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Diffstat (limited to 'subsurface-core/device.c')
-rw-r--r-- | subsurface-core/device.c | 184 |
1 files changed, 0 insertions, 184 deletions
diff --git a/subsurface-core/device.c b/subsurface-core/device.c deleted file mode 100644 index 6c4452f78..000000000 --- a/subsurface-core/device.c +++ /dev/null @@ -1,184 +0,0 @@ -#include <string.h> -#include "dive.h" -#include "device.h" - -/* - * Good fake dive profiles are hard. - * - * "depthtime" is the integral of the dive depth over - * time ("area" of the dive profile). We want that - * area to match the average depth (avg_d*max_t). - * - * To do that, we generate a 6-point profile: - * - * (0, 0) - * (t1, max_d) - * (t2, max_d) - * (t3, d) - * (t4, d) - * (max_t, 0) - * - * with the same ascent/descent rates between the - * different depths. - * - * NOTE: avg_d, max_d and max_t are given constants. - * The rest we can/should play around with to get a - * good-looking profile. - * - * That six-point profile gives a total area of: - * - * (max_d*max_t) - (max_d*t1) - (max_d-d)*(t4-t3) - * - * And the "same ascent/descent rates" requirement - * gives us (time per depth must be same): - * - * t1 / max_d = (t3-t2) / (max_d-d) - * t1 / max_d = (max_t-t4) / d - * - * We also obviously require: - * - * 0 <= t1 <= t2 <= t3 <= t4 <= max_t - * - * Let us call 'd_frac = d / max_d', and we get: - * - * Total area must match average depth-time: - * - * (max_d*max_t) - (max_d*t1) - (max_d-d)*(t4-t3) = avg_d*max_t - * max_d*(max_t-t1-(1-d_frac)*(t4-t3)) = avg_d*max_t - * max_t-t1-(1-d_frac)*(t4-t3) = avg_d*max_t/max_d - * t1+(1-d_frac)*(t4-t3) = max_t*(1-avg_d/max_d) - * - * and descent slope must match ascent slopes: - * - * t1 / max_d = (t3-t2) / (max_d*(1-d_frac)) - * t1 = (t3-t2)/(1-d_frac) - * - * and - * - * t1 / max_d = (max_t-t4) / (max_d*d_frac) - * t1 = (max_t-t4)/d_frac - * - * In general, we have more free variables than we have constraints, - * but we can aim for certain basics, like a good ascent slope. - */ -static int fill_samples(struct sample *s, int max_d, int avg_d, int max_t, double slope, double d_frac) -{ - double t_frac = max_t * (1 - avg_d / (double)max_d); - int t1 = max_d / slope; - int t4 = max_t - t1 * d_frac; - int t3 = t4 - (t_frac - t1) / (1 - d_frac); - int t2 = t3 - t1 * (1 - d_frac); - - if (t1 < 0 || t1 > t2 || t2 > t3 || t3 > t4 || t4 > max_t) - return 0; - - s[1].time.seconds = t1; - s[1].depth.mm = max_d; - s[2].time.seconds = t2; - s[2].depth.mm = max_d; - s[3].time.seconds = t3; - s[3].depth.mm = max_d * d_frac; - s[4].time.seconds = t4; - s[4].depth.mm = max_d * d_frac; - - return 1; -} - -/* we have no average depth; instead of making up a random average depth - * we should assume either a PADI rectangular profile (for short and/or - * shallow dives) or more reasonably a six point profile with a 3 minute - * safety stop at 5m */ -static void fill_samples_no_avg(struct sample *s, int max_d, int max_t, double slope) -{ - // shallow or short dives are just trapecoids based on the given slope - if (max_d < 10000 || max_t < 600) { - s[1].time.seconds = max_d / slope; - s[1].depth.mm = max_d; - s[2].time.seconds = max_t - max_d / slope; - s[2].depth.mm = max_d; - } else { - s[1].time.seconds = max_d / slope; - s[1].depth.mm = max_d; - s[2].time.seconds = max_t - max_d / slope - 180; - s[2].depth.mm = max_d; - s[3].time.seconds = max_t - 5000 / slope - 180; - s[3].depth.mm = 5000; - s[4].time.seconds = max_t - 5000 / slope; - s[4].depth.mm = 5000; - } -} - -struct divecomputer *fake_dc(struct divecomputer *dc, bool alloc) -{ - static struct sample fake_samples[6]; - static struct divecomputer fakedc; - struct sample *fake = fake_samples; - - fakedc = (*dc); - if (alloc) - fake = malloc(sizeof(fake_samples)); - - fakedc.sample = fake; - fakedc.samples = 6; - - /* The dive has no samples, so create a few fake ones */ - int max_t = dc->duration.seconds; - int max_d = dc->maxdepth.mm; - int avg_d = dc->meandepth.mm; - - memset(fake, 0, sizeof(fake_samples)); - fake[5].time.seconds = max_t; - if (!max_t || !max_d) - return &fakedc; - - /* - * We want to fake the profile so that the average - * depth ends up correct. However, in the absence of - * a reasonable average, let's just make something - * up. Note that 'avg_d == max_d' is _not_ a reasonable - * average. - * We explicitly treat avg_d == 0 differently */ - if (avg_d == 0) { - /* we try for a sane slope, but bow to the insanity of - * the user supplied data */ - fill_samples_no_avg(fake, max_d, max_t, MAX(2.0 * max_d / max_t, 5000.0 / 60)); - if (fake[3].time.seconds == 0) { // just a 4 point profile - fakedc.samples = 4; - fake[3].time.seconds = max_t; - } - return &fakedc; - } - if (avg_d < max_d / 10 || avg_d >= max_d) { - avg_d = (max_d + 10000) / 3; - if (avg_d > max_d) - avg_d = max_d * 2 / 3; - } - if (!avg_d) - avg_d = 1; - - /* - * Ok, first we try a basic profile with a specific ascent - * rate (5 meters per minute) and d_frac (1/3). - */ - if (fill_samples(fake, max_d, avg_d, max_t, 5000.0 / 60, 0.33)) - return &fakedc; - - /* - * Ok, assume that didn't work because we cannot make the - * average come out right because it was a quick deep dive - * followed by a much shallower region - */ - if (fill_samples(fake, max_d, avg_d, max_t, 10000.0 / 60, 0.10)) - return &fakedc; - - /* - * Uhhuh. That didn't work. We'd need to find a good combination that - * satisfies our constraints. Currently, we don't, we just give insane - * slopes. - */ - if (fill_samples(fake, max_d, avg_d, max_t, 10000.0, 0.01)) - return &fakedc; - - /* Even that didn't work? Give up, there's something wrong */ - return &fakedc; -} |