prenex/fastrand
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

fixed bug in ILP gen

Browse Source
This commit is contained in:
Richard Thier 2025-04-02 20:10:22 +02:00
parent d823a77bf6
commit 1a3e87e076
2 changed files with 11 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
fastrand.h
View File

@ -112,7 +112,7 @@ static inline uint32_t lcg_ilp(rand_ilp_state *state, RAND_ILP which) {
state->d = state->d * 1664525u + 1013904223u; state->d = state->d * 1664525u + 1013904223u;
return state->d; return state->d;
} else if(which == E) { } else if(which == E) {
state->e = state->a * 1664525u + 1013904223u; state->e = state->e * 1664525u + 1013904223u;
return state->e; return state->e;
} else if(which == F) { } else if(which == F) {
state->f = state->f * 1664525u + 1013904223u; state->f = state->f * 1664525u + 1013904223u;
@ -134,6 +134,10 @@ static inline uint32_t rand_until(rand_state *restrict state, uint32_t until) {
return (uint32_t)(((uint64_t)rand * until) >> 32); return (uint32_t)(((uint64_t)rand * until) >> 32);
} }
uint32_t fastmodlike(uint32_t num, uint32_t m) {
return (((uint64_t) num) * m);
}
/** /**
* Pick a "reasonably random" number in [from, to) without modulus. * Pick a "reasonably random" number in [from, to) without modulus.
* *

6
perf.cpp
View File

@ -8,8 +8,10 @@
// #define N 19999999 // #define N 19999999
// #define M 10000000 // M >= N // #define M 10000000 // M >= N
#define M 19999999 // M >= N #define M 19999999 // M >= N
/*
#define FROM 100 #define FROM 100
#define TO 576 // [FROM, TO) #define TO 576 // [FROM, TO)
*/
uint32_t res[M] = { 0 }; uint32_t res[M] = { 0 };
@ -21,6 +23,10 @@ int main() {
rand_state rs = init_rand(); rand_state rs = init_rand();
rand_ilp_state rs_ilp = init_rand_ilp(); rand_ilp_state rs_ilp = init_rand_ilp();
// Generate FROM,TO as random, because otherwise compiler optimizes out IDIV of the '%' operator!
uint32_t FROM = (uint32_t) rand();
uint32_t TO = (uint32_t) rand();
printf("Full range generation perf - %d number of cases:\n", N); printf("Full range generation perf - %d number of cases:\n", N);
auto t0 = std::chrono::high_resolution_clock::now(); auto t0 = std::chrono::high_resolution_clock::now();