Joined: Fri May 05, 2017 9:27 pm
Posts: 855
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IamRob wrote: In an earlier thread I created a HELP search engine that returned information about a word delimited by a colon.
I tried applying the same search engine to finding any word within a number of screens. But it is a lot slower than I would like it to be. The problem is that using the space as a delimiter, then every word has to be checked for a match.
In the HELP engine, a match is only checked when it comes across a colon. A lot fewer matches are made and the search is quite a bit faster.
Even though a linear search is done, and a match is checked on every word, I still expected it to be faster that it is. The order of the search is this:
1) LOAD SCREEN
2) ENCLOSE each word delimited by a SPACE
3) use MATCH to check each word against the SEARCH word
4) print screen# and line# of each matched word found
5) if not end of screen, increment pointer and return to step #2
6) if not last screen, increment screen and return to step #1
7) end
I limited the search to 16 screens ( 0 SEARCH searches 00..$0F, $10 SEARCH searches $10..$1F and so on ) which is same as searching 16k in memory. At 1 Mhz, it takes 1 min 10 secs to search all 16 screens for each occurrence of the word.
I know I could make the search into a primitive, but I was just wondering if there might be a different way to search random words to make the search programmed entirely in Forth go faster. Reducing the number of times MATCH is used (like in HELP) helped speed things up. But doing a search on every word delimited by spaces is a lot slower. In HELP, a search for a colon is done before using ENCLOSE then entering MATCH.
Any ideas?
With the Forths that I am familiar with, LOADing a screen will cause that screen to be interpreted and or compiled. Do you mean read that screen into a buffer?
Fleet Forth's editor is based on the Forth Inc. line editor presented in Forth Dimensions volume 3 issue 3. It has a word S which takes a block number and parses text up to a delimiting ^ and searches all blocks from the current one to one less than the block number that was on the stack. I ran some tests by copying a range of sixteen blocks to blocks used by the C64 Ram Expansion Module to eliminate disk access time as a variable. Depending on the text in the screens and what was searched for, I got results ranging from 11.6 to 20.2 seconds. Some of that time is the time to TYPE the information and the time it takes the Commodore 64 to scroll.
Code: OK
CLEAR.TIME $10 FH S LDA ^ ELAPSED
IP )Y LDA ^ PHA IP INC 2 8001
IP )Y LDA ^ 4 8001
IP )Y LDA ^ W 1+ STA DEY E 8001
IP )Y LDA ^ W STA CLC F 8001
IP LDA ^ 2 # ADC IP STA 1 8002
IP )Y LDA ^ PHA TYA 3 8003
0 ,X LDA ^ N ,Y STA 9 8003
0FE ,X LDA ^ 0FF ,X ORA 4 8005
IP LDA ^ 2 # ADC IP STA 8 8005
IP )Y LDA ^ PHA INY 2 8006
IP )Y LDA ^ IP 1+ STA 3 8006
IP )Y LDA ^ PHA DEY 4 8007
IP )Y LDA ^ PHA CLC 5 8007
3 ,X LDA ^ 80 # ADC PHA 6 8007
3 ,X STA 2 ,X LDA ^ PHA SEC 7 8007
0 ,X LDA ^ 2 ,X SBC TAY 8 8007
1 ,X LDA ^ 3 ,X SBC PHA 9 8007
0 ,X LDA ^ 2 ,X CMP 3 8008
1 ,X LDA ^ 3 ,X CMP 5 8008
0FE ,X LDA ^ 0FF ,X ORA 8 800A
0FE ,X LDA ^ 0FF ,X ORA 7 800B
0FE ,X LDA ^ 0FF ,X ORA C 800B
0FF ,X LDA ^ PHA 0FE ,X LDA 4 800C
0FF ,X LDA PHA 0FE ,X LDA ^ 4 800C
2 ,X LDA ^ 2 # SBC N 2+ STA 5 800D
3 ,X LDA ^ 0 # SBC N 3 + STA 6 800D
0 ,X LDY 1 ,X LDA ^ 7 800D
N )Y LDA ^ TAX INY E 800D
N )Y LDA ^ F 800D
N )Y LDA ^ 4 800E
N 2+ )Y LDA ^ A 800E
0 # LDA ^ 3 800F
N )Y LDA ^ IBIT # AND 6 800F
1 # LDA ^ 9 800F
0FF # LDA ^ TAY 4 8010
N 4 + )Y LDA ^ 8 8010
N 4 + )Y LDA ^ C 8010
0:00:20.2 OK
CLEAR.TIME $10 FH S PHA ^ ELAPSED
IP )Y LDA PHA ^ IP INC 2 8001
IP )Y LDA PHA ^ TYA 3 8003
IP )Y LDA PHA ^ INY 2 8006
IP )Y LDA PHA ^ DEY 4 8007
IP )Y LDA PHA ^ CLC 5 8007
3 ,X LDA 80 # ADC PHA ^ 6 8007
3 ,X STA 2 ,X LDA PHA ^ SEC 7 8007
1 ,X LDA 3 ,X SBC PHA ^ 9 8007
TYA PHA ^ A 8007
0FF ,X LDA PHA ^ 0FE ,X LDA 4 800C
0:00:13.4 OK
CLEAR.TIME $10 FH S ADC ^ ELAPSED
IP LDA 2 # ADC ^ IP STA 1 8002
IP LDA 2 # ADC ^ IP STA 8 8005
3 ,X LDA 80 # ADC ^ PHA 6 8007
102 ,X ADC ^ 102 ,X STA 7 8009
101 ,X ADC ^ 101 ,X STA 6 800C
TYA N ADC ^ 0 ,X STA 2 800F
N 1+ ADC ^ 1 ,X STA 4 800F
0:00:12.7 OK
78 1 RAM $10 BMOVE
87 8010
86 800F
85 800E
84 800D
83 800C
82 800B
81 800A
80 8009
7F 8008
7E 8007
7D 8006
7C 8005
7B 8004
7A 8003
79 8002
78 8001 OK
CLEAR.TIME $10 FH S DUP ^ ELAPSED
R> DUP ^2+ >R @ >BODY ! ; 3 8002
R> DUP ^COUNT + >R ; 9 8002
AP0 @ DUP ^! ; F 8002
DUP ^>IN @ UMIN 9 8005
DUP ^NEGATE UNDER+ UNDER+ ; A 8005
DUP ^0 B 8006
DUP ^0<> + NEGATE ROT + 5 800A
DUP ^SCR ! CR ." SCR# " U. 8 800C
0:00:12.9 OK
CLEAR.TIME $10 FH S DROP ^ ELAPSED
DROP ^PAUSE ; 6 8001
DROP ^PAUSE ; C 8001
'STREAM DROP ^ >IN @ C/L /MOD 9 800C
0:00:11.6 OK
CONSOLE
The word FH ( from here ) when editing, will add the number in SCR to the value on the stack. When loading a block, it will add the value in BLK to the number on the stack.
The heart of the editor's search function is the word MATCH . It takes the address and count of a string to search ( in this case, the address of the block buffer and $400) and the address and count of the string to find ( in this case, the contents of the editors find buffer, FBUF , a 65 byte buffer). MATCH returns the offset to the character just past the search string in the string to search and a flag.
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