os_cpu.h

ucosii源码的中文注解 很好的

/*
*********************************************************************************************************
*                                               uC/OS-II
*                                        The Real-Time Kernel
*
*                         (c) Copyright 1992-2002, Jean J. Labrosse, Weston, FL
*                                          All Rights Reserved
*
*                                       80x86/80x88 Specific code
*                                          LARGE MEMORY MODEL
*                                With Floating-Point Register Support
*
*                                         Borland C/C++ V4.51
*
* File         : OS_CPU.H
* By           : Jean J. Labrosse
*********************************************************************************************************
*/

#ifdef  OS_CPU_GLOBALS
#define OS_CPU_EXT
#else
#define OS_CPU_EXT  extern
#endif

/*$PAGE*/
/*
*********************************************************************************************************
*                                              DATA TYPES
*                                         (Compiler Specific)
                                            定义一些常用的数据类型
*********************************************************************************************************
*/

typedef unsigned char  BOOLEAN;
typedef unsigned char  INT8U;                    /* Unsigned  8 bit quantity                           */
typedef signed   char  INT8S;                    /* Signed    8 bit quantity                           */
typedef unsigned int   INT16U;                   /* Unsigned 16 bit quantity                           */
typedef signed   int   INT16S;                   /* Signed   16 bit quantity                           */
typedef unsigned long  INT32U;                   /* Unsigned 32 bit quantity                           */
typedef signed   long  INT32S;                   /* Signed   32 bit quantity                           */
typedef float          FP32;                     /* Single precision floating point                    */
typedef double         FP64;                     /* Double precision floating point                    */

typedef unsigned int   OS_STK;                   /* Each stack entry is 16-bit wide                    */
//每个堆栈入口是十六位宽
typedef unsigned int   OS_CPU_SR;                /* The CPU Status Word is 16-bit wide                 */
//CPU状态字是十六位宽

/* 
*********************************************************************************************************
*                              Intel 80x86 (Real-Mode, Large Model)
*
* Method #1:  Disable/Enable interrupts using simple instructions.  After critical section, interrupts
*             will be enabled even if they were disabled before entering the critical section.
*
* Method #2:  Disable/Enable interrupts by preserving the state of interrupts.  In other words, if 
*             interrupts were disabled before entering the critical section, they will be disabled when
*             leaving the critical section.
*
* Method #3:  Disable/Enable interrupts by preserving the state of interrupts.  Generally speaking you
*             would store the state of the interrupt disable flag in the local variable 'cpu_sr' and then
*             disable interrupts.  'cpu_sr' is allocated in all of uC/OS-II's functions that need to 
*             disable interrupts.  You would restore the interrupt disable state by copying back 'cpu_sr'
*             into the CPU's status register.
                                                      实时模式：
方法一：用简单指针开关中断，临界状态后，即使开始关掉中断，现在也要
                      开中断。
方法二：通过保存中断状态来开关中断，即：进入临界状态前中断是关的，
                      离开的时候中断也是关的。
方法三：通过保存中断状态来开关中断，你保存关中断标志在局部变量cpu_sr
                      中，变量由ucos调用时需要关中断，你将要通过复制变量到CPU状态寄存器
                      再次装载关中断状态
*********************************************************************************************************
*/
#define  OS_CRITICAL_METHOD    2


#define  OS_ENTER_CRITICAL()  asm {PUSHF; CLI}  /* Disable interrupts                        *///关中断
#define  OS_EXIT_CRITICAL()   asm  POPF      /* Enable  interrupts                        *///开中断

/*
*********************************************************************************************************
*                           Intel 80x86 (Real-Mode, Large Model) Miscellaneous
*********************************************************************************************************
*/

#define  OS_STK_GROWTH        1   /* Stack grows from HIGH to LOW memory on 80x86  */
//堆栈从高到低存储

#define  uCOS                 0x80    /* Interrupt vector # used for context switch    */
//中断向量，用于任务转换

#define  OS_TASK_SW() asm  INT   uCOS

/*
*********************************************************************************************************
*                                            GLOBAL VARIABLES
                                                    全局变量
*********************************************************************************************************
*/

OS_CPU_EXT  INT8U  OSTickDOSCtr;       /* Counter used to invoke DOS's tick handler every 'n' ticks    */
//每N个节拍调用DOS的时钟处理器的计数器

/*
*********************************************************************************************************
*                                          FUNCTION PROTOTYPES
*********************************************************************************************************
*/

void       OSFPInit(void);//浮点处理单元初始化
void       OSFPRestore(void *pblk);//装载浮点处理单元
void       OSFPSave(void *pblk);//保存浮点处理单元