From 9d36d1cf7b00cb8f4527c0a4a9a8d8d266ff44e4 Mon Sep 17 00:00:00 2001
From: Frank Mori Hess <fmhess@speakeasy.net>
Date: Sat, 9 Mar 2002 04:02:53 +0000
Subject: [PATCH] converted 64 bit integer division to use do_div

---
 comedi/drivers/comedi_rt_timer.c | 22 ++--------------
 comedi/drivers/comedi_test.c     | 45 +++++---------------------------
 2 files changed, 9 insertions(+), 58 deletions(-)

diff --git a/comedi/drivers/comedi_rt_timer.c b/comedi/drivers/comedi_rt_timer.c
index f07b8d4d..15d49f39 100644
--- a/comedi/drivers/comedi_rt_timer.c
+++ b/comedi/drivers/comedi_rt_timer.c
@@ -66,6 +66,7 @@ TODO:
 #include <rtl.h>
 #include <rtl_sched.h>
 #include <rtl_compat.h>
+#include <asm/div64.h>
 
 #ifndef RTLINUX_VERSION_CODE
 #define RTLINUX_VERSION_CODE 0
@@ -79,26 +80,7 @@ TODO:
 // this function sole purpose is to divide a long long by 838
 static inline RTIME nano2count(long long ns)
 {
-	unsigned long denom = 838;	// divisor
-	long ms32 = ns >> 32;	// most significant 32 bits
-	unsigned long ms32rem = ms32 % denom;	// remainder of ms32 / denom
-	unsigned long ls32 = ns & 0xffffffff;	// least significant 32 bits
-	unsigned long ls32rem = ls32 % denom;
-	unsigned long big = 0xffffffff;
-	unsigned long big_rem = big % denom;
-	unsigned long rem_rem;
-
-	// divide most significant bits
-	ns = ms32 / denom;
-	ns = ns << 32;
-	// add corrections due to rounding errors
-	ns += ms32rem * (big / denom) + (ms32rem * (big_rem + 1)) / denom;
-	// divide least significant bits
-	ns += ls32 / denom;
-	// add really small correction
-	rem_rem = (ms32rem * (big_rem + 1)) % denom;
-	ns += (ls32rem + rem_rem) / denom;
-
+	do_div(ns, 838);
 	return ns;
 }
 #ifdef rt_get_time()
diff --git a/comedi/drivers/comedi_test.c b/comedi/drivers/comedi_test.c
index f0d2715d..2ddc7c88 100644
--- a/comedi/drivers/comedi_test.c
+++ b/comedi/drivers/comedi_test.c
@@ -56,6 +56,7 @@ zero volts).
 #include <linux/time.h>
 #include <linux/init.h>
 #include <linux/comedidev.h>
+#include <asm/div64.h>
 
 /* Board descriptions */
 typedef struct waveform_board_struct{
@@ -395,54 +396,22 @@ static int waveform_ai_cancel(comedi_device *dev, comedi_subdevice *s)
 	return 0;
 }
 
-// divides an unsigned long long
-static unsigned long long my_ull_div(unsigned long long numerator, unsigned long denominator)
-{
-	u32 value;
-	unsigned long long remainder;
-	unsigned int shift = 0;
-	const unsigned long max_u32 = 0xffffffff;
-
-	if(numerator <= max_u32)
-	{
-		// numerator is small enough that we can return correct result
-		value = numerator;
-		return value / denominator;
-	}
-
-	remainder = numerator;
-
-	// otherwise shift most significant bits into 32 bit variable
-	while(numerator > max_u32)
-	{
-		numerator >>= 1;
-		shift++;
-	}
-	value = numerator;
-	value /= denominator;
-	value <<= shift;
-
-	remainder -= ((unsigned long long) value) * denominator;
-
-	return value + my_ull_div(remainder, denominator);
-}
-
 static sampl_t fake_sawtooth(comedi_device *dev, unsigned int range_index, unsigned long current_time)
 {
 	comedi_subdevice *s = dev->read_subdev;
 	unsigned int offset = s->maxdata / 2;
-	unsigned long long value;
+	u64 value;
 	comedi_krange *krange = &s->range_table->range[range_index];
-	unsigned long long binary_amplitude;
+	u64 binary_amplitude;
 
 	binary_amplitude = s->maxdata;
 	binary_amplitude *= devpriv->uvolt_amplitude;
-	binary_amplitude = my_ull_div(binary_amplitude, krange->max - krange->min);
+	do_div(binary_amplitude, krange->max - krange->min);
 
 	current_time %= devpriv->usec_period;
 	value = current_time;
 	value *= binary_amplitude * 2;
-	value = my_ull_div(value, devpriv->usec_period);
+	do_div(value, devpriv->usec_period);
 	value -= binary_amplitude;	// get rid of sawtooth's dc offset
 
 	return offset + value;
@@ -451,13 +420,13 @@ static sampl_t fake_squarewave(comedi_device *dev, unsigned int range_index, uns
 {
 	comedi_subdevice *s = dev->read_subdev;
 	unsigned int offset = s->maxdata / 2;
-	unsigned long long value;
+	u64 value;
 	comedi_krange *krange = &s->range_table->range[range_index];
 	current_time %= devpriv->usec_period;
 
 	value = s->maxdata;
 	value *= devpriv->uvolt_amplitude;
-	value = my_ull_div(value, krange->max - krange->min);
+	do_div(value, krange->max - krange->min);
 
 	if(current_time < devpriv->usec_period / 2)
 		value *= -1;
-- 
2.26.2