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Lint: Large Integer Object Library

, 15 Dec 2005
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Lint is a signed large integer data type class library.

Introduction

Lint is a signed large integer data type class library that supports all mathematical operators available to other intrinsic integer data types. The precision is not arbitrary as in other available libraries. Rather, the number of bits that make up a lint variable is dependent on the value of a #define directive declared in the header file.

Background

So why yet another large integer library? Several reasons, among which:

  • I wanted a class that supported all possible overloaded operators so that I could use a lint just exactly like I might use an intrinsic data type such as an int or long. None of the free implementations I could find seemed to support all over-loadable operators.
  • I wanted a class that was specifically created with Visual C++ and IA-32 based PC architecture in mind. I didn't want a library that sacrificed execution speed for the sake of cross-compiler and cross-platform compatibility. I wanted a library that I could optimize with in-line assembly code.
  • I wanted a class whose methods were as fast and efficient as possible. Arbitrary-precision logic and floating point logic bring with them a performance hit. This library is efficient because precision is not arbitrary and all operations are strictly integer based. In this way, I could write highly optimized assembly routines given a known data type and size.

Using the code

Once you include the header file in your source, using a lint is similar to using any other numeric data type in C++. The few notable exceptions are in declaration, assignment, and output.

#include <span class="code-string">"lint.h"
</span>
#include <span class="code-keyword"><stdio.h>
</span>

int main() {
    // value assignment of a literal
    lint a = 1234;
    // a lint is a signed integer data type
    lint b = -5678;
    // assignment to another lint value
    lint c = a;
    // use a string for those really BIG numbers
    lint d = "457639857304951675093650987359087";
    // this works for negative values too
    lint e = "-563857365015613047563";
    
    lint x, y, z;
    // math shouldn't be a problem.
    x = d*e+a*b;
    y = x/(e*e);
    
    // assignment to zero is the only ambiguous
    // operation that you need to be specific on.
    z = (signed long)0;                                

    // the class allocates its own buffer
    // to print a character representation of its value.
    // By default, it prints in base 10
    printf( "y base 10 = %s\n", z.value() );
    
    // You can print in another radix though - anything from 2 to 36
    printf( "y base 16 = %s\n", z.value(16) );
    printf( "y base 2 = %s\n", z.value(2) );
    
    // Internally, the memory for a lint is laid out
    // going from MSB to LSB in an array of 32-bit DWORDs.
    // [2047th bit ... 1024th bit ... 0th bit]
    
    // If you need more or less than 2048 bit numbers, open lint.h
    // and redefine LINT_LENGTH
    
    // Lastly, the function call operator allows direct
    // referential access to the DWORDs that comprise
    // a lint value.
    // This sets the Most Significant DWORD to 0x12345678
    y(0) = 0x12345678;
    // LAST_DWORD is a constant defined in the header file
    long my_bit_field = y(LAST_DWORD);
    
    return 0;
}

Points of Interest

Implementing the conditional testing was a real bugger. My implementation works, but I think there must be a better way to do it. There are additional things I'd like to do to the library as well.

  • Possibly implement faster multiplication and division algorithms using FFT, Barrett, or whatever.
  • Add capability to assign a value using a string in any radix from 2 to 36, not just base 10.
  • Make use of MMX and XMM registers for even faster inline assembly.

History

Initial release December 4, 2005 by Jeremy A. Wilson  
Update December 6, 2005 by Jeremy A. Wilson Discovered my comparison operators were using the wrong assembly instruction which failed to report correctly if the MSB was set in one DWORD and not the other.
Update December 9, 2005 by Jeremy A. Wilson After further review of my December 6th fix, I realized I still hadn't fixed it right. Now I have. I also ran a complete set of comparisons.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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About the Author

Jeremy A. Wilson
Software Developer
United States United States
I've worked in the industry since 1992. After the dot com crash of 2001, I went back to school and graduated from the University of North Texas in 2005. I now live in the Dallas area with my wife and two children, and work as a senior software engineer for a local company.
 
I first learned to program on a Commodore 64 when I was 12 years old. The rest is history...

Comments and Discussions

 
Generalchar *lint::value(int radix) bug PinmemberMark Oliver26-Apr-11 17:25 
GeneralGreat class, possible bug..... PinmemberCeri16-Aug-06 2:26 
Questionxlint? PinmemberOvermindDL125-Mar-06 19:05 
GeneralRegisters should be preserved PinmemberGeertMys24-Jan-06 7:03 
GeneralUnfortunately does not seem to work under MSVC Pinmemberlucchicoine20-Dec-05 13:14 
GeneralRe: Unfortunately does not seem to work under MSVC PinmemberHobbitCoder21-Dec-05 13:07 
GeneralRe: Unfortunately does not seem to work under MSVC PinmemberJeremy A. Wilson23-Dec-05 10:57 
QuestionRe: Unfortunately does not seem to work under MSVC PinmemberZsuzsi22-May-06 5:25 
GeneralConst correctness PinmemberHobbitCoder17-Dec-05 10:37 
GeneralRe: Const correctness PinmemberJeremy A. Wilson23-Dec-05 10:57 
JokeBUG Pinmemberkevincpp15-Dec-05 23:02 
GeneralRe: BUG PinmemberJeremy A. Wilson16-Dec-05 22:37 
GeneralRe: BUG PinmemberToby Opferman20-Jan-06 8:20 
GeneralRe: BUG PinmemberMadFalcon7-Jul-06 13:12 
QuestionRe: BUG PinmemberMohammed Hossny23-Aug-06 18:06 
GeneralNice Work! Pinmemberyafan15-Dec-05 11:51 
Generala few comments PinmemberWarren D Stevens15-Dec-05 9:49 
GeneralRe: a few comments PinmemberJeremy A. Wilson15-Dec-05 13:14 
Generalyou should change the name ... PinmemberMaximilien15-Dec-05 8:06 
GeneralRe: you should change the name ... PinstaffNishant Sivakumar15-Dec-05 9:47 
GeneralRe: you should change the name ... PinmemberWarren D Stevens15-Dec-05 9:50 
GeneralRe: you should change the name ... PinmemberHarold Bamford15-Dec-05 11:05 
GeneralRe: you should change the name ... PinmemberWarren D Stevens15-Dec-05 11:37 
GeneralRe: you should change the name ... PinmemberJeremy A. Wilson15-Dec-05 13:23 
GeneralRe: you should change the name ... PinmemberStephan Pilz15-Dec-05 22:19 
I vote for Linteger. It's better readable in code and I think the name should say what it is.
 
BR
Stephan

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