为什么调试的crc32的临时文件只有4个字节

// 调试用代码
   FILE *hdcd;

............


// 调试用代码
   hdcd = fopen("bcrc.bin","wb+");
   for(unsigned int i = 0; i < frs; i += bal) {
   // all channels (block), all samples
      for(unsigned int j = 0; j < bal; j ++) {
        // 调试用代码
           fwrite(&buffer[i+j],1,1,hdcd);
           crc = (crc >> 8) ^ crc32_table[(crc & 0xFF) ^ buffer[i+j]];
           }
// 调试用代码
   fclose(hdcd);