From 591e343ec94077f873b1aa12052a4ce55ae80200 Mon Sep 17 00:00:00 2001
From: Cedric Nugteren <web@cedricnugteren.nl>
Date: Sun, 15 May 2016 20:18:34 +0200
Subject: Added an example of using the half-precision HAXPY routine

---
 CMakeLists.txt  |   2 +-
 samples/haxpy.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 106 insertions(+), 1 deletion(-)
 create mode 100644 samples/haxpy.c

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 38588289..051e7643 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -120,7 +120,7 @@ include_directories(${clblast_SOURCE_DIR}/include ${OPENCL_INCLUDE_DIRS})
 # Sets the supported routines and the used kernels. New routines and kernels should be added here.
 set(KERNELS copy pad transpose padtranspose xaxpy xdot xger xgemm xgemv)
 set(SAMPLE_PROGRAMS_CPP sgemm)
-set(SAMPLE_PROGRAMS_C sasum dgemv sgemm cache)
+set(SAMPLE_PROGRAMS_C sasum dgemv sgemm haxpy cache)
 set(LEVEL1_ROUTINES xswap xscal xcopy xaxpy xdot xdotu xdotc xnrm2 xasum xamax)
 set(LEVEL2_ROUTINES xgemv xgbmv xhemv xhbmv xhpmv xsymv xsbmv xspmv xtrmv xtbmv xtpmv
                     xger xgeru xgerc xher xhpr xher2 xhpr2 xsyr xspr xsyr2 xspr2)
diff --git a/samples/haxpy.c b/samples/haxpy.c
new file mode 100644
index 00000000..3c7bb33a
--- /dev/null
+++ b/samples/haxpy.c
@@ -0,0 +1,105 @@
+
+// =================================================================================================
+// This file is part of the CLBlast project. The project is licensed under Apache Version 2.0. This
+// project loosely follows the Google C++ styleguide and uses a tab-size of two spaces and a max-
+// width of 100 characters per line.
+//
+// Author(s):
+//   Cedric Nugteren <www.cedricnugteren.nl>
+//
+// This file demonstrates the use of the HAXPY routine. It demonstrates the use of half-precision.
+//
+// Note that this example is meant for illustration purposes only. CLBlast provides other programs
+// for performance benchmarking ('client_xxxxx') and for correctness testing ('test_xxxxx').
+//
+// =================================================================================================
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+// Includes the CLBlast library (C interface)
+#include <clblast_c.h>
+
+// Includes the float-to-half and half-to-float conversion utilities
+#include <clblast_half.h>
+
+// =================================================================================================
+
+// Example use of the half-precision routine HAXPY
+int main(void) {
+
+  // OpenCL platform/device settings
+  const size_t platform_id = 0;
+  const size_t device_id = 0;
+
+  // Example HAXPY arguments
+  const size_t n = 8192;
+  const cl_half alpha = FloatToHalf(0.5f);
+
+  // Initializes the OpenCL platform
+  cl_uint num_platforms;
+  clGetPlatformIDs(0, NULL, &num_platforms);
+  cl_platform_id* platforms = (cl_platform_id*)malloc(num_platforms*sizeof(cl_platform_id));
+  clGetPlatformIDs(num_platforms, platforms, NULL);
+  cl_platform_id platform = platforms[platform_id];
+
+  // Initializes the OpenCL device
+  cl_uint num_devices;
+  clGetDeviceIDs(platform, CL_DEVICE_TYPE_ALL, 0, NULL, &num_devices);
+  cl_device_id* devices = (cl_device_id*)malloc(num_devices*sizeof(cl_device_id));
+  clGetDeviceIDs(platform, CL_DEVICE_TYPE_ALL, num_devices, devices, NULL);
+  cl_device_id device = devices[device_id];
+
+  // Creates the OpenCL context, queue, and an event
+  cl_context context = clCreateContext(NULL, 1, &device, NULL, NULL, NULL);
+  cl_command_queue queue = clCreateCommandQueue(context, device, 0, NULL);
+  cl_event event = NULL;
+
+  // Populate host vectors with some example data
+  cl_half* host_a = (cl_half*)malloc(sizeof(cl_half)*n);
+  cl_half* host_b = (cl_half*)malloc(sizeof(cl_half)*n);
+  for (size_t i=0; i<n; ++i) { host_a[i] = FloatToHalf(2.2f); }
+  for (size_t i=0; i<n; ++i) { host_b[i] = FloatToHalf(0.4f); }
+  printf("Input values at index 0: alpha * a[0] + b[0] == %.3lf * %.3lf + %.3lf\n",
+         HalfToFloat(alpha), HalfToFloat(host_a[0]), HalfToFloat(host_b[0]));
+
+  // Copy the matrices to the device
+  cl_mem device_a = clCreateBuffer(context, CL_MEM_READ_WRITE, n*sizeof(cl_half), NULL, NULL);
+  cl_mem device_b = clCreateBuffer(context, CL_MEM_READ_WRITE, n*sizeof(cl_half), NULL, NULL);
+  clEnqueueWriteBuffer(queue, device_a, CL_TRUE, 0, n*sizeof(cl_half), host_a, 0, NULL, NULL);
+  clEnqueueWriteBuffer(queue, device_b, CL_TRUE, 0, n*sizeof(cl_half), host_b, 0, NULL, NULL);
+
+  // Call the HAXPY routine.
+  StatusCode status = CLBlastHaxpy(n, alpha,
+                                   device_a, 0, 1,
+                                   device_b, 0, 1,
+                                   &queue, &event);
+
+  // Wait for completion
+  clWaitForEvents(1, &event);
+
+  // Copies the result back to the host
+  clEnqueueReadBuffer(queue, device_b, CL_TRUE, 0, n*sizeof(cl_half), host_b, 0, NULL, NULL);
+
+  // Example completed. See "clblast_c.h" for status codes (0 -> success).
+  printf("Completed HAXPY with status %d\n", status);
+
+  // Prints the first output value
+  if (status == 0) {
+    printf("Output value at index 0: b[0] = %.3lf\n", HalfToFloat(host_b[0]));
+  }
+
+  // Clean-up
+  free(platforms);
+  free(devices);
+  free(host_a);
+  free(host_b);
+  clReleaseMemObject(device_a);
+  clReleaseMemObject(device_b);
+  clReleaseCommandQueue(queue);
+  clReleaseContext(context);
+  return 0;
+}
+
+// =================================================================================================
-- 
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