Проблема с Ring Buffer. Опции

[Jenya7]

Я сделал такую реализацию.

CODE

typedef enum CycBuffState {cbsOk = 0, cbsOverwrite = 1, cbsBuffFull = 2, cbsBuffEmpty = 3, cbsError = 4} enCycBuffState;

typedef struct
{
uint32_t MaxBufSize,
HeadIdx,
TailIdx;
enCycBuffState State;
uint8_t *Buffer;
} stRingBuffer;

void RingBuf_Init (stRingBuffer *ring_buf, uint8_t *buf, uint32_t max_size)
{
ring_buf->Buffer = buf;
ring_buf->MaxBufSize = max_size;
ring_buf->HeadIdx = ring_buf->TailIdx = 0;
ring_buf->State = cbsBuffEmpty;
}

enCycBuffState RingBuf_PushByte(stRingBuffer *ring_buf, uint8_t val, uint8_t allow_overwrite)
{
if ((ring_buf->HeadIdx+1) == ring_buf->TailIdx)
{
if (!allow_overwrite)
return cbsBuffFull;
}

ring_buf->Buffer[ring_buf->HeadIdx] = val;
ring_buf->HeadIdx++;

if (ring_buf->HeadIdx >= ring_buf->MaxBufSize)
ring_buf->HeadIdx = 0;

return cbsOk;
}

enCycBuffState RingBuf_PushBytes(stRingBuffer *ring_buf, uint8_t len, uint8_t *buf, uint8_t allow_overwrite)
{
uint32_t free_space;

if (ring_buf->HeadIdx == ring_buf->TailIdx)
{
free_space = ring_buf->MaxBufSize;
}
else
{
if (ring_buf->HeadIdx >= ring_buf->TailIdx)
free_space = ring_buf->HeadIdx - ring_buf->TailIdx;
else
free_space = (ring_buf->MaxBufSize - ring_buf->TailIdx) + ring_buf->HeadIdx;

if (free_space < len)
return cbsBuffFull;
}
while (len)
{
RingBuf_PushByte(ring_buf, *buf, allow_overwrite);
buf++;
len--;
}

return cbsOk;
}

enCycBuffState RingBuf_PopByte(stRingBuffer *ring_buf, uint8_t *val)
{
if (ring_buf->HeadIdx == ring_buf->TailIdx)
return cbsError;

*val = ring_buf->Buffer[ring_buf->TailIdx];
ring_buf->Buffer[ring_buf->TailIdx] = 0;
ring_buf->TailIdx++;

if (ring_buf->TailIdx >= ring_buf->MaxBufSize)
ring_buf->TailIdx = 0;

return cbsOk;
}

enCycBuffState RingBuf_PopBytes(stRingBuffer *ring_buf, uint8_t len, uint8_t *val)
{
while (len)
{
RingBuf_PopByte(ring_buf, val);
val++;
len--;
}

return cbsOk;
}

И потом проверяю (в IAR, в симуляторе)

Код

#include <string.h>
#include "ringbuf.h"

stRingBuffer ring_buf;

uint8_t *temp_buff;
uint8_t *test_buff = "Hello World";
uint8_t *read_buff;

int main()
{
  RingBuf_Init (&ring_buf, temp_buff, 32);
  while (1)
  {
     RingBuf_PushBytes(&ring_buf, strlen(test_buff), test_buff, 0);
    
     RingBuf_PopBytes(&ring_buf, strlen(test_buff), read_buff);
  }
}

Но несмотря на то что я отслеживаю наличие свободного места.

Код

uint32_t free_space;
  
  if (ring_buf->HeadIdx == ring_buf->TailIdx)
  {
    free_space = ring_buf->MaxBufSize;
  }
  else
  {
    if (ring_buf->HeadIdx >= ring_buf->TailIdx)
       free_space = ring_buf->HeadIdx - ring_buf->TailIdx;
     else
       free_space = (ring_buf->MaxBufSize - ring_buf->TailIdx) + ring_buf->HeadIdx;
  
    if (free_space < len)
      return cbsBuffFull;

В отладчике я вижу перезапись буфера. Что я упустил?

Сообщение отредактировал Jenya7 - Aug 31 2016, 08:51

[smalcom]

Код

buf[(head + sz_contains++) % SZ_MAX] = val;

угроза переполнения "sz_contains".