38 lines
899 B
Plaintext
38 lines
899 B
Plaintext
|
All current (2001) S/390 and z/Architecture machines are single-issue,
|
||
|
|
but some newer machines have a deep pipeline. Software-pipelining is
|
||
|
|
therefore beneficial.
|
||
|
|
|
||
|
|
* mpn_add_n, mpn_sub_n: Use code along the lines below. Two-way unrolling
|
||
|
|
would be adequate.
|
||
|
|
|
||
|
|
mp_limb_t
|
||
|
|
mpn_add_n (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n)
|
||
|
|
{
|
||
|
|
mp_limb_t a, b, r, cy;
|
||
|
|
mp_size_t i;
|
||
|
|
mp_limb_t mm = -1;
|
||
|
|
|
||
|
|
cy = 0;
|
||
|
|
up += n;
|
||
|
|
vp += n;
|
||
|
|
rp += n;
|
||
|
|
i = -n;
|
||
|
|
do
|
||
|
|
{
|
||
|
|
a = up[i];
|
||
|
|
b = vp[i];
|
||
|
|
r = a + b + cy;
|
||
|
|
rp[i] = r;
|
||
|
|
cy = (((a & b) | ((a | b) & (r ^ mm)))) >> 31;
|
||
|
|
i++;
|
||
|
|
}
|
||
|
|
while (i < 0);
|
||
|
|
return cy;
|
||
|
|
}
|
||
|
|
|
||
|
|
* mpn_lshift, mpn_rshift: Use SLDL/SRDL, and two-way unrolling.
|
||
|
|
|
||
|
|
* mpn_mul_1, mpn_addmul_1, mpn_submul_1: For machines with just signed
|
||
|
|
multiply (MR), use two loops, similar to the corresponding VAX or
|
||
|
|
POWER functions. Handle carry like for mpn_add_n.
|