sum.c File Reference

#include "gdtoaimp.h"

Include dependency graph for sum.c:

Go to the source code of this file.

Functions
Bigint *	sum (Bigint *a, Bigint *b)

Function Documentation

sum()

Bigint* sum	(	Bigint *	a,
		Bigint *	b
	)

Definition at line 39 of file sum.c.

{
    Bigint* c;
    ULong carry, *xc, *xa, *xb, *xe, y;
#ifdef Pack_32
    ULong z;
#endif

    if(a->wds < b->wds)
    {
        c = b;
        b = a;
        a = c;
    }
    c = Balloc(a->k);
    c->wds = a->wds;
    carry = 0;
    xa = a->x;
    xb = b->x;
    xc = c->x;
    xe = xc + b->wds;
#ifdef Pack_32
    do
    {
        y = (*xa & 0xffff) + (*xb & 0xffff) + carry;
        carry = (y & 0x10000) >> 16;
        z = (*xa++ >> 16) + (*xb++ >> 16) + carry;
        carry = (z & 0x10000) >> 16;
        Storeinc(xc, z, y);
    } while(xc < xe);
    xe += a->wds - b->wds;
    while(xc < xe)
    {
        y = (*xa & 0xffff) + carry;
        carry = (y & 0x10000) >> 16;
        z = (*xa++ >> 16) + carry;
        carry = (z & 0x10000) >> 16;
        Storeinc(xc, z, y);
    }
#else
    do
    {
        y = *xa++ + *xb++ + carry;
        carry = (y & 0x10000) >> 16;
        *xc++ = y & 0xffff;
    } while(xc < xe);
    xe += a->wds - b->wds;
    while(xc < xe)
    {
        y = *xa++ + carry;
        carry = (y & 0x10000) >> 16;
        *xc++ = y & 0xffff;
    }
#endif
    if(carry)
    {
        if(c->wds == c->maxwds)
        {
            b = Balloc(c->k + 1);
            Bcopy(b, c);
            Bfree(c);
            c = b;
        }
        c->x[c->wds++] = 1;
    }
    return c;
}

References Balloc(), Bcopy, Bfree(), Bigint::k, Bigint::maxwds, Storeinc, Bigint::wds, and Bigint::x.

Referenced by g_ddfmt(), and strtodg().