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// | |
// EndlessSummer.c | |
// Tumbltail | |
// | |
// Created by nya on 2013/11/05. | |
// | |
// | |
#import "EndlessSummer.h" | |
typedef struct { | |
double a1; | |
int a2; | |
double b1; | |
int b2; | |
long long upperBound; | |
} ESParamBase; | |
#define PARAM_COUNT (10) | |
#define COEF_A(base) (base.a1 * pow(10, base.a2)) | |
#define COEF_B(base) (base.b1 * pow(10, base.b2)) | |
static const ESParamBase baseParams[PARAM_COUNT] = { | |
{2.374, -268, 5.342, -10, 1182114958836}, | |
{2.292, -63, 1.349, -10, 1193135035175}, | |
{1.214, -11, 3.509, -11, 1241622616806}, | |
{1.259, -22, 5.546, -11, 1283088065116}, | |
{3.805, -29, 6.716, -11, 1291075200000}, | |
{5.579, -28, 6.521, -11, 1292241600000}, | |
{4.482, -28, 6.541, -11, 1307576237375}, | |
{2.424, -28, 6.588, -11, 1313586050187}, | |
{3.923, -13, 3.922, -11, 1340572542928}, | |
{2.157, -3, 2.249, -11, LLONG_MAX}, | |
}; | |
long long GetPostIDFromUnixTime(long long utime) { | |
if (utime < 1149465600000) { | |
return -1; | |
} else if (utime == LLONG_MAX) { | |
return LLONG_MAX; | |
} | |
for (int i = 0; i < PARAM_COUNT; i++) { | |
if (utime <= baseParams[i].upperBound) { | |
return ceil(COEF_A(baseParams[i]) * exp(COEF_B(baseParams[i]) * utime)); | |
} | |
} | |
return -1; | |
} | |
long long GetUnixTimeFromPostID(long long postID) { | |
if (postID < 1) { return -1; } | |
for (int i = 0; i < PARAM_COUNT; i++) { | |
if (postID <= GetPostIDFromUnixTime(baseParams[i].upperBound)) { | |
return floor(log(postID / COEF_A(baseParams[i])) / COEF_B(baseParams[i])) / 1000; | |
} | |
} | |
return -1; | |
} | |
long long GetRandomPostID() { | |
struct tm tm = { | |
0, 0, 0, // 秒, 分, 時 (0~) | |
1, // 日 (1~31) | |
0, // 月 (0~11) | |
108, // 年 (1900 年からの年数) | |
}; | |
long long epoch = mktime(&tm); // 2008/1/1 | |
long long now = time(NULL) - 60 * 60; | |
return GetPostIDFromUnixTime(1000 * (epoch + (now - epoch) * rand() / RAND_MAX)); | |
} | |
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