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/**
* @file
*
* @ingroup ScoreCPU
*
* @brief ARM architecture support implementation.
*/
/*
* This file contains all assembly code for the ARM implementation
* of RTEMS.
*
* Copyright (c) 2007 by Ray Xu, <Rayx.cn@gmail.com>
* Thumb support added.
*
* Copyright (c) 2002 by Advent Networks, Inc.
* Jay Monkman <jmonkman@adventnetworks.com>
*
* COPYRIGHT (c) 2000 Canon Research Centre France SA.
* Emmanuel Raguet, mailto:raguet@crf.canon.fr
*
* Copyright (c) 2013-2015 embedded brains GmbH
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/asm.h>
#ifdef ARM_MULTILIB_ARCH_V4
.text
/*
* void _CPU_Context_switch( run_context, heir_context )
* void _CPU_Context_restore( run_context, heir_context )
*
* This routine performs a normal non-FP context.
*
* R0 = run_context R1 = heir_context
*
* This function copies the current registers to where r0 points, then
* restores the ones from where r1 points.
*
* Using the ldm/stm opcodes save 2-3 us on 100 MHz ARM9TDMI with
* a 16 bit data bus.
*
*/
DEFINE_FUNCTION_ARM(_CPU_Context_switch)
/* Start saving context */
mrs r2, CPSR
stmia r0, {r2, r4, r5, r6, r7, r8, r9, r10, r11, r13, r14}
#ifdef ARM_MULTILIB_VFP
add r3, r0, #ARM_CONTEXT_CONTROL_D8_OFFSET
vstm r3, {d8-d15}
#endif
#ifdef ARM_MULTILIB_HAS_THREAD_ID_REGISTER
mrc p15, 0, r3, c13, c0, 3
str r3, [r0, #ARM_CONTEXT_CONTROL_THREAD_ID_OFFSET]
#endif
#ifdef RTEMS_SMP
/* The executing context no longer executes on this processor */
dmb
mov r3, #0
strb r3, [r0, #ARM_CONTEXT_CONTROL_IS_EXECUTING_OFFSET]
.L_check_is_executing:
/* Check the is executing indicator of the heir context */
add r3, r1, #ARM_CONTEXT_CONTROL_IS_EXECUTING_OFFSET
ldrexb r4, [r3]
cmp r4, #0
bne .L_get_potential_new_heir
/* Try to update the is executing indicator of the heir context */
mov r4, #1
strexb r5, r4, [r3]
cmp r5, #0
bne .L_get_potential_new_heir
dmb
#endif
/* Start restoring context */
.L_restore:
#if !defined(RTEMS_SMP) && defined(ARM_MULTILIB_HAS_LOAD_STORE_EXCLUSIVE)
clrex
#endif
#ifdef ARM_MULTILIB_HAS_THREAD_ID_REGISTER
ldr r3, [r1, #ARM_CONTEXT_CONTROL_THREAD_ID_OFFSET]
mcr p15, 0, r3, c13, c0, 3
#endif
#ifdef ARM_MULTILIB_VFP
add r3, r1, #ARM_CONTEXT_CONTROL_D8_OFFSET
vldm r3, {d8-d15}
#endif
ldmia r1, {r2, r4, r5, r6, r7, r8, r9, r10, r11, r13, r14}
msr CPSR_fsxc, r2
#ifdef __thumb__
bx lr
nop
#else
mov pc, lr
#endif
/*
* void _CPU_Context_restore( new_context )
*
* This function copies the restores the registers from where r0 points.
* It must match _CPU_Context_switch()
*
*/
DEFINE_FUNCTION_ARM(_CPU_Context_restore)
mov r1, r0
b .L_restore
#ifdef RTEMS_SMP
.L_get_potential_new_heir:
GET_SELF_CPU_CONTROL r2
/* We may have a new heir */
/* Read the executing and heir */
ldr r4, [r2, #PER_CPU_OFFSET_EXECUTING]
ldr r5, [r2, #PER_CPU_OFFSET_HEIR]
/*
* Update the executing only if necessary to avoid cache line
* monopolization.
*/
cmp r4, r5
beq .L_check_is_executing
/* Calculate the heir context pointer */
sub r4, r1, r4
add r1, r5, r4
/* Update the executing */
str r5, [r2, #PER_CPU_OFFSET_EXECUTING]
b .L_check_is_executing
#endif
#endif /* ARM_MULTILIB_ARCH_V4 */
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