From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Lee, Chun-Yi" Subject: [RFC PATCH 10/14] rtc: improve and move week day computing function to rtc header Date: Thu, 19 Dec 2013 15:51:51 +0800 Message-ID: <1387439515-8926-11-git-send-email-jlee@suse.com> References: <1387439515-8926-1-git-send-email-jlee@suse.com> Return-path: In-Reply-To: <1387439515-8926-1-git-send-email-jlee@suse.com> Sender: linux-kernel-owner@vger.kernel.org To: "Rafael J. Wysocki" , Alessandro Zummo , "H. Peter Anvin" , Matt Fleming , Matthew Garrett Cc: Elliott@hp.com, samer.el-haj-mahmoud@hp.com, Oliver Neukum , werner@suse.com, trenn@suse.de, JBeulich@suse.com, linux-kernel@vger.kernel.org, rtc-linux@googlegroups.com, x86@kernel.org, "linux-efi@vger.kernel.org" , linux-acpi@vger.kernel.org, "Lee, Chun-Yi" List-Id: linux-efi@vger.kernel.org Due to rtc-acpid and efi time used the same logic for computing week day, so this patch moves code to rtc.h header file. Additionally using a leap year algorithm to replace the for-loop block in compute_wday for improve the performance. The first version of algorithm is from Oliver Neukum. --- drivers/rtc/rtc-acpitad.c | 13 +------------ include/linux/efi.h | 13 +------------ include/linux/rtc.h | 38 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 40 insertions(+), 24 deletions(-) diff --git a/drivers/rtc/rtc-acpitad.c b/drivers/rtc/rtc-acpitad.c index 065a033..bdf7ae1 100644 --- a/drivers/rtc/rtc-acpitad.c +++ b/drivers/rtc/rtc-acpitad.c @@ -32,23 +32,12 @@ compute_yday(struct acpi_time *acpit) static int compute_wday(struct acpi_time *acpit) { - int y; - int ndays = 0; - if (acpit->year < 1900) { pr_err("ACPI year < 1900, invalid date\n"); return -1; } - for (y = 1900; y < acpit->year; y++) - ndays += 365 + (is_leap_year(y) ? 1 : 0); - - ndays += compute_yday(acpit); - - /* - * 1=1/1/1900 was a Monday - */ - return (ndays + 1) % 7; + return rtc_wday(acpit->day, acpit->month - 1, acpit->year); } static void diff --git a/include/linux/efi.h b/include/linux/efi.h index 3859f3e..1c78ae7 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -177,23 +177,12 @@ compute_yday(efi_time_t *eft) static inline int compute_wday(efi_time_t *eft) { - int y; - int ndays = 0; - if (eft->year < 1998) { pr_err("EFI year < 1998, invalid date\n"); return -1; } - for (y = EFI_RTC_EPOCH; y < eft->year; y++) - ndays += 365 + (is_leap_year(y) ? 1 : 0); - - ndays += compute_yday(eft); - - /* - * 4=1/1/1998 was a Thursday - */ - return (ndays + 4) % 7; + return rtc_wday(eft->day, eft->month - 1, eft->year); } static inline void diff --git a/include/linux/rtc.h b/include/linux/rtc.h index e6380ec..511884f 100644 --- a/include/linux/rtc.h +++ b/include/linux/rtc.h @@ -196,6 +196,44 @@ static inline bool is_leap_year(unsigned int year) return (!(year % 4) && (year % 100)) || !(year % 400); } +#define SINCE1900 25 /* valid from 2000 */ + +static inline int rtc_wday(unsigned int day, unsigned int month, unsigned int year) +{ + int ndays, correction; + int base; + + if (year < 1900) { + pr_err("rtc: year < 1900, invalid date\n"); + return -1; + } + + if (year >= 2000) + base = year - 2000; + else + base = year - 1900; + + correction = 0; + if (base >= 0) { + correction += base / 4; + correction -= base / 100; + correction += base / 400; + if (year >= 2000) + correction += SINCE1900; + + /* later rtc_year_days will add the leap day of current year */ + correction -= ((is_leap_year(year)) ? 1 : 0); + } + + ndays = (year - 1900) * 365 + correction; + ndays += rtc_year_days(day, month, year); + + /* + * 1=1/1/1900 was a Monday + */ + return (ndays + 1) % 7; +} + #ifdef CONFIG_RTC_HCTOSYS_DEVICE extern int rtc_hctosys_ret; #else -- 1.6.4.2