linux-kernel - Re: [PATCH try#2] [MTD/MAPS] Blackfin BF5xx Maps: Handle the case where flash memory and ethernet mac/phy are mapped onto the same async bank

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Message-ID: <20080512122650.GA10014@logfs.org>
Date:	Mon, 12 May 2008 14:26:51 +0200
From:	Jörn Engel <joern@...fs.org>
To:	Bryan Wu <bryan.wu@...log.com>
Cc:	dwmw2@...radead.org, will.newton@...il.com,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Mike Frysinger <vapier.adi@...il.com>
Subject: Re: [PATCH try#2] [MTD/MAPS] Blackfin BF5xx Maps: Handle the case where flash memory and ethernet mac/phy are mapped onto the same async bank

On Sun, 3 February 2008 14:32:35 +0800, Bryan Wu wrote:
> +
> +static void bf5xx_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
> +{
> +	unsigned long i;
> +	map_word test;
> +
> +	if ((unsigned long)to & 0x1) {
> +		for (i = 0; i < len / 2 * 2; i += 2) {
> +			test = bf5xx_read(map, from + i);
> +			put_unaligned(test.x[0], (__le16 *)(to + i));
> +		}
> +	} else {
> +		for (i = 0; i < len / 2 * 2; i += 2) {
> +			test = bf5xx_read(map, from + i);
> +			*((u16*)(to + i)) = test.x[0];
                        ^^^^^^^^^^^^^^^^^

I'm not particularly fond of such constructs, maybe because I have such
a hard time understanding what the code actually does.

How about:
	u16 *foo = to;

	for (i = 0; i < (len & ~1); i++) {
		test = bf5xx_read(map, from + 2 * i);
		foo[i] = test.x[0];
	}

With perhaps a better name than "foo" and the same conversion in the
rest of the function as well?

> +		}
> +	}
> +
> +	if (len & 0x1) {
> +		test = bf5xx_read(map, from + i);
> +		*((u8*)(to + i)) = (u8)test.x[0];
> +	}
> +}

Jörn

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