rt-thread-official/libcpu/arm/am335x/context_iar.S

;/*
; * Copyright (c) 2006-2021, RT-Thread Development Team
; *
; * SPDX-License-Identifier: Apache-2.0
; *
; * Change Logs:
; * Date           Author       Notes
; * 2011-08-14     weety      copy from mini2440
; * 2015-04-15     ArdaFu     convert from context_gcc.s
; */

#define NOINT            0xc0

    SECTION    .text:CODE(6)
/*
 * rt_base_t rt_hw_interrupt_disable();
 */
    PUBLIC rt_hw_interrupt_disable
rt_hw_interrupt_disable:
    MRS     R0, CPSR
    ORR     R1, R0, #NOINT
    MSR     CPSR_C, R1
    MOV     PC, LR

/*
 * void rt_hw_interrupt_enable(rt_base_t level);
 */
    PUBLIC rt_hw_interrupt_enable
rt_hw_interrupt_enable:
    MSR     CPSR_CXSF, R0
    MOV     PC, LR

/*
 * void rt_hw_context_switch(rt_uint32 from, rt_uint32 to);
 * r0 --> from
 * r1 --> to
 */
    PUBLIC rt_hw_context_switch
rt_hw_context_switch:
    STMFD   SP!, {LR}               ; push pc (lr should be pushed in place of PC)
    STMFD   SP!, {R0-R12, LR}       ; push lr & register file
    MRS     R4, CPSR
    TST     LR, #0x01
    ORRNE   R4, R4, #0x20           ; it's thumb code
    STMFD   SP!, {R4}               ; push cpsr
    STR     SP, [R0]                ; store sp in preempted tasks TCB
    LDR     SP, [R1]                ; get new task stack pointer
    LDMFD   SP!, {R4}               ; pop new task spsr
    MSR     SPSR_cxsf, R4
    LDMFD   SP!, {R0-R12, LR, PC}^  ; pop new task r0-r12, lr & pc

/*
 * void rt_hw_context_switch_to(rt_uint32 to);
 * r0 --> to
 */
    PUBLIC rt_hw_context_switch_to
rt_hw_context_switch_to:
    LDR     SP, [R0]                ; get new task stack pointer
    LDMFD   SP!, {R4}               ; pop new task spsr
    MSR     SPSR_cxsf, R4
    BIC     R4, R4, #0x20           ; must be ARM mode
    MSR     CPSR_CXSF, R4
    LDMFD   SP!, {R0-R12, LR, PC}^  ; pop new task r0-r12, lr & pc

/*
 * void rt_hw_context_switch_interrupt(rt_uint32 from, rt_uint32 to);
 */
    IMPORT rt_thread_switch_interrupt_flag
    IMPORT rt_interrupt_from_thread
    IMPORT rt_interrupt_to_thread
    PUBLIC rt_hw_context_switch_interrupt
rt_hw_context_switch_interrupt:
    LDR     R2, =rt_thread_switch_interrupt_flag
    LDR     R3, [R2]
    CMP     R3, #1
    BEQ     _reswitch
    MOV     R3, #1                          ; set flag to 1
    STR     R3, [R2]
    LDR     R2, =rt_interrupt_from_thread   ; set rt_interrupt_from_thread
    STR     R0, [R2]
_reswitch:
    LDR     R2, =rt_interrupt_to_thread     ; set rt_interrupt_to_thread
    STR     R1, [R2]
    MOV     PC, LR
    END