for string matching
Carlos Nieves shares this code:
Here are some routines to match strings received from serial communications or other routines.
Known strings are stored in program memory, thus saving RAM locations. These routines let you to check a string while you are receiving it, and return an identifier for the received string, if it's known.
The main limitation is that there should be enough time between receiving two characters, so the routine could finish. This shouldn't be a problem in micros with USART, but must be taken into account in micros without it.
This routines require some flags handling routines, which you could find here.
The code begin here:
; Copyright (C) 2001 Carlos Nieves Onega
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2 of the License, or
; (at your option) any later version.
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
; You should have received a copy of the GNU General Public License
; along with this program; if not, write to the Free Software
; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
;**********************************************************************
;
; File: str.asm
; Version: 20011030
;
; Author: Carlos Nieves Onega
;
;
;
;**********************************************************************
;
; Required files:
; Flags handle routines (flags.asm, 20011026)
;
;**********************************************************************
;
; Notes: This file contains routines to handle strings.
; Strings must be in a single block in program memory.
;
;**********************************************************************
; Changes:
; 20011030 (cnieves): modified get_id_str_serie so it doesn't care about
; CR y LF characters.
; 20011029 (cnieves): began writing.
; Functions tested:
; getchar_strrom and get_id_str_serie.
; Simulated. They work fine.
;**********************************************************************
;**********************************************************************
; Strings to be compared must be stored in a single block in memory.
; For each string, it must be stored, sorted as shown, the following:
; * String length (1 byte): number 'n' of characters of the string.
; * String Id. (1 byte): there mustn't be two strings with the same id.
; Id must be greater than 0. The ids. begin with number 1 and
; must be correlative.
; * Characters of the string: ( 'n' bytes).
;**********************************************************************
CADS_ADDR
TABLE_JUMP
ID_CAD set 1
; Length Identifier String
CAD1 equ ID_CAD
DT d'4', ID_CAD, "CAD1"
ID_CAD set ID_CAD + 1
CAD2 equ ID_CAD
DT d'12', ID_CAD, "This is cad2"
; The last string mustn't increase ID_CAD
; Define CADS_NUM, which will be necessary to reserve space for flags.
#define CADS_NUM ID_CAD
;**********************************************************************
; Function getchar_strrom
; Description: given the id. of the string, returns the character
; at the position given in WREG (begun with 0).
; Parameters:
; WREG: position of the character within the string (the first one is 0).
; ID_CAD_GC: string id.. Always must be greater than 0.
; Returns:
; WREG: character at the given position. If the id. was not found
; or if the length is less than the given position, returns 0xFF
; Z = 1 : operation not valid (string or position invalid).
; Z = 0 : operation completed succesfully.
; Use:
; var. temp. num_cad, id_cad, pos_char.
; regs. W, INDF, FSR
;**********************************************************************
cblock
CAD_NUM_GC: 1
ID_CAD_GC: 1
POS_CHAR_GC: 1
TABLE_POS_GC: 1
endc
getchar_strrom
movwf POS_CHAR_GC
clrf TABLE_POS_GC
movlw CADS_NUM
addlw 1 ; Adds 1 because of the loop particularities
movwf CAD_NUM_GC ; num_cad = number of strings stored
BUC_GC
decfsz CAD_NUM_GC,F
goto LABEL1_GC
goto NO_ENC_GC ; If all strings were looked, it was not found.
LABEL1_GC
movlw d'1'
addwf TABLE_POS_GC,W ; W points to the string id.
call CADS_ADDR
; W = string id.
xorwf ID_CAD_GC,W ; compare the string id. with the parameter
bz ENC_GC ; If it's 0, the string was found
movf TABLE_POS_GC,W ; W = pointer to the length
call CADS_ADDR
; W = length of the string
addwf TABLE_POS_GC,F ; TABLE_POS_GC += string length
movlw d'2'
addwf TABLE_POS_GC,F ; TABLE_POS_GC += 3 (length, identifier)
; with this, TABLE_POS_GC points to the "struct" of the next string
goto BUC_GC
ENC_GC
movf TABLE_POS_GC,W
call CADS_ADDR
; W = length
subwf POS_CHAR_GC,W ; W = position (began with 0) - length (began with 1)
bc NO_ENC_GC
movlw d'2'
addwf TABLE_POS_GC,F ; FSR points to the beginning of the string
movf POS_CHAR_GC,W
addwf TABLE_POS_GC,W ; FSR points to the wanted character
call CADS_ADDR
; W = character
bcf STATUS,Z
return
NO_ENC_GC
movlw 0xff
bsf STATUS,Z
return
;**********************************************************************
; Function get_id_str_serie
; Description: Returns in WREG the id. of the string received
; from the serial port (or 0 if it doesn't match).
; Parameters: none
; Return:
; WREG: identifier of the received string. (0 if it's none of the stored).
; Use:
; Flags handle routines: set_all_flags, count_flags, look_flag
;**********************************************************************
cblock
NUM_CHAR_GISS: 1
NUM_CAD_GISS: 1
CHAR_SERIE: 1
TEMP_GISS: 1
endc
REC_SALE_GISS decfsz TEMP_GISS,1
goto REC_BUC_GISS
retlw 0
get_id_str_serie
call set_all_flags ; By now, all strings are valid. FIXME: only set those related with strings
clrf NUM_CHAR_GISS ; Initialice the character to look to 0.
BUC_OTRO_CHAR_GISS
movlw 0x80 ;Times to wait for a serial character
movwf TEMP_GISS
REC_BUC_GISS
call RX_SERIE ; getchar(serie) You should change this to your needs.
iorlw 0
bz REC_SALE_GISS
movf DATA_IN,w
movwf CHAR_SERIE
movlw CR
xorwf CHAR_SERIE,W
bz BUC_OTRO_CHAR_GISS ; If it's CR, ignore it
movlw LF
xorwf CHAR_SERIE,W
bz BUC_OTRO_CHAR_GISS ; If it's LF, ignore it
movlw d'1'
movwf NUM_CAD_GISS ; String Id. to analyze
BUC_CAD_GISS
movlw d'1'
subwf NUM_CAD_GISS,W
call look_flag
bz OTRA_CAD_GISS
movf NUM_CAD_GISS,W
movwf ID_CAD_GC ; ID_CAD_GC = Id. to look
movf NUM_CHAR_GISS,W ; W = number of character to test
call getchar_strrom
addlw d'0'
bz ENC_GISS ; If this character is 0 (string end), it was founded
xorwf CHAR_SERIE,W ; compare it with the received character.
bnz NO_CAD_GISS ; If they don't match, this string is not valid.
movf NUM_CAD_GISS,W
movwf ID_CAD_GC ; ID_CAD_GC = Id. to look
movlw d'1'
addwf NUM_CHAR_GISS,W ; W = number of the character to look + 1
call getchar_strrom ; Look the next character.
xorlw 0xff
bz ENC_GISS ; If it's 0xff (string end), it was founded
goto OTRA_CAD_GISS
NO_CAD_GISS movlw d'1'
subwf NUM_CAD_GISS,W
call clr_flag
goto OTRA_CAD_GISS
OTRA_CAD_GISS
call count_flags ; Look how many strings were not compared yet.
addlw d'0'
bz NO_ENC_GISS ; If none, then it was not founded.
movlw d'1'
addwf NUM_CAD_GISS,F
movlw CADS_NUM
subwf NUM_CAD_GISS,W ; Compare the string id. de cadena to look with the number of strings
bnc BUC_CAD_GISS ; Si it's negative (C=0), continues testing the next string
bz BUC_CAD_GISS ; idem if it's zero
movlw d'1'
addwf NUM_CHAR_GISS,F ; NUM_CHAR_GISS++ (looks the next character)
goto BUC_OTRO_CHAR_GISS
NO_ENC_GISS
retlw 0
ENC_GISS
movf NUM_CAD_GISS,W
return
See also:
| file: /Techref/microchip/string_matching.htm, 9KB, , updated: 2003/1/26 13:51, local time: 2024/12/26 06:29,
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