On 10/28/2012 8:58 AM, Stephen Warren wrote:
On 10/26/2012 05:33 AM, Vikram Narayanan wrote:
Some nitpicks.
On 10/24/2012 10:20 AM, Stephen Warren wrote:
<snip>
+static u8 bcm2835_sdhci_readb(struct sdhci_host *host, int reg) +{
- u32 val = bcm2835_sdhci_raw_readl(host, (reg& ~3));
- val = val>> (reg<< 3& 0x18)& 0xff;
- return (u8)val;
+}
Can the above used magics be made as macros?
This code was taken directly from the downstream Linux kernel, so I changed it as little as possible, to make comparisons easier. Still, if people want I can certainly make it easier to understand the expression a bit.
Seems reasonable.
I don't think the issue is the magic numbers so much as understanding what the expression does; the magic are obvious then. It's simply extracting byte n from from a u32. Would the following be more obvious:
byte_num = reg& 3; byte_shift = bytenum * 8; byte = (val>> byte_shift)& 0xff;
... and similar for the other functions?
This looks better to me than the former. Thanks.
~Vikram