1. Introduction to Programming
CGS 3460, Lecture 3
Jan 13, 2006
Hen-I Yang

2. Previously… Introduction to Computer
Writing your own program gives the total control of what your computer can do for you.
Introduction to Binary – Decimal – Hex conversions

3. Administrivia Turn in your questionnaire if you have not done so.
Course material is updated on the course web site.
My office hour will be temporarily hold in E309, effective today.
TA’s office hour schedule will be announced next Wednesday.
Comments on your responses to the questionnaire.

4. Agenda Machine Code – Assembly – C 3 Steps to a runnable program.
Software Engineering: Implementing a software that solves the problem.
Importance of commenting.

5. Machine Code
106fc: 9d e3 bf 88 save %sp, -120, %sp
10700: mov 0x19, %o0
10704: call 208c8 <_PROCEDURE_LINKAGE_TABLE_+0x78>
10708: nop
1070c: mov %o0, %g1
10710: c2 27 bf ec st %g1, [ %fp ]
10714: sethi %hi(0x10400), %g1
10718: f8 or %g1, 0x3f8, %o0 ! 107f8 <_lib_version+0x8>
1071c: e call 208d4 <_PROCEDURE_LINKAGE_TABLE_+0x84>
10720: nop
10724: sethi %hi(0x10800), %g1
10728: or %g1, 0x10, %o0 ! <_lib_version+0x20>
1072c: d2 07 bf ec ld [ %fp ], %o1
10730: c call 208e0 <_PROCEDURE_LINKAGE_TABLE_+0x90>
10734: nop
10738: sethi %hi(0x10800), %g1
1073c: or %g1, 0x18, %o0 ! <_lib_version+0x28>
10740: d2 07 bf ec ld [ %fp ], %o1
10744: a call 208ec <_PROCEDURE_LINKAGE_TABLE_+0x9c>
10748: nop
1074c: clr %g1 ! 0 <_START_-0x10000>
10750: b mov %g1, %i0
10754: 81 c7 e0 08 ret
10758: 81 e restore
1075c: 81 c3 e0 08 retl
10760: ae 03 c0 17 add %o7, %l7, %l7
Does any one uses Hex? Who uses

6. Assembly 106fc: 9d e3 bf 88 save %sp, -120, %sp
10700: mov 0x19, %o0
10704: call 208c8 <_PROCEDURE_LINKAGE_TABLE_+0x78>
10708: nop
1070c: mov %o0, %g1
10710: c2 27 bf ec st %g1, [ %fp ]
10714: sethi %hi(0x10400), %g1
10718: f8 or %g1, 0x3f8, %o0 ! 107f8 <_lib_version+0x8>
1071c: e call 208d4 <_PROCEDURE_LINKAGE_TABLE_+0x84>
10720: nop
10724: sethi %hi(0x10800), %g1
10728: or %g1, 0x10, %o0 ! <_lib_version+0x20>
1072c: d2 07 bf ec ld [ %fp ], %o1
10730: c call 208e0 <_PROCEDURE_LINKAGE_TABLE_+0x90>
10734: nop
10738: sethi %hi(0x10800), %g1
1073c: or %g1, 0x18, %o0 ! <_lib_version+0x28>
10740: d2 07 bf ec ld [ %fp ], %o1
10744: a call 208ec <_PROCEDURE_LINKAGE_TABLE_+0x9c>
10748: nop
1074c: clr %g1 ! 0 <_START_-0x10000>
10750: b mov %g1, %i0
10754: 81 c7 e0 08 ret
10758: 81 e restore
1075c: 81 c3 e0 08 retl
10760: ae 03 c0 17 add %o7, %l7, %l7

7. 106fc: 9d e3 bf 88 save %sp, -120, %sp
10700: mov 0x19, %o0
10704: call 208c8 <_PROCEDURE_LINKAGE_TABLE_+0x78>
10708: nop
1070c: mov %o0, %g1
10710: c2 27 bf ec st %g1, [ %fp ]
10714: sethi %hi(0x10400), %g1
10718: f8 or %g1, 0x3f8, %o0 ! 107f8 <_lib_version+0x8>
1071c: e call 208d4 <_PROCEDURE_LINKAGE_TABLE_+0x84>
10720: nop
10724: sethi %hi(0x10800), %g1
10728: or %g1, 0x10, %o0 ! <_lib_version+0x20>
1072c: d2 07 bf ec ld [ %fp ], %o1
10730: c call 208e0 <_PROCEDURE_LINKAGE_TABLE_+0x90>
10734: nop
10738: sethi %hi(0x10800), %g1
1073c: or %g1, 0x18, %o0 ! <_lib_version+0x28>
10740: d2 07 bf ec ld [ %fp ], %o1
10744: a call 208ec <_PROCEDURE_LINKAGE_TABLE_+0x9c>
10748: nop
1074c: clr %g1 ! 0 <_START_-0x10000>
10750: b mov %g1, %i0
10754: 81 c7 e0 08 ret
10758: 81 e restore
1075c: 81 c3 e0 08 retl
10760: ae 03 c0 17 add %o7, %l7, %l7

8. C Source Code #include <stdio.h> int main() { char *name;
name = (char *) malloc (25);
puts ("Please enter your name:");
scanf ("%20s", name);
printf ("\nHello, %s\n", name);
return 0; }

9. 3 Steps To Runnable Program
Source file (.c)
Editor: The tool you use to edit your source code.
Object file (.o)
Compiler + other utilities: The tool computer runs to create object file and executables.
Executables
The end product that actually delivers what you coded.
Demo
HD, memory, CPU

10. From Analysis to Executable
Problem Analysis (Human Perception)
Strategy Forming (Pesudo code)
Implementation (High Level Language)
Compilation (Assembly Language)
Debug
Execution (Machine Code)
Debug/Testing
Example: Greeting Program.
Compile/Interpret

11. Greetings Problem: Write a program that greets the user
Step 1: Collect User’s Name
Step 2: Print Greeting Message On Screen
Name  Collect User’s Name
Name  Screen

12. #include <stdio.h>
/**
* First sample program of CGS 3460, spring 2006
* Author: Hen-I Yang
* Date: Jan 10, 2006
* Version: 1.0
* Note: This program greets the user
* Revision:
**/
int main() {
// Declare a variable called name to store name collected
// Allocate Memory to Record User’s Name Collected
// Collect User’s Name (Name  Collect User’s Name)
// Print a Greeting Message (Name  Screen)
return 0; }

13. #include <stdio.h>
/**
* First sample program of CGS 3460, spring 2006
* Author: Hen-I Yang
* Date: Jan 10, 2006
* Version: 1.0
* Note:
* Revision:
**/
int main() {
// Declare a variable called name to store name collected
char *name;
// Allocate Memory to Record User’s Name Collected
name = (char *) malloc (25);
// Collect User’s Name (Name  Collect User’s Name)
puts ("Please enter your name:");
scanf ("%20s", name);
// Print a Greeting Message (Name  Screen)
printf ("Hello, %s\n", name);
return 0; }

14. C Source Code #include <stdio.h> int main() { char *name;
name = (char *) malloc (25);
puts ("Please enter your name:");
scanf ("%20s", name);
printf ("\nHello, %s\n", name);
return 0; }

15. Assembly 106fc: 9d e3 bf 88 save %sp, -120, %sp
10700: mov 0x19, %o0
10704: call 208c8 <_PROCEDURE_LINKAGE_TABLE_+0x78>
10708: nop
1070c: mov %o0, %g1
10710: c2 27 bf ec st %g1, [ %fp ]
10714: sethi %hi(0x10400), %g1
10718: f8 or %g1, 0x3f8, %o0 ! 107f8 <_lib_version+0x8>
1071c: e call 208d4 <_PROCEDURE_LINKAGE_TABLE_+0x84>
10720: nop
10724: sethi %hi(0x10800), %g1
10728: or %g1, 0x10, %o0 ! <_lib_version+0x20>
1072c: d2 07 bf ec ld [ %fp ], %o1
10730: c call 208e0 <_PROCEDURE_LINKAGE_TABLE_+0x90>
10734: nop
10738: sethi %hi(0x10800), %g1
1073c: or %g1, 0x18, %o0 ! <_lib_version+0x28>
10740: d2 07 bf ec ld [ %fp ], %o1
10744: a call 208ec <_PROCEDURE_LINKAGE_TABLE_+0x9c>
10748: nop
1074c: clr %g1 ! 0 <_START_-0x10000>
10750: b mov %g1, %i0
10754: 81 c7 e0 08 ret
10758: 81 e restore
1075c: 81 c3 e0 08 retl
10760: ae 03 c0 17 add %o7, %l7, %l7

16. Machine Code 106fc: 9d e3 bf 88 save %sp, -120, %sp
10700: mov 0x19, %o0
10704: call 208c8 <_PROCEDURE_LINKAGE_TABLE_+0x78>
10708: nop
1070c: mov %o0, %g1
10710: c2 27 bf ec st %g1, [ %fp ]
10714: sethi %hi(0x10400), %g1
10718: f8 or %g1, 0x3f8, %o0 ! 107f8 <_lib_version+0x8>
1071c: e call 208d4 <_PROCEDURE_LINKAGE_TABLE_+0x84>
10720: nop
10724: sethi %hi(0x10800), %g1
10728: or %g1, 0x10, %o0 ! <_lib_version+0x20>
1072c: d2 07 bf ec ld [ %fp ], %o1
10730: c call 208e0 <_PROCEDURE_LINKAGE_TABLE_+0x90>
10734: nop
10738: sethi %hi(0x10800), %g1
1073c: or %g1, 0x18, %o0 ! <_lib_version+0x28>
10740: d2 07 bf ec ld [ %fp ], %o1
10744: a call 208ec <_PROCEDURE_LINKAGE_TABLE_+0x9c>
10748: nop
1074c: clr %g1 ! 0 <_START_-0x10000>
10750: b mov %g1, %i0
10754: 81 c7 e0 08 ret
10758: 81 e restore
1075c: 81 c3 e0 08 retl
10760: ae 03 c0 17 add %o7, %l7, %l7

17. Hex to Binary Conversion
Problem: Given a number in hex(adecimal), convert it to binary representation
Get a number in Hex, print out a number in binary
Convert to Decimal
Divide the number n by 2k, (k = 3, 2, 1, 0)
if the quote is 1, put down 1, n = n – 2k
If the quote is 0, put down 0
moves on to the next k

18. Sorting
Problem: A stack of graded exam papers, sort them from the highest score to the lowest
Pick the one from the top of the pile, put it down
Pick the next one,
if the score is higher, put it on top
Otherwise, flip the paper and see if the score is higher than the next one
If it’s higher than insert it to the slot
If not, keep flipping through to the next page
If it’s to the bottom of the sorted pile, put it down on the back

19. Comments on Comments
Programs should be readable by both computer and human
Remind yourself what the code does
Extremely useful when debugging
Important for collaboration
Readability

20. Summary What is a program? Different Formats of a program.
3 steps to a runnable program.
7 steps from analysis of problem to executable.
Comments.

21. Before you go Read Chapter 1 and Section 2.1 – 2.2.
Problem: design a software for Gatorade vending machine.