queue的c实现

 用c模拟实现C++中的queue。使用了环形缓冲区，只能向队列中放指针。纯属个人娱乐。
ringbuf.h

#ifndef RING_BUG_H_
#define RING_BUG_H_
#include <memory.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#ifdef __cplusplus
extern "C" {
#endif
typedef struct _RingBuf RingBuf;
struct _RingBuf{
    void *start;
    void *end;
    int header;
    int tail;
    size_t used;
};
RingBuf *my_ring_buf_new(int cap);
void my_ring_buf_dtor(RingBuf *buf);
bool my_ring_buf_empty(RingBuf *buf);
bool my_ring_buf_has_space(RingBuf *buf);
void my_ring_buf_extend(RingBuf *buf);
void my_ring_buf_push_back(RingBuf *buf,void *ele);
void my_ring_buf_push_front(RingBuf *buf,void *ele);
void *my_ring_buf_front(RingBuf *buf);
void *my_ring_buf_back(RingBuf *buf);
void my_ring_buf_pop_front(RingBuf *buf);
void my_ring_buf_pop_back(RingBuf *buf);
typedef void (*ItorCb)(void *ele);
void my_ring_buf_itor(RingBuf *buf,ItorCb cb);
void* my_malloc(size_t size);
void my_free(void *ptr);
#ifdef __cplusplus
}
#endif
#endif // RING_BUG_H_

ringbuf.c

#include "ringbuf.h"
#define RING_BUG_CAP 2
void* my_malloc(size_t size){
    void *ptr=0;
    ptr=malloc(size);
    if(ptr){
        memset(ptr,0,size);
    }
    return ptr;
}
void my_free(void *ptr){
    if(ptr){
        free(ptr);
    }
}
RingBuf *my_ring_buf_new(int cap){
    int eles=0;
    if(!cap){
        eles=RING_BUG_CAP;
    }
    int allo=sizeof(RingBuf);
    RingBuf *buf=0;
    buf=my_malloc(allo);
    void *content=0;
    content=my_malloc(eles*sizeof(void*));
    if(buf){
        buf->start=content;
        buf->end=content+eles*sizeof(void*);
        buf->header=0;
        buf->tail=0;
        buf->used=0;
    }
    return buf;
}
void my_ring_buf_dtor(RingBuf *buf){
    if(buf){
        while(!my_ring_buf_empty(buf)){
            void *ptr;
            ptr=my_ring_buf_back(buf);
            my_ring_buf_pop_back(buf);
            my_free(ptr);
        }
        if(buf->start){
            my_free(buf->start);
            buf->start=0;
        }
        my_free(buf);
    }
}
bool my_ring_buf_empty(RingBuf *buf){
    bool ret=true;
    if(buf&&buf->used){
        ret=false;
    }
    return ret;
}
bool my_ring_buf_has_space(RingBuf *buf){
    bool ret=false;
    if(buf){
        int cap=(buf->end-buf->start)/sizeof(void*);
        if(buf->used<cap){
            ret=true;
        }
    }
    return ret;
}
void my_ring_buf_extend(RingBuf *buf){
    void *old=buf->start;
    int cap=(buf->end-buf->start)/sizeof(void*);
    void *content=my_malloc(2*cap*sizeof(void*));
    void **pos=(void**)content;
    int i=0;
    while(!my_ring_buf_empty(buf)){
        void *ele=my_ring_buf_front(buf);
        my_ring_buf_pop_front(buf);
        pos[i]=ele;
        i++;
    }
    buf->start=content;
    buf->end=content+2*cap*sizeof(void*);
    buf->tail=i-1;
    buf->header=0;
    buf->used=i;
    my_free(old);
}
void my_ring_buf_push_front(RingBuf *buf,void *ele){
    if(buf){
        if(buf->used==0){
            void *w_addr=buf->start+buf->header*sizeof(void*);
            void **pos=(void**)(w_addr);
            *pos=ele;
        }else{
            if(my_ring_buf_has_space(buf)){
            }else{
                my_ring_buf_extend(buf);
            }
            int cap=(buf->end-buf->start)/sizeof(void*);
            buf->header=(buf->header+cap-1)%cap;
            void *w_addr=buf->start+buf->header*sizeof(void*);
            void **pos=(void**)(w_addr);
            *pos=ele;
        }
        buf->used++;
    }
}
void my_ring_buf_push_back(RingBuf *buf,void *ele){
    if(buf){
        if(buf->used==0){
            void *w_addr=buf->start+buf->tail*sizeof(void*);
            void **pos=(void**)(w_addr);
            *pos=ele;
        }else{
            if(my_ring_buf_has_space(buf)){
            }else{
                my_ring_buf_extend(buf);
            }
            int cap=(buf->end-buf->start)/sizeof(void*);
            buf->tail=(buf->tail+cap+1)%cap;
            void *w_addr=buf->start+buf->tail*sizeof(void*);
            void **pos=(void**)(w_addr);
            *pos=ele;
            //help me find a bug
            //buf->tail=i-1;
            //printf("off %d\n",(w_addr-buf->start)/sizeof(void*));
        }
        buf->used++;
    }
}
void *my_ring_buf_front(RingBuf *buf){
    void *ptr=0;
    if(buf&&buf->used){
        void **pos=(void**)(buf->start+buf->header*sizeof(void*));
        ptr=*pos;
    }
    return ptr;
}
void* my_ring_buf_back(RingBuf *buf){
    void *ptr=0;
    if(buf&&buf->used){
        void **pos=(void**)(buf->start+buf->tail*sizeof(void*));
        ptr=*pos;
    }
    return ptr;
}
void my_ring_buf_pop_front(RingBuf *buf){
    if(!buf){
        return;
    }
    int cap=(buf->end-buf->start)/sizeof(void*);
    if(buf->used==1){

    }else{
        buf->header=(buf->header+cap+1)%cap;
    }
    buf->used--;
}
void my_ring_buf_pop_back(RingBuf *buf){
    if(!buf){
        return;
    }
    int cap=(buf->end-buf->start)/sizeof(void*);
    if(buf->used==1){
    }else{
        buf->tail=(buf->tail+cap-1)%cap;
    }
    buf->used--;
}
void my_ring_buf_itor(RingBuf *buf,ItorCb cb){
    int total=buf->used;
    int cap=(buf->end-buf->start)/sizeof(void*);
    int i=0;
    for(i=0;i<total;i++){
        int offset=(buf->header+i+cap)%cap;
        void **pos=(void**)(buf->start+offset*(sizeof(void*)));
        cb(*pos);
    }
}

main.c

#include <stdio.h>
#include "ringbuf.h"
typedef struct{
    int a;
}MyValue;
void PrintEle(MyValue *v){
    printf("itor %d\n",v->a);
}
int main(){
    RingBuf *buf=my_ring_buf_new(0);
    my_ring_buf_has_space(buf);

    MyValue *v=0;
    int i=0;
    for(i=0;i<5;i++){
        v=(MyValue*)my_malloc(sizeof(MyValue));
        v->a=i+1;
        my_ring_buf_push_back(buf,v);
        printf("v %p\n",v);
    }
    for(i=5;i<10;i++){
        v=(MyValue*)my_malloc(sizeof(MyValue));
        v->a=i+1;
        my_ring_buf_push_front(buf,v);
        printf("v %p\n",v);
    }
    MyValue *ptr=0;
    my_ring_buf_itor(buf,PrintEle);
    for(i=0;i<5;i++){
    ptr=my_ring_buf_back(buf);
    my_ring_buf_pop_back(buf);
    printf("ptr %p, %d\n",ptr,ptr->a);
    my_free(ptr);
    }
    my_ring_buf_dtor(buf);
    return 0;
}