Improved delay() implementation with lower overhead,
makes very short delays much more accurate.
This commit is contained in:
gwr
parent
bcfac202c8
commit
5404ccfbd7
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@ -1,4 +1,4 @@
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/* $NetBSD: param.h,v 1.31 1996/02/01 22:33:08 mycroft Exp $ */
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/* $NetBSD: param.h,v 1.32 1996/02/16 18:08:21 gwr Exp $ */
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/*
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* Copyright (c) 1994, 1995 Gordon W. Ross
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@ -149,17 +149,10 @@
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/* XXX - Does this really belong here? -gwr */
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#include <machine/psl.h>
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#ifdef _KERNEL
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#ifndef _LOCORE
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#if defined(_KERNEL) && !defined(_LOCORE)
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extern void _delay __P((unsigned));
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#define delay(us) _delay((us)<<8)
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#define DELAY(n) delay(n)
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extern int cpuspeed;
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static inline void delay2us()
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{
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register int n = cpuspeed;
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__asm __volatile ("0: subql #4,%0; jgt 0b" : "=d" (n) : "0" (n));
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}
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#endif /* !_LOCORE */
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#endif /* _KERNEL */
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#endif /* _KERNEL && !_LOCORE */
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#endif /* MACHINE */
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@ -1,4 +1,4 @@
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/* $NetBSD: param3.h,v 1.31 1996/02/01 22:33:08 mycroft Exp $ */
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/* $NetBSD: param3.h,v 1.32 1996/02/16 18:08:21 gwr Exp $ */
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/*
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* Copyright (c) 1994, 1995 Gordon W. Ross
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@ -149,17 +149,10 @@
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/* XXX - Does this really belong here? -gwr */
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#include <machine/psl.h>
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#ifdef _KERNEL
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#ifndef _LOCORE
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#if defined(_KERNEL) && !defined(_LOCORE)
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extern void _delay __P((unsigned));
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#define delay(us) _delay((us)<<8)
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#define DELAY(n) delay(n)
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extern int cpuspeed;
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static inline void delay2us()
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{
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register int n = cpuspeed;
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__asm __volatile ("0: subql #4,%0; jgt 0b" : "=d" (n) : "0" (n));
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}
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#endif /* !_LOCORE */
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#endif /* _KERNEL */
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#endif /* _KERNEL && !_LOCORE */
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#endif /* MACHINE */
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@ -1,4 +1,4 @@
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/* $NetBSD: locore.s,v 1.35 1996/02/02 02:37:42 mycroft Exp $ */
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/* $NetBSD: locore.s,v 1.36 1996/02/16 18:06:11 gwr Exp $ */
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/*
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* Copyright (c) 1994, 1995 Gordon W. Ross
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@ -1182,26 +1182,23 @@ Lm68881rdone:
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frestore a0@ | restore state
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rts
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| delay(int usecs)
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| Delay for "usec" microseconds. Minimum delay is about 5 uS.
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| This routine depends on the variable "cpuspeed"
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| which should be set based on the CPU clock rate.
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| XXX - Currently this is set in sun3_startup.c based on the
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| CPU model but this should be determined at run time...
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.globl _delay
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_delay:
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| d0 = (cpuspeed * usecs)
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movel _cpuspeed,d0
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mulsl sp@(4),d0
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| subtract some overhead
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moveq #80,d1
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/*
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* _delay(unsigned N)
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* Delay for at least (N/256) microseconds.
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* This routine depends on the variable: delay_divisor
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* which should be set based on the CPU clock rate.
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* XXX: Currently this is set in sun3_startup.c based on the
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* XXX: CPU model but this should be determined at run time...
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*/
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.globl __delay
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__delay:
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| d0 = arg = (usecs << 8)
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movl sp@(4),d0
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| d1 = delay_divisor;
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movl _delay_divisor,d1
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L_delay:
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subl d1,d0
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| This loop takes 8 clocks per cycle.
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Ldelay:
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subql #8,d0
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jgt Ldelay
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jgt L_delay
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rts
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@ -1,4 +1,4 @@
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/* $NetBSD: locore2.c,v 1.48 1995/10/17 23:16:40 gwr Exp $ */
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/* $NetBSD: locore2.c,v 1.49 1996/02/16 18:06:19 gwr Exp $ */
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/*
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* Copyright (c) 1994 Gordon W. Ross
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@ -591,8 +591,13 @@ void sun3_vm_init(kehp)
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}
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/* XXX - Should just estimate this instead... */
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int cpuspeed = 25; /* initial guess */
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/*
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* XXX - Should empirically estimate the divisor...
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* Note that the value of delay_divisor is roughly
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* 2048 / cpuclock (where cpuclock is in MHz).
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*/
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int delay_divisor = 82; /* assume the fastest (3/260) */
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void sun3_verify_hardware()
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{
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unsigned char machtype;
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@ -613,33 +618,33 @@ void sun3_verify_hardware()
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hole_start = OBMEM_BW50_ADDR;
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hole_size = OBMEM_BW2_SIZE;
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cpu_string = "50";
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cpuspeed = 16; /* MHz */
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delay_divisor = 128; /* 16 MHz */
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break;
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case SUN3_MACH_60 :
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cpu_match++;
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cpu_string = "60";
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cpuspeed = 20; /* MHz */
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delay_divisor = 102; /* 20 MHz */
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break;
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case SUN3_MACH_110:
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cpu_match++;
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cpu_string = "110";
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cpuspeed = 17; /* MHz */
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delay_divisor = 120; /* 17 MHz */
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cpu_has_vme = TRUE;
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break;
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case SUN3_MACH_160:
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cpu_match++;
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cpu_string = "160";
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cpuspeed = 17; /* MHz */
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delay_divisor = 120; /* 17 MHz */
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cpu_has_vme = TRUE;
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break;
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case SUN3_MACH_260:
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cpu_match++;
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cpu_string = "260";
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cpuspeed = 25; /* MHz */
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delay_divisor = 82; /* 25 MHz */
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cpu_has_vme = TRUE;
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#ifdef HAVECACHE
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cache_size = 0x10000; /* 64K */
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@ -649,7 +654,7 @@ void sun3_verify_hardware()
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case SUN3_MACH_E :
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cpu_match++;
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cpu_string = "E";
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cpuspeed = 20; /* MHz */ /* XXX - Correct? */
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delay_divisor = 102; /* 20 MHz XXX: Correct? */
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cpu_has_vme = TRUE;
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break;
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@ -1,4 +1,4 @@
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/* $NetBSD: sun3_startup.c,v 1.48 1995/10/17 23:16:40 gwr Exp $ */
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/* $NetBSD: sun3_startup.c,v 1.49 1996/02/16 18:06:19 gwr Exp $ */
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/*
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* Copyright (c) 1994 Gordon W. Ross
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@ -591,8 +591,13 @@ void sun3_vm_init(kehp)
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}
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/* XXX - Should just estimate this instead... */
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int cpuspeed = 25; /* initial guess */
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/*
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* XXX - Should empirically estimate the divisor...
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* Note that the value of delay_divisor is roughly
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* 2048 / cpuclock (where cpuclock is in MHz).
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*/
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int delay_divisor = 82; /* assume the fastest (3/260) */
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void sun3_verify_hardware()
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{
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unsigned char machtype;
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@ -613,33 +618,33 @@ void sun3_verify_hardware()
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hole_start = OBMEM_BW50_ADDR;
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hole_size = OBMEM_BW2_SIZE;
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cpu_string = "50";
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cpuspeed = 16; /* MHz */
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delay_divisor = 128; /* 16 MHz */
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break;
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case SUN3_MACH_60 :
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cpu_match++;
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cpu_string = "60";
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cpuspeed = 20; /* MHz */
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delay_divisor = 102; /* 20 MHz */
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break;
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case SUN3_MACH_110:
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cpu_match++;
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cpu_string = "110";
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cpuspeed = 17; /* MHz */
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delay_divisor = 120; /* 17 MHz */
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cpu_has_vme = TRUE;
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break;
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case SUN3_MACH_160:
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cpu_match++;
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cpu_string = "160";
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cpuspeed = 17; /* MHz */
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delay_divisor = 120; /* 17 MHz */
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cpu_has_vme = TRUE;
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break;
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case SUN3_MACH_260:
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cpu_match++;
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cpu_string = "260";
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cpuspeed = 25; /* MHz */
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delay_divisor = 82; /* 25 MHz */
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cpu_has_vme = TRUE;
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#ifdef HAVECACHE
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cache_size = 0x10000; /* 64K */
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@ -649,7 +654,7 @@ void sun3_verify_hardware()
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case SUN3_MACH_E :
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cpu_match++;
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cpu_string = "E";
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cpuspeed = 20; /* MHz */ /* XXX - Correct? */
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delay_divisor = 102; /* 20 MHz XXX: Correct? */
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cpu_has_vme = TRUE;
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break;
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