Question

我已经实现了一个通用的环形缓冲区，但是我遇到了一些奇怪的结果。首先我成功地推送了15个整数，但是当我尝试打印到缓冲区的内容时，它会打印出一些错误的元素。

首先我为10个整数分配内存。然后我试图推动15并调整缓冲区的大小到位。也许调整大小是以某种方式打破它，因为没有它它工作正常。

RingBuffer.c

#include<stdlib.h>
#include<string.h>
#include <stdio.h>
#include"RingBuffer.h"

unsigned char RingInit(RingBuffer* buffer, int elemLen, int elemSize, void (*fn)(void*))
{
    buffer->dataLen = elemLen;
    buffer->dataSize = elemSize;

    if( (buffer->data = malloc( buffer->dataSize * buffer->dataLen )) == NULL){

        return 1;
    }

    buffer->head = 0;
    buffer->tail = 0;
    buffer->elemCount = 0;
    buffer->freeFn = fn;
    buffer->doResize = 1;
    buffer->resizeBy = 2;

    return 0;
}

unsigned char RingPush(RingBuffer* buffer, void* elem)
{
    if(RingIsFull(buffer)){

        if(!buffer->doResize || RingResize(buffer)){

            return 1;
        }
    }

    memcpy((buffer->data + (buffer->head*buffer->dataSize)), elem, buffer->dataSize);
    buffer->head = (buffer->head + 1) % buffer->dataLen;
    buffer->elemCount++;

    return 0;
}

unsigned char RingRead(RingBuffer* buffer, void* elem)
{
    if(!RingIsEmpty(buffer)){

        memcpy(elem, (buffer->data + (buffer->tail*buffer->dataSize)), buffer->dataSize);
        buffer->tail = (buffer->tail + 1) % buffer->dataLen;
        buffer->elemCount--;

        return 0;
    }

    return 1;
}

unsigned char RingIsEmpty(RingBuffer* buffer)
{
    return (buffer->elemCount == 0);
}

unsigned char RingIsFull(RingBuffer* buffer)
{
    return (buffer->elemCount == buffer->dataLen);
}

void RingFree(RingBuffer* buffer)
{
    buffer->freeFn(buffer->data);
}

unsigned char RingResize(RingBuffer* buffer)
{
    unsigned char* newMemory = NULL;

    if ( (newMemory = realloc(buffer->data, buffer->dataLen + (buffer->resizeBy * buffer->dataSize))) == NULL){

        return 1;
    }

    buffer->data = newMemory;
    buffer->dataLen += buffer->resizeBy;    
    buffer->head = buffer->elemCount;

    return 0;
}

RingBuffer.h

#ifndef RINGBUFFER_H_
#define RINGBUFFER_H_

typedef struct
{
    void *data;
    int dataSize;
    int dataLen;
    int head;
    int tail;
    int elemCount;
    int doResize;
    int resizeBy;
    void (*freeFn)(void*);

}RingBuffer;

unsigned char RingInit      (RingBuffer* buffer, int elemLen, int elemSize, void (*fn)(void*));
unsigned char RingRead      (RingBuffer* buffer, void* elem);
unsigned char RingIsEmpty   (RingBuffer* buffer);
unsigned char RingIsFull    (RingBuffer* buffer);
void          RingFree      (RingBuffer* buffer);
unsigned char RingResize    (RingBuffer* buffer);
unsigned char RingPush      (RingBuffer* buffer, void* elem);

#endif /* RINGBUFFER_H_ */

TEST.C

#include<stdlib.h>
#include<string.h>
#include <stdio.h>
#include"RingBuffer.h"

#define ARRAY_LENGTH(a)     sizeof(a)/sizeof(a[0])

void freeInt(void* data)
{
    free(data);
}

int main(void)
{
    RingBuffer Ring;
    int buf[15] = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
    int i = 0;

    if(RingInit(&Ring, ARRAY_LENGTH(buf)-5, sizeof(int), freeInt) == 0){

        printf("\nRING INIT OK");
    }
    else{

        printf("\nRING INIT FAIL");
        RingFree(&Ring);
        return 0;
    }

    Ring.doResize = 1;
    for(i = 0 ; i < ARRAY_LENGTH(buf) ; i++){

        if(RingPush(&Ring, &buf[i])){

            printf("\nRING PUSH FAIL");
            RingFree(&Ring);
            return 0;
        }

        printf("\nRING PUSH OK->%d", buf[i]);
        printf(" %d", ((int*)(Ring.data))[i]); 
    }

    printf("\n");
    for(i = 0 ; i < ARRAY_LENGTH(buf); i++){

        printf(" %d", ((int*)(Ring.data))[i]);
    }

    memset(buf, 0, sizeof(buf));
    printf("\nLOAD ZEROS:");
    for(i = 0 ; i < ARRAY_LENGTH(buf); i++){
        printf(" %d", buf[i]);
    }

    i = 0;
    while(!RingIsEmpty(&Ring)){

        if(RingRead(&Ring, &buf[i])){

            printf("\nRING READ FAIL");
            RingFree(&Ring);
            return 0;
        }

        printf("\nRING READ OK->%d", buf[i]);
        i++;
    }

    getchar();
    RingFree(&Ring);
    return 0;
}

结果：

RING INIT OK
RING PUSH OK->1 1
RING PUSH OK->2 2
RING PUSH OK->3 3
RING PUSH OK->4 4
RING PUSH OK->5 5
RING PUSH OK->6 6
RING PUSH OK->7 7
RING PUSH OK->8 8
RING PUSH OK->9 9
RING PUSH OK->10 10
RING PUSH OK->11 11
RING PUSH OK->12 12
RING PUSH OK->13 1313427978
RING PUSH OK->14 1431314503
RING PUSH OK->15 1327515731
 1 2 3 4 5 6 -1326086846 5687 12790216 12779712 11 12 926036256 842412848 909391924
LOAD ZEROS: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
RING READ OK->1
RING READ OK->2
RING READ OK->3
RING READ OK->4
RING READ OK->5
RING READ OK->6
RING READ OK->-1326086846
RING READ OK->5687
RING READ OK->12790216
RING READ OK->12779712
RING READ OK->11
RING READ OK->12
RING READ OK->1313427978
RING READ OK->1163010119
RING READ OK->1327514689

它应该打印数字1-15。它发生的是它打印了一些错误的数字。每次启动程序时，不同的元素都是错误的。

编译

gcc Test.c RingBuffer.c

Complier Version

Answer 1

您通过buffer->dataLen + (buffer->resizeBy * buffer->dataSize)作为要在函数RingResize中分配的大小。

不幸的是，buffer->dataLen是元素的数量，而不是字节的数量。

结果，新分配的缓冲区将没有足够的字节数。这会导致错误。

要分配的大小应为buffer->dataSize * (buffer->dataLen + buffer->resizeBy)。

通用环缓冲区

1 个答案: