void
mpi_add(MPI w, MPI u, MPI v)
{
mpi_ptr_t wp, up, vp;
mpi_size_t usize, vsize, wsize;
int usign, vsign, wsign;
if( u->nlimbs < v->nlimbs ) { /* Swap U and V. */
usize = v->nlimbs;
usign = v->sign;
vsize = u->nlimbs;
vsign = u->sign;
wsize = usize + 1;
RESIZE_IF_NEEDED(w, wsize);
/* These must be after realloc (u or v may be the same as w). */
up = v->d;
vp = u->d;
}
else {
usize = u->nlimbs;
usign = u->sign;
vsize = v->nlimbs;
vsign = v->sign;
wsize = usize + 1;
RESIZE_IF_NEEDED(w, wsize);
/* These must be after realloc (u or v may be the same as w). */
up = u->d;
vp = v->d;
}
wp = w->d;
wsign = 0;
if( !vsize ) { /* simple */
MPN_COPY(wp, up, usize );
wsize = usize;
wsign = usign;
}
else if( usign != vsign ) { /* different sign */
/* This test is right since USIZE >= VSIZE */
if( usize != vsize ) {
mpihelp_sub(wp, up, usize, vp, vsize);
wsize = usize;
MPN_NORMALIZE(wp, wsize);
wsign = usign;
}
else if( mpihelp_cmp(up, vp, usize) < 0 ) {
mpihelp_sub_n(wp, vp, up, usize);
wsize = usize;
MPN_NORMALIZE(wp, wsize);
if( !usign )
wsign = 1;
}
else {
mpihelp_sub_n(wp, up, vp, usize);
wsize = usize;
MPN_NORMALIZE(wp, wsize);
if( usign )
wsign = 1;
}
}
else { /* U and V have same sign. Add them. */
mpi_limb_t cy = mpihelp_add(wp, up, usize, vp, vsize);
wp[usize] = cy;
wsize = usize + cy;
if( usign )
wsign = 1;
}
w->nlimbs = wsize;
w->sign = wsign;
}
/*
* Shift A by N bits to the right.
*/
void
gcry_mpi_rshift ( gcry_mpi_t x, gcry_mpi_t a, unsigned int n )
{
mpi_size_t xsize;
unsigned int i;
unsigned int nlimbs = (n/BITS_PER_MPI_LIMB);
unsigned int nbits = (n%BITS_PER_MPI_LIMB);
if ( x == a )
{
/* In-place operation. */
if ( nlimbs >= x->nlimbs )
{
x->nlimbs = 0;
return;
}
if (nlimbs)
{
for (i=0; i < x->nlimbs - nlimbs; i++ )
x->d[i] = x->d[i+nlimbs];
x->d[i] = 0;
x->nlimbs -= nlimbs;
}
if ( x->nlimbs && nbits )
_gcry_mpih_rshift ( x->d, x->d, x->nlimbs, nbits );
}
else if ( nlimbs )
{
/* Copy and shift by more or equal bits than in a limb. */
xsize = a->nlimbs;
x->sign = a->sign;
RESIZE_IF_NEEDED (x, xsize);
x->nlimbs = xsize;
for (i=0; i < a->nlimbs; i++ )
x->d[i] = a->d[i];
x->nlimbs = i;
if ( nlimbs >= x->nlimbs )
{
x->nlimbs = 0;
return;
}
if (nlimbs)
{
for (i=0; i < x->nlimbs - nlimbs; i++ )
x->d[i] = x->d[i+nlimbs];
x->d[i] = 0;
x->nlimbs -= nlimbs;
}
if ( x->nlimbs && nbits )
_gcry_mpih_rshift ( x->d, x->d, x->nlimbs, nbits );
}
else
{
/* Copy and shift by less than bits in a limb. */
xsize = a->nlimbs;
x->sign = a->sign;
RESIZE_IF_NEEDED (x, xsize);
x->nlimbs = xsize;
if ( xsize )
{
if (nbits )
_gcry_mpih_rshift (x->d, a->d, x->nlimbs, nbits );
else
{
/* The rshift helper function is not specified for
NBITS==0, thus we do a plain copy here. */
for (i=0; i < x->nlimbs; i++ )
x->d[i] = a->d[i];
}
}
}
MPN_NORMALIZE (x->d, x->nlimbs);
}
/****************
* Use BUFFER to update MPI.
*/
int
mpi_set_buffer( MPI a, const void *xbuffer, unsigned nbytes, int sign )
{
const uint8_t *buffer = xbuffer, *p;
mpi_limb_t alimb;
int nlimbs;
int i;
nlimbs = (nbytes + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB;
if (RESIZE_IF_NEEDED(a, nlimbs) < 0)
return -ENOMEM;
a->sign = sign;
for(i=0, p = buffer+nbytes-1; p >= buffer+BYTES_PER_MPI_LIMB; ) {
#if BYTES_PER_MPI_LIMB == 4
alimb = (mpi_limb_t)*p-- ;
alimb |= (mpi_limb_t)*p-- << 8 ;
alimb |= (mpi_limb_t)*p-- << 16 ;
alimb |= (mpi_limb_t)*p-- << 24 ;
#elif BYTES_PER_MPI_LIMB == 8
alimb = (mpi_limb_t)*p-- ;
alimb |= (mpi_limb_t)*p-- << 8 ;
alimb |= (mpi_limb_t)*p-- << 16 ;
alimb |= (mpi_limb_t)*p-- << 24 ;
alimb |= (mpi_limb_t)*p-- << 32 ;
alimb |= (mpi_limb_t)*p-- << 40 ;
alimb |= (mpi_limb_t)*p-- << 48 ;
alimb |= (mpi_limb_t)*p-- << 56 ;
#else
#error please implement for this limb size.
#endif
a->d[i++] = alimb;
}
if( p >= buffer ) {
#if BYTES_PER_MPI_LIMB == 4
alimb = *p-- ;
if( p >= buffer ) alimb |= (mpi_limb_t)*p-- << 8 ;
if( p >= buffer ) alimb |= (mpi_limb_t)*p-- << 16 ;
if( p >= buffer ) alimb |= (mpi_limb_t)*p-- << 24 ;
#elif BYTES_PER_MPI_LIMB == 8
alimb = (mpi_limb_t)*p-- ;
if( p >= buffer ) alimb |= (mpi_limb_t)*p-- << 8 ;
if( p >= buffer ) alimb |= (mpi_limb_t)*p-- << 16 ;
if( p >= buffer ) alimb |= (mpi_limb_t)*p-- << 24 ;
if( p >= buffer ) alimb |= (mpi_limb_t)*p-- << 32 ;
if( p >= buffer ) alimb |= (mpi_limb_t)*p-- << 40 ;
if( p >= buffer ) alimb |= (mpi_limb_t)*p-- << 48 ;
if( p >= buffer ) alimb |= (mpi_limb_t)*p-- << 56 ;
#else
#error please implement for this limb size.
#endif
a->d[i++] = alimb;
}
a->nlimbs = i;
if (i != nlimbs) {
printk("MPI: mpi_set_buffer: Assertion failed (%d != %d)", i, nlimbs);
BUG();
}
return 0;
}
