[[add information about this math package, added to the [core] in tcl 8.5 ]]

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[AMG]: Are there any extensions that use the tommath bignum library [http://math.libtomcrypt.com/] portion of Tcl?  I wrote one at work, but in order to make it compile, I had to create an ''empty'' file called tommath_class.h and put it somewhere in the "-I" header include path.  This is because tclTomMath.h contains the line `#include <tommath_class.h>`, but it doesn't seem to actually use anything that may be defined in tommath_class.h.  See https://sourceforge.net/tracker/?func=detail&atid=110894&aid=1941434&group_id=10894%|%1941434%|% for more information.

Once I got that out of the way, I found that tommath wasn't all that hard to use.  I couldn't find any documentation, so I just read the source, which was easy to understand.  Here's code to convert between a Tcl_WideUInt and an mp_int:

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mp_int wideuint_to_bignum(Tcl_WideUInt uwide)
{
    mp_int bignum = {0, 0, MP_ZPOS, NULL};
    if (mp_init_size(&bignum, (CHAR_BIT * sizeof(Tcl_WideUInt)
                              + DIGIT_BIT - 1) / DIGIT_BIT) == MP_OKAY) {
        for (; uwide != 0; ++bignum.used) {
            bignum.dp[bignum.used] = (mp_digit)(uwide & MP_MASK);
            uwide >>= MP_DIGIT_BIT;
        }
    }

    /* The caller is responsible for freeing the allocated digits of the bignum
     * by using mp_clear().  Tcl does this when the bignum is placed inside a
     * Tcl_Obj.  bignum_to_wideuint() likewise internally frees the digits. */
    return bignum;
}

Tcl_WideUInt bignum_to_wideuint(mp_int bignum)
{
    Tcl_WideUInt uwide = 0;
    int i;
    for (i = 0; i < bignum.used; ++i) {
        uwide = (uwide << MP_DIGIT_BIT) | bignum.dp[i];
    }
    mp_clear(&bignum);
    return uwide;
}
======

These functions are adapted from the tommath sources.  I used them with Tcl_TakeBignumFromObj() and Tcl_NewBignumObj() [http://www.tcl.tk/man/tcl8.6/TclLib/IntObj.htm] to put unsigned wide integers in [Tcl_Obj]s.

[Lars H]: Re documentation, there is a 1.1MB [PDF] file in CVS: tcl/libtommath/tommath.pdf.

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!!!!!!
%| [Category Package] | [Category Mathematics] |%
!!!!!!