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The DOSish version of ioctl performs an interrupt 0x21, function 0x44. It takes care of supplying transfer buffers in low address regions, if they are needed. For an exhaustive description of the various commands and subcommands, see Ralf Brown's interrupt list.
It is highly recommended to use only the DOS_* functions listed in `sys/ioctl.h'.
int ioctl(int fd, int cmd, ... );
The parameter fd must refer to a file descriptor for character device functions, or the number of a block device (usually current=0, A:=1, ...).
The following constants can be used for the cmd parameter:
Get device information. Returns the device information word from DX. The call to ioctl should look like this:
int ret_val = ioctl (fd, DOS_GETDEVDATA);
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