GEN
addir_sign(GEN x, long sx, GEN y, long sy)
{
long e, l, ly;
GEN z;
if (!sx) return rcopy_sign(y, sy);
e = expo(y) - expi(x);
if (!sy)
{
if (e >= 0) return rcopy_sign(y, sy);
z = itor(x, nbits2prec(-e));
setsigne(z, sx); return z;
}
ly = lg(y);
if (e > 0)
{
l = ly - divsBIL(e);
if (l < 3) return rcopy_sign(y, sy);
}
else l = ly + nbits2extraprec(-e);
z = (GEN)avma;
y = addrr_sign(itor(x,l), sx, y, sy);
ly = lg(y); while (ly--) *--z = y[ly];
avma = (pari_sp)z; return z;
}
int tbir_read_nbits( ptbir_image_data tid, int bitcount, int *value )
{
int data;
int bitsleft;
if ( tid == NULL ) {
return 0;
}
if ( tbir_read_check( tid, bitcount ) == 0 ) {
return 0;
}
bitsleft = 8 - tid->cbit;
if ( bitsleft > bitcount ) {
data = tid->buffer[tid->cbyte];
data = data >> (bitsleft - bitcount);
data = data & (expi(2, bitcount)-1);
tid->cbit += bitcount;
*value = data;
return 1;
}
static GEN
_lift_iter(void *E, GEN x2, GEN q)
{
struct _frob_lift *F = (struct _frob_lift*) E;
long N = expi(q);
GEN TN = ZXT_remi2n(F->T, N);
GEN y2 = Z2XQ_frob(x2, TN, q);
GEN x2y2 = FpX_rem(ZX_remi2n(ZX_mul(x2, y2), N), TN, q);
GEN s = ZX_add(ZX_add(x2, ZX_shifti(y2, 1)), ZX_shifti(x2y2, 3));
GEN V = ZX_add(ZX_add(ZX_sqr(s), y2), ZX_shifti(x2y2, 2));
return mkvec4(FpX_rem(ZX_remi2n(V, N), TN, q),x2,y2,s);
}
