whatcanGOwrong

go/pkg/mod/golang.org/x/exp@v0.0.0-20230224173230-c95f2b4c22f2/shootout/mandelbrot.go

@@ -0,0 +1,98 @@
+//go:build ignore
+// +build ignore
+
+/*
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the
+    documentation and/or other materials provided with the distribution.
+
+    * Neither the name of "The Computer Language Benchmarks Game" nor the
+    name of "The Computer Language Shootout Benchmarks" nor the names of
+    its contributors may be used to endorse or promote products derived
+    from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/* The Computer Language Benchmarks Game
+ * http://shootout.alioth.debian.org/
+ *
+ * contributed by The Go Authors.
+ * Based on mandelbrot.c contributed by Greg Buchholz
+ */
+
+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"os"
+)
+
+var n = flag.Int("n", 200, "size")
+
+func main() {
+	flag.Parse()
+	out := bufio.NewWriter(os.Stdout)
+	defer out.Flush()
+
+	w := float64(*n)
+	h := float64(*n)
+	bit_num := 0
+	byte_acc := byte(0)
+	const Iter = 50
+	const Zero float64 = 0
+	const Limit = 2.0
+
+	fmt.Fprintf(out, "P4\n%d %d\n", *n, *n)
+
+	for y := 0.0; y < h; y++ {
+		for x := 0.0; x < w; x++ {
+			Zr, Zi, Tr, Ti := Zero, Zero, Zero, Zero
+			Cr := (2*x/w - 1.5)
+			Ci := (2*y/h - 1.0)
+
+			for i := 0; i < Iter && (Tr+Ti <= Limit*Limit); i++ {
+				Zi = 2*Zr*Zi + Ci
+				Zr = Tr - Ti + Cr
+				Tr = Zr * Zr
+				Ti = Zi * Zi
+			}
+
+			byte_acc <<= 1
+			if Tr+Ti <= Limit*Limit {
+				byte_acc |= 0x01
+			}
+
+			bit_num++
+
+			if bit_num == 8 {
+				out.WriteByte(byte_acc)
+				byte_acc = 0
+				bit_num = 0
+			} else if x == w-1 {
+				byte_acc <<= uint(8 - uint(*n)%8)
+				out.WriteByte(byte_acc)
+				byte_acc = 0
+				bit_num = 0
+			}
+		}
+	}
+}