Carlos Nieves shares this code:
Here are some routines to handle flags or boolean variables. Each byte in RAM can store 8 flags, and this routines lets you to set, clear, or look at any flag stored there, and also count how many variables are set, and clear or set all flags. If you want to use it, you only have to define FLAGS_NUM, which is the number of flags you need. Each flag is located with an identifier. First byte contains flags 0 to 7, and so on... For example, if you want to use a flag called FLAG1, you should declare something like: #define FLAG1 0 ; this is the identifier of this flag. And use FLAG1 when calling any of these routines. The code begins here: ; Copyright (C) 2001 Carlos Nieves Onega <cnieves (at) confluencia.net> ; 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: flags.asm * ; Version: 20011026 * ; * ; Author: Carlos Nieves Onega * ; * ; * ; * ;********************************************************************** ; * ; Required files: * ; * ;********************************************************************** ; * ; Notes: This file contains routines to handle bit variables * ; All variables must be in a single block in data memory * ; Only an integer number of bytes will be used for the * ; bits table. * ; * ;********************************************************************** ; Changes: ; 20011026 (cnieves): Began writing. ; Functions tested (simulated): ; set_flag, clr_flag, set_all_flags, clr_all_flags, ; look_flag, count_flags, bit_to_reg ; They work right. ;********************************************************************** ;#define FLAGS_NUM CADS_NUM-1 ; Begun at 0 ;********************************************************************** ; Function bit_to_reg ; Description: Given a bit (the first is 0), returns the byte where is the ; flag to look at in a register ; Parameters: ; WREG: flag number to look (the first is the 0). ; Returns: ; INDF, FSR: byte where the flag is. ; RES_B2R: mask for the byte to look. ; Use: ; vars. TEMP_B2R, RES_B2R, ; regs FSR, INDF, W, STATUS ;********************************************************************** cblock TEMP_SAF: 0 TEMP_B2R: 1 ; Variable reused by set_all_flags and clr_all_flags RES_B2R: 1 FLAGS_INI_ADDR: ((FLAGS_NUM+1) >> 3) + 1 endc bit_to_reg movwf TEMP_B2R movwf RES_B2R ; Stores the bit to look in 2 temp. vars. movlw FLAGS_INI_ADDR movwf FSR ; FSR= Flags block start address bcf STATUS,C rrf TEMP_B2R,F bcf STATUS,C rrf TEMP_B2R,F bcf STATUS,C rrf TEMP_B2R,W ; Gets the offset to the byte containing the flag. addwf FSR,F ; FSR=Address of the byte containing the flag movf RES_B2R,W ; movwf TEMP_B2R ; temp. var. = Number of flag to look movlw 0x07 andwf TEMP_B2R,F ; temp. var. between 0 and 7 incf TEMP_B2R,F ; Bit a look (between 0 y 7) += 1 (for the next loop). ; Almacenar? el contador del n?mero de bit. bsf STATUS,C ; Because of rlf clrf RES_B2R BUC_B2R rlf RES_B2R,F ; Result = 1 (initial cond. if the flag number is 0). bcf STATUS,C ; C = 0 decfsz TEMP_B2R,F ; counter-- goto BUC_B2R return ;********************************************************************** ; Function set_flag ; Description: sets a given flat to 1. ; Parameters: ; WREG: flag number to be modified. ; Returns: nothing ; Use: ; func. bit_to_reg, ; regs W, INDF, FSR ;********************************************************************** set_flag call bit_to_reg movf RES_B2R,W ; W = mask of the flag to be modified (bit = 1) iorwf INDF,F ; Sets the given bit. return ;********************************************************************** ; Function clr_flag ; Description: clears a given flag to 0. ; Parameters: ; WREG: flag number to be modified. ; Returns: nothing ; Use: ; func. bit_to_reg, ; regs W, INDF, FSR ;********************************************************************** clr_flag call bit_to_reg comf RES_B2R,W ; Complement to 1 the mask. ; W = mask of the bit to be modified (bit = 0) andwf INDF,F ; Clears the right bit. return ;********************************************************************** ; Function look_flag ; Description: returns the status of a given flag. ; Parameters: ; WREG: flag number to look. ; Returns: ; W = 0 , Z = 1, if the bit is 0. ; W != 0, Z = 0, if the bit is 1. ; Use: ; func. bit_to_reg, ; regs W, INDF, FSR ;********************************************************************** look_flag call bit_to_reg movf RES_B2R,W ; W = mask of the bit to look (bit = 1) andwf INDF,W ; In W is the bit to look, and the others to 0. return ;********************************************************************** ; Function set_all_flags ; Description: sets to 1 all flags. ; Parameters: none. ; Returns: nothing ; Use: ; regs W, INDF, FSR ; var. temp TEMP_SAF ;********************************************************************** set_all_flags movlw FLAGS_NUM movwf TEMP_SAF ; TEMP_SAF = Number of bits to be modified bcf STATUS,Z rrf TEMP_SAF,F bcf STATUS,C rrf TEMP_SAF,F bcf STATUS,C rrf TEMP_SAF,F incf TEMP_SAF,F ; TEMP_SAF = Number of bits to be modified. movlw FLAGS_INI_ADDR movwf FSR ; FSR points to flag block BUC_SAF clrf INDF comf INDF,F ; Flags Byte = 0xff incf FSR,F ; FSR points to the next address. decfsz TEMP_SAF,F goto BUC_SAF return ;********************************************************************** ; Function clr_all_flags ; Description: clears to 0 all flags. ; Parameters: none ; Returns: nothing ; Use: ; regs W, INDF, FSR ; var. temp TEMP_SAF ;********************************************************************** clr_all_flags movlw FLAGS_NUM movwf TEMP_SAF ; TEMP_SAF = Number of bits to be modified. bcf STATUS,Z rrf TEMP_SAF,F rrf TEMP_SAF,F rrf TEMP_SAF,F incf TEMP_SAF,F ; TEMP_SAF = Number of bits to be modified. movlw FLAGS_INI_ADDR movwf FSR ; FSR points to the flags block BUC_CAF clrf INDF ; Flags byte= 0 incf FSR,F ; FSR points to the next address. decfsz TEMP_SAF,F goto BUC_CAF return ;********************************************************************** ; Function count_flags ; Description: count the flags being 1 ; Parameters: none ; Returns: ; W: number of flags set. ; Use: ; regs W ; var. temp. TEMP_CB, RES_CB ; func. look_flag ;********************************************************************** cblock TEMP_CB: 1 RES_CB: 1 endc count_flags clrf RES_CB movlw FLAGS_NUM movwf TEMP_CB BUC_CB movf TEMP_CB,W call look_flag btfss STATUS,Z incf RES_CB,F decfsz TEMP_CB,F goto BUC_CB movf RES_CB,W return
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