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authorDavid Howells <dhowells@redhat.com>2006-12-08 02:37:49 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-08 08:28:51 -0800
commitf0d1b0b30d250a07627ad8b9fbbb5c7cc08422e8 (patch)
tree0aa5379150574374351fb92af7881a48dbfcf2ce /arch
parentb3d7ae5f47a58a9f7b152deeaf7daa1fc558a8f1 (diff)
downloadlinux-linaro-stable-f0d1b0b30d250a07627ad8b9fbbb5c7cc08422e8.tar.gz
[PATCH] LOG2: Implement a general integer log2 facility in the kernel
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. [akpm@osdl.org: MMC fix] Signed-off-by: David Howells <dhowells@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: David Howells <dhowells@redhat.com> Cc: Wojtek Kaniewski <wojtekka@toxygen.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/alpha/Kconfig8
-rw-r--r--arch/arm/Kconfig8
-rw-r--r--arch/arm26/Kconfig8
-rw-r--r--arch/avr32/Kconfig8
-rw-r--r--arch/cris/Kconfig8
-rw-r--r--arch/frv/Kconfig8
-rw-r--r--arch/h8300/Kconfig8
-rw-r--r--arch/i386/Kconfig.cpu8
-rw-r--r--arch/ia64/Kconfig8
-rw-r--r--arch/m32r/Kconfig8
-rw-r--r--arch/m68k/Kconfig8
-rw-r--r--arch/m68knommu/Kconfig8
-rw-r--r--arch/mips/Kconfig8
-rw-r--r--arch/parisc/Kconfig8
-rw-r--r--arch/powerpc/Kconfig8
-rw-r--r--arch/ppc/Kconfig8
-rw-r--r--arch/s390/Kconfig8
-rw-r--r--arch/sh/Kconfig8
-rw-r--r--arch/sh64/Kconfig8
-rw-r--r--arch/sparc/Kconfig8
-rw-r--r--arch/sparc64/Kconfig8
-rw-r--r--arch/v850/Kconfig8
-rw-r--r--arch/x86_64/Kconfig8
-rw-r--r--arch/xtensa/Kconfig8
24 files changed, 192 insertions, 0 deletions
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 7e55ea66c6d4..84caf50725b5 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -25,6 +25,14 @@ config RWSEM_XCHGADD_ALGORITHM
bool
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_FIND_NEXT_BIT
bool
default y
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 8c05d4321ae9..aa1d400d721a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -74,6 +74,14 @@ config RWSEM_GENERIC_SPINLOCK
config RWSEM_XCHGADD_ALGORITHM
bool
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_HWEIGHT
bool
default y
diff --git a/arch/arm26/Kconfig b/arch/arm26/Kconfig
index c14fe918bc4c..74eba8b5a8ca 100644
--- a/arch/arm26/Kconfig
+++ b/arch/arm26/Kconfig
@@ -41,6 +41,14 @@ config RWSEM_GENERIC_SPINLOCK
config RWSEM_XCHGADD_ALGORITHM
bool
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_HWEIGHT
bool
default y
diff --git a/arch/avr32/Kconfig b/arch/avr32/Kconfig
index 5f1694eea842..bb059a4e1df9 100644
--- a/arch/avr32/Kconfig
+++ b/arch/avr32/Kconfig
@@ -45,6 +45,14 @@ config GENERIC_TIME
config RWSEM_XCHGADD_ALGORITHM
bool
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_BUST_SPINLOCK
bool
diff --git a/arch/cris/Kconfig b/arch/cris/Kconfig
index 6a1238a29d6c..3474309e049c 100644
--- a/arch/cris/Kconfig
+++ b/arch/cris/Kconfig
@@ -16,6 +16,14 @@ config RWSEM_GENERIC_SPINLOCK
config RWSEM_XCHGADD_ALGORITHM
bool
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_FIND_NEXT_BIT
bool
default y
diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig
index cf1c446e003a..7561d7b72e75 100644
--- a/arch/frv/Kconfig
+++ b/arch/frv/Kconfig
@@ -41,6 +41,14 @@ config TIME_LOW_RES
bool
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default y
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default y
+
mainmenu "Fujitsu FR-V Kernel Configuration"
source "init/Kconfig"
diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
index cabf0bfffc53..34a84bc4baf5 100644
--- a/arch/h8300/Kconfig
+++ b/arch/h8300/Kconfig
@@ -29,6 +29,14 @@ config RWSEM_XCHGADD_ALGORITHM
bool
default n
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_FIND_NEXT_BIT
bool
default y
diff --git a/arch/i386/Kconfig.cpu b/arch/i386/Kconfig.cpu
index 821fd269ca58..2aecfba4ac4f 100644
--- a/arch/i386/Kconfig.cpu
+++ b/arch/i386/Kconfig.cpu
@@ -248,6 +248,14 @@ config RWSEM_XCHGADD_ALGORITHM
depends on !M386
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_CALIBRATE_DELAY
bool
default y
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 75d839715b2f..fcacfe291b9b 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -34,6 +34,14 @@ config RWSEM_XCHGADD_ALGORITHM
bool
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_FIND_NEXT_BIT
bool
default y
diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig
index 41fd490af3b4..f383dab973f5 100644
--- a/arch/m32r/Kconfig
+++ b/arch/m32r/Kconfig
@@ -214,6 +214,14 @@ config RWSEM_XCHGADD_ALGORITHM
bool
default n
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_FIND_NEXT_BIT
bool
default y
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 7bc14461a6ac..70a577c89c7c 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -17,6 +17,14 @@ config RWSEM_GENERIC_SPINLOCK
config RWSEM_XCHGADD_ALGORITHM
bool
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_HWEIGHT
bool
default y
diff --git a/arch/m68knommu/Kconfig b/arch/m68knommu/Kconfig
index aa70dde54228..25993c2a8fbb 100644
--- a/arch/m68knommu/Kconfig
+++ b/arch/m68knommu/Kconfig
@@ -25,6 +25,14 @@ config RWSEM_XCHGADD_ALGORITHM
bool
default n
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_FIND_NEXT_BIT
bool
default y
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index d8af858fe3f5..57af8d8cf46f 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -819,6 +819,14 @@ config RWSEM_GENERIC_SPINLOCK
config RWSEM_XCHGADD_ALGORITHM
bool
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_FIND_NEXT_BIT
bool
default y
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index d2101237442e..0f9ff618c6d7 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -25,6 +25,14 @@ config RWSEM_GENERIC_SPINLOCK
config RWSEM_XCHGADD_ALGORITHM
bool
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_FIND_NEXT_BIT
bool
default y
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 291c95ac4b31..97c7a212cdda 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -41,6 +41,14 @@ config RWSEM_XCHGADD_ALGORITHM
bool
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_HWEIGHT
bool
default y
diff --git a/arch/ppc/Kconfig b/arch/ppc/Kconfig
index f76a146cff13..692b5ba53209 100644
--- a/arch/ppc/Kconfig
+++ b/arch/ppc/Kconfig
@@ -19,6 +19,14 @@ config RWSEM_XCHGADD_ALGORITHM
bool
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default y
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_HWEIGHT
bool
default y
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 583d9ff0a571..45e47bfb68a9 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -22,6 +22,14 @@ config RWSEM_XCHGADD_ALGORITHM
bool
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config GENERIC_HWEIGHT
bool
default y
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index d83d64af31f2..8e24c40662e3 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -59,6 +59,14 @@ config LOCKDEP_SUPPORT
bool
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
source "init/Kconfig"
menu "System type"
diff --git a/arch/sh64/Kconfig b/arch/sh64/Kconfig
index 58c678e06667..7bc0744b7ab6 100644
--- a/arch/sh64/Kconfig
+++ b/arch/sh64/Kconfig
@@ -39,6 +39,14 @@ config RWSEM_XCHGADD_ALGORITHM
config GENERIC_ISA_DMA
bool
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
source init/Kconfig
menu "System type"
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 92a7c8a636d3..d0dec1ea2eed 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -166,6 +166,14 @@ config ARCH_MAY_HAVE_PC_FDC
bool
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config SUN_PM
bool
default y
diff --git a/arch/sparc64/Kconfig b/arch/sparc64/Kconfig
index b627f8dbcaad..d391d11f245a 100644
--- a/arch/sparc64/Kconfig
+++ b/arch/sparc64/Kconfig
@@ -34,6 +34,14 @@ config ARCH_MAY_HAVE_PC_FDC
bool
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
config AUDIT_ARCH
bool
default y
diff --git a/arch/v850/Kconfig b/arch/v850/Kconfig
index 37ec644603ab..bcf825875d17 100644
--- a/arch/v850/Kconfig
+++ b/arch/v850/Kconfig
@@ -38,6 +38,14 @@ config TIME_LOW_RES
bool
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
# Turn off some random 386 crap that can affect device config
config ISA
bool
diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index 3254a616c69e..3ac581d17202 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -101,6 +101,14 @@ config GENERIC_BUG
default y
depends on BUG
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
source "init/Kconfig"
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index c1e69a1f92a4..9eccfbd1b536 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -34,6 +34,14 @@ config GENERIC_HARDIRQS
bool
default y
+config ARCH_HAS_ILOG2_U32
+ bool
+ default n
+
+config ARCH_HAS_ILOG2_U64
+ bool
+ default n
+
source "init/Kconfig"
menu "Processor type and features"