exa/codecrypt
1
0
Fork 0
Code Issues Pull requests Actions Packages Projects Releases Wiki Activity

gf2m: lowlevel speedups

Browse source
This commit is contained in:
Mirek Kratochvil 2013-05-18 10:51:47 +02:00
parent 1ef1b4277b
commit be13fe8dca
2 changed files with 30 additions and 65 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

59
src/gf2m.cpp
View file

@ -32,11 +32,6 @@ int gf2p_degree (uint p)
return r - 1;
}
inline uint gf2p_add (uint a, uint b)
{
return a ^ b;
}
uint gf2p_mod (uint a, uint p)
{
if (!p) return 0;
@ -88,14 +83,6 @@ bool is_irreducible_gf2_poly (uint p)
return true;
}
uint gf2p_tablemult (uint a, uint b, uint n,
const std::vector<uint>&log,
const std::vector<uint>&antilog)
{
if (! (a && b) ) return 0;
return antilog[ (log[a] + log[b]) % (n - 1) ];
}
bool gf2m::create (uint M)
{
if (M < 1) return false; //too small.
@ -143,49 +130,3 @@ bool gf2m::create (uint M)
return true;
}
uint gf2m::add (uint a, uint b)
{
return gf2p_add (a, b);
}
uint gf2m::mult (uint a, uint b)
{
return gf2p_tablemult (a, b, n, log, antilog);
}
uint gf2m::exp (uint a, int k)
{
if (!a) return 0;
if (a == 1) return 1;
if (k < 0) {
a = inv (a);
k = -k;
}
uint r = 1;
while (k) {
if (k & 1) r = mult (r, a);
a = mult (a, a);
k >>= 1;
}
return r;
}
uint gf2m::exp (int k)
{
//return x^k
return exp (1 << 1, k);
}
uint gf2m::inv (uint a)
{
if (!a) return 0;
return antilog[ (n - 1 - log[a]) % (n - 1) ];
}
uint gf2m::sq_root (uint a)
{
for (uint i = 1; i < m; ++i)
a = mult (a, a);
return a;
}

36
src/gf2m.h
View file

@ -37,12 +37,36 @@ public:
std::vector<uint> log, antilog;
uint add (uint, uint);
uint mult (uint, uint);
uint exp (uint, int);
uint exp (int);
uint inv (uint);
uint sq_root (uint);
inline uint add (uint a, uint b) {
return a ^ b;
}
inline uint mult (uint a, uint b) {
if (! (a && b) ) return 0;
return antilog[ (log[a] + log[b]) % (n - 1)];
}
inline uint exp (uint a, int k) {
if (!a) return 0;
return antilog[ (log[a] * k) % (n - 1)];
}
inline uint exp (int k) {
//return x^k
return exp (1 << 1, k);
}
inline uint inv (uint a) {
if (!a) return 0;
return antilog[ (n - 1 - log[a]) % (n - 1)];
}
inline uint sq_root (uint a) {
if (!a) return 0;
uint t = log[a];
if (t % 2) return antilog[ (t + n - 1) >> 1];
else return antilog[t >> 1];
}
sencode* serialize();
bool unserialize (sencode*);