more tests

various-tests/perf-2dim-pointers-all-array/go.mod

@@ -0,0 +1,3 @@
+module perf
+
+go 1.22

various-tests/perf-2dim-pointers-all-array/main.go

@@ -0,0 +1,141 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"math/rand"
+	"os"
+	"runtime/pprof"
+	"time"
+	"unsafe"
+)
+
+const (
+	max     int  = 1500
+	loops   int  = 5000
+	density int  = 8
+	debug   bool = false
+)
+
+type Cell struct {
+	State         bool
+	Neighbors     [8]*Cell
+	NeighborCount int
+}
+
+type Grid [1500][1500]Cell
+
+// https://dev.to/chigbeef_77/bool-int-but-stupid-in-go-3jb3
+func bool2int(b bool) int {
+	return int(*(*byte)(unsafe.Pointer(&b)))
+}
+
+func (cell *Cell) Count(x, y int) {
+	cell.NeighborCount = 0
+
+	for _, neighbor := range cell.Neighbors {
+		cell.NeighborCount += bool2int(neighbor.State)
+	}
+}
+
+func SetNeighbors(grid Grid, x, y int) {
+	cells := []*Cell{}
+	deadcell := &Cell{}
+
+	for nbgX := -1; nbgX < 2; nbgX++ {
+		for nbgY := -1; nbgY < 2; nbgY++ {
+			var col, row int
+
+			if x+nbgX < 0 || x+nbgX >= max || y+nbgY < 0 || y+nbgY >= max {
+				cells = append(cells, deadcell)
+			} else {
+
+				col = x + nbgX
+				row = y + nbgY
+
+				if col == x && row == y {
+					// do not add self
+					continue
+				}
+
+				cells = append(cells, &grid[row][col])
+			}
+		}
+	}
+
+	for idx, cell := range cells {
+		grid[y][x].Neighbors[idx] = cell
+	}
+}
+
+func Init() Grid {
+	grid := Grid{}
+
+	for y := 0; y < max; y++ {
+		for x := 0; x < max; x++ {
+			if rand.Intn(density) == 1 {
+				grid[y][x].State = true
+			}
+		}
+	}
+
+	for y := 0; y < max; y++ {
+		for x := 0; x < max; x++ {
+			SetNeighbors(grid, x, y)
+		}
+	}
+
+	return grid
+}
+
+func Loop(grid Grid) {
+	c := 0
+	for i := 0; i < loops; i++ {
+		for y := 0; y < max; y++ {
+			for x := 0; x < max; x++ {
+				cell := &grid[y][x]
+				state := cell.State
+
+				cell.Count(x, y)
+
+				if state && cell.NeighborCount > 1 {
+					if debug {
+						fmt.Printf(
+							"Loop %d - cell at %d,%d is %t and has %d living neighbors\n",
+							i, x, y, state, cell.NeighborCount)
+					}
+					c = 1
+				}
+			}
+		}
+	}
+
+	if c > 1 {
+		c = 0
+	}
+}
+
+func main() {
+	// enable  cpu profiling. Do  NOT use q  to stop the  game but
+	// close the window to get a profile
+	fd, err := os.Create("cpu.profile")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer fd.Close()
+
+	pprof.StartCPUProfile(fd)
+	defer pprof.StopCPUProfile()
+
+	// init
+	grid := Init()
+
+	// main loop
+	loopstart := time.Now()
+
+	Loop(grid)
+
+	loopend := time.Now()
+	diff := loopstart.Sub(loopend)
+	fmt.Printf("Loop took %.04f\n", diff.Seconds())
+}