/******************************************************************//** * @file context_gcc.S * @brief Context switch functions * COPYRIGHT (C) 2009, RT-Thread Development Team * @author Bernard, onelife * @version 0.4 beta ********************************************************************** * @section License * The license and distribution terms for this file may be found in the file LICENSE in this * distribution or at http://www.rt-thread.org/license/LICENSE ********************************************************************** * @section Change Logs * Date Author Notes * 2009-10-11 Bernard first version * 2010-12-29 onelife Modify for EFM32 *********************************************************************/ /******************************************************************//** * @addtogroup cortex-m3 * @{ *********************************************************************/ .cpu cortex-m3 .fpu softvfp .syntax unified .thumb .text .equ ICSR, 0xE000ED04 /* interrupt control state register */ .equ PENDSVSET_BIT, 0x10000000 /* value to trigger PendSV exception */ .equ SHPR3, 0xE000ED20 /* system priority register (3) */ .equ PENDSV_PRI_LOWEST, 0x00FF0000 /* PendSV priority value (lowest) */ /* * rt_base_t rt_hw_interrupt_disable(); */ .global rt_hw_interrupt_disable .type rt_hw_interrupt_disable, %function rt_hw_interrupt_disable: MRS R0, PRIMASK CPSID I BX LR /* * void rt_hw_interrupt_enable(rt_base_t level); */ .global rt_hw_interrupt_enable .type rt_hw_interrupt_enable, %function rt_hw_interrupt_enable: MSR PRIMASK, R0 BX LR /* * void rt_hw_context_switch(rt_uint32 from, rt_uint32 to); * R0 --> from * R1 --> to */ .global rt_hw_context_switch_interrupt .type rt_hw_context_switch_interrupt, %function .global rt_hw_context_switch .type rt_hw_context_switch, %function rt_hw_context_switch_interrupt: rt_hw_context_switch: /* set rt_thread_switch_interrput_flag to 1 */ LDR R2, =rt_thread_switch_interrput_flag LDR R3, [R2] CMP R3, #1 BEQ _reswitch MOV R3, #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] LDR R0, =ICSR /* trigger the PendSV exception (causes context switch) */ LDR R1, =PENDSVSET_BIT STR R1, [R0] BX LR /* R0 --> swith from thread stack * R1 --> swith to thread stack * psr, pc, LR, R12, R3, R2, R1, R0 are pushed into [from] stack */ .global rt_hw_pend_sv .type rt_hw_pend_sv, %function rt_hw_pend_sv: /* disable interrupt to protect context switch */ MRS R2, PRIMASK CPSID I /* get rt_thread_switch_interrupt_flag */ LDR R0, =rt_thread_switch_interrput_flag LDR R1, [R0] CBZ R1, pendsv_exit /* pendsv aLReady handled */ /* clear rt_thread_switch_interrput_flag to 0 */ MOV R1, #0 STR R1, [R0] LDR R0, =rt_interrupt_from_thread LDR R1, [R0] CBZ R1, swtich_to_thread /* skip register save at the first time */ MRS R1, PSP /* get from thread stack pointer */ STMFD R1!, {R4 - R11} /* push R4 - R11 register */ LDR R0, [R0] STR R1, [R0] /* update from thread stack pointer */ swtich_to_thread: LDR R1, =rt_interrupt_to_thread LDR R1, [R1] LDR R1, [R1] /* load thread stack pointer */ LDMFD R1!, {R4 - R11} /* pop R4 - R11 register */ MSR PSP, R1 /* update stack pointer */ pendsv_exit: /* restore interrupt */ MSR PRIMASK, R2 ORR LR, LR, #0x04 BX LR /* * void rt_hw_context_switch_to(rt_uint32 to); * R0 --> to */ .global rt_hw_context_switch_to .type rt_hw_context_switch_to, %function rt_hw_context_switch_to: LDR R1, =rt_interrupt_to_thread STR R0, [R1] /* set from thread to 0 */ LDR R1, =rt_interrupt_from_thread MOV R0, #0 STR R0, [R1] /* set interrupt flag to 1 */ LDR R1, =rt_thread_switch_interrput_flag MOV R0, #1 STR R0, [R1] /* set the PendSV exception priority */ LDR R0, =SHPR3 LDR R1, =PENDSV_PRI_LOWEST LDR.W R2, [R0,#0] /* read */ ORR R1, R1, R2 /* modify */ STR R1, [R0] /* write-back */ LDR R0, =ICSR /* trigger the PendSV exception (causes context switch) */ LDR R1, =PENDSVSET_BIT STR R1, [R0] CPSIE I /* enable interrupts at processor level */ /* never reach here! */ /* compatible with old version */ .global rt_hw_interrupt_thread_switch .type rt_hw_interrupt_thread_switch, %function rt_hw_interrupt_thread_switch: BX LR NOP /******************************************************************//** * @} *********************************************************************/