43 lines
1.4 KiB
Scheme
43 lines
1.4 KiB
Scheme
(library
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(mapping-tree)
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(export mapping-tree-open
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mapping-tree-lookup
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mapping-tree-each)
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(import (btree)
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(chezscheme)
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(srfi s8 receive))
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(define-record-type mapping-tree (fields dev-tree))
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(define (mapping-tree-open dev root)
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(make-mapping-tree (btree-open le64-type dev root)))
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;; (values <block> <time>)
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(define time-mask (- (fxsll 1 24) 1))
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(define (unpack-block-time bt)
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(values (fxsrl bt 24) (fxlogand bt time-mask)))
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;; FIXME: unpack the block time
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(define (mapping-tree-lookup mtree dev-id vblock default)
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(let* ((unique (gensym))
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(dev-tree (mapping-tree-dev-tree mtree))
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(root2 (btree-lookup dev-tree dev-id unique)))
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(if (eq? unique root2)
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default
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(btree-lookup (btree-open le64-type (btree-dev dev-tree) root2) vblock default))))
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;;; Visits every entry in the mapping tree calling (fn dev-id vblock pblock time).
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(define (mapping-tree-each mtree fn)
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(let ((dev-tree (mapping-tree-dev-tree mtree)))
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(define (visit-dev dev-id mapping-root)
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(btree-each (btree-open le64-type (btree-dev dev-tree) mapping-root)
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(lambda (vblock mapping)
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(receive (block time) (unpack-block-time mapping)
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(fn dev-id vblock block time)))))
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(btree-each dev-tree visit-dev))))
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