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BlueDroid代码分析之GKI
1. 概述
GKI以库libbt-brcm_gki.so(Static Lib?)的形式提供给BlueDroid使用
该层是一个适配层,适配了OS相关的进程、内存相关的管理,还可以用于线程间传递消息
主要通过变量gki_cb实现对进程的统一管理
typedef struct{ pthread_mutex_t GKI_mutex; pthread_t thread_id[GKI_MAX_TASKS]; pthread_mutex_t thread_evt_mutex[GKI_MAX_TASKS]; pthread_cond_t thread_evt_cond[GKI_MAX_TASKS]; pthread_mutex_t thread_timeout_mutex[GKI_MAX_TASKS]; pthread_cond_t thread_timeout_cond[GKI_MAX_TASKS]; int no_timer_suspend; /* 1: no suspend, 0 stop calling GKI_timer_update() */ pthread_mutex_t gki_timer_mutex; pthread_cond_t gki_timer_cond;#if (GKI_DEBUG == TRUE) pthread_mutex_t GKI_trace_mutex;#endif} tGKI_OS;typedef struct{ ... UINT8 *OSStack[GKI_MAX_TASKS]; /* pointer to beginning of stack */ UINT16 OSStackSize[GKI_MAX_TASKS]; /* stack size available to each task */ INT8 *OSTName[GKI_MAX_TASKS]; /* name of the task */ UINT8 OSRdyTbl[GKI_MAX_TASKS]; /* current state of the task */ UINT16 OSWaitEvt[GKI_MAX_TASKS]; /* events that have to be processed by the task */ UINT16 OSWaitForEvt[GKI_MAX_TASKS]; /* events the task is waiting for*/ UINT32 OSTicks; /* system ticks from start */ UINT32 OSIdleCnt; /* idle counter */ INT16 OSDisableNesting; /* counter to keep track of interrupt disable nesting */ INT16 OSLockNesting; /* counter to keep track of sched lock nesting */ INT16 OSIntNesting; /* counter to keep track of interrupt nesting */ /* Timer related variables */ INT32 OSTicksTilExp; /* Number of ticks till next timer expires */#if (defined(GKI_DELAY_STOP_SYS_TICK) && (GKI_DELAY_STOP_SYS_TICK > 0)) UINT32 OSTicksTilStop; /* inactivity delay timer; OS Ticks till stopping system tick */#endif INT32 OSNumOrigTicks; /* Number of ticks between last timer expiration to the next one */ INT32 OSWaitTmr [GKI_MAX_TASKS]; /* ticks the task has to wait, for specific events */ ... /* Buffer related variables */ BUFFER_HDR_T *OSTaskQFirst[GKI_MAX_TASKS][NUM_TASK_MBOX]; /* array of pointers to the first event in the task mailbox */ BUFFER_HDR_T *OSTaskQLast [GKI_MAX_TASKS][NUM_TASK_MBOX]; /* array of pointers to the last event in the task mailbox */ /* Define the buffer pool management variables */ FREE_QUEUE_T freeq[GKI_NUM_TOTAL_BUF_POOLS]; UINT16 pool_buf_size[GKI_NUM_TOTAL_BUF_POOLS]; UINT16 pool_max_count[GKI_NUM_TOTAL_BUF_POOLS]; UINT16 pool_additions[GKI_NUM_TOTAL_BUF_POOLS]; /* Define the buffer pool start addresses */ UINT8 *pool_start[GKI_NUM_TOTAL_BUF_POOLS]; /* array of pointers to the start of each buffer pool */ UINT8 *pool_end[GKI_NUM_TOTAL_BUF_POOLS]; /* array of pointers to the end of each buffer pool */ UINT16 pool_size[GKI_NUM_TOTAL_BUF_POOLS]; /* actual size of the buffers in a pool */ /* Define the buffer pool access control variables */ void *p_user_mempool; /* User O/S memory pool */ UINT16 pool_access_mask; /* Bits are set if the corresponding buffer pool is a restricted pool */ UINT8 pool_list[GKI_NUM_TOTAL_BUF_POOLS]; /* buffer pools arranged in the order of size */ UINT8 curr_total_no_of_pools; /* number of fixed buf pools + current number of dynamic pools */ BOOLEAN timer_nesting; /* flag to prevent timer interrupt nesting */ /* Time queue arrays */ TIMER_LIST_Q *timer_queues[GKI_MAX_TIMER_QUEUES]; /* System tick callback */ SYSTEM_TICK_CBACK *p_tick_cb; BOOLEAN system_tick_running; /* TRUE if system tick is running. Valid only if p_tick_cb is not NULL */#if (GKI_DEBUG == TRUE) UINT16 ExceptionCnt; /* number of GKI exceptions that have happened */ EXCEPTION_T Exception[GKI_MAX_EXCEPTION];#endif} tGKI_COM_CB;typedef struct{ tGKI_OS os; tGKI_COM_CB com;} tGKI_CB;tGKI_CB gki_cb<style type="text/css">.csharpcode, .csharpcode pre{ font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/}.csharpcode pre { margin: 0em; }.csharpcode .rem { color: #008000; }.csharpcode .kwrd { color: #0000ff; }.csharpcode .str { color: #006080; }.csharpcode .op { color: #0000c0; }.csharpcode .preproc { color: #cc6633; }.csharpcode .asp { background-color: #ffff00; }.csharpcode .html { color: #800000; }.csharpcode .attr { color: #ff0000; }.csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em;}.csharpcode .lnum { color: #606060; }</style>
2. 线程
2.1 主要函数
- GKI_init() 初始化变量gki_cb
- GKI_create_task() 创建线程
- GKI_destroy_task() 销毁线程
- GKI_run() 时间相关执行函数,目前不知道有何效果
2.2 功能
使用pthread库实现线程相关功能
GKI管理三个线程
#define BTU_TASK 0#define BTIF_TASK 1#define A2DP_MEDIA_TASK 2
3. 事件
3.1 主要函数
- GKI_wait() 等待事件的发生
- GKI_send_event()向指定进程发送事件
- GKI_send_msg() 向指定进程发送buffer
- GKI_read_mbox() 从mailbox中读取buffer
3.2 功能
tGKI_CB.os.thread_evt_mutex[] 事件的互斥锁tGKI_CB.os.thread_evt_cond[] 事件的条件变量tGKI_CB.com.OSWaitEvt[] 表示当前进程的事件tGKI_CB.com.OSTaskQFirst[][] 指向进程的mailbox中第一个事件tGKI_CB.com.OSTaskQLast[][] 指向进程的mailbox中最后一个事件<style type="text/css">.csharpcode, .csharpcode pre{ font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/}.csharpcode pre { margin: 0em; }.csharpcode .rem { color: #008000; }.csharpcode .kwrd { color: #0000ff; }.csharpcode .str { color: #006080; }.csharpcode .op { color: #0000c0; }.csharpcode .preproc { color: #cc6633; }.csharpcode .asp { background-color: #ffff00; }.csharpcode .html { color: #800000; }.csharpcode .attr { color: #ff0000; }.csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em;}.csharpcode .lnum { color: #606060; }</style>
首先我们要了解Posix互斥锁和条件变量的使用
tip: 值得一提的是pthread_cond_wait()函数在调用后解锁参数中的互斥锁,直至被唤醒后重新对该互斥锁加锁
GKI事件的原理
通过GKI_send_event()/GKI_send_msg()发送事件/MBox事件,接收线程通过GKI_wait()可检测事件的发生,并对不同的事件进行不同的处理
对于MBox事件,需要再循环调用GKI_read_mbox()来得到MBOX Buffer
tip: 事件可以除了可以发往其他线程,也可以发往本线程
每个线程都有四个Mailbox
事件有16个(evt: 0~15)
- 4个保留事件用于Mailbox消息的接收 evt: 0~3
- 4个保留事件用于超时 evt: 4~7
- 8个通用事件共APP使用 evt: 8~15
可依次由EVENT_MASK(evt)得到