Full restructure in accordance with

- pkg/{subsystem}/{package} style
  - modify Makefile to reflect the new style,
    consolidate various entries
  - add a dummy ``main.go`` at top level

pkg/utils/cpu/cpu.go

@@ -0,0 +1,36 @@
+/*
+ * Mini Object Storage, (C) 2014 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// +build amd64
+
+package cpu
+
+// int has_sse41 (void);
+// int has_avx (void);
+// int has_avx2 (void);
+import "C"
+
+func HasSSE41() bool {
+	return int(C.has_sse41()) == 1
+}
+
+func HasAVX() bool {
+	return int(C.has_avx()) == 1
+}
+
+func HasAVX2() bool {
+	return int(C.has_avx2()) == 1
+}

pkg/utils/cpu/cpu_amd64.S

@@ -0,0 +1,138 @@
+/*
+ * Mini Object Storage, (C) 2014 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License") ;
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifdef __APPLE__
+#define HAS_SSE _has_sse41
+#define HAS_AVX _has_avx
+#define HAS_AVX2 _has_avx2
+#else
+#define HAS_SSE has_sse41
+#define HAS_AVX has_avx
+#define HAS_AVX2 has_avx2
+#endif
+
+	.file	"cpufeatures.c"
+	.text
+cpuid:
+.LFB2:
+	.cfi_startproc
+	pushq	%rbp
+	.cfi_def_cfa_offset 16
+	.cfi_offset 6, -16
+	movq	%rsp, %rbp
+	.cfi_def_cfa_register 6
+	pushq	%rbx
+	.cfi_offset 3, -24
+	movq	%rdi, -16(%rbp)
+	movl	%esi, -20(%rbp)
+	movq	-16(%rbp), %rax
+	leaq	4(%rax), %r10
+	movq	-16(%rbp), %rax
+	leaq	8(%rax), %r9
+	movq	-16(%rbp), %rax
+	leaq	12(%rax), %r8
+	movl	-20(%rbp), %eax
+	movl	$0, %edx
+	movl	%edx, %ecx
+#APP
+# 21 "cpufeatures.c" 1
+	cpuid
+# 0 "" 2
+#NO_APP
+	movl	%ebx, %esi
+	movl	%eax, %edi
+	movq	-16(%rbp), %rax
+	movl	%edi, (%rax)
+	movl	%esi, (%r10)
+	movl	%ecx, (%r9)
+	movl	%edx, (%r8)
+	popq	%rbx
+	popq	%rbp
+	.cfi_def_cfa 7, 8
+	ret
+	.cfi_endproc
+.LFE2:
+	.globl	HAS_SSE
+HAS_SSE:
+.LFB3:
+	.cfi_startproc
+	pushq	%rbp
+	.cfi_def_cfa_offset 16
+	.cfi_offset 6, -16
+	movq	%rsp, %rbp
+	.cfi_def_cfa_register 6
+	subq	$16, %rsp
+	leaq	-16(%rbp), %rax
+	movl	$1, %esi
+	movq	%rax, %rdi
+	call	cpuid
+	movl	-8(%rbp), %eax
+	andl	$524288, %eax
+	testl	%eax, %eax
+	setne	%al
+	movzbl	%al, %eax
+	leave
+	.cfi_def_cfa 7, 8
+	ret
+	.cfi_endproc
+.LFE3:
+	.globl	HAS_AVX
+HAS_AVX:
+.LFB4:
+	.cfi_startproc
+	pushq	%rbp
+	.cfi_def_cfa_offset 16
+	.cfi_offset 6, -16
+	movq	%rsp, %rbp
+	.cfi_def_cfa_register 6
+	subq	$16, %rsp
+	leaq	-16(%rbp), %rax
+	movl	$1, %esi
+	movq	%rax, %rdi
+	call	cpuid
+	movl	-8(%rbp), %eax
+	andl	$268435456, %eax
+	testl	%eax, %eax
+	setne	%al
+	movzbl	%al, %eax
+	leave
+	.cfi_def_cfa 7, 8
+	ret
+	.cfi_endproc
+.LFE4:
+	.globl	HAS_AVX2
+HAS_AVX2:
+.LFB5:
+	.cfi_startproc
+	pushq	%rbp
+	.cfi_def_cfa_offset 16
+	.cfi_offset 6, -16
+	movq	%rsp, %rbp
+	.cfi_def_cfa_register 6
+	subq	$16, %rsp
+	leaq	-16(%rbp), %rax
+	movl	$7, %esi
+	movq	%rax, %rdi
+	call	cpuid
+	movl	-12(%rbp), %eax
+	andl	$32, %eax
+	testl	%eax, %eax
+	setne	%al
+	movzbl	%al, %eax
+	leave
+	.cfi_def_cfa 7, 8
+	ret
+	.cfi_endproc

pkg/utils/cpu/cpu_test.go

@@ -0,0 +1,80 @@
+/*
+ * Mini Object Storage, (C) 2014 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// +build amd64
+
+package cpu
+
+import (
+	"errors"
+	"os/exec"
+	"runtime"
+	"strings"
+	"testing"
+
+	. "gopkg.in/check.v1"
+)
+
+func Test(t *testing.T) { TestingT(t) }
+
+type MySuite struct{}
+
+var _ = Suite(&MySuite{})
+
+func hasCpuFeatureFromOS(feature string) (bool, error) {
+	if runtime.GOOS == "linux" {
+		command := exec.Command("/bin/cat", "/proc/cpuinfo")
+		output, err := command.Output()
+		if err != nil {
+			return false, err
+		}
+		if strings.Contains(string(output), feature) {
+			return true, nil
+		} else {
+			return false, nil
+		}
+	} else {
+		// TODO find new way to test cpu flags on windows
+		return false, errors.New("Not Implemented on this platform")
+	}
+}
+
+func (s *MySuite) TestHasSSE41(c *C) {
+	if runtime.GOOS == "linux" {
+		var flag = HasSSE41()
+		osCheck, err := hasCpuFeatureFromOS("sse4_1")
+		c.Assert(err, IsNil)
+		c.Check(flag, Equals, osCheck)
+	}
+}
+
+func (s *MySuite) TestHasAVX(c *C) {
+	if runtime.GOOS == "linux" {
+		var flag = HasAVX()
+		osFlag, err := hasCpuFeatureFromOS("avx")
+		c.Assert(err, IsNil)
+		c.Check(osFlag, Equals, flag)
+	}
+}
+
+func (s *MySuite) TestHasAVX2(c *C) {
+	if runtime.GOOS == "linux" {
+		var flag = HasAVX2()
+		osFlag, err := hasCpuFeatureFromOS("avx2")
+		c.Assert(err, IsNil)
+		c.Check(osFlag, Equals, flag)
+	}
+}

pkg/utils/cpu/doc.go

@@ -0,0 +1,11 @@
+// Package cpu provides wrapper around assembly functions for checking processor
+// instruction capabilities for SSE4.1, AVX, AVX2 support
+//
+// Example
+//
+// ``cpu.HasSSE41()`` returns true for SSE4.1 instruction support, false otherwise
+//
+// ``cpu.HasAVX()`` returns true for AVX instruction support, false otherwise
+//
+// ``cpu.HasAVX2()`` returns true for AVX2 instruction support, false otherwise
+package cpu