; ----------------------- TASK -------------------------
;
; e-310 Column-wise 2d-array
;
; Insert code to print out the value of array element
; t[i,j]. Array t has 4 rows and 10 columns. Values for
; i and j are read from input. Negative i completes the
; program.
;
; Array t is stored column-wise. For example,
; the 1st item in memory at memory location t is t[0,0],
; and memory location t+1 has value is t[1,0].
;
; You may assume, that both i (0..3) and j (0..9) are
; within their limits.
;
; Test with input 1,1,2,3,3,9,-1.
;
; Estimated code size: max 10 instructions.

; ---- BEGINNING OF CODE -- DO NOT MODIFY --------------

t ds 40  ; 4 * 10 array (4 rows, 10 columns)
i dc 0  ; row index: 0..3
j dc 0  ; column index: 0..9

main push sp, =t
     push sp, =40
     call sp, init

loop in r1, =kbd
     store r1, i
     jneg  r1, done
     in r1, =kbd
     store r1, j

; ------------- YOUR CODE -------------------------------

; Insert code to print out the value of array element
; t[i,j]. Array t has 4 rows and 10 columns. Values for
; i and j are read from input. Negative i completes the
; program.

; Array t is stored column-wise. For example,
; the 1st item in memory at memory location t is t[0,0],
; and memory location t+1 has value is t[1,0].

        ; calc the column
        load r1, =4
        mul r1, j

        add r1, i

        ; load value to reg so we can print
        load r2, t(r1)
        out r2, =crt

; -------- END OF CODE -- DO NOT MODIFY -----------------

     jump loop

done svc sp, =halt

;  init (pt, sz) - initialize array pt[sz]
;  pt call-by-ref
;  sz call-by-value
pt  equ -3
sz equ -2
init  pushr sp
      load r5, =85  ; mask
      load r1, =0
      load r2, pt(fp)
ini   load r4, r1
      and r4, r5
      store r4, (r2)  ; initialize array element
      add  r1, =1

      add r2, =1

      comp r1, sz(fp)
      jles ini

      popr sp
      exit sp, =2