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+/*
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+ * File : context_gcc.S
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+ * This file is part of RT-Thread RTOS
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+ * COPYRIGHT (C) 2009, RT-Thread Development Team
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+ *
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+ * The license and distribution terms for this file may be
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+ * found in the file LICENSE in this distribution or at
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+ * http://www.rt-thread.org/license/LICENSE
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+ *
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+ * Change Logs:
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+ * Date Author Notes
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+ * 2009-10-11 Bernard first version
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+ */
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+
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+/**
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+ * @addtogroup STM32
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+ */
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+/*@{*/
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+
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+.cpu cortex-m3
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+.fpu softvfp
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+.syntax unified
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+.thumb
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+.text
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+
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+.equ NVIC_INT_CTRL, 0xE000ED04 /* interrupt control state register */
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+.equ NVIC_SYSPRI2, 0xE000ED20 /* system priority register (2) */
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+.equ NVIC_PENDSV_PRI, 0x00FF0000 /* PendSV priority value (lowest) */
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+.equ NVIC_PENDSVSET, 0x10000000 /* value to trigger PendSV exception */
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+
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+/*
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+ * rt_base_t rt_hw_interrupt_disable();
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+ */
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+.global rt_hw_interrupt_disable
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+.type rt_hw_interrupt_disable, %function
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+rt_hw_interrupt_disable:
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+ MRS r0, PRIMASK
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+ CPSID I
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+ BX LR
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+
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+/*
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+ * void rt_hw_interrupt_enable(rt_base_t level);
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+ */
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+.global rt_hw_interrupt_enable
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+.type rt_hw_interrupt_enable, %function
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+rt_hw_interrupt_enable:
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+ MSR PRIMASK, r0
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+ BX LR
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+
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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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+ */
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+.global rt_hw_context_switch_interrupt
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+.type rt_hw_context_switch_interrupt, %function
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+.global rt_hw_context_switch
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+.type rt_hw_context_switch, %function
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+
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+rt_hw_context_switch_interrupt:
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+rt_hw_context_switch:
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+ /* set rt_thread_switch_interrupt_flag to 1 */
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+ LDR r2, =rt_thread_switch_interrupt_flag
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+ LDR r3, [r2]
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+ CMP r3, #1
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+ BEQ _reswitch
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+ MOV r3, #1
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+ STR r3, [r2]
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+
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+ LDR r2, =rt_interrupt_from_thread /* set rt_interrupt_from_thread */
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+ STR r0, [r2]
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+
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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]
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+
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+ LDR r0, =NVIC_INT_CTRL /* trigger the PendSV exception (causes context switch) */
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+ LDR r1, =NVIC_PENDSVSET
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+ STR r1, [r0]
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+ BX LR
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+
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+/* r0 --> swith from thread stack
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+ * r1 --> swith to thread stack
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+ * psr, pc, lr, r12, r3, r2, r1, r0 are pushed into [from] stack
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+ */
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+.global PendSV_Handler
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+.type PendSV_Handler, %function
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+PendSV_Handler:
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+ /* disable interrupt to protect context switch */
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+ MRS r2, PRIMASK
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+ CPSID I
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+
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+ /* get rt_thread_switch_interrupt_flag */
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+ LDR r0, =rt_thread_switch_interrupt_flag
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+ LDR r1, [r0]
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+ CBZ r1, pendsv_exit /* pendsv already handled */
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+
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+ /* clear rt_thread_switch_interrupt_flag to 0 */
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+ MOV r1, #0x00
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+ STR r1, [r0]
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+
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+ LDR r0, =rt_interrupt_from_thread
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+ LDR r1, [r0]
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+ CBZ r1, swtich_to_thread /* skip register save at the first time */
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+
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+ MRS r1, psp /* get from thread stack pointer */
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+ STMFD r1!, {r4 - r11} /* push r4 - r11 register */
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+ LDR r0, [r0]
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+ STR r1, [r0] /* update from thread stack pointer */
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+
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+swtich_to_thread:
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+ LDR r1, =rt_interrupt_to_thread
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+ LDR r1, [r1]
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+ LDR r1, [r1] /* load thread stack pointer */
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+
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+ LDMFD r1!, {r4 - r11} /* pop r4 - r11 register */
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+ MSR psp, r1 /* update stack pointer */
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+
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+pendsv_exit:
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+ /* restore interrupt */
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+ MSR PRIMASK, r2
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+
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+ ORR lr, lr, #0x04
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+ BX lr
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+
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+/*
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+ * void rt_hw_context_switch_to(rt_uint32 to);
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+ * r0 --> to
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+ */
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+.global rt_hw_context_switch_to
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+.type rt_hw_context_switch_to, %function
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+rt_hw_context_switch_to:
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+ LDR r1, =rt_interrupt_to_thread
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+ STR r0, [r1]
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+
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+ /* set from thread to 0 */
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+ LDR r1, =rt_interrupt_from_thread
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+ MOV r0, #0x0
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+ STR r0, [r1]
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+
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+ /* set interrupt flag to 1 */
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+ LDR r1, =rt_thread_switch_interrupt_flag
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+ MOV r0, #1
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+ STR r0, [r1]
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+
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+ /* set the PendSV exception priority */
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+ LDR r0, =NVIC_SYSPRI2
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+ LDR r1, =NVIC_PENDSV_PRI
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+ LDR.W r2, [r0,#0x00] /* read */
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+ ORR r1,r1,r2 /* modify */
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+ STR r1, [r0] /* write-back */
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+
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+ LDR r0, =NVIC_INT_CTRL /* trigger the PendSV exception (causes context switch) */
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+ LDR r1, =NVIC_PENDSVSET
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+ STR r1, [r0]
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+
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+ CPSIE I /* enable interrupts at processor level */
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+
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+ /* never reach here! */
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+
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+/* compatible with old version */
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+.global rt_hw_interrupt_thread_switch
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+.type rt_hw_interrupt_thread_switch, %function
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+rt_hw_interrupt_thread_switch:
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+ BX lr
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+ NOP
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+
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+.global HardFault_Handler
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+.type HardFault_Handler, %function
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+HardFault_Handler:
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+ /* get current context */
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+ MRS r0, psp /* get fault thread stack pointer */
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+ PUSH {lr}
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+ BL rt_hw_hard_fault_exception
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+ POP {lr}
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+
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+ ORR lr, lr, #0x04
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+ BX lr
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