; Kira Swab 
; Assembly Language Programming
; March 2001

.model  small
.stack  100h
.data

; This program uses input and output to calculate heating degree days
; for specified cities.  

titlestring   db    "    Heating Degree Days Derived from City Temperatures",0
citystring    db    "City Name: ",0
cityname      db    50 dup(0)
lowstring     db    "Low Temperature: ",0
highstring    db    "High Temperature: ",0
lowtemp		  dw	0
lowesttemp	  dw    115
hightemp      dw    0
highesttemp   dw    0
tempbyte      db    65
outcome1      db    " had ",0
outcome2      db    " heating degree days.",0
heatdays      dw     ?
daysum        dw     0
sumstring     db     "Total heating degree days for all the cities: ",0
loweststring  db     "Overall LOWEST temperature for all the cities: ",0
higheststring db     "Overall HIGHEST temperature for all the cities: ",0   

.code
extrn Readstring:proc, Writestring:proc
extrn Readint:proc, Writeint:proc, crlf:proc, Writeint_signed:proc

main proc

mov   ax,    @data
mov   ds,    ax
mov   dx,    offset titlestring
call  writestring
call  crlf

info:
call  crlf
call  crlf
mov   dx,    offset citystring  ;sets dx to location of 1st string
call  Writestring               ;writes 1st string with city name
mov   cx,    50

mov   dx,    offset cityname    ;sets dx with location of 2cd string
call  Readstring                ;reads a string of chars from input
cmp   ax,    0				    ;if no city name, jumps to end
je    totals

call    crlf                    ;line feed, carriage return

mov   dx,    offset lowstring   ;sets dx location of low temp prompt
call  Writestring               ;reads low temp string

call  Readint                   ;input an integer
mov   lowtemp,  ax	            ;moves integer to lowtemp
mov   bx, ax
cmp   lowesttemp, ax		    ;compares to find lowest temp
jg    newlow                    ;if temp lower, then replaces

lowmarker:
      
call    crlf

mov     dx,  offset highstring  ;sets dx location of hightemp prompt
call    Writestring             ;reads hi temp string to output
call    Readint                 ;input an integer
mov     hightemp, ax
cmp     highesttemp, ax
jl      newhigh

highmarker:

call    crlf

add    bx,  ax          ;adds the two temperatures
sar    bx,  1           ;divides by shifting to get average
mov    al,  tempbyte    ;moves 65 into register
sub    ax,  bx          ;subtracts the avg from 65, the norm temp
jz     none             ;jumps to none if average is equal to 65
js     none             ;jumps to none if avg is greater than 65
jmp    output


none:
mov   ax,   0           ;if avg is >= 65, heat days = zero

output:
call crlf
mov  dx,    offset cityname   ;displays cityname
call writestring
mov  dx,    offset outcome1   ;writes output single city 
call Writestring           
add  heatdays,  ax            ;moves heatdays to output
mov  bx,    10                ;moves decimal setting to output
call writeint
mov  dx,    offset outcome2   ;finishes city output
call Writestring
mov  bx,    0
add  bx,    heatdays          ;totals heating degree days
mov  daysum, bx
jmp  info                     ;jumps to beginning of loop

totals:

call crlf
call crlf

mov dx, offset sumstring       ;outputs last city string 
call Writestring               ; and total heating days
mov ax, daysum
call Writeint_signed

call crlf                      ;outputs lowest temp
mov dx, offset loweststring    ; for all cities
call Writestring
mov ax, lowesttemp
call Writeint_signed

call crlf                      ;outputs highest temp
mov dx, offset higheststring   ; for all cities
call Writestring
mov ax, highesttemp
call Writeint_signed
call crlf

jmp exit

newlow:
mov lowesttemp, ax
jmp  lowmarker

newhigh:
mov highesttemp, ax
jmp highmarker

exit:
call crlf
mov    ax, 4c00h
int    21h              ;exit to DOS

main endp
end main