Consider a function sum below designed to calculate the sum of the neighbors of an element at position $($i$,$ j$)$ in a $2$D array represented in a linear array format. Here's a quick breakdown:

$$ val is a pointer to the array.

$($i$,$ j$)$ are the coordinates of the current element.

$$ n is the number of columns in the $2$D array.

$$ The function calculates the sum of the elements directly above, below, to the left, and to the right of $($i$,$ j$)$

long sum $($long $*$val$,$ long i$,$ long j$,$ long n$)\{/*$ Sum neighbors of i$,$j $*/$

long up$,$ down, left, right, sum;

up $=$ val$[($i$-1)*$n $+$ j $]$;

down $=$ val$[($i$+1)*$n $+$ j $]$;

left $=$ val$[$i$*$n $+$ j$-1]$;

right $=$ val$[$i$*$n $+$ j$+1]$;

sum $=$ up $+$ down $+$ left $+$ right;

return sum;

$\}$

The function is rewritten as an optimized function long sum$\_$opt

long sum$\_$opt$($long $*$val$,$ long i$,$ long j$,$ long n$)\{$

long up$,$ down, left, right, sum, opt $=$ i$*$n $+$ j;

up $=$ val$[$opt $-$ n$]$;

down $=$ val$[$opt $+$ n$]$;

left $=$ val$[$opt $-1]$;

right $=$ val$[$opt $+1]$;

sum $=$ up $+$ down $+$ left $+$ right;

return sum;

$\}$

Write assembly in RISC V codes for the function with and without optimization. Comment on the results.