1. Yung-Hsiang Lu Purdue University
Stack Memory 3
Yung-Hsiang Lu
Purdue University

2. Stack Memory may store three things:
return location
arguments
local variables

3. Memory is "address-value" pairs
Memory is organized into rows. Each row has an address and stores a value.
The addresses are always distinct.
You can think of the addresses in memory as home addresses and the values are the names of the families living at that address
Address
Value
001
C Language
002
Year 2016
003 5
004
36.97
Taylor
Smith
Johnson

4. Some Rules about Addresses
Addresses are assigned by operating systems
Two different pieces of information have different addresses, guaranteed by operating systems
A programmer has no control of the address given by the operating system
"Zero" is never a valid address. C programs has a special symbol (NULL) for this address.

5. Value Address Frame of f3 106 z = 3.2 105 y = 7 104 VA 102 103 line 5
void f1(int x) 2 { 3
int a; 4
a = f3(7, 3.2); 5
... 6 7 } 8
int f3(int y,
double z) 9 10 11
return ...
Frame of f3
106
z = 3.2
105
y = 7
104
VA 102
103
line 5
Frame of f1
102
a =
101
x =
100
line ?

6. Memory Organization Frame Symbol Address Value f3 z 106 3.2 y 105 7 VA
void f1(int x) 2 { 3
int a; 4
a = f3(7, 3.2); 5
... 6 7 } 8
int f3(int y,
double z) 9 10 11
return ...
Frame
Symbol
Address
Value f3 z
106
3.2 y
105 7 VA
104
102 RL
103
line 5 f1 a x
101
100
line ?
RL: return location
VA: value address

7. Frames and Symbols for Humans Computers Know Only Addresses and Values

8. Memory Organization Frame Symbol Address Value f3 z 106 3.2 y 105 7 VA
For Humans 1
void f1(int x) 2 { 3
int a; 4
a = f3(7, 3.2); 5
... 6 7 } 8
int f3(int y,
double z) 9 10 11
return ...
Frame
Symbol
Address
Value f3 z
106
3.2 y
105 7 VA
104
102 RL
103
line 5 f1 a x
101
100
line ?
RL: return location
VA: value address

9. Stack Memory may store three things:
return locations
arguments
local variables
value addresses