Date: Sat, 11 Mar 2017 14:03:06 +0000 From: Anindya Mukherjee <anindya49@hotmail.com> To: "freebsd-drivers@freebsd.org" <freebsd-drivers@freebsd.org> Subject: RE: uiomove question Message-ID: <MWHPR2201MB13893C02D022695130ECF14EB6230@MWHPR2201MB1389.namprd22.prod.outlook.com> In-Reply-To: <MWHPR2201MB1389E09A18BCBEEB53ADCD96B6210@MWHPR2201MB1389.namprd22.prod.outlook.com> References: <MWHPR2201MB1389E09A18BCBEEB53ADCD96B6210@MWHPR2201MB1389.namprd22.prod.outlook.com>
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An example of the usage I am talking about:
xxx_write(...)
{
...
amount = MIN(uio->uio_resid, // 0. This is the no of bytes in the uio left to write
(BUFFER_SIZE - 1 - uio->uio_offset > 0) ?
BUFFER_SIZE - 1 - uio->uio_offset : 0); // 1. amount to write is computed
//assuming write will happen at uio_offset in sc_buffer
if (amount == 0)
return (error);
error = uiomove(sc->sc_buffer, amount, uio); // 2. sc_buffer is not offset
...
}
xxx_read(...)
{
...
amount = MIN(uio->uio_resid,
(sc->sc_length - uio->uio_offset > 0) ?
sc->sc_length - uio->uio_offset : 0); // 3. Same as comment 1 above
error = uiomove(sc->sc_buffer + uio->uio_offset, amount, uio); // 4. Here buffer is offset
...
}
Anindya
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