MPuint MPuint::operator-(const MPuint& mpu)
{
MPuint out;
LPuint *a1 = m_data->A, *a2 = mpu.m_data->A, *a3 = out.m_data->A;
int l1 = m_data->len, l2 = mpu.m_data->len;
out.m_data->len = l1;
unsigned char rem = 0;
for (int i = 0; i < l2; i++)
{
rem = _subborrow_u64(rem, a1[i], a2[i], a3 + i);
}
if (rem == 0)
memcpy(a3 + l2, a1 + l2, (l1 - l2) * sizeof(LPuint));
else
{
for (int i = l2; i < l1; i++)
{
rem = _subborrow_u64(rem, a1[i], 0, a3 + i);
}
}
while (a3[out.m_data->len - 1] == 0)
out.m_data->len--;
return out;
}
static void
adx_test (void)
{
volatile unsigned char c;
unsigned long long x;
volatile unsigned long long y, sum_ref;
c = 0;
x = y = 0xFFFFFFFFFFFFFFFFLL;
sum_ref = 0xFFFFFFFFFFFFFFFELL;
/* X = 0xFFFFFFFFFFFFFFFF, Y = 0xFFFFFFFFFFFFFFFF, C = 0. */
c = _addcarryx_u64 (c, x, y, &x);
/* X = 0xFFFFFFFFFFFFFFFE, Y = 0xFFFFFFFFFFFFFFFF, C = 1. */
c = _addcarryx_u64 (c, x, y, &x);
/* X = 0xFFFFFFFFFFFFFFFE, Y = 0xFFFFFFFFFFFFFFFF, C = 1. */
if (x != sum_ref)
abort ();
c = 0;
x = y = 0xFFFFFFFFFFFFFFFFLL;
sum_ref = 0xFFFFFFFFFFFFFFFELL;
/* X = 0xFFFFFFFFFFFFFFFF, Y = 0xFFFFFFFFFFFFFFFF, C = 0. */
c = _addcarry_u64 (c, x, y, &x);
/* X = 0xFFFFFFFFFFFFFFFE, Y = 0xFFFFFFFFFFFFFFFF, C = 1. */
c = _addcarry_u64 (c, x, y, &x);
/* X = 0xFFFFFFFFFFFFFFFE, Y = 0xFFFFFFFFFFFFFFFF, C = 1. */
if (x != sum_ref)
abort ();
c = 0;
x = 1LL;
y = 0LL;
sum_ref = 0x0LL;
/* X = 0x0000000000000001, Y = 0x0000000000000000, C = 0. */
c = _subborrow_u64 (c, x, y, &x);
/* X = 0xFFFFFFFFFFFFFFFF, Y = 0x0000000000000000, C = 1. */
c = _subborrow_u64 (c, x, y, &x);
/* X = 0x0000000000000000, Y = 0x0000000000000000, C = 1. */
if (x != sum_ref)
abort ();
}
uint2048& operator-=(uint2048& operand_a, const uint2048& operand_b){
uint64_t a, b;
uint64_t* c;
uint8_t borrow_flag = 0u;
for (auto i = 0u; i < 32u; ++i){
a = operand_a.parts_[i];
b = operand_b.parts_[i];
c = &(operand_a.parts_[i]);
// intrinsic function
// sbb instruction
// *c = a - (b + borrow)
// borrow_flag is set to 1 if (a < (b + borrow))
borrow_flag = _subborrow_u64(borrow_flag, a, b, c);
}
return operand_a;
}
