FatFs - f

f_read

The f_read function reads data from a file.

FRESULT f_read (
  FIL* fp,     /* [IN] File object */
  void* buff,  /* [OUT] Buffer to store read data */
  UINT btr,    /* [IN] Number of bytes to read */
  UINT* br     /* [OUT] Number of bytes read */
);

Parameters

fp: Pointer to the open file object.
buff: Pointer to the buffer to store the read data.
btr: Number of bytes to read in range of UINT type. If the file needs to be read fast, it should be read in large chunk as possible.
br: Pointer to the UINT variable that receives number of bytes read. This value is always valid after the function call regardless of the function return code. If the return value is equal to btr, the function return code should be FR_OK.

Return Values

FR_OK, FR_DISK_ERR, FR_INT_ERR, FR_DENIED, FR_INVALID_OBJECT, FR_TIMEOUT

Description

The function starts to read data from the file at the file offset pointed by read/write pointer. The read/write pointer advances as number of bytes read. After the function succeeded, *br should be checked to detect end of the file. In case of *br < btr, it means the read/write pointer hit end of the file during read operation.

QuickInfo

Always available.

Example

Refer to the example in f_open.