", default=False,
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description="Enable unstable fiber API."))
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def prepare(repo, options):
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repo.add_modules_recursive("ext", modulefile="*.lb")
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repo.add_modules_recursive("src", modulefile="*.lb")

‎src/modm/architecture/utils.hpp

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/// Marks a declaration as deprecated and displays a message.
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#define modm_deprecated(msg)
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/// Tells the compiler to not generate prologue/epilogue code for this function.
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#define modm_naked
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/// Places a function in the fastest executable memory:
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/// instruction cache, core coupled memory or SRAM as fallback.
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#define modm_fastcode
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#define modm_fallthrough __attribute__((fallthrough))
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#define modm_noreturn __attribute__((noreturn))
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#define modm_warn_unused_result __attribute__((warn_unused_result))
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#define modm_naked __attribute__((naked))
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#ifdef MODM_COMPILER_MINGW
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// FIXME: Windows Object Format PE does not support weak symbols

‎src/modm/processing/fiber.hpp

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/*
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* Copyright (c) 2020, Erik Henriksson
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*
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* This file is part of the modm project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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// ----------------------------------------------------------------------------
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#include "fiber/fiber.hpp"
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#include "fiber/scheduler.hpp"

‎src/modm/processing/fiber/context.h

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/*
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* Copyright (c) 2020, Erik Henriksson
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* Copyright (c) 2021, Niklas Hauser
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*
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* This file is part of the modm project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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// ----------------------------------------------------------------------------
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#pragma once
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#include <stdint.h>
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#include <stddef.h>
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#include <modm/architecture/utils.hpp>
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#ifdef __cplusplus
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extern "C"
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{
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#endif
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struct modm_context_t
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{
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uintptr_t sp;
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size_t stack_size;
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};
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/// Prepares the stack to jump into function with arg and call end on return
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modm_context_t
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modm_context_init(uintptr_t stack, uintptr_t arg, uintptr_t fn, uintptr_t end);
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/// Switches control from the main context to the user context.
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void
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modm_context_start(uintptr_t sp);
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/// Jumps from the "from" user context to the "to" user context.
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void
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modm_context_jump(uintptr_t* from_sp, uintptr_t to_sp);
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/// Switches control back to the main context from the user context.
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void __attribute__((noreturn))
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modm_context_end();
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#ifdef __cplusplus
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}
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#endif

‎src/modm/processing/fiber/context_arm_m.cpp.in

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/*
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* Copyright (c) 2020, Erik Henriksson
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* Copyright (c) 2021, Niklas Hauser
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*
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* This file is part of the modm project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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// ----------------------------------------------------------------------------
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#include "context.h"
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/* Stack layout (growing downwards):
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* Registers r4-r11 must be preserved across subroutine calls.
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*
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* LR
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%% if not cm0
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* r11
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* r10
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* r9
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* r8
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%% endif
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* r7
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* r6
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* r5
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* r4
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%% if cm0
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* r11
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* r10
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* r9
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* r8
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%% endif
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%% if with_fpu
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* s31
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* s30
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* s29
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* s28
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* s27
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* s26
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* s25
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* s24
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* s23
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* s22
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* s21
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* s20
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* s19
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* s18
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* s17
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* s16
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*
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* From the PCSAA:
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* Registers s16-s31 (d8-d15, q4-q7) must be preserved across subroutine calls;
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* registers s0-s15 (d0-d7, q0- q3) do not need to be preserved (and can be used
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* for passing arguments or returning results in standard procedure-call
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* variants). Registers d16-d31 (q8-q15), if present, do not need to be
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* preserved.
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%% endif
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*/
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static void modm_naked
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modm_context_entry()
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{
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asm volatile
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(
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"pop {r0} \n\t" // Loads return address
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"mov lr, r0 \n\t" // Set LR
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"pop {r0, pc} \n\t" // Load argument and jump
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);
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}
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modm_context_t
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modm_context_init(uintptr_t stack, uintptr_t arg, uintptr_t fn, uintptr_t end)
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{
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uintptr_t* sp = (uintptr_t*)arg;
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*--sp = fn; // actual fiber function
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*--sp = arg; // r0 argument
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*--sp = end; // called after fn returns
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*--sp = (uintptr_t) modm_context_entry;
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sp -= 8{% if with_fpu %}+16{% endif %}; // r4-r11{% if with_fpu %}, s16-s31{% endif %}
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return {(uintptr_t) sp, arg - stack};
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}
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#define MODM_PUSH_CONTEXT() \
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%% if cm0
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"push {r4-r7, lr} \n\t" \
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"mov r4, r8 \n\t" \
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"mov r5, r9 \n\t" \
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"mov r6, r10 \n\t" \
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"mov r7, r11 \n\t" \
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"push {r4-r7} \n\t"
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%% else
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"push {r4-r11, lr} \n\t"{% if with_fpu %} \
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"vpush {d8-d15} \n\t"{% endif %}
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%% endif
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%#
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#define MODM_POP_CONTEXT() \
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%% if cm0
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"pop {r4-r7} \n\t" \
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"mov r8, r4 \n\t" \
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"mov r9, r5 \n\t" \
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"mov r10, r6 \n\t" \
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"mov r11, r7 \n\t" \
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"pop {r4-r7, pc} \n\t"
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%% else
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%% if with_fpu
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"vpop {d8-d15} \n\t" \
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%% endif
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"pop {r4-r11, pc} \n\t"
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%% endif
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%#
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void modm_naked
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modm_context_start(uintptr_t)
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{
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asm volatile
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(
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MODM_PUSH_CONTEXT()
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"mrs r2, control \n\t"
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%% if cm0
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"mov r1, #2 \n\t"
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"orr r2, r2, r1 \n\t" // Set SPSEL
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%% else
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"orr r2, r2, #2 \n\t" // Set SPSEL
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%% endif
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"msr control, r2 \n\t"
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"mov sp, r0 \n\t" // Set PSP to fiber stack (to.sp)
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MODM_POP_CONTEXT()
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);
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}
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void modm_naked
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modm_context_jump(uintptr_t*, uintptr_t)
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{
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asm volatile
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(
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MODM_PUSH_CONTEXT()
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%#
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%% if cm0
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"mov r2, sp \n\t"
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"str r2, [r0] \n\t" // Store the SP in "from"
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%% else
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"str sp, [r0] \n\t" // Store the SP in "from"
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%% endif
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"mov sp, r1 \n\t" // Restore SP from "to"
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MODM_POP_CONTEXT()
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);
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}
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void modm_naked
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modm_context_end()
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{
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asm volatile
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(
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"mrs r0, control \n\t"
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%% if cm0
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"mov r1, #2 \n\t"
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"bic r0, r0, r1 \n\t" // Unset SPSEL
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%% else
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"bic r0, r0, #2 \n\t" // Unset SPSEL
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%% endif
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"msr control, r0 \n\t"
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MODM_POP_CONTEXT()
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);
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}

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