Bfile_ReadFile_OS

Synopsis #

Header: fxcg/file.h
Syscall index: 0x1DAC
Function signature: int Bfile_ReadFile_OS(int handle, void *buf, int size, int pos)

Reads bytes from an open file.

Parameters #

handle: File handle as returned by Bfile_OpenFile_OS.
buf: Location to store data read from file.
size: Number of bytes to read.
pos: File offset to read at, or -1 to read from the current file pointer (like stdio).

Returns #

Number of bytes read, or a negative error code on failure.

Comments #

Large values for size (one megabyte or more) may cause issues (hang the calculator).

If size is >0, then the position in the file handle will be moved to pos+size after the function. If size is 0, the position will not be set to pos. Use Bfile_SeekFile_OS to set the file pointer.

Using Bfile functions while user timers are installed can cause SYSTEM ERRORs and other undefined behavior, especially with functions that change data on the file system. Make sure to stop and uninstall all timers before using Bfile functions (and optionally restore them later). See Incompatibility_between_Bfile_Syscalls_and_Timers for more information.