linux-kernel - [Q]staging/comedi: Considation of *_find

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Date:	Wed, 30 Jan 2013 00:41:35 +0100
From:	Peter Hüwe <PeterHuewe@....de>
To:	Ian Abbott <abbotti@....co.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:	ian Abbott <ian.abbott@....co.uk>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>
Subject: [Q]staging/comedi: Considation of *_find_boardinfo possible?

Hi,

while analyzing the comedi drivers, I noticed that quite a lot of them use a 
more or less similar find_boardinfo function.
e.g.: 
cb_pcidas64.c 

static const struct pcidas64_board
*cb_pcidas64_find_pci_board(struct pci_dev *pcidev)
{
	unsigned int i;

	for (i = 0; i < ARRAY_SIZE(pcidas64_boards); i++)
		if (pcidev->device == pcidas64_boards[i].device_id)
			return &pcidas64_boards[i];
	return NULL;
}

and ni_6527.c:
static const struct ni6527_board *
ni6527_find_boardinfo(struct pci_dev *pcidev)
{
	unsigned int dev_id = pcidev->device;
	unsigned int n;

	for (n = 0; n < ARRAY_SIZE(ni6527_boards); n++) {
		const struct ni6527_board *board = &ni6527_boards[n];
		if (board->dev_id == dev_id)
			return board;
	}
	return NULL;
}




The names and the exact implementation differ slightly, but in most cases it 
boils down to:
	unsigned int i;

	for (i = 0; i < ARRAY_SIZE(__BOARD_ARRAY__); i++)
		if (pcidev->device == __BOARD_ARRAY__[i].device_id)
			return &__BOARD_ARRAY__[i];
	return NULL;

unfortunately the __BOARD_ARRAY__ is always of a different type (but all 
contain the device_id field) and size.


---> is there a way to consolidate these functions into one function (which 
can operate on the different types) ?  It's almost a bit like 'templates'.
Maybe with some gcc extensions or kernel magic functions ?

I already thought about passing a void pointer to the __BOARD_ARRAY__ and the 
size of one element of the __BOARD_ARRAY__ and doing pointer calculations - 
but I guess there must be a better way.

Or is the only option to write a macro ?


Looking forward to your replies.

Thanks,
Peter


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