|
|
Login or register: |
|
|
 |
||||
|
|
|
|
|
|||||||
|
||||||||||
|
|
|
|
|
|
|
||||
|
|
|
Resources: ImageServer Friends: Jon Sullivan Mark Blair |
|
|
|
||||
| ||
I program in quite a few languages. Here is the master list, in psudo-cronological order:
;The second working assembly language program written by Erik G. Burrows ;A prime number generator that is capable of finding all the prime numbers ;up to 4 billion, and uses only registers to do so, except when printing ;them, which it does in decimal. .MODEL SMALL ;One Data and One Code Segment .386 ;Enable 32 bit register usage .STACK ;A 1k stack .CODE ;Code segment .STARTUP ;Entry point MOV EAX, 1 ;The first number JMP FoundPrime ;One is prime, print it NewNum: ;Next Number INC EAX ;Advance number MOV EBX, 1 BeginTest: ;Start test loop INC EBX ;Advance divisor CMP EAX, EBX ;Check if number = divisor JE FoundPrime ;If so, it's prime, loop finished MOV ECX, EAX ;Save the number XOR EDX, EDX ;Zero high DWord of divisor DIV EBX ;Divide number by divisor XCHG EDX, ECX ;Prep remainder for testing MOV EAX, EDX ;Put number back JCXZ NewNum ;If no renainder it's not prime JMP BeginTest ;Next in test loop FoundPrime: ;Print the prime number MOV EBX, EAX ;Store current number MOV ESI, 10 ;Load divisor with 10 XOR ECX, ECX ;Zero digit count NON_ZERO: ;Calculate digits XOR EDX, EDX ;Zero high DWord of divisor DIV ESI ;Divide number by divisor PUSH EDX ;Put the digit on the stack INC ECX ;Add one more digit to count OR EAX, EAX ;Check for end of loop JNE NON_ZERO ;Next digit to print MOV EAX, EBX ;Restore the current number WRITE_DIGIT_LOOP: ;Print digits POP EDX ;Get digit in reverse order ADD DL,"0" ;Add ascii 0 to the value MOV SI, AX ;Store ascii value MOV AH,2 ;Function 2h INT 21h ;Print it MOV AX, SI ;Restore the ascii value LOOP WRITE_DIGIT_LOOP ;Next digit to print MOV DL, " " ;A space MOV ECX, EAX ;Store the current number MOV AH,2 ;Function 2h INT 21h ;Print it MOV EAX, ECX ;Restore the test number JMP NewNum ;Go next number .EXIT ;Exit (never gets executed) END ;End address | ||
|
Comments: Cataboligne (2004-01-04): So few who understand this almost Zen truth. I used to work with a few who didnt "get" this. To them code was just a way to make money, run a business, or satisfy a customer. I simply couldnt explain the brilliance that went into a beautiful piece of code. I almost felt sad for the vision they lack. My best code, has no flow chart, no map, no design stage, no project management, and no notes besides the thoughts in my mind in the dark. Sure one day machines will be self programming...and I know they will never write code the likes of mine. You dont mention which assembly besides x86. I can claim familiarity with these: Z80, 6502, 808x, 68000, VAX Asm. Of those Z80 and 6502 are my strongest. Any good thoughts can be sent to cataboligne@kmfms.com, dont expect a quick reply. :-) Erik (2004-01-05): Actually, x86 assembly is all I ever learned. I'd love to play with some alpha or powerpc assembly. It'd feel so freeing to be able to use those extra registers! depala5@yahoo.com (2004-03-24): hi, this is something really excellent..I'm very new to this assembly language... but i sure do appreciate this work...if you have time enough.. can you send me a detail explanation of this program..... I'd love to understand it better ...... Erik (2004-03-24): Well thank you, but I don't think I can explain or comment the program any more than it is. Walk through the program, read the comments, you'll see, it's pretty straight-forward. Please.... (2004-03-25): can you mail me an assembly program that shows first 100 prime numbers... Erik (2004-03-25): It's right there. On this page, it outputs all the prime numbers up to four billion! Run it, and grab the first 100 lines. Josephat (2004-07-12): This code is great...commendable ! Erik (2004-07-12): Thank you! giqonyo@yahoo.com (2004-07-19): I've run this program and does ok.However I'd like to understand the algorithm it follows.Thank u Erik (2004-07-19): There are two major parts of the program. The loop which tests numbers for primeness, and the loop which prints out numbers in decimal for humans to read. The lines between the BeginTest and FoundPrime labels are the logic to test a number to see if it's prime, and then loop to the next number to test. The test is simply a loop from 2 to the number being tested, where each loop tests to see if the number being tested is evenly divisible by the divisor. It's prime if none of the numbers from 2 to the number being tested evenly divide it. If a prime number is found, a jump to the FoundPrime label is made. This is another loop, but this time the number is divided by 10 over and over until less than 10 remains. Each time the number is divided by 10, we have another digit to print. lam (2004-11-10): how would you alter the program to fit n(a max number) instead of 4 bilion? thanks Erik (2004-11-11): The program goes to 4 billion, because it uses 32 bit registers for counters. In order to increase the scanning range, you'd need to use larger variables. In assembly, this means using a larger width CPU (like the 64 bit Opteron) or faking larger registers by using two or more registers, or main system RAM. lam (2004-11-11): what I meant to say was how would you change the code to find prime numbers up to n (a number entered by the user). Per se the user doesen't want all prime numbers up to 4 billion but just primes up to 1000 or 2000. Erik (2004-11-11): Ah, I see. A very good question to which I'm sorry, but I have no answer. You could add a hard-coded conditional break to the code. A better way would be to get a maximum range from the command line, and to do that you would need to convert the number specified (as a string) into a binary number. Good luck! Linel Ortiz (2004-11-29): Hi. I need a similar assembly program. My program needs to search the space from 002 to 999 and prints the numbers that are prime. Please send it to me, it is very important for me. Thank you so much. Erik (2004-11-30): Linel, feel free to modify the above program for your use, but I won't do your homework for you. LilLinda327 (2004-11-30): I dont even know where to start from Erik (2004-12-01): Where to start what, Linda? Programming? I suggest a class in BASIC. That's where most of us started. Or, "Learning Perl" is one of the best language introduction books I have ever read, or ever heard of. Or, if it's assembly language you want to start with (the above program is written in x86 assembly for the MASM assembler), try your local book store. I picked up the fattest book I could, and read it cover to cover. K (2004-12-01): I guess everybody is looking for this homework ahahah. :) Montu (2005-04-15): You good its looks very nice and simple insense of coding and how you have used the code its very impressive,, i have not yet check by computer but i know that it will works out. Erik (2005-04-17): Thank you Montu, I hope it can be of use to you. surinder singh kundu (2005-11-23): it was realy nice ,it helps me alot ian nillas (2006-02-22): Please explain to me how RAM reservations and constants were important? Why it is very important in Assembly language programming? Erik (2006-03-01): Ian, I'm not sure what you mean by RAM reservations, but constants are used in assembly programming, similarly to how they are used in any language. dave (2006-03-11): I'm far from a assembly type guy, but couldn't you get some cheap improvements by assuming 1 and 2 are prime and neither testing even numbers nor testing with even numbers. Also perhaps only test up to n/2 rather then up to n? nice code, been a while since I've looked at any assembly, much less well organized code. almost makes me want to try some of it out again. Erik (2006-03-11): Dave, yes, all of those would improve performance, but would make the main loop so much less pretty. :-) Besides, on a modern processor it should get to 2^32 in just a few seconds anyway. marcos (2006-08-29): its very beatiful code, tks very much. i try in the masm32 but i cant compile. but i take the book art of assembly and i´m studying the code to understande your art in deep. tks Tyler (2007-01-31): Very clear and concise code, I'm taking a MASM class at OSU right now and this is perfect, it follows our next program guidelines almost exactly. I'm not going to steal it, but definitely use it as a reference. Thanks for the great work! Erik (2007-02-01): Wow, I'm amazed any university actually still teaches assembly! Glad I could help! ashish (2007-03-18): thanks,bcoz of u i m able to complete myassignment Juri (2007-03-29): This site provides very easy code in Assembly Language to generate Prime numbers then any other sites till I have searched. cornelius (2007-07-28): this code compiles and links fine but falls over when I try to run it. illegal instruction 132 Erik (2007-07-31): cornelius, it's been years and years since I compiled this code, but it ran OK under DOS. I don't know if you're trying to run it under Windows, or what affect that would have. If you're not already, try running it from the 'cmd' program, so it has a text terminal. amenda (2007-11-24): hi Erik! i am working on a project in assembly language that calculates the number of primes in the first 2^32-1 numbers! can u help me in this plz? the anser to this is 203, 280, 221 btw! thanks ! Erik (2007-11-25): Amenda, you can start with the above program, and replace the print routine with a counter. Good luck! ;Pe (2008-05-01): I have a similar problem with generating prime numbers but for the x86 assember and I was wondering if you could help me out Erik (2008-05-01): Pe, what problem are you having? permalink |
