Write an ARMv$8$ assembly function $($using Linaro Toolchain$)$ named count$\_$wd that finds the number of three$-$letter words in a given sentence. The base address of the input sentence $($C$-$String$)$ is passed using register X$1$ and the number of three letter words is returned using register X$0.$ Write an assembly program $($main$)$ to test the assembly function. Create a static character array $($C$-$String$)$ for the input sentence which is stored in the data section of the assembly code and the base address is passed to the function. The user's input sentence will be in correct format without errors and will not have punctuation marks. The maximum size of the input sentence is $63$ characters. Store the returned value $($number of three$-$letter words$)$ from the function in register X$20.$ Assume all the registers are used by the main $($caller$)$ program to store some data before calling the function. Assemble, test, and simulate the assembly code using DS$-5$ simulator. Do not upload the entire DS$-5$ project. Only upload the assembly file $(.$S file$)$ from the DS$-5$ project. Comment your assembly code.

Example Assembly code $($string$\_$code.S$)$ that shows how to store and read strings:

$/*$ This assembly code simply loads the lower case alphabets from the below $*/$

$/*$ static array $($str $1)$ and converts the alphabets to a upper case alphabets $*/$

$/*$ and stores the upper case alphabets in static array $($str $2)*/$

$.$data $//$ data section

$.$type str$1,\%$object $//$ defining object str$1$

$.$size str$1,4//$ string $1$

$.$type str$2,\%$object $//$ defining object str$2$

$.$size str$2,4//$ string $2$

str$1$:

$.$asciz "abc$\backslash 0"//$ char values as string

str$2$:

$.$byte $0,0,0,0//$ null char values

$.$text $//$ program section

$.$global main $//$ main

$.$arch armv$8-$a$+$fp$+$simd $//$ processor type

$.$type main, $\%$function $//$ main function

main:

ADR X$9,$ str$1//$ Load the array address to X$9$

ADR X$10,$ str$2//$ Load the array address to X$10$

LDURB W$19,[$X$9,$ #$0]//$ Load the first char from string $1$

SUB W$19,$ W$19,$ #$32//$ Convert to upper case

STURB W$19,[$X$10,$ #$0]//$ Store the upper case alphabet to string $2$

LDURB W$19,[$X$9,$ #$1]//$ Load the second char from string $1$

SUB W$19,$ W$19,$ #$32//$ Convert to upper case

STURB W$19,[$X$10,$ #$1]//$ Store the upper case alphabet to string $2$

LDURB W$19,[$X$9,$ #$2]//$ Load the third char from string $1$

SUB W$19,$ W$19,$ #$32//$ Convert to upper case

STURB W$19,[$X$10,$ #$2]//$ Store the upper case alphabet to string $2$

LDURB W$19,[$X$9,$ #$3]//$ Load the null from string $1$

STURB W$19,[$X$10,$ #$3]//$ Store the null to string $2$

NOP