A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-28 18:51:56 -04:00
Code Issues Projects Releases Packages Wiki Activity

[PATCH] LOG2: Implement a general integer log2 facility in the kernel

Browse source 
This facility provides three entry points:

	ilog2()		Log base 2 of unsigned long
	ilog2_u32()	Log base 2 of u32
	ilog2_u64()	Log base 2 of u64

These facilities can either be used inside functions on dynamic data:

	int do_something(long q)
	{
		...;
		y = ilog2(x)
		...;
	}

Or can be used to statically initialise global variables with constant values:

	unsigned n = ilog2(27);

When performing static initialisation, the compiler will report "error:
initializer element is not constant" if asked to take a log of zero or of
something not reducible to a constant.  They treat negative numbers as
unsigned.

When not dealing with a constant, they fall back to using fls() which permits
them to use arch-specific log calculation instructions - such as BSR on
x86/x86_64 or SCAN on FRV - if available.

[[email protected]: MMC fix]
Signed-off-by: David Howells <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Herbert Xu <[email protected]>
Cc: David Howells <[email protected]>
Cc: Wojtek Kaniewski <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
David Howells 2006-12-08 02:37:49 -08:00 • committed by Linus Torvalds
commit f0d1b0b30d
36 changed files with 384 additions and 28 deletions
Download patch file Download diff file Expand all files Collapse all files

4
mm/page_alloc.c
View file

@ -3244,7 +3244,7 @@ void *__init alloc_large_system_hash(const char *tablename,
if (numentries > max)
numentries = max;
log2qty = long_log2(numentries);
log2qty = ilog2(numentries);
do {
size = bucketsize << log2qty;
@ -3266,7 +3266,7 @@ void *__init alloc_large_system_hash(const char *tablename,
printk("%s hash table entries: %d (order: %d, %lu bytes)\n",
tablename,
(1U << log2qty),
long_log2(size) - PAGE_SHIFT,
ilog2(size) - PAGE_SHIFT,
size);
if (_hash_shift)