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do_div_signed()

RFC PATCH In review john stultz 2 participants 3 messages May 22, 2007

Subsystems (3)
Library code Generic include/asm header files Timekeeping, clocksource core, NTP, alarmtimer
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john stultz

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#0 lore raw

RFC PATCH 1/1 do_div_signed()

Here's a quick pass at adding do_div_signed() which provides a signed version of do_div, avoiding having do_div users hack around signed issues (like in ntp.c).

It probably could be optimized further, so let me know if you have any suggestions.

Other thoughts?

thanks
-john

Signed-off-by John Stultz<[email protected]>
include/asm-arm/div64.h +1 -0
index 0b5f881..af44e10 100644
@@ -225,5 +225,6 @@
 #endif
 
 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 
 #endif
include/asm-generic/div64.h +1 -0
index a4a4937..e1cac65 100644
@@ -62,4 +62,5 @@ extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
 
 #endif /* BITS_PER_LONG */
 
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 #endif /* _ASM_GENERIC_DIV64_H */
include/asm-i386/div64.h +1 -0
index 438e980..05320a5 100644
@@ -49,4 +49,5 @@ div_ll_X_l_rem(long long divs, long div, long *rem)
 }
 
 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 #endif
include/asm-m68k/div64.h +1 -0
index 33caad1..3c76059 100644
@@ -26,4 +26,5 @@
 })
 
 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 #endif /* _M68K_DIV64_H */
include/asm-mips/div64.h +1 -0
index 66189f5..851ce40 100644
@@ -111,5 +111,6 @@ static inline uint64_t div64_64(uint64_t dividend, uint64_t divisor)
 }
 
 #endif /* (_MIPS_SZLONG == 64) */
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 
 #endif /* _ASM_DIV64_H */
include/asm-um/div64.h +1 -0
index 7b73b2c..1fc4a2c 100644
@@ -4,4 +4,5 @@
 #include "asm/arch/div64.h"
 
 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 #endif
kernel/time/ntp.c +4 -9
index 87aa5ff..7c093ad 100644
@@ -302,16 +302,11 @@ int do_adjtimex(struct timex *txc)
 		    freq_adj = time_offset * mtemp;
 		    freq_adj = shift_right(freq_adj, time_constant * 2 +
 					   (SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
-		    if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
+		    if (mtemp >= MINSEC && 
+		    		(time_status & STA_FLL || mtemp > MAXSEC)) {
 			temp64 = time_offset << (SHIFT_NSEC - SHIFT_FLL);
-			if (time_offset < 0) {
-			    temp64 = -temp64;
-			    do_div(temp64, mtemp);
-			    freq_adj -= temp64;
-			} else {
-			    do_div(temp64, mtemp);
-			    freq_adj += temp64;
-			}
+			do_div_signed(&temp64, mtemp);
+			freq_adj += temp64;
 		    }
 		    freq_adj += time_freq;
 		    freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
lib/div64.c +34 -0
index b71cf93..e6ff440 100644
@@ -79,3 +79,37 @@ uint64_t div64_64(uint64_t dividend, uint64_t divisor)
 EXPORT_SYMBOL(div64_64);
 
 #endif /* BITS_PER_LONG == 32 */
+
+/* Signed 64 bit dividend, result, rem. Signed 32 bit divisor */
+int64_t do_div_signed(int64_t *n, int32_t base)
+{
+	uint64_t num, den;
+	int64_t rem;
+	int num_sign = (*n < 0);
+	int den_sign = (base < 0);
+
+	if (num_sign)
+		num = (uint64_t)(-*n);
+	else
+		num = (uint64_t)*n;
+	
+	/* XXX this is sort of obnoxious,but seems necessary 
+	 * to handle the base possibly being negative as well
+	 */
+	if (den_sign)
+		den = (uint32_t)(-base);
+	else
+	den = (uint32_t)base;
+
+	rem = do_div(num, den);
+
+	*n = (int64_t)num;
+	if(num_sign ^ den_sign)
+		*n = -*n;
+	if(num_sign)
+		rem = -rem;
+
+	return rem;
+}
+
+EXPORT_SYMBOL(do_div_signed);
#1 lore raw

Hi,

Quoted 9 lines · john stultz

Here's a quick pass at adding do_div_signed() which provides a signed version of do_div, avoiding having do_div users hack around signed issues (like in ntp.c).

It probably could be optimized further, so let me know if you have any suggestions.

Other thoughts?

Did I mention that this API could use a little cleanup? :) Below is what I had in mind, this makes it more clear what types the functions are working on. As bonus I cleaned up the i386 div64 implementation to get rid of the ugly asm casts, so gcc can do better register allocation and generate better code.

bye, Roman

Signed-off-by Roman Zippel <[email protected]>
---
 include/asm-generic/div64.h |   14 ++++++++++++++
 include/asm-i386/div64.h    |   20 ++++++++++++++++++++
 include/linux/calc64.h      |   28 ++++++++++++++++++++++++++++
 kernel/time.c               |   26 +++++++-------------------
 kernel/time/ntp.c           |   21 +++++----------------
 lib/div64.c                 |   21 ++++++++++++++++++++-
 6 files changed, 94 insertions(+), 36 deletions(-)
include/asm-generic/div64.h +14 -0
Index: linux-2.6/include/asm-generic/div64.h
===================================================================
@@ -35,6 +35,20 @@ static inline uint64_t div64_64(uint64_t
 	return dividend / divisor;
 }
 
+static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
+{
+	*remainder = dividend % divisor;
+	return dividend / divisor;
+}
+#define div_u64_rem	div_u64_rem
+
+static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
+{
+	*remainder = dividend % divisor;
+	return dividend / divisor;
+}
+#define div_s64_rem	div_s64_rem
+
 #elif BITS_PER_LONG == 32
 
 extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
include/asm-i386/div64.h +20 -0
Index: linux-2.6/include/asm-i386/div64.h
===================================================================
@@ -48,5 +48,25 @@ div_ll_X_l_rem(long long divs, long div,
 
 }
 
+static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
+{
+	union {
+		u64 v64;
+		u32 v32[2];
+	} d = { dividend };
+	u32 upper;
+
+	upper = d.v32[1];
+	if (upper) {
+		upper = d.v32[1] % divisor;
+		d.v32[1] = d.v32[1] / divisor;
+	}
+	asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
+		"rm" (divisor), "0" (d.v32[0]), "1" (upper));
+	return d.v64;
+}
+#define div_u64_rem	div_u64_rem
+
 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
+
 #endif
include/linux/calc64.h +28 -0
Index: linux-2.6/include/linux/calc64.h
===================================================================
@@ -46,4 +46,32 @@ static inline long div_long_long_rem_sig
 	return res;
 }
 
+#ifndef div_u64_rem
+static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
+{
+	*remainder = do_div(dividend, divisor);
+	return dividend;
+}
+#endif
+
+#ifndef div_u64
+static inline u64 div_u64(u64 dividend, u32 divisor)
+{
+	u32 remainder;
+	return div_u64_rem(dividend, divisor, &remainder);
+}
+#endif
+
+#ifndef div_s64_rem
+extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
+#endif
+
+#ifndef div_s64
+static inline s64 div_s64(s64 dividend, s32 divisor)
+{
+	s32 remainder;
+	return div_s64_rem(dividend, divisor, &remainder);
+}
+#endif
+
 #endif
kernel/time.c +7 -19
Index: linux-2.6/kernel/time.c
===================================================================
@@ -661,9 +661,7 @@ clock_t jiffies_to_clock_t(long x)
 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
 	return x / (HZ / USER_HZ);
 #else
-	u64 tmp = (u64)x * TICK_NSEC;
-	do_div(tmp, (NSEC_PER_SEC / USER_HZ));
-	return (long)tmp;
+	return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
 #endif
 }
 EXPORT_SYMBOL(jiffies_to_clock_t);

@@ -675,16 +673,12 @@ unsigned long clock_t_to_jiffies(unsigne
 		return ~0UL;
 	return x * (HZ / USER_HZ);
 #else
-	u64 jif;
-
 	/* Don't worry about loss of precision here .. */
 	if (x >= ~0UL / HZ * USER_HZ)
 		return ~0UL;
 
 	/* .. but do try to contain it here */
-	jif = x * (u64) HZ;
-	do_div(jif, USER_HZ);
-	return jif;
+	return div_u64((u64)x * HZ, USER_HZ);
 #endif
 }
 EXPORT_SYMBOL(clock_t_to_jiffies);

@@ -692,17 +686,15 @@ EXPORT_SYMBOL(clock_t_to_jiffies);
 u64 jiffies_64_to_clock_t(u64 x)
 {
 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
-	do_div(x, HZ / USER_HZ);
+	return div_u64(x, HZ / USER_HZ);
 #else
 	/*
 	 * There are better ways that don't overflow early,
 	 * but even this doesn't overflow in hundreds of years
 	 * in 64 bits, so..
 	 */
-	x *= TICK_NSEC;
-	do_div(x, (NSEC_PER_SEC / USER_HZ));
+	return div_u64(x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
 #endif
-	return x;
 }
 
 EXPORT_SYMBOL(jiffies_64_to_clock_t);

@@ -710,21 +702,17 @@ EXPORT_SYMBOL(jiffies_64_to_clock_t);
 u64 nsec_to_clock_t(u64 x)
 {
 #if (NSEC_PER_SEC % USER_HZ) == 0
-	do_div(x, (NSEC_PER_SEC / USER_HZ));
+	return div_u64(x, NSEC_PER_SEC / USER_HZ);
 #elif (USER_HZ % 512) == 0
-	x *= USER_HZ/512;
-	do_div(x, (NSEC_PER_SEC / 512));
+	return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
 #else
 	/*
          * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
          * overflow after 64.99 years.
          * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
          */
-	x *= 9;
-	do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) /
-				  USER_HZ));
+	return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
 #endif
-	return x;
 }
 
 #if (BITS_PER_LONG < 64)
kernel/time/ntp.c +5 -16
Index: linux-2.6/kernel/time/ntp.c
===================================================================
@@ -53,10 +53,8 @@ static void ntp_update_frequency(void)
 
 	tick_length_base = second_length;
 
-	do_div(second_length, HZ);
-	tick_nsec = second_length >> TICK_LENGTH_SHIFT;
-
-	do_div(tick_length_base, NTP_INTERVAL_FREQ);
+	tick_nsec = div_u64(second_length, HZ) >> TICK_LENGTH_SHIFT;
+	tick_length_base = div_u64(tick_length_base, NTP_INTERVAL_FREQ);
 }
 
 /**

@@ -197,7 +195,7 @@ void __attribute__ ((weak)) notify_arch_
 int do_adjtimex(struct timex *txc)
 {
 	long mtemp, save_adjust, rem;
-	s64 freq_adj, temp64;
+	s64 freq_adj;
 	int result;
 
 	/* In order to modify anything, you gotta be super-user! */

@@ -300,17 +298,8 @@ int do_adjtimex(struct timex *txc)
 		    freq_adj = time_offset * mtemp;
 		    freq_adj = shift_right(freq_adj, time_constant * 2 +
 					   (SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
-		    if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
-			temp64 = time_offset << (SHIFT_NSEC - SHIFT_FLL);
-			if (time_offset < 0) {
-			    temp64 = -temp64;
-			    do_div(temp64, mtemp);
-			    freq_adj -= temp64;
-			} else {
-			    do_div(temp64, mtemp);
-			    freq_adj += temp64;
-			}
-		    }
+		    if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC))
+			freq_adj += div_s64(time_offset << (SHIFT_NSEC - SHIFT_FLL), mtemp);
 		    freq_adj += time_freq;
 		    freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
 		    time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
lib/div64.c +20 -1
Index: linux-2.6/lib/div64.c
===================================================================
@@ -18,7 +18,7 @@
 
 #include <linux/types.h>
 #include <linux/module.h>
-#include <asm/div64.h>
+#include <linux/calc64.h>
 
 /* Not needed on 64bit architectures */
 #if BITS_PER_LONG == 32

@@ -78,4 +78,23 @@ uint64_t div64_64(uint64_t dividend, uin
 }
 EXPORT_SYMBOL(div64_64);
 
+#ifndef div_s64_rem
+s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
+{
+	u64 quotient;
+
+	if (dividend < 0) {
+		quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);
+		*remainder = -*remainder;
+		if (divisor > 0)
+			quotient = -quotient;
+	} else {
+		quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder);
+		if (divisor < 0)
+			quotient = -quotient;
+	}
+	return quotient;
+}
+#endif
+
 #endif /* BITS_PER_LONG == 32 */
author Acked-by
#2 lore raw
Quoted 12 lines · Roman Zippel

Hi,

Quoted 8 lines · john stultz

Here's a quick pass at adding do_div_signed() which provides a signed version of do_div, avoiding having do_div users hack around signed issues (like in ntp.c).

It probably could be optimized further, so let me know if you have any suggestions.

Quoted 8 lines
Quoted 1 line

Other thoughts?

Did I mention that this API could use a little cleanup? :) Below is what I had in mind, this makes it more clear what types the functions are working on. As bonus I cleaned up the i386 div64 implementation to get rid of the ugly asm casts, so gcc can do better register allocation and generate better code.

Yep. Much nicer then mine!

thanks!
-john

Quoted 2 lines
Signed-off-by Roman Zippel <[email protected]>
Acked-by John Stultz <[email protected]>
Quoted 262 lines
---
 include/asm-generic/div64.h |   14 ++++++++++++++
 include/asm-i386/div64.h    |   20 ++++++++++++++++++++
 include/linux/calc64.h      |   28 ++++++++++++++++++++++++++++
 kernel/time.c               |   26 +++++++-------------------
 kernel/time/ntp.c           |   21 +++++----------------
 lib/div64.c                 |   21 ++++++++++++++++++++-
 6 files changed, 94 insertions(+), 36 deletions(-)

Index: linux-2.6/include/asm-generic/div64.h
===================================================================

include/asm-generic/div64.h +14 -0
@@ -35,6 +35,20 @@ static inline uint64_t div64_64(uint64_t
 	return dividend / divisor;
 }
 
+static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
+{
+	*remainder = dividend % divisor;
+	return dividend / divisor;
+}
+#define div_u64_rem	div_u64_rem
+
+static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
+{
+	*remainder = dividend % divisor;
+	return dividend / divisor;
+}
+#define div_s64_rem	div_s64_rem
+
 #elif BITS_PER_LONG == 32
 
 extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);

Index: linux-2.6/include/asm-i386/div64.h
===================================================================

include/asm-i386/div64.h +20 -0
@@ -48,5 +48,25 @@ div_ll_X_l_rem(long long divs, long div,
 
 }
 
+static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
+{
+	union {
+		u64 v64;
+		u32 v32[2];
+	} d = { dividend };
+	u32 upper;
+
+	upper = d.v32[1];
+	if (upper) {
+		upper = d.v32[1] % divisor;
+		d.v32[1] = d.v32[1] / divisor;
+	}
+	asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
+		"rm" (divisor), "0" (d.v32[0]), "1" (upper));
+	return d.v64;
+}
+#define div_u64_rem	div_u64_rem
+
 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
+
 #endif

Index: linux-2.6/include/linux/calc64.h
===================================================================

include/linux/calc64.h +28 -0
@@ -46,4 +46,32 @@ static inline long div_long_long_rem_sig
 	return res;
 }
 
+#ifndef div_u64_rem
+static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
+{
+	*remainder = do_div(dividend, divisor);
+	return dividend;
+}
+#endif
+
+#ifndef div_u64
+static inline u64 div_u64(u64 dividend, u32 divisor)
+{
+	u32 remainder;
+	return div_u64_rem(dividend, divisor, &remainder);
+}
+#endif
+
+#ifndef div_s64_rem
+extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
+#endif
+
+#ifndef div_s64
+static inline s64 div_s64(s64 dividend, s32 divisor)
+{
+	s32 remainder;
+	return div_s64_rem(dividend, divisor, &remainder);
+}
+#endif
+
 #endif

Index: linux-2.6/kernel/time.c
===================================================================

kernel/time.c +7 -19
@@ -661,9 +661,7 @@ clock_t jiffies_to_clock_t(long x)
 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
 	return x / (HZ / USER_HZ);
 #else
-	u64 tmp = (u64)x * TICK_NSEC;
-	do_div(tmp, (NSEC_PER_SEC / USER_HZ));
-	return (long)tmp;
+	return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
 #endif
 }
 EXPORT_SYMBOL(jiffies_to_clock_t);

@@ -675,16 +673,12 @@ unsigned long clock_t_to_jiffies(unsigne
 		return ~0UL;
 	return x * (HZ / USER_HZ);
 #else
-	u64 jif;
-
 	/* Don't worry about loss of precision here .. */
 	if (x >= ~0UL / HZ * USER_HZ)
 		return ~0UL;
 
 	/* .. but do try to contain it here */
-	jif = x * (u64) HZ;
-	do_div(jif, USER_HZ);
-	return jif;
+	return div_u64((u64)x * HZ, USER_HZ);
 #endif
 }
 EXPORT_SYMBOL(clock_t_to_jiffies);

@@ -692,17 +686,15 @@ EXPORT_SYMBOL(clock_t_to_jiffies);
 u64 jiffies_64_to_clock_t(u64 x)
 {
 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
-	do_div(x, HZ / USER_HZ);
+	return div_u64(x, HZ / USER_HZ);
 #else
 	/*
 	 * There are better ways that don't overflow early,
 	 * but even this doesn't overflow in hundreds of years
 	 * in 64 bits, so..
 	 */
-	x *= TICK_NSEC;
-	do_div(x, (NSEC_PER_SEC / USER_HZ));
+	return div_u64(x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
 #endif
-	return x;
 }
 
 EXPORT_SYMBOL(jiffies_64_to_clock_t);

@@ -710,21 +702,17 @@ EXPORT_SYMBOL(jiffies_64_to_clock_t);
 u64 nsec_to_clock_t(u64 x)
 {
 #if (NSEC_PER_SEC % USER_HZ) == 0
-	do_div(x, (NSEC_PER_SEC / USER_HZ));
+	return div_u64(x, NSEC_PER_SEC / USER_HZ);
 #elif (USER_HZ % 512) == 0
-	x *= USER_HZ/512;
-	do_div(x, (NSEC_PER_SEC / 512));
+	return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
 #else
 	/*
          * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
          * overflow after 64.99 years.
          * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
          */
-	x *= 9;
-	do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) /
-				  USER_HZ));
+	return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
 #endif
-	return x;
 }
 
 #if (BITS_PER_LONG < 64)

Index: linux-2.6/kernel/time/ntp.c
===================================================================

kernel/time/ntp.c +5 -16
@@ -53,10 +53,8 @@ static void ntp_update_frequency(void)
 
 	tick_length_base = second_length;
 
-	do_div(second_length, HZ);
-	tick_nsec = second_length >> TICK_LENGTH_SHIFT;
-
-	do_div(tick_length_base, NTP_INTERVAL_FREQ);
+	tick_nsec = div_u64(second_length, HZ) >> TICK_LENGTH_SHIFT;
+	tick_length_base = div_u64(tick_length_base, NTP_INTERVAL_FREQ);
 }
 
 /**

@@ -197,7 +195,7 @@ void __attribute__ ((weak)) notify_arch_
 int do_adjtimex(struct timex *txc)
 {
 	long mtemp, save_adjust, rem;
-	s64 freq_adj, temp64;
+	s64 freq_adj;
 	int result;
 
 	/* In order to modify anything, you gotta be super-user! */

@@ -300,17 +298,8 @@ int do_adjtimex(struct timex *txc)
 		    freq_adj = time_offset * mtemp;
 		    freq_adj = shift_right(freq_adj, time_constant * 2 +
 					   (SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
-		    if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
-			temp64 = time_offset << (SHIFT_NSEC - SHIFT_FLL);
-			if (time_offset < 0) {
-			    temp64 = -temp64;
-			    do_div(temp64, mtemp);
-			    freq_adj -= temp64;
-			} else {
-			    do_div(temp64, mtemp);
-			    freq_adj += temp64;
-			}
-		    }
+		    if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC))
+			freq_adj += div_s64(time_offset << (SHIFT_NSEC - SHIFT_FLL), mtemp);
 		    freq_adj += time_freq;
 		    freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
 		    time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);

Index: linux-2.6/lib/div64.c
===================================================================

lib/div64.c +20 -1
@@ -18,7 +18,7 @@
 
 #include <linux/types.h>
 #include <linux/module.h>
-#include <asm/div64.h>
+#include <linux/calc64.h>
 
 /* Not needed on 64bit architectures */
 #if BITS_PER_LONG == 32

@@ -78,4 +78,23 @@ uint64_t div64_64(uint64_t dividend, uin
 }
 EXPORT_SYMBOL(div64_64);
 
+#ifndef div_s64_rem
+s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
+{
+	u64 quotient;
+
+	if (dividend < 0) {
+		quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);
+		*remainder = -*remainder;
+		if (divisor > 0)
+			quotient = -quotient;
+	} else {
+		quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder);
+		if (divisor < 0)
+			quotient = -quotient;
+	}
+	return quotient;
+}
+#endif
+
 #endif /* BITS_PER_LONG == 32 */