diff options
| author | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2013-05-15 10:26:50 -0400 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2013-05-15 10:26:50 -0400 |
| commit | 12e04ffcd93b25dfd726d46338c2ee7d23de556e (patch) | |
| tree | f91479a62805619168994fd3ee55e3ffa23fc24e /lib/int_sqrt.c | |
| parent | 9eff37a8713939f218ab8bf0dc93f1d67af7b8b4 (diff) | |
| parent | f722406faae2d073cc1d01063d1123c35425939e (diff) | |
Merge tag 'v3.10-rc1' into stable/for-linus-3.10
Linux 3.10-rc1
* tag 'v3.10-rc1': (12273 commits)
Linux 3.10-rc1
[SCSI] qla2xxx: Update firmware link in Kconfig file.
[SCSI] iscsi class, qla4xxx: fix sess/conn refcounting when find fns are used
[SCSI] sas: unify the pointlessly separated enums sas_dev_type and sas_device_type
[SCSI] pm80xx: thermal, sas controller config and error handling update
[SCSI] pm80xx: NCQ error handling changes
[SCSI] pm80xx: WWN Modification for PM8081/88/89 controllers
[SCSI] pm80xx: Changed module name and debug messages update
[SCSI] pm80xx: Firmware flash memory free fix, with addition of new memory region for it
[SCSI] pm80xx: SPC new firmware changes for device id 0x8081 alone
[SCSI] pm80xx: Added SPCv/ve specific hardware functionalities and relevant changes in common files
[SCSI] pm80xx: MSI-X implementation for using 64 interrupts
[SCSI] pm80xx: Updated common functions common for SPC and SPCv/ve
[SCSI] pm80xx: Multiple inbound/outbound queue configuration
[SCSI] pm80xx: Added SPCv/ve specific ids, variables and modify for SPC
[SCSI] lpfc: fix up Kconfig dependencies
[SCSI] Handle MLQUEUE busy response in scsi_send_eh_cmnd
dm cache: set config value
dm cache: move config fns
dm thin: generate event when metadata threshold passed
...
Diffstat (limited to 'lib/int_sqrt.c')
| -rw-r--r-- | lib/int_sqrt.c | 32 |
1 files changed, 19 insertions, 13 deletions
diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c index fc2eeb7cb2e..1ef4cc34497 100644 --- a/lib/int_sqrt.c +++ b/lib/int_sqrt.c @@ -1,3 +1,9 @@ +/* + * Copyright (C) 2013 Davidlohr Bueso <davidlohr.bueso@hp.com> + * + * Based on the shift-and-subtract algorithm for computing integer + * square root from Guy L. Steele. + */ #include <linux/kernel.h> #include <linux/export.h> @@ -10,23 +16,23 @@ */ unsigned long int_sqrt(unsigned long x) { - unsigned long op, res, one; + unsigned long b, m, y = 0; - op = x; - res = 0; + if (x <= 1) + return x; - one = 1UL << (BITS_PER_LONG - 2); - while (one > op) - one >>= 2; + m = 1UL << (BITS_PER_LONG - 2); + while (m != 0) { + b = y + m; + y >>= 1; - while (one != 0) { - if (op >= res + one) { - op = op - (res + one); - res = res + 2 * one; + if (x >= b) { + x -= b; + y += m; } - res /= 2; - one /= 4; + m >>= 2; } - return res; + + return y; } EXPORT_SYMBOL(int_sqrt); |