Soewono Effendi wrote:
> Hi all,
>
>
> I'm just curious if there is any particular reason to use the following code
>
> return !!*buf;
>
> instead of the simple
>
> return (int) *buf;
>
This would be a trick to return 0 or 1.
Take for example *buf equal to 3.
!*buf -> !3 -> !(true) -> false -> 0
!!*buf -> !0 -> 1
return !!*buf returns 1, while return (int) *buf returns 3;
> in function "uhci_hub_status_data", file: usb/host/uhci-hub.c
>
> static int uhci_hub_status_data(struct usb_hcd *hcd, char *buf)
> {
> struct uhci_hcd *uhci = hcd_to_uhci(hcd);
> unsigned int io_addr = uhci->io_addr;
> int i, len = 1;
>
> *buf = 0;
> for (i = 0; i < uhci->rh_numports; i++) {
> *buf |= ((inw(io_addr + USBPORTSC1 + i * 2) & 0xa) > 0 ? (1 << (i +
>1)) : 0);
> len = (i + 1) / 8 + 1;
> }
>
> return !!*buf;
> }
>
>
> Little notes in code will be helpful.
>
> Best regards,
> sE
>
--
Johann Deneux
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