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next.cpp
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next.cpp
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#include <cstring>
#include <future>
#include <iostream>
#include <thread>
#include <vector>
#include "board.h"
#include "next.h"
#include "padding.h"
#include "threads.h"
inline uint64_t uint8s_to_uint64(Cell* ns) {
return *reinterpret_cast<uint64_t*>(ns);
}
constexpr uint8_t LOOKUP[20] = {
0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0,
};
uint isAlive(const uint& i, const Cell* input, const uint& realWidth) {
const Cell* top = &input[i - realWidth - 1];
const Cell* middle = &input[i - 1];
const Cell* bottom = &input[i + realWidth - 1];
const auto a = top[0] + middle[0] + bottom[0];
const auto b = top[1] + middle[1] * 9 + bottom[1];
const auto c = top[2] + middle[2] + bottom[2];
return LOOKUP[a + b + c];
}
inline void revokeSkipForNeighbours(const uint& i, Cell* skips, const uint& realWidth) {
*reinterpret_cast<uint32_t*>(&skips[(i - realWidth - 1) / SKIPS_PER_BYTE]) = NO_SKIP_BYTE;
*reinterpret_cast<uint32_t*>(&skips[(i - 1) / SKIPS_PER_BYTE]) = NO_SKIP_BYTE;
*reinterpret_cast<uint32_t*>(&skips[(i + realWidth - 1) / SKIPS_PER_BYTE]) = NO_SKIP_BYTE;
}
void nextBoardSection(
uint i,
const uint endI,
const uint realWidth,
Cell* input,
Cell* output,
uint8_t* inSkip,
uint8_t* outSkip) {
while (i < endI) {
while (uint8s_to_uint64(&inSkip[i / SKIPS_PER_BYTE]) == SKIP_EIGHT_BYTES)
i += SKIPS_PER_BYTE * 8;
output[i] = isAlive(i, input, realWidth);
if (input[i] != output[i]) {
revokeSkipForNeighbours(i, outSkip, realWidth);
}
i++;
}
}
void nextBoard(Board& board, const uint& threadCount, const uint& jobCount) {
board.setOutputToInput();
// Create segments
std::vector<std::tuple<uint, uint>> segments(jobCount);
const uint segmentSize = (board.height / jobCount + board.height % jobCount) * board.rawWidth;
uint endI = board.rawWidth;
for (auto& segment : segments) {
const uint beginI = endI;
endI = std::min(board.rawSize - board.rawWidth, endI + segmentSize);
segment = {beginI, endI};
};
// Create jobs
std::vector<std::function<void()>> jobs(jobCount);
for (uint i = 0; i < jobCount; i++) {
const auto& beginI = std::get<0>(segments[i]);
const auto& endI = std::get<1>(segments[i]);
// Reset next border
if (i == jobCount - 1) {
std::memset(
&board.outSkip[(endI - board.rawWidth) / SKIPS_PER_BYTE], SKIP_BYTE,
(board.rawSize - (endI - board.rawWidth)) / SKIPS_PER_BYTE);
} else {
const auto borderSize = std::min(board.rawSize, endI + board.rawWidth * 3);
std::memset(&board.outSkip[endI - board.rawWidth], SKIP_BYTE, (borderSize - endI) / SKIPS_PER_BYTE);
}
jobs[i] = [&, beginI, endI]() {
// Reset inner skips
if (endI == beginI)
return;
const auto max = std::max(beginI + board.rawWidth, endI - board.rawWidth);
std::memset(
&board.outSkip[(beginI + board.rawWidth) / SKIPS_PER_BYTE], SKIP_BYTE,
(max - beginI - board.rawWidth) / SKIPS_PER_BYTE);
nextBoardSection(beginI + 1, endI - 1, board.rawWidth, board.input, board.output, board.inSkip, board.outSkip);
};
board.inSkip[endI] = NO_SKIP_BYTE; // Never skip last cell of segment
};
// Reset first border
std::memset(board.outSkip, SKIP_BYTE, (sizeof(Cell) * board.rawWidth) / SKIPS_PER_BYTE);
std::atomic<uint> job = {0};
std::vector<std::thread> threads(threadCount - 1);
for (auto& thread : threads) {
thread = std::thread([&]() {
uint current = job.fetch_add(1);
while (current < jobCount) {
jobs[current]();
current = job.fetch_add(1);
}
});
};
uint current = job.fetch_add(1);
while (current < jobCount) {
jobs[current]();
current = job.fetch_add(1);
}
for (auto& thread : threads) {
thread.join();
}
assignBoardPadding(board);
}
std::thread startNextBoardLoopThread(
const ulong& maxGenerations,
const uint& threadCount,
const uint& jobCount,
Board& board,
ulong& computedGenerations) {
return std::thread{[&]() {
while (computedGenerations < maxGenerations) {
board.lock.pauseIfRequested();
nextBoard(board, threadCount, jobCount);
++computedGenerations;
}
}};
}