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Names: »filtertx «
└─⟦01e83a425⟧ Bits:30008166 Bånd med SW8010 og SW8500 source code
└─⟦75ff9bef3⟧
└─⟦this⟧ »filtertx «
; dh 87.05.06 filter algorithm for search page ...00...
b. a11, b3, c1, d5 w.
;This algorithm enables search to filter the output of catalog entries
;found according to a given scope specification. The filter works on
;the entry name and the document name of an entry.
;
;Syntax (augments):
;------------------
;( )1 ( )*
;(<out file> = ) search <scope spec> (<filter>)
;( )0 ( )0
;
; ( )*
;<filter> ::= <substring>(.<substring>)
; ( )0
;
; ( <generalized name> )
;<substring> ::= ( <name> )
; (<apostrophized name>)
;
;Function:
;---------
; The main catalog is scanned, and a subset of it is listed with an
;output format as for lookup. If an outfile is specified, the list of
;catalog entries is printed on that file, otherwise current output is
;used. Messages from search are always printed on current output.
; If no filters are given, all entries from the main catalog accor-
;ding to the scope spec (see Scope specification) are listed, other-
;wise, the set of catalog entries is further delimited by means of
;filters (see Filter specification below).
;
;Filter specification:
;---------------------
; A filter consists of one or more substrings concatenated by period.
;If a list of filters exists, an entry selected for listing will only
;be listed if either its name or its document name contain all the sub-
;strings of at least one of the filters. The order of the substrings
;in a filter is irrellevant.
; Thus, in a possible list of filters, you may consider space as "or"
;and period as "and", where the precedence of "and" and "or" is as in
;Algol.
\f
; dh 87.05.07 filter algorithm for search page ...01...
;requirements:
; w0 w1 w2 w3 r0 r1
;
;entry: irr. irr. irr. return item after catalog
; scope spec entry
;
;exit: all registers and variables unchanged.
;
; the procedure returns to return+0 in case of failure
; and to return+2 in case of success.
;
ds. w3 b3. ; save registers
rl. w3 r0. ;
el w2 x3 ; if item after scope spec = end command
sh w2 2 ; then goto letitpass1;
jl. a11. ;
ds. w1 b2. ;
rl. w2 r1. ; name in entry := entry name;
al w2 x2+6 ;
c1: al w3 x3+2 ; repeat <* entry- and document-name *>
ds. w3 d1. ; text part(item) := first item addr + 2;
al w3 10 ; x := 10;
; string := name in entry;
a0: rs. w3 d2. ;
al w1 x3 ; repeat
jl. w3 c0. ; namelength := x;
rl. w3 d2. ; l := takechar(x, string);
al w3 x3-1 ; x := namelength - 1;
sn w1 0 ; until l <> 0;
jl. a0. ;
a1: ; repeat <* all possibillities of filter *>
\f
; dh 87.05.05 filter algorithm for search page ...02...
;a1: ; repeat <* items in a filter *>
rl. w0 d2. ; j := namelength; <* charcount in an entry *>
a2: rs. w0 d3. ; repeat <* stepping backward through the
; name in the entry *>
al w3 0 ;
jl. a4. ; for i := 0,
a3: rl. w3 d4. ; <*i controls pos in an item *>
al w3 x3+1 ; i+1 while l = k do
se. w1 (d5.) ; begin
jl. a5. ;
a4: rs. w3 d4. ;
am. (d3.) ; k := takechar
al w1 x3 ; (j+i, name in entry);
rl. w2 d0. ;
jl. w3 c0. ;
rs. w1 d5. ;
rl. w1 d4. ; l := takechar
rl. w2 d1. ; (i, item);
jl. w3 c0. ;
sn w1 0 ; if l = 0
jl. a6. ; then goto found;
jl. a3. ; end while loop;
a5: rl. w0 d3. ;
es. w0 1 ; j := j - 1;
sl w0 0 ; until j < 0 <* end backward stepping *>;
jl. a2. ; comment when the loop is exhausted, l<>0;
a6: ;found:
al w2 x2+10 ; nopass := l <> 0; <* variable kept in w1 *>
rs. w2 d1. ; item := next item;
el w0 x2-2 ; sep := item separator;
se w0 8 ; until sep <> '.'
jl. a7. ; or nopass <* end items in a filter *>;
sn w1 0 ; comment hereafter either all substrings in a
jl. a1. ; filter have suceeded, or a filter failed;
\f
; dh 87.05.07 filter algorithm for search page ...03...
a7: sn w1 0 ; if -,nopass <* i.e. a filter suceeded *>
jl. a10. ; then goto letitpass;
a8: se w0 8 ; comment a filter failed, therfore: ;
jl. a9. ; while sep = '.' do
al w2 x2+10 ; begin
el w0 x2-2 ; item := next item; sep := item separator;
jl. a8. ; end;
a9: rs. w2 d1. ; comment we may now examine the next filter;
sl w0 4 ; until sep = end command;
jl. a1. ; comment all filters have failed on this name;
rl. w2 r1. ; name in entry := document name;
al w2 x2+16 ; item := item after scope spec;
rl. w3 r0. ;
se. w2 (d0.) ; until document name tested once before;
jl. c1. ; comment the names have been tested with all filters;
dl. w1 b2. ;failure:
dl. w3 b3. ; restore registers;
jl x3 ; return failure;
a10: dl. w1 b2. ;letitpass:
a11: dl. w3 b3. ;letitpass1: restore registers;
jl x3+2 ; return success;
\f
; dh 87.05.05 filter algorithm for search page ...04...
c0: ;subprocedure takechar(pos, string);
; call: w0: -; w1: pos; w2: string; w3: return
al w0 0 ; exit: w0: -; w1: char; w2: unch; w3: unch
wd. w1 b0. ; addr := pos // 3;
am x1 ; subpos := pos mod 3;
am x1 ;
rl w1 x2 ; substring := word(2*addr + string);
ls w0 3 ;
am (0) ; char := substring shift(subpos*8 -16)
ls w1 -16 ; extract 7;
la. w1 b1. ;
jl x3 ; return;
b0: 3 ; constant 3 <* chars per word *>
b1: 8.177 ; constant: last 7 bits;
0, b2: 0, 0, b3: 0 ; room for registers;
d0: 0 ; addr of name in an entry;
d1: 0 ; addr of text part of an item;
d2: 0 ; namelength, i.e. length of name part in an entry
d3: 0 ; var: j <* stepping through name in an entry *>
d4: 0 ; var: i <* stepping through an item *>
d5: 0 ; var: k <* char from an entry *>
e. ; end block
▶EOF◀