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package com.oracle.graal.compiler.hsail.test;

import org.junit.*;

import com.oracle.graal.compiler.hsail.test.infra.*;

/**
 * Tests bitwise right shift of long values. Generates an shr_s64 instruction.
 */
public class LongBitwiseShiftRightTest extends GraalKernelTester {

    static final int num = 100;
    // Output array containing the results of shift operations.
    @Result protected long[] outArray = new long[num];

    /**
     * The static "kernel" method we will be testing. This method performs a bitwise shift righj
     * operation on an element of an input array and writes the result to the corresponding index of
     * an output array. By convention the gid is the last parameter.
     * 
     * @param out the output array
     * @param ina the input array
     * @param shiftAmount an array of values used for the shift magnitude
     * @param gid the parameter used to index into the input and output arrays
     */
    public static void run(long[] out, long[] ina, int[] shiftAmount, int gid) {
        out[gid] = ina[gid] >> shiftAmount[gid];
    }

    /**
     * Tests the HSAIL code generated for this unit test by comparing the result of executing this
     * code with the result of executing a sequential Java version of this unit test.
     */
    @Test
    public void test() {
        super.testGeneratedHsail();
    }

    /**
     * Initializes the arrays passed to the run routine.
     * 
     * We do this in such a way that the input arrays contain a mix of negative and positive values.
     * As a result, the work items will exercise all the different combinations for the sign of the
     * value being shifted and the sign of the shift magnitude.
     * 
     * @param in the input array
     */
    void setupArrays(long[] in, int[] shiftAmount) {
        for (int i = 0; i < num; i++) {
            /**
             * Fill lower half of in[] with positive numbers and upper half with negative numbers.
             */
            in[i] = i < num / 2 ? i : -i;
            /**
             * Fill shiftAmount[] so that even elements are positive and odd elements are negative.
             */
            shiftAmount[i] = (i & 1) == 0 ? i : -i;
            outArray[i] = 0;
        }
    }

    /**
     * Dispatches the HSAIL kernel for this test case.
     */
    @Override
    public void runTest() {
        long[] inArray = new long[num];
        int[] shiftAmount = new int[num];
        setupArrays(inArray, shiftAmount);
        dispatchMethodKernel(num, outArray, inArray, shiftAmount);
    }
}