SUBROUTINE TO CONVERT CHARACTERS IN MEMORY TO A DECIMAL VALUE

***********************************************************************************************************
                              AUTHOR:  ANUEBUNWA VICTOR OGECHUKWU                                            

               SUBROUTINE TO CONVERT CHARACTERS IN MEMORY TO A DECIMAL VALUE                            
 Subroutine CHAR2INTR converts characters in memory to a decimal value and stores it in AX.             
 i.e '1','2','3','4' in memory ==> 1234 in AX                                                          
 .......................................................................HOW TO USE......................................................................
 (1) Load the starting address of the memory into SI register.                                          
 (2) Call CHAR2INTR.                                                                                                          ***********************************************************************************************************

;         SAMPLE PROGRAM
.MODEL SMALL
.STACK
.DATA
    AVON DB ?
.CODE
START:        MOV AX, @DATA
            MOV DS, AX
           
            MOV AH, 3FH
            LEA DX, AVON
            INT 21H                    ;Reads characters into memory, using AVON as a starting address
           
            LEA SI, AVON            ;Loads starting address into SI
            CALL CHAR2INTR            ;Calls CHAR2INTR to convert characters to a decimal value
            MOV DX, AX                ;Puts decimal value into DX
            MOV AH, 02H
            INT 21H                    ;Displays character whose ASCII code equals the decimal value
           
            MOV AH, 4CH
            INT 21H

;Subroutine CHAR2INTR
CHAR2INTR PROC
            PUSH BX
            PUSH CX
            PUSH DX
            PUSH SI
            PUSHF
           
            MOV AX, 0000H
            MOV CX, 0000H
CLOOP1:        MOV AX, [SI]            ;Loads character currently pointed to into AX
            CMP AL, '9'
            JNLE XCLOOP1            ;Exits loop if character is not less or equal to '9'
            CMP AL, '0'
            JNGE XCLOOP1            ;Exits loop if character is not greater or equal to '0'
            INC CL                    ;Else, Keeps count of the number of characters being processed
            INC SI                    ;Moves pointer to the next character
            SUB AL, 30H                ;Converts character to digit
            PUSH AX                    ;Pushes digit to stack
            JMP CLOOP1                ;continues loop

XCLOOP1:    MOV BX, 0001H
            MOV DX, 0000H
CLOOP2:        CMP CL, 0                ;Checks number of characters processed
            JE XCLOOP2                ;Exits loop if no character was processed i.e CL = 0
            POP AX                    ;Else, pops digit from stack to AX
            MUL BL                    ;Multiplies digit with it's PLACEMENT-VALUE. RECALL: unit = 1, tens = 10, hundreds = 100 ...
            ADD DX, AX                ;Adds (digit * PLACEMENT-VALUE)s together. RECALL: 234 = (4 * 1) + (3 * 10) + (2 * 100) where 1,10,100 represent their PLACEMENT-VALUES
            MOV AX, 10               
            MUL BL                    ;Multiplies current PLACEMENT-VALUE by 10 to advance to the next PLACEMENT-VALUE.
            XCHG AX, BX                ;Puts result from multiplication back to BX
            DEC CX                    ;Reduces count
            JMP CLOOP2                ;Loop continues
           
XCLOOP2:    MOV AX, DX                ;Moves converted value to AX
           
            POPF
            POP SI
            POP DX
            POP CX
            POP BX
            RET
CHAR2INTR ENDP
;End of Subroutine CHAR2INTR

END START

view in pastebin

PROCEDURE TO DISPLAY CHARACTERS IN MEMORY

********************************************************************************************************************
                       AUTHOR: ANUEBUNWA VICTOR OGECHUKWU                                                        

                    PROCEDURE TO DISPLAY CHARACTERS IN MEMORY                                                   
 Procedure DISPLAY displays characters in memory starting from a given address till it encounters CARRIAGE-RETURN.
 ............................................HOW TO USE..........................................................
 (1) Load the starting address of the memory into SI register.                                                   
 (2) Call DISPLAY.                                                                                           
;********************************************************************************************************************

;         SAMPLE PROGRAM
.MODEL SMALL
.STACK
.DATA
    AVON DB ?
.CODE
START:        MOV AX, @DATA
            MOV DS, AX
           
            MOV AH, 3FH                ;Input string function
            LEA DX, AVON
            INT 21H
           
            LEA SI, AVON
            CALL DISPLAY
           
            MOV AH, 4CH
            INT 21H

;;Procedure DISPLAY
DISPLAY PROC
            PUSH AX
            PUSH DX
            PUSH SI
            PUSHF
           
            MOV AH, 02H
DLOOP1:        MOV DL, [SI]            ;Moves character at current address to DL
            CMP DL, 13
            JE XDLOOP1                ;Exits loop if DL contains CARRIAGE-RETURN
            INT 21H                    ;Else, displays character
            INC SI                    ;Moves to next address
            JMP DLOOP1                ;Continues loop
           
XDLOOP1:    POPF
            POP SI
            POP DX
            POP AX
            RET
DISPLAY ENDP
;End of procedure DISPLAY
   
END START

view in pastebin

PROCEDURE TO COLLECT MULTIPLE DIGITS AS INPUT IN 8086 ASSEMBLY

;PROCEDURE TO COLLECT MULTIPLE DIGITS AS INPUT IN 8086 ASSEMBLY
;AUTHOR: ANUEBUNWA VICTOR O.
;ASSEMBLER: MASM611

;You should have the following declared in your data segment.
value DB 0000H
e1 DB "Wrong input",'$'

e2 DB 'No value entered',0AH,0DH,'Program exiting...','$'


;You may avoid using PUSHA and POPA if it gives error during assembling but be sure to backup needed values in AX,BX,CX and DX before calling this procedure.

;Beginning of procedure
read proc
PUSHA                           ;Push current values in register to stack
MOV AX, 0000H ;
MOV CX, 0000H ;
MOV BX, 0000H ;
MOV DX, 0000H ;Clears register AX,BX,CX and DX
.tryloop1:         MOV AH, 01H
INT 21H ;Calls DOS funtion to receive a character
JMP check ;Jumps to check character recieved
continue_loop: ;Where loop continues assuming character passes check
MOV BX, 0000H ;Clears BX again
MOV BL, AL ;Moves AL to BL
SUB BX, 30H ;Subtracts 30H to get the actual value of character
PUSH BX ;Push BX to stack
INC CX ;Increments CX to track the lenght of the value
CMP AL, 0DH ;Checks if character was carriage return
JNE .tryloop1 ;Jumps if not carrige return

CMP CX, 1 ;Checks if no value was entered
JE error_msg2 ;jumps if no value was entered
POP AX ;Pops out last value in stack(carrige return)
dec CX ;Decrements counter

MOV BX, 1 ;initialize multiplier
.tryloop2:          MOV AX, 0000H ;Clears AX
POP AX ;Pops data to AX
MUL BX ;Multiplies AX by BX
ADD value, AX ;Add AX to value

XCHG AX, BX ;Exchanges AX and BX
MOV BX, 10 ;Moves 10 into BX
MUL BX ;Multiplies AX by BX(containing 10)
XCHG AX, BX ;Exchanges back AX and BX
dec CX ;Decrements counter
JNE .tryloop2 ;Repeats until CX equals zero

MOV AH, 02H
MOV DL, 0aH
INT 21H ;Prints line-feed
POPA                      ;Pops values of register before procedure call from stack
RET ;returns control
read endp                                          ;End of procedure.

check: CMP AL, 0DH ;Checks if the character is carriage return

JE continue_loop ;Jumps back into loop if carriage return

CMP AL, '0' ;Checks if a non-digit was entered

JNGE error_msg

CMP AL, '9'

JNLE error_msg ;Displays error if a non-digit was entered

JMP continue_loop ;Else it jumps back into loop

error_msg: MOV AH, 02H

MOV DL, 0AH

INT 21H ;Prints line-feed

LEA DX, e1

MOV AH, 09H

INT 21H ;Prints string

JMP start ;Restarts program(assuming you have Start: as your starting label)


error_msg2: MOV AH, 02H
MOV DL, 0AH
INT 21H ;Prints line-feed
LEA DX, e2
MOV AH, 09H
INT 21H ;Prints string
JMP stp ;Stops program

view in pastebin