Question

(By using HCS12 assembly)You have a table of 10 Fahrenheit temperatures stored as words in Flash. Use the posted lab1_b.asm file as starting point. Write an assembly program that converts every Fahrenheit temperature element in Fahrs array into a Celsius temperature and stores the result at the corresponding element in Cels array. Use this relation: C = (5/ 9) * (F 32) for conversion. Because temperatures are signed, you will have to use signed multiplication and division instructions in your work.

lab1_b.asm file:

; export symbols
            XDEF Entry, _Startup            ; export 'Entry' symbol
            ABSENTRY Entry        ; for absolute assembly: mark this as application entry point

ROMStart:            EQU $4000
Temps_Count:      EQU 10

; variable data goes in RAM
            ORG $1000

Cels:    DS.W 10    ; an array of 10 words!

; code section
            ORG   ROMStart
Entry:
_Startup:

        
          ; for every F in Fahrs
          ;    convert F into C
          ;    store C into the corresponding location in Cels
        
        
        

Here:        
          BRA Here

    
    

; an array of 10 constant words!
Fahrs: dc.w 0,20,40,60,80,100,120,140,160,180

;**************************************************************
;*                 Interrupt Vectors                          *
;**************************************************************
            ORG   $FFFE
            DC.W Entry           ; Reset Vector

Answer 1

SOLUTION:

N.B : FOLLOWING code is compiled in assembly 8086 language .

data_seg segment

temp dw ? ; input number

ten dw 10 ; Defining constant ten for extracting the digits

Fahrs dw 1000 dup(?)

cels dw 1000 dup(?)

msg1 dw 10,13, ” Total how many temperature : $ ”

msg2 dw 10,13, ” enter temp in Fahrenheit: $ ”

msg3 dw 10,13, ”Temp. in Celsius are following : $ ”

five dw 5

nine dw 9

n dw ?

counter dw 0

data_seg ends

code_seg segment

assume cs: code_seg, ds: data_seg

print_string proc ; Procedure to print a string on monitor screen

pop si ; Save Top of Stack(ToS) content (Return Address) in SI register

pop dx

mov ah, 9 ; Put the service code for printing string on monitor screen

int 21h ; Invoke the Software Interrupt 21H

push si ; Push the saved Return Address onto the stack

ret ; Return to Main Program

print_string endp

read_char proc ; Procedure to read a character from key board

pop di ; Save top of stack content (Return Address) in DI register

mov ah, 1 ; Put service code for reading a character from keyboard

int 21h ; Invoke the Software Interrupt

mov ah, 0

push ax ; Push read character onto stack

push di ; Push the saved Return Address onto the stack

ret ; Return to the main program

read_char endp

read_number proc ; Procedure to read a number

pop si ; Pop the ToS content (the Return Address) into SI

mov bx,0 ; Initialize bx, dx

mov dx,0

next_digit:

call read_char

pop ax ; Get the read character in AX from ToS

cmp al, 0Dh ; Check if the input character is CR indicating end of the number

je done

sub al, 30h ; Convert ASCII to binary

mov cl, al ; Save the digit value in CX as a word

mov ch, 0 ;

mov ax, bx ; Get back the saved partial MS digits value to AX

mul ten ; Shift left the partial MS digits value by 1 digits

add ax, cx ; Add the last digit to the shifted MS digits value

mov bx, ax ; Save the new partial MS digits value in BX

jmp next_digit ; loop back read the next digit

done: push bx ; Push the read number onto the stack

push si ; Push the Return Address back on the ToS

ret ; Return to the main program

read_number endp

start:

mov ax, data_seg ; Initialize DS

mov ds, ax

push offset msg1 ; Print the Input Prompt Message on Screen

call print_string

call read_number ; Call the number read procedure.

pop dx ; Take the number into dx from ToS.

mov n, dx ; Place the input number in the n variable

lea di, Fahrs

lea bi cels

mov counter,0

repeat_step:

mov cx,n

cmp counter,cx

je print_part

push offset msg2 ; Print the Input Prompt Message on Screen

call print_string

call read_number ; Call the number read procedure.

pop dx

mov [di],dx

sub dx,32

mov ax,dx

mul five

div nine

mov [bi],ax

add bi,2

add di,2

inc counter

jmp repeat_step

printing_part:

lea dx ,msg3

mov ah,9

int 21h

mov cx,n

mov counter,cx

lea bi,cels

repeat_digit:

cmp counter ,0

je stop

mov dx,[bi]

mov ah,2

int 21h

add bi,2

dec counter

jmp repeat_digit

stop:

mov ah, 4ch ; Enter the service code to AH register

mov al, 0 ; Set return status of the program

int 21h ; Invoke the ISR to return the control to the Operating System

code_seg ends

end start