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|
package main
import (
"bufio"
"fmt"
"math/rand/v2"
"os"
"runtime"
"sync"
"time"
"golang.org/x/term"
)
var stdout = bufio.NewWriter(os.Stdout)
const (
left = -(1 + iota)
right
)
func readKeys(out chan<- rune) {
defer close(out)
stdin := bufio.NewReader(os.Stdin)
for {
b, err := stdin.ReadByte()
if err != nil {
break
}
if b == '\x1b' {
buf := make([]byte, 2)
n, err := stdin.Read(buf)
switch string(buf[:n]) {
case "[D":
out <- left
case "[C":
out <- right
}
if err != nil {
break
}
} else {
out <- rune(b)
}
}
}
type board struct {
buf []bool
rows int
cols int
}
func newBoard(rows, cols int) board {
return board{
buf: make([]bool, rows*cols),
rows: rows,
cols: cols,
}
}
func (b board) row(i int) []bool {
start := i * b.cols
return b.buf[start : start+b.cols]
}
func (b board) neighborCount(i, j int) int {
count := 0
for di := -1; di <= 1; di++ {
for dj := -1; dj <= 1; dj++ {
if di == 0 && dj == 0 {
continue
}
ii := i + di
jj := j + dj
if ii < 0 {
ii = b.rows - 1
} else if ii == b.rows {
ii = 0
}
if jj < 0 {
jj = b.cols - 1
} else if jj == b.cols {
jj = 0
}
if b.row(ii)[jj] {
count++
}
}
}
return count
}
var numCPU = runtime.NumCPU()
func step(nextBoard, activeBoard board) {
chunkSize := (activeBoard.rows + numCPU - 1) / numCPU
wg := new(sync.WaitGroup)
for start := 0; start < activeBoard.rows; start += chunkSize {
wg.Add(1)
go func() {
defer wg.Done()
for i := start; i < min(start+chunkSize, activeBoard.rows); i++ {
for j := range activeBoard.cols {
count := activeBoard.neighborCount(i, j)
nextBoard.row(i)[j] = count == 3 || count == 2 && activeBoard.row(i)[j]
}
}
}()
}
wg.Wait()
}
func life() error {
cols, rows, err := term.GetSize(int(os.Stdout.Fd()))
if err != nil {
return err
}
oldState, err := term.MakeRaw(int(os.Stdin.Fd()))
if err != nil {
return err
}
defer term.Restore(int(os.Stdin.Fd()), oldState)
board1 := newBoard(rows, cols)
for i := range board1.rows {
for j := range board1.cols {
board1.row(i)[j] = rand.IntN(2) != 0
}
}
board2 := newBoard(rows, cols)
activeBoard := board1
nextBoard := board2
const minDelay = time.Second / 300
delay := 250 * time.Millisecond
running := true
oneTick := false
frameTimer := time.NewTicker(minDelay)
defer frameTimer.Stop()
lastFrameTime := time.Now()
accumulator := time.Duration(0)
keyCh := make(chan rune, 1024)
go readKeys(keyCh)
for now := range frameTimer.C {
Read:
for {
var key rune
select {
case key = <-keyCh:
default:
break Read
}
switch key {
case 'q':
return nil
case ' ':
running = !running
case '.':
if !running {
oneTick = true
}
case left:
delay += delay / 3
case right:
delay = max(delay-delay/3, minDelay)
}
}
accumulator += now.Sub(lastFrameTime)
lastFrameTime = now
if oneTick || accumulator >= delay {
if accumulator >= delay {
accumulator -= delay
}
if running || oneTick {
oneTick = false
step(nextBoard, activeBoard)
activeBoard, nextBoard = nextBoard, activeBoard
}
}
// Prevent falling behind.
if accumulator > delay {
accumulator = delay
}
stdout.WriteString("\x1b[H")
for i := range activeBoard.rows {
if i > 0 {
stdout.WriteString("\r\n")
}
for j := range activeBoard.cols {
if activeBoard.row(i)[j] {
stdout.WriteByte('#')
} else {
stdout.WriteByte(' ')
}
}
}
stdout.Flush()
}
panic("unreachable")
}
func main() {
if err := life(); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}
|
