EE3376 – Embedded Systems - Fall 2006 - Exam 3 – MacDonald – Page 1
Student Name:______________________________ Student ID: _______________
Problem 3
Below is the code for a simple subroutine (do_it) that uses one local variable
implemented with a stack frame. Given the initialized values in the table, fill in the rest
of the table describing the registers and memory locations at different times during the
execution of the function.
TEMP set -1
do_it: pshb
pshx
tsx
leas TEMP,SP
movb #$20, TEMP, X
suba TEMP, X
txs
pulx
pulb
rts
Location Prior to JSR After LEAS After SUBA AFTER RTS
a10
b1
x 1000
y 3000
sp 2002
mem 1ff9 0
mem 1ffa 0
mem 1ffb 0
mem 1ffc 0
mem 1ffd 0
mem 1ffe 0
mem 1fff 0
mem 2000 0
mem 2001 0
