entry:

ldi r$16,0$xFF

mov r$1,$ r$16$

ldi r$22,0$x$10$

ldi r$16,0$xCC

mov r$4,$ r$16$

$//$ DO NOT EDIT ABOVE THIS LINE $//$

$/**$ WARNING:

Do not modify the data in the following registers unless specified

by the exercise:

R$1($Ex $2\mathrm{.}1)$

R$4($Ex $2\mathrm{.}9)$

R$20($Ex $2\mathrm{.}2)$

R$22($Ex $2\mathrm{.}6)$

$*/$

$/**$ EX: $2\mathrm{.}0$

TASK: Write assembly code to add the numbers $53$ and $34$ together and

store the resulting sum in register R$0.$

$*/$

$/**$ CODE: Write your code for Ex $2\mathrm{.}0$ above this line. $*/$

mov r$16,$ r$0$

call avremu$\_$r$16$out

$/**$ EX: $2\mathrm{.}1$

TASK: Using the "and" instruction, clear only bits $2,3,$ and $7$ of

register R$1.$

$*/$

$/**$ CODE: Write your code for Ex $2\mathrm{.}1$ above this line. $*/$

mov r$16,$ r$1$

call avremu$\_$r$16$out

$/**$ EX: $2\mathrm{.}2$

TASK: Using the "ori" instruction, set only bits $1,3,$ and $5$ of

register R$20.$

$*/$

$/**$ CODE: Write your code for Ex $2\mathrm{.}2$ above this line. $*/$

mov r$16,$ r$20$

call avremu$\_$r$16$out

$/**$ EX: $2\mathrm{.}3$

TASK: Using exactly one instruction, add $1$ to the value of R$0.$

See AVR Instruction Set Manual Table $5-2$ Arithmetic and Logic

Instructions on p$.18.$

$*/$

$/**$ CODE: Write your code for Ex $2\mathrm{.}3$ above this line. $*/$

mov r$16,$ r$0$

call avremu$\_$r$16$out

$/**$ EX: $2\mathrm{.}4$

TASK: Write assembly code to add $44$ to $14685,$ storing the resulting

sum in register pair R$31$:R$30($low byte in R$30).$

$*/$

$/**$ CODE: Write your code for Ex $2\mathrm{.}4$ above this line. $*/$

mov r$16,$ r$30$

call avremu$\_$r$16$out

mov r$16,$ r$31$

call avremu$\_$r$16$out

$/**$ EX: $2\mathrm{.}5$

TASK: Follow the steps below to complete this exercise.

$1.$ Encode the decimal value $-4$ as a two's complement $8-$bit number.

$2.$ Express the result from step $1$ as a hexadecimal literal.

$3.$ Swap the two nibbles of the result from step $2.$

$4.$ Load the result of step $3$ into register R$21.$

$*/$

$/**$ CODE: Write your code for Ex $2\mathrm{.}5$ above this line. $*/$

mov r$16,$ r$21$

call avremu$\_$r$16$out

$/**$ EX: $2\mathrm{.}6$

TASK: Write assembly code to subtract the value in R$22$ from $91$ using

the "add" instruction, storing the resulting value in R$23.$

$*/$

$/**$ CODE: Write your code for Ex $2\mathrm{.}6$ above this line. $*/$

mov r$16,$ r$23$

call avremu$\_$r$16$out

$/**$ EX: $2\mathrm{.}7$

TASK: Write assembly code to multiply the number $20$ by $2$ using the

$"$lsl$"$ instruction, storing the resulting value in R$2.$

$*/$

$/**$ CODE: Write your code for Ex $2\mathrm{.}7$ above this line. $*/$

mov r$16,$ r$2$

call avremu$\_$r$16$out

$/**$ EX: $2\mathrm{.}8$

TASK: Write assembly code to divide the number $-37$ by $4$ using the

"asr" instruction, storing the resulting value in R$3.$

$*/$

$/**$ CODE: Write your code for Ex $2\mathrm{.}8$ above this line. $*/$

mov r$16,$ r$3$

call avremu$\_$r$16$out

$/**$ EX: $2\mathrm{.}9$

TASK: Write assembly code to toggle the most significant bit, and

least significant $4$ bits of R$4.$

$*/$

$/**$ CODE: Write your code for Ex $2\mathrm{.}9$ above this line. $*/$

mov r$16,$ r$4$

call avremu$\_$r$16$out

$//$ END OF TUTORIAL$02$ EXERCISES $//$

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

ldi r$16,0$x$22//$ DISP$\_$EN $($PB$1)|$ DISP$\_$DP $($PB$5)$

sts $0$x$0420,$ r$16//$ Set as outputs

sts $0$x$0424,$ r$16//$ Drive high

break

ldi r$16,0$x$20//$ DISP$\_$DP $($PB$5)$

ldi r$17,0$x$00$

loop:

$//$ Delay

com r$17$

brne loop

inc r$18$

brne loop

inc r$19$

brne loop

$//$ Toggle DP LED

sts $0$x$0427,$ r$16$

rjmp loop $//$ Loop indefinitely

$//$ This procedure outputs the contents of R$16$ when using the emulator.

$//$ Address $0$x$1500$ is reserved in the memory map so this procedure has

$//$ no effect when running on the ATtiny$1626$ hardware.

avremu$\_$r$16$out:

sts $0$x$1500,$ r$16$

ret