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\ *****************************************************************************
\ * Copyright (c) 2004, 2008 IBM Corporation
\ * All rights reserved.
\ * This program and the accompanying materials
\ * are made available under the terms of the BSD License
\ * which accompanies this distribution, and is available at
\ * http://www.opensource.org/licenses/bsd-license.php
\ *
\ * Contributors:
\ * IBM Corporation - initial implementation
\ ****************************************************************************/
\ Use the HPET to calculate various frequencies.
\ Make HPET run.
1 10 hpet!
\ Set PMC1 to count CPU cycles.
f00 mmcr0!
d# 1000000000000000 4 hpet@ / CONSTANT hpet-freq
: get-times tbl@ pmc1@ f0 hpet@ ;
\ Calculate the CPU and TB frequencies.
: calibrate get-times dup >r swap >r swap >r hpet-freq d# 100 / + >r
BEGIN get-times dup r@ < WHILE 3drop REPEAT r> drop
rot r> - ffffffff and \ TB
rot r> - ffffffff and \ CPU
rot r> - >r \ HPET
hpet-freq * r@ / swap
hpet-freq * r> / ;
: round-to tuck 2/ + over / * ;
calibrate TO tb-frequency d# 100000000 round-to TO cpu-frequency
\ Stop HPET.
0 10 hpet!
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