经常在工作中遇到一些队列处理的场景，以前要么是借用FreeRTOS这样的系统中的相关功能，要么是通过数组做一个简单的队列模型。但是，这两种方案都具有一定的局限性能，前者要求的FreeRTOS不见得相应的软件中有，而后者只能够是设计专用的功能。为此，尝试找了一个开源的通用方案。
参考链接： GitHub - SMFSW/cQueue: Queue handling library (written in plain c)
● Initialize a Queue using q_init(Queue_t * pQ, size_t size_rec, uint16_t nb_recs, QueueType type, bool overwrite):pQ - pointer to the queue struct
○ size_rec - size of a record in the queue
○ nb_recs - number of records in the queue
○ type - queue implementation type: FIFO, LIFO
○ overwrite - overwrite previous records when queue is full if set to true
● OR a statically allocated Queue using q_init_static(Queue_t * pQ, size_t size_rec, uint16_t nb_recs, QueueType type, bool overwrite, void * pQDat, size_t lenQDat):pQ - pointer to the queue struct
○ size_rec - size of a record in the queue
○ nb_recs - number of records in the queue
○ type - queue implementation type: FIFO, LIFO
○ overwrite - overwrite previous records when queue is full if set to true
○ pQDat - pointer to static data queue
○ lenQDat - length of static data queue (in bytes)
● Push stuff to the queue using q_push(Queue_t * pQ, void * rec)returns true if successfully pushed into queue
○ returns false is queue is full
● Pop stuff from the queue using q_pop(Queue_t * pQ, void * rec) or q_pull(Queue_t * pQ, void * rec)returns true if successfully popped from queue
○ returns false if queue is empty
● Peek stuff from the queue using q_peek(Queue_t * pQ, void * rec)returns true if successfully peeked from queue
○ returns false if queue is empty
● Drop stuff from the queue using q_drop(Queue_t * pQ)returns true if successfully dropped from queue
○ returns false if queue is empty
● Peek stuff at index from the queue using q_peekIdx(Queue_t * pQ, void * rec, uint16_t idx)returns true if successfully peeked from queue
○ returns false if index is out of range
○ warning: no associated drop function, not to use with q_drop
● Peek latest stored from the queue using q_peekPrevious(Queue_t * pQ, void * rec)returns true if successfully peeked from queue
○ returns false if queue is empty
○ warning: no associated drop function, not to use with q_drop
○ note: only useful with FIFO implementation, use q_peek instead with a LIFO
● Other methods:q_isInitialized(Queue_t * pQ): true if initialized properly, false otherwise
○ q_isEmpty(Queue_t * pQ): true if empty, false otherwise
○ q_isFull(Queue_t * pQ): true if full, false otherwise
○ q_sizeof(Queue_t * pQ): queue size in bytes (returns 0 in case queue allocation failed)
○ q_getCount(Queue_t * pQ) or q_nbRecs(Queue_t * pQ): number of records stored in the queue
○ q_getRemainingCount(Queue_t * pQ): number of records left in the queue
○ q_clean(Queue_t * pQ) or q_flush(Queue_t * pQ): remove all items in the queue
就这个模块库提供的基本功能来说还是很全面了，尤其是针对小型的嵌入式系统，提供的这种静态创建的方式非常不错。
接下来，针对常用的接口做个简单的测试：
#include <stdio.h>`
`#include <stdint.h>`
`#include "cQueue.h"`
`Queue_t queue_hanlde;`
`uint8_t * queue_data[5];`
`uint8_t a = 1U;`
`uint8_t b = 2U;`
`uint8_t c = 3U;`
`uint8_t d = 4U;`
`void queue_lld_init(void)`
`{`
` (void)q_init_static(&queue_hanlde, sizeof(uint8_t *), 5U, FIFO, false, queue_data, sizeof(uint8_t *) * 5);`
`}`
`int main(void)`
`{`
` uint8_t *rec;`
` printf("test for queue.\n");`
` printf("initialize the queue.\n");`
` queue_lld_init();`
` printf("size of queue: %d\n", q_sizeof(&queue_hanlde));`
` printf("count of queue: %d\n", q_getCount(&queue_hanlde));`
` printf("push data...\n");`
` printf("count of queue: %d\n", q_getCount(&queue_hanlde));`
` printf("remaining count: %d\n", q_getRemainingCount(&queue_hanlde));`
` rec = &a;`
` q_push(&queue_hanlde, &rec);`
` printf("count of queue: %d\n", q_getCount(&queue_hanlde));`
` printf("remaining count: %d\n", q_getRemainingCount(&queue_hanlde));`
` rec = &b;`
` q_push(&queue_hanlde, &rec);`
` printf("count of queue: %d\n", q_getCount(&queue_hanlde));`
` printf("remaining count: %d\n", q_getRemainingCount(&queue_hanlde));`
` rec = &c;`
` q_push(&queue_hanlde, &rec);`
` printf("count of queue: %d\n", q_getCount(&queue_hanlde));`
` printf("remaining count: %d\n", q_getRemainingCount(&queue_hanlde));`
` rec = &d;`
` q_push(&queue_hanlde, &rec);`
` printf("count of queue: %d\n", q_getCount(&queue_hanlde));`
` printf("remaining count: %d\n", q_getRemainingCount(&queue_hanlde));`
` printf("push data done...\n");`
` printf("pop data...\n");`
` q_pop(&queue_hanlde, &rec);`
` printf("count of queue: %d\n", q_getCount(&queue_hanlde));`
` printf("remaining count: %d\n", q_getRemainingCount(&queue_hanlde));`
` printf("data 1: %d\n", *rec);`
` q_pop(&queue_hanlde, &rec);`
` printf("count of queue: %d\n", q_getCount(&queue_hanlde));`
` printf("remaining count: %d\n", q_getRemainingCount(&queue_hanlde));`
` printf("data 2: %d\n", *rec);`
` q_pop(&queue_hanlde, &rec);`
` printf("count of queue: %d\n", q_getCount(&queue_hanlde));`
` printf("remaining count: %d\n", q_getRemainingCount(&queue_hanlde));`
` printf("data 3: %d\n", *rec);`
` q_pop(&queue_hanlde, &rec);`
` printf("count of queue: %d\n", q_getCount(&queue_hanlde));`
` printf("remaining count: %d\n", q_getRemainingCount(&queue_hanlde));`
` printf("data 4: %d\n", *rec);`
` return 0;`
`}`
`测试运行效果：
这里只是做了一个简单的功能性的尝试，这个模块的优点还在于具备了类似FreeRTOS的复用性。有这样的功能之后，一些嵌入式中的处理功能写起来就更加得心应手了。