/*
* needs workspace of (size*2) words
*/
static void mpprndbits(mpbarrett* p, size_t bits, size_t lsbset, const mpnumber* min, const mpnumber* max, randomGeneratorContext* rc, mpw* wksp)
{
register size_t size = p->size;
register size_t msbclr = MP_WORDS_TO_BITS(size) - bits;
/* assume that mpbits(max) == bits */
/* calculate k=max-min; generate q such that 0 <= q <= k; then set p = q + min */
/* for the second step, set the appropriate number of bits */
if (max)
{
mpsetx(size, wksp, max->size, max->data);
}
else
{
mpfill(size, wksp, MP_ALLMASK);
wksp[0] &= (MP_ALLMASK >> msbclr);
}
if (min)
{
mpsetx(size, wksp+size, min->size, min->data);
}
else
{
mpzero(size, wksp+size);
wksp[size] |= (MP_MSBMASK >> msbclr);
}
mpsub(size, wksp, wksp+size);
rc->rng->next(rc->param, (byte*) p->modl, MP_WORDS_TO_BYTES(size));
p->modl[0] &= (MP_ALLMASK >> msbclr);
while (mpgt(size, p->modl, wksp))
mpsub(size, p->modl, wksp);
mpadd(size, p->modl, wksp+size);
if (lsbset)
p->modl[size-1] |= (MP_ALLMASK >> (MP_WBITS - lsbset));
}
static int Zmpbinv_w(const mpbarrett* b, size_t xsize, const mpw* xdata, mpw* result, mpw* wksp)
{
size_t ysize = b->size+1;
size_t ubits, vbits;
int k = 0;
mpw* u = wksp;
mpw* v = u+ysize;
mpw* A = v+ysize;
mpw* B = A+ysize;
mpw* C = B+ysize;
mpw* D = C+ysize;
mpsetx(ysize, u, xsize, xdata);
mpsetx(ysize, v, b->size, b->modl);
mpsetw(ysize, A, 1);
mpzero(ysize, B);
mpzero(ysize, C);
mpsetw(ysize, D, 1);
for (k = 0; mpeven(ysize, u) && mpeven(ysize, v); k++) {
mpdivtwo(ysize, u);
mpdivtwo(ysize, v);
}
if (mpeven(ysize, u))
(void) mpadd(ysize, u, v);
if (_debug < 0)
fprintf(stderr, " u: "), mpfprintln(stderr, ysize, u);
if (_debug < 0)
fprintf(stderr, " v: "), mpfprintln(stderr, ysize, v);
if (_debug < 0)
fprintf(stderr, " A: "), mpfprintln(stderr, ysize, A);
if (_debug < 0)
fprintf(stderr, " B: "), mpfprintln(stderr, ysize, B);
if (_debug < 0)
fprintf(stderr, " C: "), mpfprintln(stderr, ysize, C);
if (_debug < 0)
fprintf(stderr, " D: "), mpfprintln(stderr, ysize, D);
ubits = vbits = MP_WORDS_TO_BITS(ysize);
do {
while (mpeven(ysize, v)) {
mpsdivtwo(ysize, v);
vbits -= 1;
if (mpodd(ysize, C)) {
(void) mpaddx(ysize, C, b->size, b->modl);
(void) mpsubx(ysize, D, xsize, xdata);
}
mpsdivtwo(ysize, C);
mpsdivtwo(ysize, D);
if (_debug < 0)
fprintf(stderr, "-->> v: "), mpfprintln(stderr, ysize, v);
}
if (ubits >= vbits) {
mpw* swapu;
size_t swapi;
if (_debug < 0)
fprintf(stderr, "--> (swap u <-> v)\n");
swapu = u; u = v; v = swapu;
swapi = ubits; ubits = vbits; vbits = swapi;
swapu = A; A = C; C = swapu;
swapu = B; B = D; D = swapu;
}
if (!((u[ysize-1] + v[ysize-1]) & 0x3)) {
if (_debug < 0)
fprintf(stderr, "--> (even parity)\n");
mpadd(ysize, v, u);
mpadd(ysize, C, A);
mpadd(ysize, D, B);
} else {
if (_debug < 0)
fprintf(stderr, "--> (odd parity)\n");
mpsub(ysize, v, u);
mpsub(ysize, C, A);
mpsub(ysize, D, B);
}
if (_debug < 0)
fprintf(stderr, " v: "), mpfprintln(stderr, ysize, v);
if (_debug < 0)
fprintf(stderr, " C: "), mpfprintln(stderr, ysize, C);
if (_debug < 0)
fprintf(stderr, " D: "), mpfprintln(stderr, ysize, D);
vbits++;
} while (mpnz(ysize, v));
#ifdef NOTYET
if (!mpisone(ysize, u))
return 0;
#endif
if (result) {
mpsetx(b->size, result, ysize, A);
/*@-usedef@*/
if (*A & 0x80000000)
(void) mpneg(b->size, result);
/*@=usedef@*/
while (--k > 0)
mpadd(b->size, result, result);
}
fprintf(stderr, "=== EXIT: "), mpfprintln(stderr, b->size, result);
fprintf(stderr, " u: "), mpfprintln(stderr, ysize, u);
fprintf(stderr, " v: "), mpfprintln(stderr, ysize, v);
fprintf(stderr, " A: "), mpfprintln(stderr, ysize, A);
fprintf(stderr, " B: "), mpfprintln(stderr, ysize, B);
fprintf(stderr, " C: "), mpfprintln(stderr, ysize, C);
fprintf(stderr, " D: "), mpfprintln(stderr, ysize, D);
return 1;
}
