110 lines
3.5 KiB
ArmAsm
110 lines
3.5 KiB
ArmAsm
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/*
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* Copyright (c) 2006-2018, RT-Thread Development Team
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Change Logs:
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* Date Author Notes
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*/
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.global rt_hw_interrupt_disable
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.global rt_hw_interrupt_enable
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.global rt_hw_context_switch
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.global rt_hw_context_switch_to
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.global rt_hw_context_switch_interrupt
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.equ NOINT, 0xc0
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/*
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* rt_base_t rt_hw_interrupt_disable();
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关闭中断，关闭前返回CPSR寄存器值
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*/
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rt_hw_interrupt_disable:
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//EXPORT rt_hw_interrupt_disable
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MRS r0, cpsr
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ORR r1, r0, #NOINT
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MSR cpsr_c, r1
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BX lr
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//ENDP
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/*
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* void rt_hw_interrupt_enable(rt_base_t level);
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恢复中断状态
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*/
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rt_hw_interrupt_enable:
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//EXPORT rt_hw_interrupt_enable
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MSR cpsr_c, r0
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BX lr
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//ENDP
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/*
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* void rt_hw_context_switch(rt_uint32 from, rt_uint32 to);
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* r0 --> from
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* r1 --> to
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进行线程的上下文切换
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*/
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rt_hw_context_switch:
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//EXPORT rt_hw_context_switch
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STMFD sp!, {lr} /* push pc (lr should be pushed in place of PC) */
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/* 把LR寄存器压入栈（这个函数返回后的下一个执行处） */
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STMFD sp!, {r0-r12, lr} /* push lr & register file */
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/* 把R0 – R12以及LR压入栈 */
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MRS r4, cpsr /* 读取CPSR寄存器到R4寄存器 */
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STMFD sp!, {r4} /* push cpsr */
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/* 把R4寄存器压栈（即上一指令取出的CPSR寄存器） */
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MRS r4, spsr /* 读取SPSR寄存器到R4寄存器 */
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STMFD sp!, {r4} /* push spsr */
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/* 把R4寄存器压栈（即SPSR寄存器） */
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STR sp, [r0] /* store sp in preempted tasks TCB */
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/* 把栈指针更新到TCB的sp，是由R0传入此函数 */
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/* 到这里换出线程的上下文都保存在栈中 */
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LDR sp, [r1] /* get new task stack pointer */
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/* 载入切换到线程的TCB的sp */
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/* 从切换到线程的栈中恢复上下文，次序和保存的时候刚好相反 */
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LDMFD sp!, {r4} /* pop new task spsr */
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/* 出栈到R4寄存器（保存了SPSR寄存器） */
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MSR spsr_cxsf, r4 /* 恢复SPSR寄存器 */
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LDMFD sp!, {r4} /* pop new task cpsr */
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/* 出栈到R4寄存器（保存了CPSR寄存器） */
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MSR cpsr_cxsf, r4 /* 恢复CPSR寄存器 */
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LDMFD sp!, {r0-r12, lr, pc} /* pop new task r0-r12, lr & pc */
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/* 对R0 – R12及LR、PC进行恢复 */
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//ENDP
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rt_hw_context_switch_to:
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//EXPORT rt_hw_context_switch_to
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LDR sp, [r0] /* get new task stack pointer */
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/* 获得切换到线程的SP指针 */
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LDMFD sp!, {r4} /* pop new task spsr */
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/* 出栈R4寄存器（保存了SPSR寄存器值） */
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MSR spsr_cxsf, r4 /* 恢复SPSR寄存器 */
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LDMFD sp!, {r4} /* pop new task cpsr */
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/* 出栈R4寄存器（保存了CPSR寄存器值） */
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MSR cpsr_cxsf, r4 /* 恢复CPSR寄存器 */
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LDMFD sp!, {r0-r12, lr, pc} /* pop new task r0-r12, lr & pc */
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/* 恢复R0 – R12，LR及PC寄存器 */
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//ENDP
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rt_hw_context_switch_interrupt:
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//EXPORT rt_hw_context_switch_interrupt
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LDR r2, =rt_thread_switch_interrupt_flag
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LDR r3, [r2] /* 载入中断中切换标致地址 */
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CMP r3, #1 /* 等于 1 ？*/
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BEQ _reswitch /* 如果等于1，跳转到_reswitch*/
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MOV r3, #1 /* set rt_thread_switch_interrupt_flag to 1*/
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/* 设置中断中切换标志位1 */
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STR r3, [r2] /* */
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LDR r2, =rt_interrupt_from_thread /* set rt_interrupt_from_thread*/
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STR r0, [r2] /* 保存切换出线程栈指针*/
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_reswitch:
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LDR r2, =rt_interrupt_to_thread /* set rt_interrupt_to_thread*/
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STR r1, [r2] /* 保存切换到线程栈指针*/
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BX lr
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//ENDP
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//END
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