From 8471ad55b2dda6ed38389883a291511c1f8ab0c2 Mon Sep 17 00:00:00 2001
From: Hans-Kristian Arntzen <hans-kristian.arntzen@arm.com>
Date: Wed, 25 May 2016 08:40:02 +0100
Subject: [PATCH] Add atomics C++ sample.

---
 samples/cpp/atomics.comp | 29 +++++++++++++
 samples/cpp/atomics.cpp  | 90 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 119 insertions(+)
 create mode 100644 samples/cpp/atomics.comp
 create mode 100644 samples/cpp/atomics.cpp

diff --git a/samples/cpp/atomics.comp b/samples/cpp/atomics.comp
new file mode 100644
index 00000000..0bf6d2ad
--- /dev/null
+++ b/samples/cpp/atomics.comp
@@ -0,0 +1,29 @@
+#version 310 es
+layout(local_size_x = 64) in;
+
+layout(set = 0, binding = 0, std430) readonly buffer SSBO0
+{
+	float inputs[];
+};
+
+layout(set = 0, binding = 1, std430) writeonly buffer SSBO1
+{
+	float outputs[];
+};
+
+layout(set = 0, binding = 2, std430) buffer SSBO2
+{
+	uint counter;
+};
+
+void main()
+{
+	// Builds a tightly packed list of all values less than 10.0.
+	// The output order is random.
+	float value = inputs[gl_GlobalInvocationID.x];
+	if (value < 10.0)
+	{
+		uint output_index = atomicAdd(counter, 1u);
+		outputs[output_index] = value;
+	}
+}
diff --git a/samples/cpp/atomics.cpp b/samples/cpp/atomics.cpp
new file mode 100644
index 00000000..e11fc1b9
--- /dev/null
+++ b/samples/cpp/atomics.cpp
@@ -0,0 +1,90 @@
+/*
+ * Copyright 2015-2016 ARM Limited
+ *
+ * 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.
+ */
+
+#include "spirv_cross/external_interface.h"
+#include <stdio.h>
+
+#ifndef GLM_SWIZZLE
+#define GLM_SWIZZLE
+#endif
+
+#ifndef GLM_FORCE_RADIANS
+#define GLM_FORCE_RADIANS
+#endif
+
+#include <glm/glm.hpp>
+using namespace glm;
+
+int main()
+{
+	// First, we get the C interface to the shader.
+	// This can be loaded from a dynamic library, or as here,
+	// linked in as a static library.
+	auto *iface = spirv_cross_get_interface();
+
+	// Create an instance of the shader interface.
+	auto *shader = iface->construct();
+
+	// Build some input data for our compute shader.
+#define NUM_WORKGROUPS 4
+	float a[64 * NUM_WORKGROUPS];
+	float b[64 * NUM_WORKGROUPS] = {};
+	uint32_t counter = 0;
+
+	for (int i = 0; i < 64 * NUM_WORKGROUPS; i++)
+	{
+		a[i] = i * 0.46f;
+	}
+
+	void *aptr = a;
+	void *bptr = b;
+	void *cptr = &counter;
+
+	// Bind resources to the shader.
+	// For resources like samplers and buffers, we provide a list of pointers,
+	// since UBOs, SSBOs and samplers can be arrays, and can point to different types,
+	// which is especially true for samplers.
+	spirv_cross_set_resource(shader, 0, 0, &aptr, sizeof(aptr));
+	spirv_cross_set_resource(shader, 0, 1, &bptr, sizeof(bptr));
+	spirv_cross_set_resource(shader, 0, 2, &cptr, sizeof(cptr));
+
+	// We also have to set builtins.
+	// The relevant builtins will depend on the shader,
+	// but for compute, there are few builtins, which are gl_NumWorkGroups and gl_WorkGroupID.
+	// LocalInvocationID and GlobalInvocationID are inferred when executing the invocation.
+	uvec3 num_workgroups(NUM_WORKGROUPS, 1, 1);
+	uvec3 work_group_id(0, 0, 0);
+	spirv_cross_set_builtin(shader, SPIRV_CROSS_BUILTIN_NUM_WORK_GROUPS, &num_workgroups, sizeof(num_workgroups));
+	spirv_cross_set_builtin(shader, SPIRV_CROSS_BUILTIN_WORK_GROUP_ID, &work_group_id, sizeof(work_group_id));
+
+	// Execute 4 work groups.
+	for (unsigned i = 0; i < NUM_WORKGROUPS; i++)
+	{
+		work_group_id.x = i;
+		iface->invoke(shader);
+	}
+
+	// Call destructor.
+	iface->destruct(shader);
+
+	// Verify our output.
+	// TODO: Implement a test framework that asserts results computed.
+	fprintf(stderr, "Counter = %u\n", counter);
+	for (unsigned i = 0; i < counter; i++)
+	{
+		fprintf(stderr, "[%3u] = %.1f\n", i, b[i]);
+	}
+}