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Calculate the equivalent of `SHIFT_HZ' at run time, in initclocks().

This commit is contained in:
mycroft 1996-03-15 07:56:00 +00:00
parent 0a659c65f3
commit 6b1f642521
1 changed files with 63 additions and 94 deletions
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157
sys/kern/kern_clock.c
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@ -1,4 +1,4 @@
/* $NetBSD: kern_clock.c,v 1.30 1996/03/08 06:27:30 mycroft Exp $ */
/* $NetBSD: kern_clock.c,v 1.31 1996/03/15 07:56:00 mycroft Exp $ */
/*-
* Copyright (c) 1982, 1986, 1991, 1993
@ -259,44 +259,6 @@ extern struct timeval clock_offset; /* Highball clock offset */
long clock_cpu = 0; /* CPU clock adjust */
#endif /* HIGHBALL */
#endif /* EXT_CLOCK */
/*
* NetBSD notes:
*
* SHIFT_HZ is strongly recommended to be a constant, not a variable,
* for performance reasons, so we define it appropriately here.
* Ataris uses 48, or 96 Hz (as well as 64). Sparcs and Sun-3s use
* 100Hz. Non-power-of-two values for HZ are rounded up when
* we define SHIFT_HZ, and then special-cased in the kernel
* timekeeping code in kern_clock.c.
* Alphas use 1024. Decstations use 256, which covers all the powers
* of 2 from 64 to 1024, inclusive.
* Precision timekeeping does not support 48 Hz, so Ataris at 48Hz are
* out of luck.
*/
#if HZ == 64 || HZ == 60
# define SHIFT_HZ 6 /* log2(64) */
#else
#if HZ == 128 || HZ == 100 || HZ == 96
# define SHIFT_HZ 7 /* log2(128), 100 and 96 are fudged. */
#else
#if HZ == 256
# define SHIFT_HZ 8 /* log2(256) */
#else
#if HZ == 1024
# define SHIFT_HZ 10 /* log2(1024) */
#else
#error HZ is not a supported value. Please change HZ in your kernel config file
#endif /* 1024Hz */
#endif /* 256Hz */
#endif /* 128HZ or 100Hz (or 96Hz, untested) */
#endif /* 64Hz or 60Hz */
/*
* End of SHIFT_HZ computation
*/
#endif /* NTP */
@ -322,7 +284,10 @@ static int psdiv, pscnt; /* prof => stat divider */
int psratio; /* ratio: prof / stat */
int tickfix, tickfixinterval; /* used if tick not really integral */
static int tickfixcnt; /* number of ticks since last fix */
#ifdef NTP
int fixtick; /* used by NTP for same */
int shifthz;
#endif
volatile struct timeval time;
volatile struct timeval mono_time;
@ -349,6 +314,28 @@ initclocks()
if (profhz == 0)
profhz = i;
psratio = profhz / i;
#ifdef NTP
switch (hz) {
case 60:
case 64:
shifthz = SHIFT_SCALE - 6;
break;
case 96:
case 100:
case 128:
shifthz = SHIFT_SCALE - 7;
break;
case 256:
shifthz = SHIFT_SCALE - 8;
break;
case 1024:
shifthz = SHIFT_SCALE - 10;
break;
default:
panic("weird hz");
}
#endif
}
/*
@ -445,12 +432,10 @@ hardclock(frame)
#endif
BUMPTIME(&mono_time, delta);
#ifdef NTP /* XXX Start of David L. Mills' ntp precision-time fragment */
#ifdef NTP
time_update = delta;
/*
* Beginning of precision-kernel code fragment
*
* Compute the phase adjustment. If the low-order bits
* (time_phase) of the update overflow, bump the high-order bits
* (time_update).
@ -460,8 +445,7 @@ hardclock(frame)
ltemp = -time_phase >> SHIFT_SCALE;
time_phase += ltemp << SHIFT_SCALE;
time_update -= ltemp;
}
else if (time_phase >= FINEUSEC) {
} else if (time_phase >= FINEUSEC) {
ltemp = time_phase >> SHIFT_SCALE;
time_phase -= ltemp << SHIFT_SCALE;
time_update += ltemp;
@ -523,35 +507,35 @@ hardclock(frame)
* replaced.
*/
switch (time_state) {
case TIME_OK:
case TIME_OK:
if (time_status & STA_INS)
time_state = TIME_INS;
else if (time_status & STA_DEL)
time_state = TIME_DEL;
break;
case TIME_INS:
case TIME_INS:
if (time.tv_sec % 86400 == 0) {
time.tv_sec--;
time_state = TIME_OOP;
}
break;
case TIME_DEL:
case TIME_DEL:
if ((time.tv_sec + 1) % 86400 == 0) {
time.tv_sec++;
time_state = TIME_WAIT;
}
break;
case TIME_OOP:
case TIME_OOP:
time_state = TIME_WAIT;
break;
case TIME_WAIT:
case TIME_WAIT:
if (!(time_status & (STA_INS | STA_DEL)))
time_state = TIME_OK;
break;
}
/*
@ -571,9 +555,8 @@ hardclock(frame)
ltemp = (MAXPHASE / MINSEC) <<
SHIFT_UPDATE;
time_offset += ltemp;
time_adj = -ltemp << (SHIFT_SCALE - SHIFT_HZ -
SHIFT_UPDATE);
} else {
time_adj = -ltemp << (shifthz - SHIFT_UPDATE);
} else if (time_offset > 0) {
ltemp = time_offset;
if (!(time_status & STA_FLL))
ltemp >>= SHIFT_KG + time_constant;
@ -581,9 +564,9 @@ hardclock(frame)
ltemp = (MAXPHASE / MINSEC) <<
SHIFT_UPDATE;
time_offset -= ltemp;
time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ -
SHIFT_UPDATE);
}
time_adj = ltemp << (shifthz - SHIFT_UPDATE);
} else
time_adj = 0;
/*
* Compute the frequency estimate and additional phase
@ -606,54 +589,43 @@ hardclock(frame)
#endif /* PPS_SYNC */
if (ltemp < 0)
time_adj -= -ltemp >>
(SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
time_adj -= -ltemp >> (SHIFT_USEC - shifthz);
else
time_adj += ltemp >>
(SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
time_adj += (long)fixtick << (SHIFT_SCALE - SHIFT_HZ);
time_adj += ltemp >> (SHIFT_USEC - shifthz);
time_adj += (long)fixtick << shifthz;
#if SHIFT_HZ == 7
/*
* When the CPU clock oscillator frequency is not a
* power of 2 in Hz, the SHIFT_HZ is only an approximate
* scale factor. In the SunOS kernel, this results in a
* PLL gain factor of 1/1.28 = 0.78 what it should be.
* In the following code the overall gain is increased
* by a factor of 1.25, which results in a residual
* error less than 3 percent.
* power of 2 in Hz, shifthz is only an approximate
* scale factor.
*/
if (hz == 100) {
switch (hz) {
case 96:
case 100:
/*
* In the following code the overall gain is increased
* by a factor of 1.25, which results in a residual
* error less than 3 percent.
*/
if (time_adj < 0)
time_adj -= -time_adj >> 2;
else
time_adj += time_adj >> 2;
}
else
if (hz == 96) {
if (time_adj < 0)
time_adj -= -time_adj >> 2;
else
time_adj += time_adj >> 2;
}
#endif /* SHIFT_HZ */
#if SHIFT_HZ == 6
/*
* 60 Hz m68k and vaxes have a PLL gain factor of of
* 60/64 (15/16) of what it should be. In the following code
* the overall gain is increased by a factor of 1.0625,
* (17/16) which results in a residual error of just less
* than 0.4 percent.
*/
if (hz == 60) {
break;
case 60:
/*
* 60 Hz m68k and vaxes have a PLL gain factor of of
* 60/64 (15/16) of what it should be. In the following code
* the overall gain is increased by a factor of 1.0625,
* (17/16) which results in a residual error of just less
* than 0.4 percent.
*/
if (time_adj < 0)
time_adj -= -time_adj >> 4;
else
time_adj += time_adj >> 4;
break;
}
#endif /* SHIFT_HZ */
#ifdef EXT_CLOCK
/*
@ -697,10 +669,7 @@ hardclock(frame)
#endif /* EXT_CLOCK */
}
/*
* End of precision-kernel code fragment
*/
#endif /*NTP*/ /* XXX End of David L. Mills' ntp precision-time fragment */
#endif /* NTP */
/*
* Process callouts at a very low cpu priority, so we don't keep the