$/**$ CODE: Include any header files and macro definitions here. $*/$

#include

#include

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$/**$ EX: E$3\mathrm{.}0$

In this week's tutorial, we used some functions from the libraries

qutyio.h and stdio.h to output data via the serial interface. This can

be a useful tool for debugging your program.

To use the serial interface you first need to initialise the required

hardware on the ATtiny$1626,$ and, if you wish to use certain functions

from the stdio.h library, also redirect the standard input $($stdin$)$ and

standard output $($stdout$)$ streams to the serial interface.

This has been done for you in the qutyio.h library, through the function

serial$\_$init$().$

In this exercise, we will use the printf$()$ function to output formatted

strings to stdout. The syntax for printf$()$ is:

printf$([,$ arguments$]...)$;

where is a string that may contain format specifiers

that are replaced by the values of one or more $[$arguments$].$ If no format

specifiers are present in this string, no additional arguments are

required in this function call. Some examples are provided below:

printf$("$CAB$202")-$ prints the string "CAB$202"$ to stdout.

printf$("")-$ prints a space to stdout.

printf$("\%02$X$",$ x$)-$ prints the $8-$bit integer $"$x$"$ to stdout,

formatted as two uppercase hexadecimal digits,

with $0$ padding.

printf$("\%$u$",$ x$)-$ prints the $16-$bit integer $"$x$"$ to stdout, encoded

as an unsigned decimal number. Prefix $\text{'}$u$\text{'}$ with

$\text{'}$l$\text{'}$ to print an unsigned $32-$bit integer.

printf$("$

$")-$ prints a newline character to stdout.

Note that the format string can consist of multiple parts, for example:

uint$16\_$t x $=0$xAB;

printf$("$x: $0$x$\%03$X $=\%$lu

$",$ x$,$ x$)$;

prints:

$($START$)$x: $0$x$0$AB $=171$

$($END$)$

TASK: Write C code that performs the following steps:

$1.$ Include qutyio.h and stdio.h$,$ and initialise the serial interface

using serial$\_$init$().$

$2.$ Create a variable "state" to store your student number in decimal.

You should use the smallest fixed$-$width integer type from the

stdint.h header file that can hold this value.

$3.$ Iterate through all the numbers from $0$ to $255$ in sequence, and for

each number, perform the following steps:

a$.$ Take the bitwise XOR of the number with the variable "state",

storing the result back into "state".

b$.$ Rotate right the bits in "state" at least one time, and until the

LSB of "state" is a zero. If there are no cleared bits in "state",

do nothing.

c$.$ Print the least significant two bytes of "state" to the stdout

as four uppercase hexadecimal digits, followed by a space.

The prefix $"0$x$"$ is not required.

d$.$ Inspect bits $11-4$ of "state" $($where bit $0$ is the LSB$),$ and:

$-$ if the most significant nibble of this byte is equal to the

second last digit of your student number, print the word "foo"

to stdout.

$-$ if the least significant nibble of this byte is equal to the

final digit of your student number print the word "bar" to

stdout.

$-$ if both of the above conditions are satisfied, print "foobar".

e$.$ Print a newline character to stdout.

After step $3,$ your program should have printed $256$ lines to stdout.

EXAMPLES:

Assuming the student number n$12345678,$ if after step $3$b "state" holds:

$-0$xE$00$B$\_$C$614,$ the program should print: $"$C$614$

$"$

$-0$xD$76$F$\_77$F$0,$ the program should print: $"77$F$0$ foo

$"$

$-0$x$7802\_$F$184,$ the program should print: $"$F$184$ bar

$"$

$-0$xAFB$6\_$F$784,$ the program should print: $"$F$784$ foobar

$"$

after step $3$e$.$

$*/$

int main$($void$)$

$\{$

$/**$ CODE: Write your code for Ex E$3\mathrm{.}0$ below this line. $*/$

$/**$ CODE: Write your code for Ex E$3\mathrm{.}0$ above this line. $*/$

$//$ END OF EXTENSION$03$ EXERCISES $//$

$//$ DO NOT EDIT BELOW THIS LINE $//$

while $(1)$

; $//$ Loop indefinitely

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