lkml.org 
[lkml]   [2012]   [Aug]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH v2 04/31] arm64: MMU definitions
Date
On Tuesday 14 August 2012, Catalin Marinas wrote:
>
> +/*
> + * TCR flags.
> + */
> +#define TCR_TxSZ(x) (((64 - (x)) << 16) | ((64 - (x)) << 0))
> +#define TCR_IRGN_NC ((0 << 8) | (0 << 24))
> +#define TCR_IRGN_WBWA ((1 << 8) | (1 << 24))
> +#define TCR_IRGN_WT ((2 << 8) | (2 << 24))
> +#define TCR_IRGN_WBnWA ((3 << 8) | (3 << 24))
> +#define TCR_IRGN_MASK ((3 << 8) | (3 << 24))
> +#define TCR_ORGN_NC ((0 << 10) | (0 << 26))
> +#define TCR_ORGN_WBWA ((1 << 10) | (1 << 26))
> +#define TCR_ORGN_WT ((2 << 10) | (2 << 26))
> +#define TCR_ORGN_WBnWA ((3 << 10) | (3 << 26))
> +#define TCR_ORGN_MASK ((3 << 10) | (3 << 26))
> +#define TCR_SHARED ((3 << 12) | (3 << 28))
> +#define TCR_TG0_64K (1 << 14)
> +#define TCR_TG1_64K (1 << 30)
> +#define TCR_IPS_40BIT (2 << 32)
> +#define TCR_ASID16 (1 << 36)
> +

As a matter of coding style, I would much prefer tables like this to be
written as

#define TCR_IRGN_MASK 0x0000000003000300
#define TCR_IRGN_WBnWA 0x0000000003000300
#define TCR_IRGN_WT 0x0000000002000200
#define TCR_IRGN_WBWA 0x0000000001000100
#define TCR_IRGN_NC 0x0000000000000000

#define TCR_ORGN_MASK 0x000000000c000c00
#define TCR_ORGN_WBnWA 0x000000000c000c00
#define TCR_ORGN_WT 0x0000000008000800
#define TCR_ORGN_WBWA 0x0000000004000400
#define TCR_ORGN_NC 0x0000000000000000

The advantage of this is that you can visually compare the bitmasks
to a hex dump, and if you are suffering from endian-confused documentation
authors, there is no ambiguity about which end of the word is bit zero.

Arnd


\
 
 \ /
  Last update: 2012-08-15 16:02    [W:0.970 / U:42.312 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site