1 files changed, 104 insertions, 0 deletions
diff --git a/misc/cgo/gmp/pi.go b/misc/cgo/gmp/pi.go
new file mode 100644
index 000000000..d22bbc653
--- /dev/null
+++ b/misc/cgo/gmp/pi.go
@@ -0,0 +1,104 @@
+/*
+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 pidigits.c (by Paolo Bonzini & Sean Bartlett,
+ *                      modified by Michael Mellor)
+ */
+
+package main
+
+import (
+	big "gmp";
+	"fmt";
+	"runtime";
+)
+
+var (
+	tmp1 = big.NewInt(0);
+	tmp2 = big.NewInt(0);
+	numer = big.NewInt(1);
+	accum = big.NewInt(0);
+	denom = big.NewInt(1);
+	ten = big.NewInt(10);
+)
+
+func extractDigit() int64 {
+	if big.CmpInt(numer, accum) > 0 {
+		return -1;
+	}
+	tmp1.Lsh(numer, 1).Add(tmp1, numer).Add(tmp1, accum);
+	big.DivModInt(tmp1, tmp2, tmp1, denom);
+	tmp2.Add(tmp2, numer);
+	if big.CmpInt(tmp2, denom) >= 0 {
+		return -1;
+	}
+	return tmp1.Int64();
+}
+
+func nextTerm(k int64) {
+	y2 := k*2 + 1;
+	accum.Add(accum, tmp1.Lsh(numer, 1));
+	accum.Mul(accum, tmp1.SetInt64(y2));
+	numer.Mul(numer, tmp1.SetInt64(k));
+	denom.Mul(denom, tmp1.SetInt64(y2));
+}
+
+func eliminateDigit(d int64) {
+	accum.Sub(accum, tmp1.Mul(denom, tmp1.SetInt64(d)));
+	accum.Mul(accum, ten);
+	numer.Mul(numer, ten);
+}
+
+func main() {
+	i := 0;
+	k := int64(0);
+	for {
+		d := int64(-1);
+		for d < 0 {
+			k++;
+			nextTerm(k);
+			d = extractDigit();
+		}
+		eliminateDigit(d);
+		fmt.Printf("%c", d + '0');
+
+		if i++; i%50 == 0 {
+			fmt.Printf("\n");
+			if i >= 1000 {
+				break;
+			}
+		}
+	}
+
+	fmt.Printf("\n%d calls; bit sizes: %d %d %d\n", runtime.Cgocalls(), numer.Len(), accum.Len(), denom.Len());
+}