05-LibraryProcedures.pptLibrary Procedures

Libraries and Procedures
COE 205
Computer Organization and Assembly Language
Computer Engineering Department
King Fahd University of Petroleum and Minerals

Libraries and Procedures COE 205 – KFUPM
© Muhamed Mudawar – slide 2
Presentation Outline
 Link Library Overview
 The Book's Link Library
 Runtime Stack and Stack Operations
 Defining and Using Procedures
 Program Design Using Procedures

Link Library Overview
 A link library is a file containing procedures that have
been assembled into machine code
 Can be constructed from one or more object (.OBJ) files
 Textbook provides link libraries to simplify Input/Output
 Irvine32.lib is for programs written in 32-bit protected mode
 Irvine16.lib is for programs written in 16-bit real-address mode
 You can also construct your own link library
 Start with one or more assembler source files (extension .ASM)
 Assemble each source file into an object file (extension .OBJ)
 Create an empty link library file (extension .LIB)
 Add the OBJ files to the library file using the Microsoft LIB utility

Procedure Prototypes & Include File
 Before calling an external procedure in a library …
 You should make the external procedure visible to your program
 To make an external procedure visible, use a prototype
 Examples of Procedure Prototypes
ClrScr PROTO ; Clear the screen
WriteChar PROTO ; Write a character
WriteInt PROTO ; Write a signed integer
ReadString PROTO ; Read a string
 The procedure prototypes are placed in an include file
 The Irvine32.inc include file (extension .INC) contains the
prototypes of the procedures that are defined in Irvine32.lib
 The INCLUDE directive copies the content of the include file

Calling a Library Procedure
 To call a library procedure, use the CALL instruction
 Some procedures require input arguments
 We can pass arguments in registers
 The following example displays "1A8C" on the console
INCLUDE Irvine32.inc
.code
mov eax, 1A8Ch ; eax = argument
call WriteHex ; Display eax in hex
call Crlf ; Display end of line
...
Crlf PROTO
WriteHex PROTO
...
Irvine32.inc

Linking to a Library
 Your program links to Irvine32.lib
 The link32.exe executable file is the 32-bit linker
 The linker program combines a program's object file with one or
more object files and link libraries
 To link myprog.obj to Irvine32.lib & kernel32.lib type …
link32 myprog.obj Irvine32.lib kernel32.lib
Your program
kernel32.lib
kernel32.dll
Irvine32.lib
links to
executes
links to
can link to
 If a procedure you are calling is
not in the link library, the linker
issues an error message
 Kernel32.dll is called a dynamic
link library, part of MS-Windows.
It contains procedures that
perform character-base I/O

Next . . .

The Book's Link Library
 The book's link library Irvine32.lib consists of …
 Input procedures: ReadInt, ReadChar, ReadString, …
 Output procedures: Clrscr, WriteInt, WriteHex, WriteString, …
 Dumping registers and memory: DumpRegs and DumpMem
 Random number generation: Randomize, Random32, …
 Cursor control procedures: GetMaxXY and Gotoxy
 Miscellaneous procedures: SetTextColor, Delay, …
 Console Window
 Text-only window created by MS-Windows (cmd.exe program)
 The Irvine32.lib writes output to the console (standard output)
 The Irvine32.lib reads input from the keyboard (standard input)

Output Procedures
Procedure Description
Clrscr Clears screen, locates cursor at upper left corner.
Crlf Writes end of line sequence (CR,LF) to standard output.
WriteChar Writes character in register AL to standard output.
WriteString Writes a null-terminated string to standard output.
String address should be passed in register EDX.
WriteHex Writes EAX in hexadecimal format to standard output.
WriteInt Writes EAX in signed decimal format to standard output.
WriteDec Writes EAX in unsigned decimal format to standard output.
WriteBin Writes EAX in binary format to standard output.

Example: Displaying a String
.data
str1 BYTE "Assembly language is easy!",0
.code
mov edx, OFFSET str1
call WriteString
call Crlf
Displaying a null-terminated string
Moving the cursor to the beginning of the next line
Adding the CR/LF control characters to the string definition
.data
str1 BYTE "Assembly language is easy!",13,10,0
.code
call WriteString
CR LF
No need to call Crlf

Example: Displaying an Integer
.code
mov eax, -1000
call WriteBin ; display binary
call Crlf
call WriteHex ; display hexadecimal
call Crlf
call WriteInt ; display signed decimal
call Crlf
call WriteDec ; display unsigned decimal
call Crlf
1111 1111 1111 1111 1111 1100 0001 1000
FFFFFC18
-1000
4294966296
Sample output

Input Procedures
ReadChar Reads a char from keyboard and returns it in the AL register.
The character is NOT echoed on the screen.
ReadHex Reads a 32-bit hex integer and returns it in the EAX register.
Reading stops when the user presses the [Enter] key.
No leading spaces. No error checking is performed.
ReadInt Reads a 32-bit signed integer and returns it in EAX.
Leading spaces are ignored. Optional + or – is allowed.
Error checking is performed (error message) for invalid input.
ReadDec Reads a 32-bit unsigned integer and returns it in EAX.
ReadString Reads a string of characters from keyboard.
Additional null-character is inserted at the end of the string.
EDX = address of array where input characters are stored.
ECX = maximum characters to be read + 1 (for null byte)
Return EAX = count of non-null characters read.

Example: Reading a String
.data
inputstring BYTE 21 DUP(0) ; extra 1 for null byte
actualsize DWORD 0
.code
mov edx, OFFSET inputstring
mov ecx, SIZEOF inputstring
call ReadString
mov actualsize, eax
Before calling ReadString …
EDX should have the address of the string.
ECX specifies the maximum number of input chars + 1 (null byte).
Actual number of characters read is returned in EAX
A null byte is automatically appended at the end of the string

Dumping Registers and Memory
 DumpRegs
 Writes EAX, EBX, ECX, and EDX on first line in hexadecimal
 Writes ESI, EDI, EBP, and ESP on second line in hexadecimal
 Writes EIP, EFLAGS, CF, SF, ZF, and OF on third line
 DumpMem
 Writes a range of memory to standard output in hexadecimal
 ESI = starting address
 ECX = number of elements to write
 EBX = element size (1, 2, or 4)

Example: Dumping a Word Array
.data
array WORD 2 DUP (0, 10, 1234, 3CFFh)
.code
mov esi, OFFSET array
mov ecx, LENGTHOF array
mov ebx, TYPE array
call DumpMem
Dump of offset 00405000
-------------------------------
0000 000A 04D2 3CFF 0000 000A 04D2 3CFF
Console Output

Random Number Generation
 Randomize
 Seeds the random number generator with the current time
 The seed value is used by Random32 and RandomRange
 Random32
 Generates an unsigned pseudo-random 32-bit integer
 Returns value in EAX = random (0 to FFFFFFFFh)
 RandomRange
 Generates an unsigned pseudo-random integer from 0 to n – 1
 Call argument: EAX = n
 Return value in EAX = random (0 to n – 1)

Example on Random Numbers
 Generate and display 5 random numbers from 0 to 999
mov ecx, 5 ; loop counter
L1: mov eax, 1000 ; range = 0 to 999
call RandomRange ; eax = random integer
call WriteDec ; display it
call Crlf ; one number per line
loop L1
194
702
167
257
607
Console Output

Additional Library Procedures
WaitMsg Displays "Press [Enter] to Continue …" and waits for user.
SetTextColor Sets the color for all subsequent text output.
Bits 0 – 3 of EAX = foreground color.
Bits 4 – 7 of EAX = background color.
Delay Delay program for a given number of milliseconds.
EAX = number of milliseconds.
GetMseconds Return in EAX the milliseconds elapsed since midnight.
Gotoxy Locates cursor at a specific row and column on the console.
DH = row number
DL = column number
GetMaxXY Return the number of columns and rows in console window buffer
Return value DH = current number of rows
Return value DL = current number of columns

Example on TextColor
.data
str1 BYTE "Color output is easy!",0
.code
mov eax, yellow + (blue * 16)
call SetTextColor
call Clrscr
call WriteString
call Crlf
Display a null-terminated string with
yellow characters on a blue background
The colors defined in Irvine32.inc are:
black, white, brown, yellow, blue, green, cyan, red, magenta, gray, lightBlue,
lightGreen, lightCyan, lightRed, lightMagenta, and lightGray.

.data
time BYTE "Execution time in milliseconds: ",0
start DWORD ? ; start execution time
.code
main PROC
call GetMseconds ; EAX = milliseconds since midnight
mov start, eax ; save starting execution time
call WaitMsg ; Press [Enter] to continue ...
mov eax, 2000 ; 2000 milliseconds
call delay ; pause for 2 seconds
lea edx, time
call WriteString
call GetMseconds
sub eax, start
call WriteDec
exit
main ENDP
END main
Measuring Program Execution Time

Next . . .

What is a Stack?
 Stack is a Last-In-First-Out (LIFO) data structure
 Analogous to a stack of plates in a cafeteria
 Plate on Top of Stack is directly accessible
 Two basic stack operations
 Push: inserts a new element on top of the stack
 Pop: deletes top element from the stack
 View the stack as a linear array of elements
 Insertion and deletion is restricted to one end of array
 Stack has a maximum capacity
 When stack is full, no element can be pushed
 When stack is empty, no element can be popped

Runtime Stack
 Runtime stack: array of consecutive memory locations
 Managed by the processor using two registers
 Stack Segment register SS
 Not modified in protected mode, SS points to segment descriptor
 Stack Pointer register ESP
 For 16-bit real-address mode programs, SP register is used
 ESP register points to the top of stack
 Always points to last data item placed on the stack
 Only words and doublewords can be pushed and popped
 But not single bytes
 Stack grows downward toward lower memory addresses

Runtime Stack Allocation
 .STACK directive specifies a runtime stack
 Operating system allocates memory for the stack
 Runtime stack is initially empty
 The stack size can change dynamically at runtime
 Stack pointer ESP
 ESP is initialized by the operating system
 Typical initial value of ESP = 0012FFC4h
 The stack grows downwards
 The memory below ESP is free
 ESP is decremented to allocate stack memory
ESP = 0012FFC4
?
?
?
?
?
?
?
?
?
.
.
.
low
address
high
address

Stack Instructions
 Two basic stack instructions:
 push source
 pop destination
 Source can be a word (16 bits) or doubleword (32 bits)
 General-purpose register
 Segment register: CS, DS, SS, ES, FS, GS
 Memory operand, memory-to-stack transfer is allowed
 Immediate value
 Destination can be also a word or doubleword
 General-purpose register
 Segment register, except that pop CS is NOT allowed
 Memory, stack-to-memory transfer is allowed

Push Instruction
 Push source32 (r/m32 or imm32)
 ESP is first decremented by 4
 ESP = ESP – 4 (stack grows by 4 bytes)
 32-bit source is then copied onto the stack at the new ESP
 [ESP] = source32
 Push source16 (r/m16)
 ESP is first decremented by 2
 ESP = ESP – 2 (stack grows by 2 bytes)
 16-bit source is then copied on top of stack at the new ESP
 [ESP] = source16
 Operating system puts a limit on the stack capacity
 Push can cause a Stack Overflow (stack cannot grow)

Examples on the Push Instruction
 Suppose we execute:
 PUSH EAX ; EAX = 125C80FFh
 PUSH EBX ; EBX = 2Eh
 PUSH ECX ; ECX = 9B61Dh
ESP
0012FFC4
0012FFC0
0012FFBC
0012FFB8
0012FFB4
125C80FF
AFTER
0000002E
0009B61D
ESP
0012FFC4
BEFORE
0012FFC0
0012FFBC
0012FFB8
0012FFB4
The stack grows
downwards
The area below
ESP is free

Pop Instruction
 Pop dest32 (r/m32)
 32-bit doubleword at ESP is first copied into dest32
 dest32 = [ESP]
 ESP is then incremented by 4
 ESP = ESP + 4 (stack shrinks by 4 bytes)
 Pop dest16 (r/m16)
 16-bit word at ESP is first copied into dest16
 dest16 = [ESP]
 ESP is then incremented by 2
 ESP = ESP + 2 (stack shrinks by 2 bytes)
 Popping from an empty stack causes a stack underflow

Examples on the Pop Instruction
 Suppose we execute:
 POP SI
 POP DI
0012FFC4
0012FFC0
0012FFBC
0012FFB8
0012FFB4
125C80FF
AFTER
0000002E
0009B61D
ESP
The stack shrinks
upwards
The area at & above
ESP is allocated
ESP
0012FFC4
0012FFC0
0012FFBC
0012FFB8
0012FFB4
125C80FF
BEFORE
0000002E
0009B61D
; SI = B61Dh
; DI = 0009h

Uses of the Runtime Stack
 Runtime Stack can be utilized for
 Temporary storage of data and registers
 Transfer of program control in procedures and interrupts
 Parameter passing during a procedure call
 Allocating local variables used inside procedures
 Stack can be used as temporary storage of data
 Example: exchanging two variables in a data segment
push var1 ; var1 is pushed
push var2 ; var2 is pushed
pop var1 ; var1 = var2 on stack
pop var2 ; var2 = var1 on stack

Temporary Storage of Registers
 Stack is often used to free a set of registers
push EBX ; save EBX
push ECX ; save ECX
. . .
; EBX and ECX can now be modified
. . .
pop ECX ; restore ECX first, then
pop EBX ; restore EBX
 Example on moving DX:AX into EBX
push DX ; push most significant word first
push AX ; then push least significant word
pop EBX ; EBX = DX:AX

Example: Nested Loop
mov ecx, 100 ; set outer loop count
L1: . . . ; begin the outer loop
push ecx ; save outer loop count
mov ecx, 20 ; set inner loop count
L2: . . . ; begin the inner loop
. . . ; inner loop
loop L2 ; repeat the inner loop
. . . ; outer loop
pop ecx ; restore outer loop count
loop L1 ; repeat the outer loop
When writing a nested loop, push the outer loop counter
ECX before entering the inner loop, and restore ECX after
exiting the inner loop and before repeating the outer loop

Push/Pop All Registers
 pushad
 Pushes all the 32-bit general-purpose registers
 EAX, ECX, EDX, EBX, ESP, EBP, ESI, and EDI in this order
 Initial ESP value (before pushad) is pushed
 ESP = ESP – 32
 pusha
 Same as pusha but pushes all 16-bit registers AX through DI
 ESP = ESP – 16
 popad
 Pops into registers EDI through EAX in reverse order of pushad
 ESP is not read from stack. It is computed as: ESP = ESP + 32
 popa
 Same as popad but pops into 16-bit registers. ESP = ESP + 16

Stack Instructions on Flags
 Special Stack instructions for pushing and popping flags
 pushfd
 Push the 32-bit EFLAGS
 popfd
 Pop the 32-bit EFLAGS
 No operands are required
 Useful for saving and restoring the flags
 For 16-bit programs use pushf and popf
 Push and Pop the 16-bit FLAG register

Next . . .

Procedures
 A procedure is a logically self-contained unit of code
 Called sometimes a function, subprogram, or subroutine
 Receives a list of parameters, also called arguments
 Performs computation and returns results
 Plays an important role in modular program development
 Example of a procedure (called function) in C language
int sumof ( int x,int y,int z ) {
int temp;
temp = x + y + z;
return temp;
}
 The above function sumof can be called as follows:
sum = sumof( num1,num2,num3 );
Result type
Actual parameter list
Return function result
Formal parameter list

Defining a Procedure in Assembly
 Assembler provides two directives to define procedures
 PROC to define name of procedure and mark its beginning
 ENDP to mark end of procedure
 A typical procedure definition is
procedure_name PROC
. . .
; procedure body
. . .
procedure_name ENDP
 procedure_name should match in PROC and ENDP

Documenting Procedures
 Suggested Documentation for Each Procedure:
 Does: Describe the task accomplished by the procedure
 Receives: Describe the input parameters
 Returns: Describe the values returned by the procedure
 Requires: Optional list of requirements called preconditions
 Preconditions
 Must be satisfied before the procedure is called
 If a procedure is called without its preconditions satisfied, it will
probably not produce the expected output

Example of a Procedure Definition
 The sumof procedure receives three integer parameters
 Assumed to be in EAX, EBX, and ECX
 Computes and returns result in register EAX
;------------------------------------------------
; Sumof: Calculates the sum of three integers
; Receives: EAX, EBX, ECX, the three integers
; Returns: EAX = sum, and the flags:CF,OF,ZF,SF
; Requires: nothing
;------------------------------------------------
sumof PROC
add EAX, EBX ; EAX = EAX + second number
add EAX, ECX ; EAX = EAX + third number
ret ; return to caller
sumof ENDP
 The ret instruction returns control to the caller

The Call Instruction
 To invoke a procedure, the call instruction is used
 The call instruction has the following format
call procedure_name
 Example on calling the procedure sumof
 Caller passes actual parameters in EAX, EBX, and ECX
 Before calling procedure sumof
mov EAX, num1 ; pass first parameter in EAX
mov EBX, num2 ; pass second parameter in EBX
mov ECX, num3 ; pass third parameter in ECX
call sumof ; result is in EAX
mov sum, EAX ; save result in variable sum
 call sumof will call the procedure sumof

How a Procedure Call / Return Works
 How does a procedure know where to return?
 There can be multiple calls to same procedure in a program
 Procedure has to return differently for different calls
 It knows by saving the return address (RA) on the stack
 This is the address of next instruction after call
 The call instruction does the following
 Pushes the return address on the stack
 Jumps into the first instruction inside procedure
 ESP = ESP – 4; [ESP] = RA; EIP = procedure address
 The ret (return) instruction does the following
 Pops return address from stack
 Jumps to return address: EIP = [ESP]; ESP = ESP + 4

Free Area
Allocated
Before Call
ESP = 0012FFC4
Details of CALL and Return
ESP
ESP
Address Machine Code Assembly Language
.CODE
main PROC
00401020 A1 00405000 mov EAX, num1
00401025 8B 1D 00405004 mov EBX, num2
0040102B 8B 0D 00405008 mov ECX, num3
00401031 E8 0000004B call sumof
00401036 A3 0040500C mov sum, EAX
. . . . . . . . .
exit
main ENDP
sumof PROC
00401081 03 C3 add EAX, EBX
00401083 03 C1 add EAX, ECX
00401085 C3 ret
sumof ENDP
END main
RA=00401036
IP-relative call
EIP = 00401036
0000004B
EIP = 00401081
+
After Call
ESP = 0012FFC0
After Ret (Return)
ESP = 0012FFC4
Runtime
Stack

Don’t Mess Up the Stack !
 Just before returning from a procedure
 Make sure the stack pointer ESP is pointing at return address
 Example of a messed-up procedure
 Pushes EAX on the stack before returning
 Stack pointer ESP is NOT pointing at return address!
main PROC
call messedup
. . .
exit
main ENDP
messedup PROC
push EAX
ret
messedup ENDP
Free Area
Used
high addr
Stack
ESP
Return Addr
ESP
ESP EAX Value Where to return?
EAX value is NOT
the return address!

Nested Procedure Calls
By the time Sub3 is called, the stack
contains all three return addresses
main PROC
.
.
call Sub1
exit
main ENDP
Sub1 PROC
.
.
call Sub2
ret
Sub1 ENDP
Sub2 PROC
.
.
call Sub3
ret
Sub2 ENDP
Sub3 PROC
.
.
ret
Sub3 ENDP
return address of call Sub3 ESP
return address of call Sub2
return address of call Sub1

Parameter Passing
 Parameter passing in assembly language is different
 More complicated than that used in a high-level language
 In assembly language
 Place all required parameters in an accessible storage area
 Then call the procedure
 Two types of storage areas used
 Registers: general-purpose registers are used (register method)
 Memory: stack is used (stack method) is not covered here
 Two common mechanisms of parameter passing
 Pass-by-value: parameter value is passed
 Pass-by-reference: address of parameter is passed

Passing Parameters in Registers
;-----------------------------------------------------
; ArraySum: Computes the sum of an array of integers
; Receives: ESI = pointer to an array of doublewords
; ECX = number of array elements
; Returns: EAX = sum
;-----------------------------------------------------
ArraySum PROC
mov eax,0 ; set the sum to zero
L1: add eax, [esi] ; add each integer to sum
add esi, 4 ; point to next integer
loop L1 ; repeat for array size
ret
ArraySum ENDP
ESI: Reference parameter = array address
ECX: Value parameter = count of array elements

Preserving Registers
 Need to preserve the registers across a procedure call
 Stack can be used to preserve register values
 Which registers should be saved?
 Those registers that are modified by the called procedure
 But still used by the calling procedure
 We can save all registers using pusha if we need most of them
 However, better to save only needed registers when they are few
 Who should preserve the registers?
 Calling procedure: saves and frees registers that it uses
 Registers are saved before procedure call and restored after return
 Called procedure: preferred method for modular code
 Register preservation is done in one place only (inside procedure)

Example on Preserving Registers
;-----------------------------------------------------
; ArraySum: Computes the sum of an array of integers
; Receives: ESI = pointer to an array of doublewords
; ECX = number of array elements
; Returns: EAX = sum
;-----------------------------------------------------
ArraySum PROC
push esi ; save esi, it is modified
push ecx ; save ecx, it is modified
L1: add eax, [esi] ; add each integer to sum
pop ecx ; restore registers
pop esi ; in reverse order
ret
ArraySum ENDP No need to save EAX. Why?

USES Operator
 The USES operator simplifies the writing of a procedure
 Registers are frequently modified by procedures
 Just list the registers that should be preserved after USES
 Assembler will generate the push and pop instructions
ArraySum PROC USES esi ecx
mov eax,0
L1: add eax, [esi]
add esi, 4
loop L1
ret
ArraySum ENDP
ArraySum PROC
push esi
push ecx
mov eax,0
L1: add eax, [esi]
add esi, 4
loop L1
pop ecx
pop esi
ret
ArraySum ENDP

Next . . .

Program Design using Procedures
 Program Design involves the Following:
 Break large tasks into smaller ones
 Use a hierarchical structure based on procedure calls
 Test individual procedures separately
Integer Summation Program:
Write a program that prompts the user for multiple 32-bit integers,
stores them in an array, calculates the array sum, and displays the
sum on the screen.
Main steps:
1. Prompt user for multiple integers
2. Calculate the sum of the array
3. Display the sum

Structure Chart
Summation
Program (main)
Clrscr PromptForIntegers ArraySum DisplaySum
WriteString
WriteString ReadInt WriteInt
WriteInt
Structure Chart
Above diagram is called a structure chart
Describes program structure, division into procedure, and call sequence
Link library procedures are shown in grey

Integer Summation Program – 1 of 4
INCLUDE Irvine32.inc
ArraySize EQU 5
.DATA
prompt1 BYTE "Enter a signed integer: ",0
prompt2 BYTE "The sum of the integers is: ",0
array DWORD ArraySize DUP(?)
.CODE
main PROC
call Clrscr ; clear the screen
mov esi, OFFSET array
mov ecx, ArraySize
call PromptForIntegers ; store input integers in array
call ArraySum ; calculate the sum of array
call DisplaySum ; display the sum
exit
main ENDP

;-----------------------------------------------------
; PromptForIntegers: Read input integers from the user
; Receives: ESI = pointer to the array
; ECX = array size
; Returns: Fills the array with the user input
;-----------------------------------------------------
PromptForIntegers PROC USES ecx edx esi
mov edx, OFFSET prompt1
L1:
call WriteString ; display prompt1
call ReadInt ; read integer into EAX
call Crlf ; go to next output line
mov [esi], eax ; store integer in array
add esi, 4 ; advance array pointer
loop L1
ret
PromptForIntegers ENDP

;-----------------------------------------------------
; ArraySum: Calculates the sum of an array of integers
; Receives: ESI = pointer to the array,
; ECX = array size
; Returns: EAX = sum of the array elements
;-----------------------------------------------------
ArraySum PROC USES esi ecx
L1:
add eax, [esi] ; add each integer to sum
ret ; sum is in EAX
ArraySum ENDP

;-----------------------------------------------------
; DisplaySum: Displays the sum on the screen
; Receives: EAX = the sum
; Returns: nothing
;-----------------------------------------------------
DisplaySum PROC
mov edx, OFFSET prompt2
call WriteString ; display prompt2
call WriteInt ; display sum in EAX
call Crlf
ret
DisplaySum ENDP
END main

Sample Output
Enter a signed integer: 550
Enter a signed integer: -23
Enter a signed integer: -96
The sum of the integers is: +458

Summary
 Procedure – Named block of executable code
 CALL: call a procedure, push return address on top of stack
 RET: pop the return address and return from procedure
 Preserve registers across procedure calls
 Runtime stack – LIFO structure – Grows downwards
 Holds return addresses, saved registers, etc.
 PUSH – insert value on top of stack, decrement ESP
 POP – remove top value of stack, increment ESP
 Use the Irvine32.lib library for standard I/O
 Include Irvine32.inc to make procedure prototypes visible
 You can learn more by studying Irvine32.asm code

05-LibraryProcedures.pptLibrary Procedures

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