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