On Wed, 5 Dec 2007, Andi Drebes wrote:
>
> +#ifdef __BIG_ENDIAN
> +
> +/* Converts a cramfs_inode's offset field
> + from little endianto cpu endian */
> +static u32 cramfs_offset_to_cpu(struct cramfs_inode *inode)
> +{
> + u8 *inode_bytes = (u8 *)inode;
> + return ((inode_bytes[8] & 0xc0) >> 6) | (inode_bytes[9] << 2) |
> + (inode_bytes[10] << 10) | (inode_bytes[11] << 18);
> +}
...
> +#elif defined(__LITTLE_ENDIAN)
> +
> +/* Converts a cramfs_inode's offset field
> + from little endian to cpu endian */
> +static u32 cramfs_offset_to_cpu(struct cramfs_inode *inode)
> +{
> + return inode->offset;
> +}
No, no, what I meant about not having any #ifdef __LITTLE_ENDIAN was to do
the code do the same thing *regardless* of endianness. In other words, a
simple:
struct cramfs_inode {
__le32 mode_uid; /* CRAMFS_MODE_WIDTH:CRAMFS_UID_WIDTH */
__le32 size_gid; /* CRAMFS_SIZE_WIDTH:CRAMFS_GID_WIDTH */
__le32 namelen_offset; /*
CRAMFS_NAMELEN_WIDTH:CRAMFS_OFFSET_WIDTH */
};
#define CRAMFS_UID_MASK ((1ul << CRAMFS_UID_WIDTH)-1)
#define CRAMFS_GID_MASK ((1ul << CRAMFS_GID_WIDTH)-1)
#define CRAMFS_NAMELEN_MASK ((1ul << CRAMFS_NAMELEN_WIDTH)-1)
static inline u32 cramfs_mode(struct cramfs_inode *inode)
{
return le32_to_cpu(node->mode_uid) >> CRAMFS_UID_WIDTH;
}
static inline u32 cramfs_uid(struct cramfs_inode *inode)
{
return le32_to_cpu(node->mode_uid) & CRAMFS_UID_MASK;
}
static inline u32 cramfs_size(struct cramfs_inode *inode)
{
return le32_to_cpu(node->size_gid) >> CRAMFS_GID_WIDTH;
}
static inline u32 cramfs_gid(struct cramfs_inode *inode)
{
return le32_to_cpu(node->size_gid) & CRAMFS_GID_MASK;
}
static inline u32 cramfs_offset(struct cramfs_inode *inode)
{
return le32_to_cpu(node->namelen_offset) >>
CRAMFS_NAMELEN_WIDTH;
}
static inline u32 cramfs_namelen(struct cramfs_inode *inode)
{
return le32_to_cpu(node->namelen_offset) & CRAMFS_NAMELEN_MASK;
}
See? No #ifdef's required, no different code-paths, and the code generated
will be pretty much optimal too.
(No, the above is not tested in any way, shape, or form, and no, I didn't
double-check that I actually extracted the right bits, but you get the
idea).
Linus
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