Introduction to Programming

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. 1001 1101 1110 0011 Machine Code 106fc: 9d e3 bf 88 save %sp, -120, %sp 10700: 90 10 20 19 mov 0x19, %o0 10704: 40 00 40 71 call 208c8 <_PROCEDURE_LINKAGE_TABLE_+0x78> 10708: 01 00 00 00 nop 1070c: 82 10 00 08 mov %o0, %g1 10710: c2 27 bf ec st %g1, [ %fp + -20 ] 10714: 03 00 00 41 sethi %hi(0x10400), %g1 10718: 90 10 63 f8 or %g1, 0x3f8, %o0 ! 107f8 <_lib_version+0x8> 1071c: 40 00 40 6e call 208d4 <_PROCEDURE_LINKAGE_TABLE_+0x84> 10720: 01 00 00 00 nop 10724: 03 00 00 42 sethi %hi(0x10800), %g1 10728: 90 10 60 10 or %g1, 0x10, %o0 ! 10810 <_lib_version+0x20> 1072c: d2 07 bf ec ld [ %fp + -20 ], %o1 10730: 40 00 40 6c call 208e0 <_PROCEDURE_LINKAGE_TABLE_+0x90> 10734: 01 00 00 00 nop 10738: 03 00 00 42 sethi %hi(0x10800), %g1 1073c: 90 10 60 18 or %g1, 0x18, %o0 ! 10818 <_lib_version+0x28> 10740: d2 07 bf ec ld [ %fp + -20 ], %o1 10744: 40 00 40 6a call 208ec <_PROCEDURE_LINKAGE_TABLE_+0x9c> 10748: 01 00 00 00 nop 1074c: 82 10 20 00 clr %g1 ! 0 <_START_-0x10000> 10750: b0 10 00 01 mov %g1, %i0 10754: 81 c7 e0 08 ret 10758: 81 e8 00 00 restore 1075c: 81 c3 e0 08 retl 10760: ae 03 c0 17 add %o7, %l7, %l7

6. Assembly 106fc: 9d e3 bf 88 save %sp, -120, %sp 10700: 90 10 20 19 mov 0x19, %o0 10704: 40 00 40 71 call 208c8 <_PROCEDURE_LINKAGE_TABLE_+0x78> 10708: 01 00 00 00 nop 1070c: 82 10 00 08 mov %o0, %g1 10710: c2 27 bf ec st %g1, [ %fp + -20 ] 10714: 03 00 00 41 sethi %hi(0x10400), %g1 10718: 90 10 63 f8 or %g1, 0x3f8, %o0 ! 107f8 <_lib_version+0x8> 1071c: 40 00 40 6e call 208d4 <_PROCEDURE_LINKAGE_TABLE_+0x84> 10720: 01 00 00 00 nop 10724: 03 00 00 42 sethi %hi(0x10800), %g1 10728: 90 10 60 10 or %g1, 0x10, %o0 ! 10810 <_lib_version+0x20> 1072c: d2 07 bf ec ld [ %fp + -20 ], %o1 10730: 40 00 40 6c call 208e0 <_PROCEDURE_LINKAGE_TABLE_+0x90> 10734: 01 00 00 00 nop 10738: 03 00 00 42 sethi %hi(0x10800), %g1 1073c: 90 10 60 18 or %g1, 0x18, %o0 ! 10818 <_lib_version+0x28> 10740: d2 07 bf ec ld [ %fp + -20 ], %o1 10744: 40 00 40 6a call 208ec <_PROCEDURE_LINKAGE_TABLE_+0x9c> 10748: 01 00 00 00 nop 1074c: 82 10 20 00 clr %g1 ! 0 <_START_-0x10000> 10750: b0 10 00 01 mov %g1, %i0 10754: 81 c7 e0 08 ret 10758: 81 e8 00 00 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: 90 10 20 19 mov 0x19, %o0 10704: 40 00 40 71 call 208c8 <_PROCEDURE_LINKAGE_TABLE_+0x78> 10708: 01 00 00 00 nop 1070c: 82 10 00 08 mov %o0, %g1 10710: c2 27 bf ec st %g1, [ %fp + -20 ] 10714: 03 00 00 41 sethi %hi(0x10400), %g1 10718: 90 10 63 f8 or %g1, 0x3f8, %o0 ! 107f8 <_lib_version+0x8> 1071c: 40 00 40 6e call 208d4 <_PROCEDURE_LINKAGE_TABLE_+0x84> 10720: 01 00 00 00 nop 10724: 03 00 00 42 sethi %hi(0x10800), %g1 10728: 90 10 60 10 or %g1, 0x10, %o0 ! 10810 <_lib_version+0x20> 1072c: d2 07 bf ec ld [ %fp + -20 ], %o1 10730: 40 00 40 6c call 208e0 <_PROCEDURE_LINKAGE_TABLE_+0x90> 10734: 01 00 00 00 nop 10738: 03 00 00 42 sethi %hi(0x10800), %g1 1073c: 90 10 60 18 or %g1, 0x18, %o0 ! 10818 <_lib_version+0x28> 10740: d2 07 bf ec ld [ %fp + -20 ], %o1 10744: 40 00 40 6a call 208ec <_PROCEDURE_LINKAGE_TABLE_+0x9c> 10748: 01 00 00 00 nop 1074c: 82 10 20 00 clr %g1 ! 0 <_START_-0x10000> 10750: b0 10 00 01 mov %g1, %i0 10754: 81 c7 e0 08 ret 10758: 81 e8 00 00 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

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.

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: 90 10 20 19 mov 0x19, %o0 10704: 40 00 40 71 call 208c8 <_PROCEDURE_LINKAGE_TABLE_+0x78> 10708: 01 00 00 00 nop 1070c: 82 10 00 08 mov %o0, %g1 10710: c2 27 bf ec st %g1, [ %fp + -20 ] 10714: 03 00 00 41 sethi %hi(0x10400), %g1 10718: 90 10 63 f8 or %g1, 0x3f8, %o0 ! 107f8 <_lib_version+0x8> 1071c: 40 00 40 6e call 208d4 <_PROCEDURE_LINKAGE_TABLE_+0x84> 10720: 01 00 00 00 nop 10724: 03 00 00 42 sethi %hi(0x10800), %g1 10728: 90 10 60 10 or %g1, 0x10, %o0 ! 10810 <_lib_version+0x20> 1072c: d2 07 bf ec ld [ %fp + -20 ], %o1 10730: 40 00 40 6c call 208e0 <_PROCEDURE_LINKAGE_TABLE_+0x90> 10734: 01 00 00 00 nop 10738: 03 00 00 42 sethi %hi(0x10800), %g1 1073c: 90 10 60 18 or %g1, 0x18, %o0 ! 10818 <_lib_version+0x28> 10740: d2 07 bf ec ld [ %fp + -20 ], %o1 10744: 40 00 40 6a call 208ec <_PROCEDURE_LINKAGE_TABLE_+0x9c> 10748: 01 00 00 00 nop 1074c: 82 10 20 00 clr %g1 ! 0 <_START_-0x10000> 10750: b0 10 00 01 mov %g1, %i0 10754: 81 c7 e0 08 ret 10758: 81 e8 00 00 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: 90 10 20 19 mov 0x19, %o0 10704: 40 00 40 71 call 208c8 <_PROCEDURE_LINKAGE_TABLE_+0x78> 10708: 01 00 00 00 nop 1070c: 82 10 00 08 mov %o0, %g1 10710: c2 27 bf ec st %g1, [ %fp + -20 ] 10714: 03 00 00 41 sethi %hi(0x10400), %g1 10718: 90 10 63 f8 or %g1, 0x3f8, %o0 ! 107f8 <_lib_version+0x8> 1071c: 40 00 40 6e call 208d4 <_PROCEDURE_LINKAGE_TABLE_+0x84> 10720: 01 00 00 00 nop 10724: 03 00 00 42 sethi %hi(0x10800), %g1 10728: 90 10 60 10 or %g1, 0x10, %o0 ! 10810 <_lib_version+0x20> 1072c: d2 07 bf ec ld [ %fp + -20 ], %o1 10730: 40 00 40 6c call 208e0 <_PROCEDURE_LINKAGE_TABLE_+0x90> 10734: 01 00 00 00 nop 10738: 03 00 00 42 sethi %hi(0x10800), %g1 1073c: 90 10 60 18 or %g1, 0x18, %o0 ! 10818 <_lib_version+0x28> 10740: d2 07 bf ec ld [ %fp + -20 ], %o1 10744: 40 00 40 6a call 208ec <_PROCEDURE_LINKAGE_TABLE_+0x9c> 10748: 01 00 00 00 nop 1074c: 82 10 20 00 clr %g1 ! 0 <_START_-0x10000> 10750: b0 10 00 01 mov %g1, %i0 10754: 81 c7 e0 08 ret 10758: 81 e8 00 00 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.