// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <threads.h>
#include <unistd.h>

#include <zircon/compiler.h>
#include <unittest/unittest.h>

#define THREAD_COUNT 8
#define ITER 1000000

/* expected double bit pattern for each thread */
static const uint64_t expected[THREAD_COUNT] = {
    0x4284755ed4188b3e,
    0x4284755ed6cb84c0,
    0x4284755ed97e7dd3,
    0x4284755edc317770,
    0x4284755edee471b9,
    0x4284755ee1976c19,
    0x4284755ee44a648b,
    0x4284755ee6fd5fa7,
};

/* optimize this function to cause it to try to use a lot of registers */
__OPTIMIZE("O3")
static int float_thread(void* arg) {
    double* val = arg;
    unsigned int i, j;
    double a[16];

    unittest_printf("float_thread arg %f, running %u iterations\n", *val, ITER);
    usleep(500000);

    /* do a bunch of work with floating point to test context switching */
    a[0] = *val;
    for (i = 1; i < countof(a); i++) {
        a[i] = a[i - 1] * 1.01;
    }

    for (i = 0; i < ITER; i++) {
        a[0] += i;
        for (j = 1; j < countof(a); j++) {
            a[j] += a[j - 1] * 0.00001;
        }
    }

    *val = a[countof(a) - 1];
    return 0;
}

bool fpu_test(void) {
    BEGIN_TEST;

    unittest_printf("welcome to floating point test\n");

    /* test lazy fpu load on separate thread */
    thrd_t t[THREAD_COUNT];
    double val[countof(t)];
    char name[ZX_MAX_NAME_LEN];

    unittest_printf("creating %zu floating point threads\n", countof(t));
    for (unsigned int i = 0; i < countof(t); i++) {
        val[i] = i;
        snprintf(name, sizeof(name), "fpu thread %u", i);
        thrd_create_with_name(&t[i], float_thread, &val[i], name);
    }

    for (unsigned int i = 0; i < countof(t); i++) {
        thrd_join(t[i], NULL);
        void* v = &val[i];
        uint64_t int64_val = *(uint64_t*)v;

        unittest_printf("float thread %u returns val %f %#"
                        PRIx64 ", expected %#" PRIx64 "\n",
                        i, val[i], int64_val, expected[i]);
        EXPECT_EQ(int64_val, expected[i], "Value does not match as expected");
    }

    unittest_printf("floating point test done\n");
    END_TEST;
}

BEGIN_TEST_CASE(fpu_tests)
RUN_TEST(fpu_test);
END_TEST_CASE(fpu_tests)