Basic Number-Theoretic Functions - Cryptography in C and C++ - page 201

for (i = 1; i < noofeq; i++)
{
ai_l = *(coeff_l++);
mi_l = *(coeff_l++);
xgcd_l (m_l, mi_l, g_l, u_l, &sign_u, v_l, &sign_v);
if (!EQONE_L (g_l))
{
return 2;
}
In the following an overflow error is recorded. At the end of the function the status
is indicated in the return of the error code stored in error .
err = mul_l (u_l, m_l, u_l);
if (E_CLINT_OK == error)
{
error = err;
}
err = mul_l (u_l, ai_l, u_l);
if (E_CLINT_OK == error)
{
error = err;
}
err = mul_l (v_l, mi_l, v_l);
if (E_CLINT_OK == error)
{
error = err;
}
err = mul_l (v_l, x_l, v_l);
if (E_CLINT_OK == error)
{
error = err;
}
The auxiliary functions sadd() and smod() take care of the signs sign_u and sign_v
(respectively sign_x ) of the variables u_l and v_l (respectively 4).