Two consecutive fread errors and fread return values

 

I am writing a code today. I want to read a buffer frame into a file. Because there are two different implementations of neon and opencl, I need to read the file twice. The Code is as follows:

 

 1   FILE *file; 2   int i = 0; 3   INTER_BLOCK_SIZE_GPU_RS *block_size; 4   file = fopen(name, "rb"); 5   if (file == NULL) { 6     LOGE("Can‘t open file: %s\n", name); 7     return ; 8   } 9 //    LOGI("file open OK:%s",name);10     #if USE_OCL11      LOGI("read pool buffer");12          int readCount=0;13       for(i=0;i<50;++i){14        readCount=fread(rs_obj.buffer_pool_map_ptr, rs_obj.buffer_pool_size,1,  file);15          LOGI("OCL read buffer pool count==%d",readCount);16           if(readCount == 1)17                   break;18       }19 20     #if USE_NEON21       for(i=0;i<50;++i){22                readCount=fread(rs_obj.pool, rs_obj.buffer_pool_size,1,  file);23               LOGI("NEON read[%d] buffer pool count==%d",i,readCount);    24 25                 if(readCount == 1)26                   break;27               28          }29       LOGI("  ");30       #endif

It is found that the previous file was successfully read, And the next 50 times failed to read the file. I don't know why for a long time?

 

Later, we found that the pointer file * file to be read by C language files is compiled to read the file content. When reading a text file, the file is at the end of the file, C language output input pointers are indeed shared.

Therefore, when you use fread for the second time, 0 is always returned. You only need to add the code before the second execution of fread:

Fseek (file, 0, seek_set. Solve the problem.

 

In additionSize_tFread (Void*Buffer,Size_tSize,Size_tCount,File*Stream);

Returns the number of actually read count, which is the size. For example:

A file contains four char characters: 1, 2, 3, 4

Count = fread (rs_obj.buffer_pool_map_ptr, 1, sizeof (INT), file); 4,

Count = fread (rs_obj.buffer_pool_map_ptr,Sizeof (INT ),1, file); returns 1

Therefore, the actual read is a multiple of the size.

Two consecutive fread errors and fread return values