;'variables' ;region ;counters COUNT1 EQU 0x60 COUNT2 EQU 0x61 COUNT3 EQU 0x62 ;for subroutines INPUT EQU 0x63 TEMP EQU 0x64 RESULT EQU 0x65 ;store the information concerning a cell of the sudoku (2 bytes) VALUE1 EQU 0x66 VALUE2 EQU 0x67 ;old value of FSR FSROLD EQU 0x68 ;current BANK BANK EQU 0x69 ;bit 0 indicates whether a value has been set in this iteration or not ;bit 1 indicates whether we are on part 1 of the attack (remove possibilities) or part 2 of the attack (set sure values) FLAGS EQU 0x6A ;endregion ;EQU's ;region EMP1 EQU b'11111111' EMP2 EQU b'10000000' ONE1 EQU b'10000000' ONE2 EQU b'01010000' TWO1 EQU b'01000000' TWO2 EQU b'01010000' THR1 EQU b'00100000' THR2 EQU b'01010000' FOU1 EQU b'00010000' FOU2 EQU b'01010000' FIV1 EQU b'00001000' FIV2 EQU b'01010000' SIX1 EQU b'00000100' SIX2 EQU b'01010000' SEV1 EQU b'00000010' SEV2 EQU b'01010000' EIG1 EQU b'00000001' EIG2 EQU b'01010000' NIN1 EQU b'00000000' NIN2 EQU b'11010000' ;endregion ORG 0x0000 ;sudoku input ;region BCF STATUS,RP0 BCF STATUS,RP1 MOVLW SEV1 MOVWF 0x20 MOVLW SEV2 MOVWF 0x21 MOVLW EMP1 MOVWF 0x22 MOVLW EMP2 MOVWF 0x23 MOVLW EMP1 MOVWF 0x24 MOVLW EMP2 MOVWF 0x25 MOVLW ONE1 MOVWF 0x26 MOVLW ONE2 MOVWF 0x27 MOVLW EMP1 MOVWF 0x28 MOVLW EMP2 MOVWF 0x29 MOVLW EMP1 MOVWF 0x2A MOVLW EMP2 MOVWF 0x2B MOVLW EMP1 MOVWF 0x2C MOVLW EMP2 MOVWF 0x2D MOVLW EMP1 MOVWF 0x2E MOVLW EMP2 MOVWF 0x2F MOVLW SIX1 MOVWF 0x30 MOVLW SIX2 MOVWF 0x31 MOVLW EMP1 MOVWF 0x32 MOVLW EMP2 MOVWF 0x33 MOVLW THR1 MOVWF 0x34 MOVLW THR2 MOVWF 0x35 MOVLW EMP1 MOVWF 0x36 MOVLW EMP2 MOVWF 0x37 MOVLW NIN1 MOVWF 0x38 MOVLW NIN2 MOVWF 0x39 MOVLW EMP1 MOVWF 0x3A MOVLW EMP2 MOVWF 0x3B MOVLW EMP1 MOVWF 0x3C MOVLW EMP2 MOVWF 0x3D MOVLW EMP1 MOVWF 0x3E MOVLW EMP2 MOVWF 0x3F MOVLW TWO1 MOVWF 0x40 MOVLW TWO2 MOVWF 0x41 MOVLW EIG1 MOVWF 0x42 MOVLW EIG2 MOVWF 0x43 MOVLW EMP1 MOVWF 0x44 MOVLW EMP2 MOVWF 0x45 MOVLW FIV1 MOVWF 0x46 MOVLW FIV2 MOVWF 0x47 MOVLW EMP1 MOVWF 0x48 MOVLW EMP2 MOVWF 0x49 MOVLW EMP1 MOVWF 0x4A MOVLW EMP2 MOVWF 0x4B MOVLW EMP1 MOVWF 0x4C MOVLW EMP2 MOVWF 0x4D MOVLW EMP1 MOVWF 0x4E MOVLW EMP2 MOVWF 0x4F MOVLW EMP1 MOVWF 0x50 MOVLW EMP2 MOVWF 0x51 MOVLW EMP1 MOVWF 0x52 MOVLW EMP2 MOVWF 0x53 MOVLW EMP1 MOVWF 0x54 MOVLW EMP2 MOVWF 0x55 BSF STATUS,RP0 BCF STATUS,RP1 MOVLW EMP1 MOVWF 0x20 MOVLW EMP2 MOVWF 0x21 MOVLW EMP1 MOVWF 0x22 MOVLW EMP2 MOVWF 0x23 MOVLW THR1 MOVWF 0x24 MOVLW THR2 MOVWF 0x25 MOVLW EIG1 MOVWF 0x26 MOVLW EIG2 MOVWF 0x27 MOVLW EMP1 MOVWF 0x28 MOVLW EMP2 MOVWF 0x29 MOVLW SIX1 MOVWF 0x2A MOVLW SIX2 MOVWF 0x2B MOVLW NIN1 MOVWF 0x2C MOVLW NIN2 MOVWF 0x2D MOVLW ONE1 MOVWF 0x2E MOVLW ONE2 MOVWF 0x2F MOVLW EMP1 MOVWF 0x30 MOVLW EMP2 MOVWF 0x31 MOVLW EMP1 MOVWF 0x32 MOVLW EMP2 MOVWF 0x33 MOVLW FOU1 MOVWF 0x34 MOVLW FOU2 MOVWF 0x35 MOVLW ONE1 MOVWF 0x36 MOVLW ONE2 MOVWF 0x37 MOVLW EMP1 MOVWF 0x38 MOVLW EMP2 MOVWF 0x39 MOVLW EMP1 MOVWF 0x3A MOVLW EMP2 MOVWF 0x3B MOVLW EMP1 MOVWF 0x3C MOVLW EMP2 MOVWF 0x3D MOVLW EMP1 MOVWF 0x3E MOVLW EMP2 MOVWF 0x3F MOVLW SIX1 MOVWF 0x40 MOVLW SIX2 MOVWF 0x41 MOVLW EMP1 MOVWF 0x42 MOVLW EMP2 MOVWF 0x43 MOVLW EMP1 MOVWF 0x44 MOVLW EMP2 MOVWF 0x45 MOVLW EIG1 MOVWF 0x46 MOVLW EIG2 MOVWF 0x47 MOVLW EMP1 MOVWF 0x48 MOVLW EMP2 MOVWF 0x49 MOVLW EMP1 MOVWF 0x4A MOVLW EMP2 MOVWF 0x4B MOVLW EMP1 MOVWF 0x4C MOVLW EMP2 MOVWF 0x4D MOVLW SEV1 MOVWF 0x4E MOVLW SEV2 MOVWF 0x4F MOVLW EMP1 MOVWF 0x50 MOVLW EMP2 MOVWF 0x51 MOVLW EMP1 MOVWF 0x52 MOVLW EMP2 MOVWF 0x53 MOVLW EMP1 MOVWF 0x54 MOVLW EMP2 MOVWF 0x55 BSF STATUS,RP1 BCF STATUS,RP0 MOVLW NIN1 MOVWF 0x20 MOVLW NIN2 MOVWF 0x21 MOVLW EMP1 MOVWF 0x22 MOVLW EMP2 MOVWF 0x23 MOVLW EMP1 MOVWF 0x24 MOVLW EMP2 MOVWF 0x25 MOVLW SEV1 MOVWF 0x26 MOVLW SEV2 MOVWF 0x27 MOVLW TWO1 MOVWF 0x28 MOVLW TWO2 MOVWF 0x29 MOVLW EMP1 MOVWF 0x2A MOVLW EMP2 MOVWF 0x2B MOVLW EMP1 MOVWF 0x2C MOVLW EMP2 MOVWF 0x2D MOVLW EMP1 MOVWF 0x2E MOVLW EMP2 MOVWF 0x2F MOVLW EMP1 MOVWF 0x30 MOVLW EMP2 MOVWF 0x31 MOVLW EMP1 MOVWF 0x32 MOVLW EMP2 MOVWF 0x33 MOVLW EMP1 MOVWF 0x34 MOVLW EMP2 MOVWF 0x35 MOVLW EMP1 MOVWF 0x36 MOVLW EMP2 MOVWF 0x37 MOVLW EMP1 MOVWF 0x38 MOVLW EMP2 MOVWF 0x39 MOVLW EMP1 MOVWF 0x3A MOVLW EMP2 MOVWF 0x3B MOVLW ONE1 MOVWF 0x3C MOVLW ONE2 MOVWF 0x3D MOVLW TWO1 MOVWF 0x3E MOVLW TWO2 MOVWF 0x3F MOVLW EMP1 MOVWF 0x40 MOVLW EMP2 MOVWF 0x41 MOVLW EMP1 MOVWF 0x42 MOVLW EMP2 MOVWF 0x43 MOVLW EIG1 MOVWF 0x44 MOVLW EIG2 MOVWF 0x45 MOVLW EMP1 MOVWF 0x46 MOVLW EMP2 MOVWF 0x47 MOVLW EMP1 MOVWF 0x48 MOVLW EMP2 MOVWF 0x49 MOVLW EMP1 MOVWF 0x4A MOVLW EMP2 MOVWF 0x4B MOVLW FOU1 MOVWF 0x4C MOVLW FOU2 MOVWF 0x4D MOVLW EMP1 MOVWF 0x4E MOVLW EMP2 MOVWF 0x4F MOVLW EMP1 MOVWF 0x50 MOVLW EMP2 MOVWF 0x51 MOVLW EMP1 MOVWF 0x52 MOVLW EMP2 MOVWF 0x53 MOVLW EMP1 MOVWF 0x54 MOVLW EMP2 MOVWF 0x55 BCF STATUS,RP0 BCF STATUS,RP1 ;endregion START: CLRF BANK ;BANK equals zero at a start ;setbank ;region SETBANK: BTFSC BANK,0 GOTO ODDBANK BTFSC BANK,1 GOTO BANK2 GOTO BANK0 ODDBANK: BTFSC BANK,1 GOTO NEW ;means we finished GOTO BANK1 ;BANK1 BANK0: MOVLW 0x20 ;that's where the GPRs start BCF STATUS,IRP GOTO INIT BANK1: MOVLW 0xA0 BCF STATUS,IRP GOTO INIT BANK2: MOVLW 0x20 BSF STATUS,IRP ;indirect addressing, we'll need that bit to be set GOTO INIT ;endregion INIT: MOVWF FSR ; ;0x36 equals 54 in decimal, that's the amount of bytes we have to go through in a given bank (27 sudoku cells * 2 bytes per cell) MOVLW 0x36 MOVWF COUNT1 ;so, for each byte LOOP: ;we check if it's an even byte or an odd byte BTFSC FSR,0 GOTO SECOND ;even byte, aka first byte of that cell, we simply store its value at VALUE1 FIRST: MOVF INDF, W MOVWF VALUE1 GOTO NEXT ;odd byte, aka second byte SECOND: ;we store the second byte of our cell at VALUE2 MOVF INDF, W MOVWF VALUE2 ;we'll behave differently whether that cell is already set or not BTFSC INDF,6 GOTO ISSET GOTO ISNOTSET ;is set ;region ISSET: ;if we are on part 1 of the attack (that is, removing possibilities), a set cell is juicy ;if not, we just move on to next byte BTFSC FLAGS,1 GOTO NEXT BTFSS INDF,5 ;we check whether that value has already been removed from it's column/zone/row or not (don't want to do it more than once) GOTO DELETE GOTO NEXT ;now that we are here, we are going to delete our value as possible from every cell in our column, zone and row ;we'll only remove it from cells without a sure value, so we won't remove it from ours! DELETE: BSF INDF,5 ;we make sure that we won't do this more than once ;we save current FSR, since we are going to modify its value, and we'll want to have it back later MOVF FSR,W MOVWF FSROLD ;delete our value as possible from our column ;region CALL COLUMNSTARTS ;places in W the memory location where the first cell of our column is located MOVWF FSR ;and we move right there ;for each cell of our column MOVLW 0x9 MOVWF COUNT2 LOOPCOLUMN: ;we check if the cell has a sure value INCF FSR,F BTFSS INDF,6 GOTO DELFROMCOL ;it has not a sure value, so let's delete ours (in case it's there, anyways) GOTO NEXTINCOLUMN ;it has a sure value, so let's move on to next cell DELFROMCOL: CALL DELETEFROMINDF NEXTINCOLUMN: ;move on to next cell in the column INCF FSR,F DECFSZ COUNT2,F GOTO LOOPCOLUMN ;endregion ;delete our value as possible from our zone ;region CALL ZONESTARTS ;places in W the memory location where the first cell of our zone is located MOVWF FSR ;and we move right there ;going through every cell in a zone is a bit harder, remember it's 3x3 MOVLW 0x3 MOVWF COUNT2 MOVWF COUNT3 LOOPZONE: ;we check if the cell has a sure value INCF FSR,F BTFSS INDF,6 GOTO DELFROMZONE ;it has not a sure value, so let's delete ours (in case it's there, anyways) GOTO NEXTINZONE ;it has a sure value so let's move on to next cell DELFROMZONE: CALL DELETEFROMINDF NEXTINZONE: ;move on to next cell in the column INCF FSR,F DECFSZ COUNT2,F GOTO LOOPZONE DECFSZ COUNT3,F GOTO AUXZONE ;and COUNT3 is not GOTO FINISHZONE ;and COUNT3 is, too AUXZONE: ;we'll go through 3 more cells MOVLW 0x3 MOVWF COUNT2 ;that are in the next column (adding 0xC makes you move on to next column) MOVLW 0xC ADDWF FSR,F GOTO LOOPZONE ;we are done with the zone FINISHZONE: ;endregion ;delete our value as possible from our row ;region CALL ROWSTARTS ;places in W the memory location where the first cell of our row is located MOVWF FSR ;and we move right there BCF STATUS,IRP ;all rows start in BANK 0 (keep in mind that not all cells in a row are in the same bank, as opposed to what happened with columns and zones) ;3 cells in each one of the 3 banks MOVLW 0x3 MOVWF COUNT2 MOVWF COUNT3 LOOPROW: ;we check if the cell has a sure value INCF FSR,F BTFSS INDF,6 GOTO DELFROMROW ;it has not a sure value, so let's delete ours (in case it's there, anyways) GOTO NEXTINROW ;it has a sure value so let's move on to next cell DELFROMROW: CALL DELETEFROMINDF NEXTINROW: ;adding 0x11 takes you to the next cell MOVLW 0x11 ADDWF FSR,F DECFSZ COUNT2,F GOTO LOOPROW DECFSZ COUNT3,F GOTO AUXROW ;COUNT2 is zero, COUNT3 is not GOTO FINISHROW ;both COUNT2 and COUNT3 are zero AUXROW: ;3 more cells, next bank MOVLW 0x3 MOVWF COUNT2 ;check which bank we are currently at BTFSC FSR,7 GOTO SETIRP ;we are in bank 1, so let's move on to bank 2 (by setting IRP) ;we are in bank 0, so simply by increasing FSR we can move on to bank 1 MOVLW 0x4A ADDWF FSR,F GOTO LOOPROW SETIRP: BSF STATUS,IRP MOVLW 0xB6 SUBWF FSR,F GOTO LOOPROW ;we want our old FSR back FINISHROW: MOVF FSROLD,W MOVWF FSR ;and our old bank back too, please BTFSC BANK,1 GOTO ROWSETIRP BCF STATUS,IRP GOTO NEXT ROWSETIRP: BSF STATUS,IRP ;endregion GOTO NEXT ;endregion ;is not set ;region ISNOTSET: ;if we are on part 2 of the attack (that is, setting sure values), a free cell is juicy ;if not, we just move on to next byte BTFSS FLAGS,1 GOTO NEXT ;we save current FSR, since we are going to modify its value, and we'll want to have it back later MOVF FSR,W MOVWF FSROLD ;set the value as sure if it has only one possible value ;region ;get the number of 1s at VALUE1 (that is the number of possible values from 1 to 8) MOVF VALUE1,W MOVWF INPUT CALL NUMBEROF1S ;it'll store the result in W ;if W equals 0, this cell must be a 9, so we set it's value ANDLW 0xFF ;this is just so the flags of STATUS are refreshed BTFSS STATUS,Z GOTO ISNOTZERO ;so yes, W equals 0 BSF INDF,6 ;the value is set BSF FLAGS,0 ;we have set a value GOTO NEXT ;in case W doesn't equal 0 ISNOTZERO: ;if W was 1, and 9 wasn't a possible value, we can set its value too MOVWF TEMP DECFSZ TEMP,F GOTO UNIQUEINCOL ;W doesn't equal 1 either, it's more than that, we can't set it BTFSC INDF,7 ;W equals 1 and it can't be a 9 GOTO UNIQUEINCOL ;W equals 1, but it could be a 9 too, so we know nothing BSF INDF,6 ;the value is set BSF FLAGS,0 ;we have set a value GOTO NEXT ;endregion ;set the value as sure if it's the only at its column with a certain value as possible ;region UNIQUEINCOL: CALL COLUMNSTARTS ;places in W the memory location where the first cell of our column is located MOVWF FSR ;and we move right there ;for each cell of our column MOVLW 0x9 MOVWF COUNT2 LOOPCOLUMN2: ;we check if the cell is not the one we are trying to find a value for (which is stored at FSROLD) INCF FSR,W SUBWF FSROLD,W BTFSS STATUS,Z GOTO DELPOSCOL ;it isn't the one we are trying to find a value for ;could be the one we are trying to find a value for, or could be one with same FSR but different bank BTFSC BANK,1 GOTO BANK2UC ;if we are here it means that if STATUS,IRP equals 0 this is the one we are trying to find a value for BTFSC STATUS,IRP GOTO DELPOSCOL ;heh, it's not the one GOTO ITISTHEONEC BANK2UC: ;if we are here it means that if STATUS,IRP equals 1 this is the one we are trying to find a value for BTFSS STATUS,IRP GOTO DELPOSCOL ITISTHEONEC: INCF FSR,F GOTO NEXTINCOL ;it is the one we are trying to find a value for DELPOSCOL: CALL DELETEFROMVALUE12 NEXTINCOL: ;move on to next cell in the column INCF FSR,F DECFSZ COUNT2,F GOTO LOOPCOLUMN2 ;we are done with the column, let's get our old FSR back (it points to the second byte of the cell) and make it point to the 1st byte MOVF FSROLD,W MOVWF FSR ;if there's a bit at VALUE1 (or VALUE2, in case it's a nine) that equals 1, the cell can be set! and we move the contents from VALUE1 and VALUE2 to the cell's MOVF VALUE1,W MOVWF INPUT CALL NUMBEROF1S ;if W equals 0, our only chance is that the cell is 9 ANDLW 0xFF ;this is just so the flags of STATUS are refreshed BTFSS STATUS,Z GOTO CANSETVALUE ;so yes, W equals 0, let's see if it's a nine BTFSS VALUE2,7 GOTO UNIQUEINZON ;it's not a 9, we can't set it :( (so we try another attack) ;in case W doesn't equal 0, we can set it's value! we move the contents from VALUE1 and VALUE2 to the cell's CANSETVALUE: CALL SETVALSUB GOTO NEXT ;endregion ;set the value as sure if it's the only at its zone with a certain value as possible ;region UNIQUEINZON: ;reset value1 and value2 CALL RESETVAL12 CALL ZONESTARTS ;places in W the memory location where the first cell of our zone is located MOVWF FSR ;and we move right there ;going through every cell in a zone is a bit harder, remember it's 3x3 MOVLW 0x3 MOVWF COUNT2 MOVWF COUNT3 LOOPZONE2: ;we check if the cell is not the one we are trying to find a value for (which is stored at FSROLD) INCF FSR,W SUBWF FSROLD,W BTFSS STATUS,Z GOTO DELPOSZON ;it isn't the one we are trying to find a value for ;could be the one we are trying to find a value for, or could be one with same FSR but different bank BTFSC BANK,1 GOTO BANK2UZ ;if we are here it means that if STATUS,IRP equals 0 this is the one we are trying to find a value for BTFSC STATUS,IRP GOTO DELPOSZON ;heh, it's not the one GOTO ITISTHEONEZ BANK2UZ: ;if we are here it means that if STATUS,IRP equals 1 this is the one we are trying to find a value for BTFSS STATUS,IRP GOTO DELPOSZON ITISTHEONEZ: INCF FSR,F GOTO NEXTINZON ;it is the one we are trying to find a value for DELPOSZON: CALL DELETEFROMVALUE12 NEXTINZON: ;move on to next cell in the column INCF FSR,F DECFSZ COUNT2,F GOTO LOOPZONE2 DECFSZ COUNT3,F GOTO AUXZONE2 ;and COUNT3 is not GOTO FINISHZONE2 ;and COUNT3 is, too AUXZONE2: ;we'll go through 3 more cells MOVLW 0x3 MOVWF COUNT2 ;that are in the next column (adding 0xC makes you move on to next column) MOVLW 0xC ADDWF FSR,F GOTO LOOPZONE2 FINISHZONE2: ;we are done with the zone, let's get our old FSR back MOVF FSROLD,W MOVWF FSR ;if there's a bit at VALUE1 (or VALUE2, in case it's a nine) that equals 1, the cell can be set! and we move the contents from VALUE1 and VALUE2 to the cell's MOVF VALUE1,W MOVWF INPUT CALL NUMBEROF1S ;if W equals 0, our only chance is that the cell is 9 ANDLW 0xFF ;this is just so the flags of STATUS are refreshed BTFSS STATUS,Z GOTO CANSETVALUE2 ;so yes, W equals 0, let's see if it's a nine BTFSS VALUE2,7 GOTO UNIQUEINROW ;it's not a 9, we can't set it :( ;in case W doesn't equal 0, we can set it's value! we move the contents from VALUE1 and VALUE2 to the cell's CANSETVALUE2: CALL SETVALSUB GOTO NEXT ;endregion ;set the value as sure if it's the only at its row with a certain value as possible ;region UNIQUEINROW: ;reset value1 and value2 CALL RESETVAL12 CALL ROWSTARTS ;places in W the memory location where the first cell of our row is located MOVWF FSR ;and we move right there BCF STATUS,IRP ;all rows start in BANK 0 (keep in mind that not all cells in a row are in the same bank, as opposed to what happened with columns and zones) ;3 cells in each one of the 3 banks MOVLW 0x3 MOVWF COUNT2 MOVWF COUNT3 LOOPROW2: ;we check if the cell is not the one we are trying to find a value for (which is stored at FSROLD) INCF FSR,W SUBWF FSROLD,W BTFSS STATUS,Z GOTO DELPOSROW ;it isn't the one we are trying to find a value for ;could be the one we are trying to find a value for, or could be one with same FSR but different bank BTFSC BANK,1 GOTO BANK2UR ;if we are here it means that if STATUS,IRP equals 0 this is the one we are trying to find a value for BTFSC STATUS,IRP GOTO DELPOSROW ;heh, it's not the one GOTO ITISTHEONER BANK2UR: ;if we are here it means that if STATUS,IRP equals 1 this is the one we are trying to find a value for BTFSS STATUS,IRP GOTO DELPOSROW ITISTHEONER: INCF FSR,F GOTO NEXTINR ;it is the one we are trying to find a value for DELPOSROW: CALL DELETEFROMVALUE12 NEXTINR: ;adding 0x11 takes you to the next cell MOVLW 0x11 ADDWF FSR,F DECFSZ COUNT2,F GOTO LOOPROW2 DECFSZ COUNT3,F GOTO AUXROW2 ;COUNT2 is zero, COUNT3 is not GOTO FINISHROW2 ;both COUNT2 and COUNT3 are zero AUXROW2: ;3 more cells, next bank MOVLW 0x3 MOVWF COUNT2 ;check which bank we are currently at BTFSC FSR,7 GOTO SETIRP2 ;we are in bank 1, so let's move on to bank 2 (by setting IRP) ;we are in bank 0, so simply by increasing FSR we can move on to bank 1 MOVLW 0x4A ADDWF FSR,F GOTO LOOPROW2 SETIRP2: BSF STATUS,IRP MOVLW 0xB6 SUBWF FSR,F GOTO LOOPROW2 ;we want our old FSR back FINISHROW2: MOVF FSROLD,W MOVWF FSR ;and our old bank back too, please BTFSC BANK,1 GOTO ROWSETIRP2 BCF STATUS,IRP GOTO KEEPONUNR ROWSETIRP2: BSF STATUS,IRP KEEPONUNR: ;if there's a bit at VALUE1 (or VALUE2, in case it's a nine) that equals 1, the cell can be set! and we move the contents from VALUE1 and VALUE2 to the cell's MOVF VALUE1,W MOVWF INPUT CALL NUMBEROF1S ;if W equals 0, our only chance is that the cell is 9 ANDLW 0xFF ;this is just so the flags of STATUS are refreshed BTFSS STATUS,Z GOTO CANSETVALUE3 ;so yes, W equals 0, let's see if it's a nine BTFSS VALUE2,7 GOTO NEXT ;it's not a 9, we can't set it :( ;in case W doesn't equal 0, we can set it's value! we move the contents from VALUE1 and VALUE2 to the cell's CANSETVALUE3: CALL SETVALSUB GOTO NEXT ;endregion ;endregion NEXT: INCF FSR,F DECFSZ COUNT1,F GOTO LOOP ;COUNT1 reached zero, move on to next bank INCF BANK,F GOTO SETBANK NEW: ;we reach this point each time we have gone through every cell of the sudoku ;let's check if we are on attack 1 (remove possible values) or attack 2 (set values as sure) BTFSS FLAGS,1 GOTO FIRSTATTACK ;we are on attack 2 BTFSS FLAGS,0 GOTO ENDING ;and we didn't set any new values, I'm afraid we are done with this sudoku ;we did set at least one! restart the process BCF FLAGS,1 GOTO START FIRSTATTACK: ;let's move on to second attack BSF FLAGS,1 ;and we haven't set any values yet BCF FLAGS,0 GOTO START ;subroutine that places in W the memory address where the first cell of our column is located (our cell's address is stored in FSROLD) ;region COLUMNSTARTS: ;it basically checks which interval FSROLD is in (out of 6 possibilities) MOVF FSROLD,W SUBLW 0xC3 BTFSS STATUS,C RETLW 0xC4 MOVF FSROLD,W SUBLW 0xB1 BTFSS STATUS,C RETLW 0xB2 MOVF FSROLD,W SUBLW 0x9F BTFSS STATUS,C RETLW 0xA0 MOVF FSROLD,W SUBLW 0x43 BTFSS STATUS,C RETLW 0x44 MOVF FSROLD,W SUBLW 0x31 BTFSS STATUS,C RETLW 0x32 MOVF FSROLD,W SUBLW 0x1F BTFSS STATUS,C RETLW 0x20 ;endregion ;subroutine that places in W the memory address where the first cell of our zone is located (our cell's address is stored in FSROLD) ;region ZONESTARTS: MOVF FSROLD,W ANDLW 0x7F ;we get rid of it's most significative bit MOVWF TEMP SUBLW 0x50-1 BTFSS STATUS,C GOTO SUBZONEA MOVF TEMP,W SUBLW 0x4A-1 BTFSS STATUS,C GOTO SUBZONEB MOVF TEMP,W SUBLW 0x44-1 BTFSS STATUS,C GOTO SUBZONEC MOVF TEMP,W SUBLW 0x3E-1 BTFSS STATUS,C GOTO SUBZONEA MOVF TEMP,W SUBLW 0x38-1 BTFSS STATUS,C GOTO SUBZONEB MOVF TEMP,W SUBLW 0x32-1 BTFSS STATUS,C GOTO SUBZONEC MOVF TEMP,W SUBLW 0x2C-1 BTFSS STATUS,C GOTO SUBZONEA MOVF TEMP,W SUBLW 0x26-1 BTFSS STATUS,C GOTO SUBZONEB MOVF TEMP,W SUBLW 0x20-1 BTFSS STATUS,C GOTO SUBZONEC ;and it's now that we take that most significative bit of FSROLD into account SUBZONEA: RLF FSROLD,W BTFSS STATUS,C RETLW 0x2C RETLW 0xAC SUBZONEB: RLF FSROLD,W BTFSS STATUS,C RETLW 0x26 RETLW 0xA6 SUBZONEC: RLF FSROLD,W BTFSS STATUS,C RETLW 0x20 RETLW 0xA0 ;endregion ;subroutine that places in W the memory address where the first cell of our row is located (our cell's address is stored in FSROLD) ;region ROWSTARTS: MOVF FSROLD,W ANDLW 0x7F ;we get rid of its most significative bit MOVWF TEMP SUBROW: MOVF TEMP,W SUBLW 0x21 BTFSC STATUS,Z RETLW 0x20 MOVF TEMP,W SUBLW 0x23 BTFSC STATUS,Z RETLW 0x22 MOVF TEMP,W SUBLW 0x25 BTFSC STATUS,Z RETLW 0x24 MOVF TEMP,W SUBLW 0x27 BTFSC STATUS,Z RETLW 0x26 MOVF TEMP,W SUBLW 0x29 BTFSC STATUS,Z RETLW 0x28 MOVF TEMP,W SUBLW 0x2B BTFSC STATUS,Z RETLW 0x2A MOVF TEMP,W SUBLW 0x2D BTFSC STATUS,Z RETLW 0x2C MOVF TEMP,W SUBLW 0x2F BTFSC STATUS,Z RETLW 0x2E MOVF TEMP,W SUBLW 0x31 BTFSC STATUS,Z RETLW 0x30 ;if it reached this point, it means we aren't in a first-column cell, so we move on to previous column (same row) MOVLW 0x12 SUBWF TEMP,F GOTO SUBROW ;endregion ;subroutine that finds out (and places in W) how many 1s there are at INPUT ;region NUMBEROF1S: CLRF RESULT SUBNUMBERA: BCF STATUS,C ANDLW 0xFF BTFSS STATUS,Z ;if it's zero, there won't be any more bits with a value of 1, so we can stop counting GOTO SUBNUMBERB ;if not (there will be more 1s) MOVF RESULT,W RETURN SUBNUMBERB: RLF INPUT,W BTFSC STATUS,C INCF RESULT,F ;we found a 1 (the carry was set after the rotation) MOVWF INPUT GOTO SUBNUMBERA ;endregion ;subroutine that deletes a value (which is sure at some cell) from the list of possible values of another cell ;region DELETEFROMINDF: ;delete from its first byte DECF FSR,F COMF VALUE1,W ANDWF INDF,F ;delete from its second byte INCF FSR,F COMF VALUE2,W ANDWF INDF,F RETURN ;endregion ;subroutine that deletes possibilities (which are possible at some cell) from a copy of the list of possible values of another cell (the copy being at VALUE1, VALUE2) ;region DELETEFROMVALUE12: ;delete from its first byte COMF INDF,W ANDWF VALUE1,F ;delete from its second byte INCF FSR,F COMF INDF,W ANDWF VALUE2,F RETURN ;endregion ;subroutine that sets the content of VALUE1, VALUE2 into INDF ;region SETVALSUB: DECF FSR,F MOVF VALUE1,W MOVWF INDF INCF FSR,F MOVF VALUE2,W MOVWF INDF BSF INDF,6 ;the value is set BSF FLAGS,0 ;we have set a value RETURN ;endregion ;subroutine that reselts the content of VALUE1 and VALUE2 ;region RESETVAL12: MOVF FSROLD,W MOVWF FSR MOVF INDF,W MOVWF VALUE2 DECF FSR,F MOVF INDF,W MOVWF VALUE1 RETURN ;endregion ENDING: END