# timetemplate.asm

a$)$ Rewrite the following $C$ function as an assembly$-$language subroutine with the same behavior.

void delay$($ int ms $)/*$ Wait a number of milliseconds, specified by the parameter value. $*/$

$\{$

int $i$;

while $(ms>0)$

$\{$

$ms=ms-1$;

$\frac{?}{?}**$ Executing the following for loop should take $1ms*/$

for $\frac{i}{*}=0$;$i<mn\; id="EditorElement\_2046958">4</mn><mn\; id="EditorElement\_2046959">7</mn><mn\; id="EditorElement\_2046960">1</mn><mn\; id="EditorElement\_2046961">1</mn>$;$i=i+1*$ The constant $4711$ must be easy to change! $*/$

$\{$

$/*$ Do nothing. $*/$

$\}$

$\}$

$\}$

Important note for all subroutines $($reprise$)$: When a subroutine returns, registers $$s0-$$$s7,$$$gp,$ $sp$,$

$$fp,$ and $ ra must have the same contents as when the subroutine was called. If a subroutine uses

any of these registers, the original contents must be saved, and restored before the subroutine

returns. As a special case, the contents of registers $$k0$ and $$k1$ may not be modified at all; these

registers are reserved for interrupt$-$handling code. All other register contents may be modified by

any subroutine.

b$)$ Replace the three$-$line delay subroutine from the previous Assignment, with your own

assembly$-$language subroutine de lay in file timetemplate.asm.

c$)$ Test your program using MARS. Adjust the constant in the for loop to get a delay of $1000ms$

when de lay is called with a parameter value of $1000,$ and a delay of $3000ms$ when de lay is called

with a parameter value of $3000..$macro PUSH $(\%$reg$)$

addi $sp$,$$sp$,-4$

sw $\%$reg,$0($$sp$)$

$.$end$\_$macro

$.$macro POP $(\%$reg$)$

lw $\%$reg,$0($$sp$)$

addi $sp$,$$sp$,4$

$.$end$\_$macro

$.$data

$.$align $2$

mytime: $.$word $0$x$5957$

timstr: $.$ascii "text more text lots of text$\backslash 0"$

$.$text

main:

# print timstr

la $a$0,$timstr

li $v$0,4$

syscall

nop

# wait a little

li $a$0,2$

jal delay

nop

# call tick

la $a$0,$mytime

jal tick

nop

# call your function time$2$string

la $a$0,$timstr

la $t$0,$mytime

lw $a$1,0($$t$0)$

jal time$2$string

nop

# print a newline

li $a$0,10$

li $v$0,11$

syscall

nop

# go back and do it all again

j main

nop

# tick: update time pointed to by $a$0$

tick: lw $t$0,0($$a$0)$ # get time

addiu $t$0,$$t$0,1$ # increase

andi $t$1,$$t$0,0$xf # check lowest digit

sltiu $t$2,$$t$1,0$xa # if digit $$ a$,$ okay

bnez $t$2,$tiend

nop

addiu $t$0,$$t$0,0$x$6$ # adjust lowest digit

andi $t$1,$$t$0,0$xf$0$ # check next digit

sltiu $t$2,$$t$1,0$x$60$ # if digit okay

bnez $t$2,$tiend

nop

addiu $t$0,$$t$0,0$xa$0$ # adjust digit

andi $t$1,$$t$0,0$xf$00$ # check minute digit

sltiu $t$2,$$t$1,0$xa$00$ # if digit $$ a$,$ okay

bnez $t$2,$tiend

nop

addiu $t$0,$$t$0,0$x$600$ # adjust digit

andi $t$1,$$t$0,0$xf$000$ # check last digit

sltiu $t$2,$$t$1,0$x$6000$ # if digit okay

bnez $t$2,$tiend

nop

addiu $t$0,$$t$0,0$xa$000$ # adjust last digit

tiend: sw $t$0,0($$a$0)$ # save updated result

jr $ra # return

nop

# you can write your code for subroutine "hexasc" below this line

#