threadx学习笔记(48页).doc

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1、-threadx学习笔记tx_ill.s文件用来处理初始化过程中的汇编语言，它是面向处理器和开发工具的。Void_tx_initialize_low_level1、CPSCR|= FIQ_ MODE,SET SP_fiq;2、CPSCR|=IRQ_MODE,SET SP_irp;3、CPSCR|=SVC_MODE,SET SP_svc;4、设置中断向量表IRQ_TABLE;5、设置内部TIMER线程的堆栈起始地址，堆栈大小和优先级：tx_timer_stack_start,_tx_timer_stack_size,_tx_timer_priorit;6、设置初始化后未使用内存地址的初始值_tx

2、_initialize_unused_memory;Tx_tcs.s负责在中断发生时对上次的运行现场进行保存，它保存中断上下文，为了不覆盖R14_irq离得中断返回地址，TCS的返回是通过跳到_tx_irq_processing_return地址做到的。Tx_TCR.S负责中断处理程序执行完后的处理。Void _tx_thread_context_save1、把表示中断嵌套个数的变量_tx_thread_system_state+;2、if _tx_thread_system_state1,PUSH R0-R3,CPSR,R14 in IRQ stack,B _tx_irq_processin

3、g_return;3、else if _tx_thread_current_ptr=0判断是否有线程正在运行，if not ,B _tx_irq_processing_return;4、else,PUSH Context_irq in threads stack,SP_thread=new SP,B _tx_irq_processing_return;由于R13和R14在不同的CPU模式下对应的是不同的物理寄存器，所以若要得到中断前的线程堆栈指针，需要先返回到该线程的运行模式，同时禁止中断，取值后再返回到终端模式。R14_irq保存的是终端发生时PC值+8，R14_svc保存得失中断前线程自己

4、的返回地址。所以在中段上下文中，（R14_irq-4）应该存在中断地址，而R14_svc存在R14的位置。Void _tx_thread_context_restore1、_tx_thread_system_state-,if _tx_thread_system_state0,POP R0-R3,CPSR,R14 from IRQ stack,BX R14;2、else if _tx_thread_current_ptr=0?if =0 CPSR|=VC_MODE,CPSR|=TX_INT_ENABLE,跳到线程调度程序B _tx_thread_schedule;3、if!=0,则判断线程抢占

5、是否禁止 if _tx_thread_preempt_disable=0?if!=0,POP Context_irq from threads stack,BX R14;4、if=0,_tx_timer_time_slice=new value,_tx_thread_current_ptr=0,CPSR|=SVC_MODE,设置堆栈指针为系统指针SP=SP_svc，CPSR|=TX_INT_ENABLE;5、B _tx_thread_schedule;Tx_tsr.s用于从线程退回到系统态，负责保存线程的最小语境并退回到Threadx的调度循环状态。它保存的上下文是请求上下文。Void _tx

6、_thread_system_return1、 PUSH Context_request:in threads stack,CPSR|=TX_INT_DISABLE;2、 _tx_thread_current_ptr-SP=SP,CPSR|=SVC_MODE;3、 设置堆栈指针为系统指针SP=SP_svc，_tx_thread_current_ptr=0,CPSR|=TX_INT_ENABLE;4、 B _tx_thread_schedule;由于用户模式不能直接更改CPSR来关断的，所以要通过SWI指令进入特权模式，而且特权模式和用户模式的SP对应不同的物理寄存器，所以要在转入系统模式取得用

7、户模式下SP，最后再回到特权模式。TX_TS.S负责调度和恢复就绪的优先级最高的线程的最后语境。Void _tx_thread_schedule1、 while(_tx_thread_execute_ptr=0);2、 CPSR|=TX_INT_DISABLE,_tx_threadx_current_ptr=_tx_thread_execute_ptr;3、 _tx_thread_current_ptr-TX_run_count+,_tx_timer_time_slice=_tx_thread_current_ptr-tx_time_slice;4、 If线程堆栈的中断类型=1，restore

8、 Context_irq,else restore Context_request;Tx_tic.s用于开中断和关中断。Unint _tx_thread_interrupt_control(unint new _posture)1、 R1=CPSR;2、 SWI；3、 CPSR|=RO=new posture;4、 R0=R1,R0为返回值；移植该函数时，针对不同的处理器，应盖根据准热爱寄存器CPSR的中断禁止未来设置开关中断向量，主要修改TX_PORT.H中的TX_INT_ENABLE和TX_INT_DISABLE.R0用来传递的参数和结果。Tx_tsb.s负责创建每个线程的初始堆栈结构，这

9、个初始的结构在线程创建时会引起中断上下文返回到_tx_thread_shell_entry函数的开头。然后这个函数调用指定线程入口函数。其中断类型设置为1，表示中断上下文。Void _tx_thread_stack_build(TXTHREAD *thread_ptr,void (*function)(void)1、 保证堆栈起始地址八字节对齐；2、 中断地址存入线程调用的入口地址PUSH function_ptr;3、 R0-R12,R14的初始值都设置为0，PUSH初始值；4、 要存入堆栈的CPSR值设置为用户模式，开中断，标志位清零，R1=USER_MODE,PUSH R1;5、 Thr

10、ead_ptr-sp=new SP;当处理一个低级的中断时，tx_tpc.s决定是否发生抢占，它是可选的，大多数端口都用不到。TX_TIMIN.S负责处理定时中断。这两个函数只要将它们翻译成相应ARM汇编语言就可以了。threadx学习笔记（二）-1tx_kernel_enter();进入threadx核tx_kernel_enter()void tx_kernel_enter(void)所属文件调用者开关量demo.C启动代码无操作系统首先从从量表直接进入该函数，在函数以前没有进行任何的硬件及软件的初始化！该函数主要包含_tx_initialize_low_level()，_tx_initi

11、alize_high_level()，tx_application_define(_tx_initialize_unused_memory)，_tx_thread_schedule()。VOID _tx_initialize_kernel_enter(VOID)/*确定编译器是否已经初始化过 */if (_tx_thread_system_state != TX_INITIALIZE_ALMOST_DONE)/* 没有初始化的话执行下面程序 */* 设置系统状态变量来表示现正在处理过程中 注意该变量在后边的中断嵌套中会使用*/_tx_thread_system_state = TX_INITI

12、ALIZE_IN_PROGRESS;/* 进行一些基本硬件设置，启动程序等 */_tx_initialize_low_level();/*进行一些高级的初始化*/_tx_initialize_high_level();/*设置系统状态变量来表示现正在处理过程中 注意该变量在后边的中断嵌套中会使用*/_tx_thread_system_state = TX_INITIALIZE_IN_PROGRESS;/* 调用初始化中提供的应用程序 把第一个未使用的变量地址传送给它 */tx_application_define(_tx_initialize_unused_memory);/*设置系统壮伟进入

13、线程调度做准备*/_tx_thread_system_state = TX_INITIALIZE_IS_FINISHED;/* 进入线程循环开始执行线程 */_tx_thread_schedule();_tx_initialize_low_level()void tx_kernel_enter(void)所属文件调用者开关量tx_till.s启动代码无该函数实现对FIQ、IRQ和SVC模式下的sp寄存器的初始化，并对定时堆栈的基地址、大小和定时优先级变量进行初始化。/* 进行一些基本硬件设置，启动程序等 */*该函数在文件tx_ill.s文件中*/_tx_initialize_low_leve

14、l();/* VOID _tx_initialize_low_level(VOID);EXPORT _tx_initialize_low_level_tx_initialize_low_level; /* 保存系统堆栈指针. */; /* _tx_thread_system_stack_ptr = (VOID_PTR) A7 (SP); */;/*设置各个模式下的sp（堆栈指针）*/; /* We must be in SVC mode at this point! */;LDR a2, =|Image$ZI$Limit| ; Get end of non-initialized RAM ar

15、eaLDR a3, pc, #FIQ_STACK_SIZE-.-8 ; 获得FIO堆栈地址（这里没有弄明白，有待？）MOV a1, #FIQ_MODE ; 设置FIQ_MODEMSR CPSR_c, a1 ; 进入FIQ模式ADD a2, a2, a3 ;计算FIQ堆栈的开始BIC a2, a2, #3 ; 将a2的低两位清零确保堆栈的的开始为long对齐SUB a2, a2, #4 ; 往回退一个字MOV sp, a2 ; 建立FIQ 堆栈指针（即FIQ模式的sp）MOV sl, #0 ; Clear sl（R10）MOV fp, #0 ; Clear fp(R11)LDR a3, pc,

16、#SYS_STACK_SIZE-.-8 ;获得 IRQ (system stack size)MOV a1, #IRQ_MODE ; 建立IRQ模式的 CPSRMSR CPSR_c, a1 ; 进入IRQ模式ADD a2, a2, a3 ; 计算IRQ stack的开始BIC a2, a2, #3 ; 将a2的低两位清零确保堆栈的的开始为long对齐SUB a2, a2, #4 ; 往回退一个字MOV sp, a2 ; 建立 IRQ 堆栈指针MOV a1, #SVC_MODE ; 建立SVC模式的CPSRMSR CPSR_c, a1 ; 进入 SVC模式LDR a4, pc, #SYS_STA

17、CK_PTR-.-8 ; 获得stack 指针STR a2, a4, #0 ; 保存系统堆栈; /* Save the system stack pointer. */; _tx_thread_system_stack_ptr = (VOID_PTR) (sp);LDR a2, pc, #SYS_STACK_PTR-.-8 ; 获得系统堆栈指针的地址LDR a1, a2, #0 ; 获得系统堆栈指针 ADD a1, a1, #4 ; 增加一个long长度; /* Pickup the first available memory address. */; /* Allocate space f

18、or the timer threads stack. */; _tx_timer_stack_start = first_available_memory; _tx_timer_stack_size = stack_size; _tx_timer_priority = 0;LDR a2, pc, #TIMER_STACK-.-8 ; 获得定时堆栈指针地址LDR a4, pc, #TIMER_STACK_SIZE-.-8 ; 获得定时堆栈大小地址LDR a3, pc, #TIM_STACK_SIZE-.-8 ; 获得实际定时堆栈大小STR a1, a2, #0 ;将定时堆栈的基地址放在堆栈指针

19、地址所对应的内存中STR a3, a4, #0 ; 存储定时器堆栈大小ADD a1, a1, a3 ; 新的空内存地址LDR a2, pc, #TIMER_PRIORITY-.-8 ; 获得定时器优先级地址MOV a3, #0 ; 获得定时器线程优先级STR a3, a2, #0 ; 存储定时器线程优先级; /*保存第一个变量内存地址. */; _tx_initialize_unused_memory = (VOID_PTR) System Stack + Timer Stack;LDR a3, pc, #UNUSED_MEMORY-.-8 ;获得没有使用的内存指针地址STR a1, a3,

20、#0 ; 保存第一个空内存地址; /* 建立周期性的定时中断. */STMDB LR/让lr入栈，保护lrBLTargetInit/TargetInit（）为C语言编写的中断定时函数LDMIA lr/让lr出栈在这里加上ARM定时器已实现周期性的中断; /* Done, return to caller. */;MOV pc, lr ; Return to caller;_tx_irq_handler所属文件调用者开关量tx_till.s IRQ中断无该函数是在定时中断后调用，该函数调用了_tx_thread_context_save函数（包含在tx_tcs.s中），该函数又调用到_tx_ir

21、q_processing_return函数处（包含在tx_till.s）EXPORT _tx_irq_handlerEXPORT _tx_irq_processing_return _tx_irq_handler; /* 调用函数保存线程上下文环境. */B _tx_thread_context_save_tx_irq_processing_return; /* At this point execution is still in the IRQ mode. The CPSR, point of; interrupt, and all C scratch registers are avai

22、lable for use. In ; addition, IRQ interrupts may be re-enabled - with certain restrictions -; if nested IRQ interrupts are desired. Interrupts may be re-enabled over; small code sequences where lr is saved before enabling interrupts and ; restored after interrupts are again disabled. */; /* For debu

23、g purpose, execute the timer interrupt processing here. In; a real system, some kind of status indication would have to be checked; before the timer interrupt handler could be called. */;BL clearflag;清除中断标志位很重要（自己移植时加的，位置是否恰当？）BL _tx_timer_interrupt ; 定时中断处理函数; /* 系统线程上下文环境恢复函数 */B _tx_thread_contex

24、t_restore_tx_timer_interrupt所属文件调用者开关量tx_timin.s启动代码无该函数主要是中断后将系统时钟加1，时间切片减1。定时部分比较多，没有完全看明白。IMPORT _tx_timer_time_sliceIMPORT _tx_timer_system_clockIMPORT _tx_timer_current_ptrIMPORT _tx_timer_list_startIMPORT _tx_timer_list_endIMPORT _tx_timer_expired_time_sliceIMPORT _tx_timer_expiredIMPORT _tx_t

25、imer_threadIMPORT _tx_thread_current_ptrIMPORT _tx_thread_time_sliceIMPORT _tx_thread_resumeIMPORT _tx_thread_preempt_disable;PRESERVE8AREA |C$code|, CODE, READONLY|x$codeseg| DATA;VOID _tx_timer_interrupt(VOID);EXPORT _tx_timer_interrupt_tx_timer_interrupt; /* Upon entry to this routine, it is assu

26、med that context save has already; been called, and therefore the compiler scratch registers are available; for use. */; /* Increment the system clock. */; _tx_timer_system_clock+;LDR a2, pc, #SYSTEM_CLOCK-.-8 ; 获得系统时钟地址LDR a1, a2, #0 ; 获得系统时钟ADD a1, a1, #1 ; 将系统时钟加1STR a1, a2, #0 ; 存储新的系统时钟时间; /* T

27、est for time-slice expiration. */; if (_tx_timer_time_slice); ;LDR a4, pc, #TIME_SLICE-.-8 ; 获得链表中的定时切片数地址LDR a3, a4, #0 ; 获得定时切片数的值CMP a3, #0 ; 定时切片是否有效，0有效，=0无效BEQ _tx_timer_no_time_slice ; =0时，跳到_tx_timer_no_time_slice处; /* 时间切片减1. */; _tx_timer_time_slice-;SUB a3, a3, #1 ; 时间切片值减1STR a3, a4, #0

28、; 存储新的时间切片值; /* 检查是否到期. */; if (_tx_timer_time_slice = 0);CMP a3, #0 ; 0还是=0？BNE _tx_timer_no_time_slice ; 如果0,;当没有定时切片时，将定时切片数标志位置1，表示链表中没有切片了。; /* Set the time-slice expired flag. */; _tx_timer_expired_time_slice = TX_TRUE;LDR a4, pc, #EXPIRED_TIME_SLICE-.-8 ; 获得定时切片数是否为0标志地址MOV a1, #1 ; 将标志设为1STR

29、 a1, a4, #0 ; 设立到时标志; ;_tx_timer_no_time_slice; /* Test for timer expiration. */; if (*_tx_timer_current_ptr); ;LDR a2, pc, #TIMER_CURRENT_PTR-.-8 ; 获得的是_tx_timer_current_ptr的地址;而TIMER_DECLARE TX_INTERNAL_TIMER *_tx_timer_current_ptr;LDR a1, a2, #0 ; 获得当前的_tx_timer_current_ptrLDR a3, a1, #0 ; 获得定时列表

30、的入口定时切片指针CMP a3, #0 ;链表中是否有定时切片存在BEQ _tx_timer_no_timer ; 不存在, 调用_tx_timer_no_time将；_tx_timer_current_ptr+; /* Set expiration flag. */; _tx_timer_expired = TX_TRUE;LDR a4, pc, #EXPIRED-.-8 ; Pickup expriation flag addressMOV a3, #1 ; Build expired valueSTR a3, a4, #0 ; Set expired flagB _tx_timer_do

31、ne ; Finished timer processing; ; else; _tx_timer_no_timer; /* No timer expired, increment the timer pointer. */; _tx_timer_current_ptr+;ADD a1, a1, #4 ; Move to next timer; /* Check for wrap-around. */; if (_tx_timer_current_ptr = _tx_timer_list_end);LDR a4, pc, #LIST_END-.-8 ; Pickup addr of timer

32、 list endLDR a3, a4, #0 ; Pickup list endCMP a1, a3 ; Are we at list end?BNE _tx_timer_skip_wrap ; No, skip wrap-around logic; /* Wrap to beginning of list. */; _tx_timer_current_ptr = _tx_timer_list_start;LDR a4, pc, #LIST_START-.-8 ; Pickup addr of timer list startLDR a1, a4, #0 ; Set current poin

33、ter to list start;_tx_timer_skip_wrap;STR a1, a2, #0 ; Store new current timer pointer; ;_tx_timer_done; /* See if anything has expired. */; if (_tx_timer_expired_time_slice) | (_tx_timer_expired); ;LDR a4, pc, #EXPIRED_TIME_SLICE-.-8 ; Pickup addr of expired flagLDR a3, a4, #0 ; Pickup time-slice e

34、xpired flagCMP a3, #0 ; Did a time-slice expire?BNE _tx_something_expired ; If non-zero, time-slice expiredLDR a2, pc, #EXPIRED-.-8 ; Pickup addr of other expired flagLDR a1, a2, #0 ; Pickup timer expired flagCMP a1, #0 ; Did a timer expire?BEQ _tx_timer_nothing_expired ; No, nothing expired;_tx_som

35、ething_expired;STR lr, sp, #-4! ; Save the lr register on the stack; /* Did a timer expire? */; if (_tx_timer_expired); ;LDR a2, pc, #EXPIRED-.-8 ; Pickup addr of expired flagLDR a1, a2, #0 ; Pickup timer expired flagCMP a1, #0 ; Check for timer expirationBEQ _tx_timer_dont_activate ; If not set, sk

36、ip timer activation; /* Increment the preempt disable counter in preparation for ; thread resumption. */; _tx_thread_preempt_disable+;LDR a4, pc, #PREEMPT_DISABLE-.-8 ; Pickup addr of preempt disable LDR a3, a4, #0 ; Pickup actual flagADD a3, a3, #1 ; Incrment the preempt disable countSTR a3, a4, #0

37、 ; Store it back; /* Activate the system timer thread. */; _tx_thread_resume(&_tx_timer_thread);LDR a1, pc, #TIMER_THREAD-.-8 ; Get timer thread control block addrBL _tx_thread_resume ; Call thread resume to wake up the; timer thread; _tx_timer_dont_activate; /* Did time slice expire? */; if (_tx_ti

38、mer_expired_time_slice); ;LDR a4, pc, #EXPIRED_TIME_SLICE-.-8 ; Pickup addr of time-slice expired LDR a3, a4, #0 ; Pickup the actual flagCMP a3, #0 ; See if the flag is setBEQ _tx_timer_not_ts_expiration ; No, skip time-slice processing; /* Time slice interrupted thread. */; if (!_tx_thread_time_sli

39、ce(); _tx_timer_time_slice = _tx_thread_current_ptr - tx_time_slice;BL _tx_thread_time_slice ; Call time-slice processingCMP a1, #0 ; Check return statusBNE _tx_timer_not_ts_expiration ; If time-sliced, skip reset processingLDR a2, pc, #CURRENT_PTR-.-8 ; Pickup addr of current thread pointerLDR a1,

40、a2, #0 ; Pickup thread pointerLDR a3, a1, #24 ; Pickup fresh time-slice for thread; (a fresh time slice was setup in ; the _tx_thread_time_slice function)LDR a4, pc, #TIME_SLICE-.-8 ; Pickup addr of time-slice variableSTR a3, a4, #0 ; Setup new time-slice; ;_tx_timer_not_ts_expiration;LDR a4, pc, #E

41、XPIRED_TIME_SLICE-.-8 ; Pickup address of expired time-slice flagMOV a1, #0 ; Clear valueSTR a1, a4, #0 ; Clear time-slice expired flag;LDR lr, sp, #4 ; Recover lr register; ;_tx_timer_nothing_expired;MOV pc, lr ; Return to caller;TIME_SLICEDCD _tx_timer_time_sliceSYSTEM_CLOCKDCD _tx_timer_system_clockTIMER_CURRENT_PTRDCD _tx_timer_current_ptrLIST_STARTDCD _tx_timer_list_startLIST_ENDDCD _tx_timer_list_endEXPIRED_TIME_SLICEDCD _tx_timer_expired_time_sliceEXPIREDDCD _tx_timer_expiredTIMER_THREADDCD _tx_timer_threadCURRENT_PTRDCD _tx_thread_current_ptrTHREAD_TIME_SLICEDCD _tx