source code
/* The Computer Language Benchmarks Game
http://benchmarksgame.alioth.debian.org/
contributed by Jos Hirth,
calculation block borrowed from the C# version which was
created by Isaac Gouy, Antti Lankila, The Anh Tran, and Robert F. Tobler
*/
import 'dart:io';
import 'dart:isolate';
import 'dart:async';
import 'dart:typed_data';
void main(args) {
int n = args.length > 0 ? int.parse(args[0]) : 2000;
var threads = Platform.numberOfProcessors;
var segmentFutures = new List(threads);
int lineLen = (n - 1) ~/ 8 + 1;
var lines = new List<Uint8List>(n);
var segmentSize = new List.filled(threads, n ~/ threads);
segmentSize[0] += n % threads;
int from = 0;
for (int i = 0; i < threads; i++) {
var len = segmentSize[i];
var response = new ReceivePort();
int localFrom = from;
Future<Isolate> remote = Isolate.spawn(calculateSegment, response.sendPort);
segmentFutures[i] = remote.then((_) => response.first).then((sendPort) {
ReceivePort response = new ReceivePort();
sendPort.send({
'n': n,
'from': localFrom,
'len': len,
'port': response.sendPort
});
return response.first;
});
from += len;
}
stdout.write('P4\n$n $n\n');
Future.wait(segmentFutures).then((segments) {
for (var segment in segments) {
for (var line in segment) {
stdout.add(line);
}
}
});
}
Uint8List calculateLine (int n, int y) {
int lineLen = (n - 1) ~/ 8 + 1;
var line = new Uint8List(lineLen);
int xbyte = 0, bits = 1;
double ci = y * 2.0 / n - 1.0;
for (int x = 0; x < n; x++) {
double cr = x * 2.0 / n - 1.5;
if (bits > 0xff) {
line[xbyte++] = bits;
bits = 1;
}
double zr = cr,
zi = ci,
tr = cr * cr,
ti = ci * ci;
int i = 49;
do {
zi = zr * zi + zr * zi + ci;
zr = tr - ti + cr;
tr = zr * zr;
ti = zi * zi;
} while ((tr + ti <= 4.0) && (--i > 0));
bits = (bits << 1) | (i == 0 ? 1 : 0);
} while (bits < 0x100) bits = (bits << 1);
line[xbyte] = bits;
return line;
}
void calculateSegment (SendPort initialReplyTo) {
var port = new ReceivePort();
initialReplyTo.send(port.sendPort);
port.listen((msg) {
int n = msg['n'];
int from = msg['from'];
int len = msg['len'];
SendPort replyTo = msg['port'];
var lines = new List<Uint8List>(len);
for (int i = 0; i < len; i++) {
lines[i] = calculateLine(n, from + i);
}
replyTo.send(lines);
port.close();
});
}