$[50$ points$]$ Consider the following program:

P$1$: $\{$

shared int $x$;

$x=10$;

while $(1)\{$

$x=x-1$;

$x=x+1$;

if $(x10)$

printf$("x$ is $\%d,x)$

$\}$

$\}$

P$2$ : $\{$

shared int $x$;

$x=10$;

while $(1)\{$

$x=x-1$;

$x=x+1$;

if $(x10)$

printf $("x$ is $\%d,x)$

$\}$

$\}$

Note that the scheduler in a uniprocessor system would implement pseudo parallel

execution of these two concurrent processes by interleaving their instructions, without

restriction on the order of the interleaving.

$1\mathrm{.}1.[25$ points$]$ Show a sequence $($i$.$e$.,$ trace the sequence of interleavings of statements$)$

such that the statement $"x$ is $10"$ is printed.

$1\mathrm{.}2.[35$ points$]$ Show a sequence such that the statement $"x$ is $8"$ is printed.

You should remember that the increment$/$decrements at the source language level are

not done atomically, that is$,$ the assembly language code:

LD R$0,\frac{x}{*}*$ load R$0$ from memory location $x*\frac{*}{?}$

INCR RO $/*$ increment RO $*/$

STO RO$,\frac{x}{*}*$ store the incremented value back in $x*\frac{*}{?}$