Added a Go demo

README.md

@@ -36,6 +36,11 @@ and if you are daring:
 
 make install 
 
+Go
+===
+
+If you are a go user, there is a "go" folder where you will find a simple demo.
+
 References
 ===========
 

go/README.md

@@ -0,0 +1,13 @@
+Simple Go demo
+==============
+
+Setup
+======
+
+Start by installing the simdcomp library (make && make install).
+
+Then type:
+
+go run test.go
+
+

go/test.go

@@ -0,0 +1,71 @@
+/////////
+// This particular file is in the public domain.
+// Author: Daniel Lemire
+////////
+
+package main 
+
+/*
+#cgo LDFLAGS: -lsimdcomp
+#include <simdcomp.h>
+*/
+import "C"
+import "fmt"
+
+//////////
+// For this demo, we pack and unpack blocks of 128 integers
+/////////
+func main() {
+        // I am going to use C types. Alternative might be to use unsafe.Pointer calls, see http://bit.ly/1ndw3W3
+        // this is our original data
+        var data [128]C.uint32_t
+        for i := C.uint32_t(0); i < C.uint32_t(128); i++ {
+            data[i] = i
+        }
+
+
+
+
+
+        ////////////
+        // We first pack without differential coding
+        ///////////
+        // computing how many bits per int. is needed
+        b  := C.maxbits(&data[0])
+        ratio := 32.0/float64(b)
+        fmt.Println("Bit width  ", b)
+        fmt.Println(fmt.Sprintf("Compression ratio %f ", ratio))
+         // we are now going to create a buffer to receive the packed data (each __m128i uses 128 bits)
+        out := make([] C.__m128i,b)       
+        C.simdpackwithoutmask( &data[0],&out[0],b);
+        var recovereddata [128]C.uint32_t
+        C.simdunpack(&out[0],&recovereddata[0],b)
+        for i := 0; i < 128; i++ {
+            if data[i] != recovereddata[i]  {
+                  fmt.Println("Bug ")
+                  return
+            }
+        } 
+
+        ///////////
+        // Next, we use differential coding
+        //////////
+        offset := C.uint32_t(0) // if you pack data from K to K + 128, offset should be the value at K-1. When K = 0, choose a default
+        b1  := C.simdmaxbitsd1(offset,&data[0])
+        ratio1 := 32.0/float64(b1)
+        fmt.Println("Bit width  ", b1)
+        fmt.Println(fmt.Sprintf("Compression ratio %f ", ratio1))
+         // we are now going to create a buffer to receive the packed data (each __m128i uses 128 bits)
+        out = make([] C.__m128i,b1)       
+        C.simdpackwithoutmaskd1(offset, &data[0],&out[0],b1);
+        C.simdunpackd1(offset,&out[0],&recovereddata[0],b1)
+        for i := 0; i < 128; i++ {
+            if data[i] != recovereddata[i]  {
+                  fmt.Println("Bug ")
+                  return
+            }
+        } 
+
+        fmt.Println("test succesful.")
+
+}