Nicolas Pitre wrote:
> On Tue, 11 Aug 2009, Nicolas Pitre wrote:
>
>> On Tue, 11 Aug 2009, Linus Torvalds wrote:
>>
>>> On Tue, 11 Aug 2009, Nicolas Pitre wrote:
>>>> #define SHA_SRC(t) \
>>>> ({ unsigned char *__d = (unsigned char *)&data[t]; \
>>>> (__d[0] << 24) | (__d[1] << 16) | (__d[2] << 8) | (__d[3] << 0); })
>>>>
>>>> And this provides the exact same performance as the ntohl() based
>>>> version (4.980s) except that this now cope with unaligned buffers too.
>>> The actual object SHA1 calculations are likely not aligned (we do that
>>> object header thing), and if you can't do the htonl() any better way I
>>> guess the byte-based thing is the way to go..
>
> OK, even better: 4.400s.
>
> This is with this instead of the above:
>
> #define SHA_SRC(t) \
> ({ unsigned char *__d = (unsigned char *)data; \
> (__d[(t)*4 + 0] << 24) | (__d[(t)*4 + 1] << 16) | \
> (__d[(t)*4 + 2] << 8) | (__d[(t)*4 + 3] << 0); })
>
> The previous version would allocate a new register for __d and then
> index it with an offset of 0, 1, 2 or 3. This version always uses the
> register containing the data pointer with absolute offsets. The binary
> is a bit smaller too.
In that case, why not change the interface of blk_SHA1Block() so that its
second argument is const unsigned char* and get rid of __d and the { } ?
Then it will look like this:
static void blk_SHA1Block(blk_SHA_CTX *ctx, const unsigned char *data);
...
#define SHA_SRC(t) \
( (data[(t)*4 + 0] << 24) | (data[(t)*4 + 1] << 16) | \
(data[(t)*4 + 2] << 8) | (data[(t)*4 + 3] << 0) )
Plus, we need something like the following to handle storing the hash to
an unaligned buffer (warning copy/pasted):
@@ -73,8 +74,12 @@ void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *c
/* Output hash
*/
- for (i = 0; i < 5; i++)
- ((unsigned int *)hashout)[i] = htonl(ctx->H[i]);
+ for (i = 0; i < 5; i++) {
+ *hashout++ = (unsigned char) (ctx->H[i] >> 24);
+ *hashout++ = (unsigned char) (ctx->H[i] >> 16);
+ *hashout++ = (unsigned char) (ctx->H[i] >> 8);
+ *hashout++ = (unsigned char) (ctx->H[i] >> 0);
+ }
}
#if defined(__i386__) || defined(__x86_64__)
With these two changes plus a few other minor tweaks, the block-sha1 code compiles
and passes the test suite on sparc (solaris 7) and mips (irix 6.5).
-brandon
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html