mars/lib_rank.c
2013-01-20 23:24:21 +01:00

80 lines
1.6 KiB
C

// (c) 2010 Thomas Schoebel-Theuer / 1&1 Internet AG
// (c) 2012 Thomas Schoebel-Theuer
//#define BRICK_DEBUGGING
//#define MARS_DEBUGGING
//#define IO_DEBUGGING
#include <linux/kernel.h>
#include <linux/module.h>
#include "mars.h"
#include "lib_rank.h"
void ranking_compute(struct rank_data *rkd, const struct rank_info rki[], int rki_count, int x)
{
int i;
MARS_IO("rki_count = %d at x = %d\n", rki_count, x);
BUG_ON(rki_count < 2);
rki_count--;
for (i = 0; i < rki_count; i++) {
int x0 = rki[i].rki_x;
int x1;
int y0;
int y1;
int points;
if (x < x0 && i+1 < rki_count)
continue;
x1 = rki[i+1].rki_x;
BUG_ON(x1 == x0);
y0 = rki[i].rki_y;
y1 = rki[i+1].rki_y;
// linear interpolation
points = ((long long)(x - x0) * (long long)(y1 - y0)) / (x1 - x0) + y0;
MARS_IO("i = %d x0 = %d x1 = %d y0 = %d y1 = %d points = %d\n", i, x0, x1, y0, y1, points);
rkd->rkd_tmp += points;
break;
}
}
EXPORT_SYMBOL_GPL(ranking_compute);
int ranking_select(struct rank_data rkd[], int rkd_count)
{
int res = -1;
int max = INT_MIN / 2;
int i;
MARS_IO("rkd_count = %d\n", rkd_count);
for (i = 0; i < rkd_count; i++) {
struct rank_data *tmp = &rkd[i];
int rest = tmp->rkd_current_points;
if (rest <= 0)
continue;
rest -= tmp->rkd_got;
if (rest > max) {
max = rest;
res = i;
}
}
/* Prevent underflow in the long term
* and reset the "clocks" after each round of
* weighted round-robin selection.
*/
if (max <= 0 && res >= 0) {
for (i = 0; i < rkd_count; i++)
rkd[i].rkd_got -= rkd[i].rkd_current_points;
}
MARS_IO("res = %d\n", res);
return res;
}
EXPORT_SYMBOL_GPL(ranking_select);