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stepcompress: Use inclusive range on min/maxadd 

Change the min/maxadd variables to use an inclusive range instead of
exclusive.  This better matches min/maxinterval.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2016-12-14 10:59:15 -05:00
parent a217c0f394
commit e4c4a4628b
1 changed files with 11 additions and 11 deletions
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22
klippy/stepcompress.c
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@ -115,7 +115,7 @@ minmax_point(struct stepcompress *sc, uint64_t *pos)
// The maximum add delta between two valid quadratic sequences of the
// form "add*count*(count-1)/2 + interval*count" is "(6 + 4*sqrt(2)) *
// maxerror / (count*count)". The "6 + 4*sqrt(2)" is 11.65685, but
// using 11 and rounding up when dividing works well in practice.
// using 11 works well in practice.
#define QUADRATIC_DEV 11
struct step_move {
@ -130,7 +130,7 @@ compress_bisect_add(struct stepcompress *sc)
{
struct points point = minmax_point(sc, sc->queue_pos);
int32_t outer_mininterval = point.minp, outer_maxinterval = point.maxp;
int32_t add = 0, minadd = -0x8001, maxadd = 0x8000;
int32_t add = 0, minadd = -0x8000, maxadd = 0x7fff;
int32_t bestinterval = 0, bestcount = 1, bestadd = 1, bestreach = INT32_MIN;
for (;;) {
@ -174,17 +174,17 @@ compress_bisect_add(struct stepcompress *sc)
int32_t nextaddfactor = nextcount*(nextcount-1)/2;
int32_t nextreach = add*nextaddfactor + interval*nextcount;
if (nextreach < nextpoint.minp) {
minadd = add;
minadd = add + 1;
outer_maxinterval = nextmaxinterval;
} else {
maxadd = add;
maxadd = add - 1;
outer_mininterval = nextmininterval;
}
// The maximum valid deviation between two quadratic sequences
// can be calculated and used to further limit the add range.
if (count > 1) {
int32_t errdelta = DIV_UP(sc->max_error*QUADRATIC_DEV, count*count);
int32_t errdelta = sc->max_error*QUADRATIC_DEV / (count*count);
if (minadd < add - errdelta)
minadd = add - errdelta;
if (maxadd > add + errdelta)
@ -193,16 +193,16 @@ compress_bisect_add(struct stepcompress *sc)
// See if next point would further limit the add range
int32_t c = outer_maxinterval * nextcount;
if ((minadd+1)*nextaddfactor < nextpoint.minp - c)
minadd = idiv_up(nextpoint.minp - c, nextaddfactor) - 1;
if (minadd*nextaddfactor < nextpoint.minp - c)
minadd = idiv_up(nextpoint.minp - c, nextaddfactor);
c = outer_mininterval * nextcount;
if ((maxadd-1)*nextaddfactor > nextpoint.maxp - c)
maxadd = idiv_down(nextpoint.maxp - c, nextaddfactor) + 1;
if (maxadd*nextaddfactor > nextpoint.maxp - c)
maxadd = idiv_down(nextpoint.maxp - c, nextaddfactor);
// Bisect valid add range and try again with new 'add'
add = (minadd + maxadd) / 2;
if (add <= minadd || add >= maxadd)
if (minadd > maxadd)
break;
add = (minadd + maxadd) / 2;
}
return (struct step_move){ bestinterval, bestcount, bestadd };
}