/*
 * Copyright © 2018, VideoLAN and dav1d authors
 * Copyright © 2018, Two Orioles, LLC
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include "tests/checkasm/checkasm.h"

#include <math.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <time.h>

#include "src/cpu.h"

#ifdef _WIN32
#include <windows.h>
#define COLOR_RED    FOREGROUND_RED
#define COLOR_GREEN  FOREGROUND_GREEN
#define COLOR_YELLOW (FOREGROUND_RED|FOREGROUND_GREEN)
#else
#include <unistd.h>
#define COLOR_RED    1
#define COLOR_GREEN  2
#define COLOR_YELLOW 3
#endif

/* List of tests to invoke */
static const struct {
    const char *name;
    void (*func)(void);
} tests[] = {
    { "itx_8bpc", checkasm_check_itx_8bpc },
    { "itx_10bpc", checkasm_check_itx_10bpc },
    { "mc_8bpc", checkasm_check_mc_8bpc },
    { "mc_10bpc", checkasm_check_mc_10bpc },
    { 0 }
};

/* List of cpu flags to check */
static const struct {
    const char *name;
    const char *suffix;
    unsigned flag;
} cpus[] = {
#if ARCH_X86
    { "SSE",     "sse",    DAV1D_X86_CPU_FLAG_SSE },
    { "SSE2",    "sse2",   DAV1D_X86_CPU_FLAG_SSE2 },
    { "SSE3",    "sse3",   DAV1D_X86_CPU_FLAG_SSE3 },
    { "SSSE3",   "ssse3",  DAV1D_X86_CPU_FLAG_SSSE3 },
    { "SSE4.1",  "sse4",   DAV1D_X86_CPU_FLAG_SSE41 },
    { "SSE4.2",  "sse42",  DAV1D_X86_CPU_FLAG_SSE42 },
    { "AVX",     "avx",    DAV1D_X86_CPU_FLAG_AVX },
    { "AVX2",    "avx2",   DAV1D_X86_CPU_FLAG_AVX2 },
    { "AVX-512", "avx512", DAV1D_X86_CPU_FLAG_AVX512 },
#elif ARCH_AARCH64 || ARCH_ARM
    { "NEON",    "neon",   DAV1D_ARM_CPU_FLAG_NEON },
#endif
    { 0 }
};

typedef struct CheckasmFuncVersion {
    struct CheckasmFuncVersion *next;
    void *func;
    int ok;
    unsigned cpu;
    int iterations;
    uint64_t cycles;
} CheckasmFuncVersion;

/* Binary search tree node */
typedef struct CheckasmFunc {
    struct CheckasmFunc *child[2];
    CheckasmFuncVersion versions;
    uint8_t color; /* 0 = red, 1 = black */
    char name[1];
} CheckasmFunc;

/* Internal state */
static struct {
    CheckasmFunc *funcs;
    CheckasmFunc *current_func;
    CheckasmFuncVersion *current_func_ver;
    const char *current_test_name;
    const char *bench_pattern;
    int bench_pattern_len;
    int num_checked;
    int num_failed;
    int nop_time;
    unsigned cpu_flag;
    const char *cpu_flag_name;
    const char *test_name;
} state;

/* float compare support code */
typedef union {
    float f;
    uint32_t i;
} intfloat;

static int is_negative(const intfloat u) {
    return u.i >> 31;
}

int float_near_ulp(const float a, const float b, const unsigned max_ulp) {
    intfloat x, y;

    x.f = a;
    y.f = b;

    if (is_negative(x) != is_negative(y)) {
        // handle -0.0 == +0.0
        return a == b;
    }

    if (llabs((int64_t)x.i - y.i) <= max_ulp)
        return 1;

    return 0;
}

int float_near_ulp_array(const float *const a, const float *const b,
                         const unsigned max_ulp, const int len)
{
    for (int i = 0; i < len; i++)
        if (!float_near_ulp(a[i], b[i], max_ulp))
            return 0;

    return 1;
}

int float_near_abs_eps(const float a, const float b, const float eps) {
    return fabsf(a - b) < eps;
}

int float_near_abs_eps_array(const float *const a, const float *const b,
                             const float eps, const int len)
{
    for (int i = 0; i < len; i++)
        if (!float_near_abs_eps(a[i], b[i], eps))
            return 0;

    return 1;
}

int float_near_abs_eps_ulp(const float a, const float b, const float eps,
                           const unsigned max_ulp)
{
    return float_near_ulp(a, b, max_ulp) || float_near_abs_eps(a, b, eps);
}

int float_near_abs_eps_array_ulp(const float *const a, const float *const b,
                                 const float eps, const unsigned max_ulp,
                                 const int len)
{
    for (int i = 0; i < len; i++)
        if (!float_near_abs_eps_ulp(a[i], b[i], eps, max_ulp))
            return 0;

    return 1;
}

/* Print colored text to stderr if the terminal supports it */
static void color_printf(const int color, const char *const fmt, ...) {
    static int8_t use_color = -1;
    va_list arg;

#ifdef _WIN32
    static HANDLE con;
    static WORD org_attributes;

    if (use_color < 0) {
        CONSOLE_SCREEN_BUFFER_INFO con_info;
        con = GetStdHandle(STD_ERROR_HANDLE);
        if (con && con != INVALID_HANDLE_VALUE &&
            GetConsoleScreenBufferInfo(con, &con_info))
        {
            org_attributes = con_info.wAttributes;
            use_color = 1;
        } else
            use_color = 0;
    }
    if (use_color)
        SetConsoleTextAttribute(con, (org_attributes & 0xfff0) |
                                (color & 0x0f));
#else
    if (use_color < 0) {
        const char *const term = getenv("TERM");
        use_color = term && strcmp(term, "dumb") && isatty(2);
    }
    if (use_color)
        fprintf(stderr, "\x1b[%d;3%dm", (color & 0x08) >> 3, color & 0x07);
#endif

    va_start(arg, fmt);
    vfprintf(stderr, fmt, arg);
    va_end(arg);

    if (use_color) {
#ifdef _WIN32
        SetConsoleTextAttribute(con, org_attributes);
#else
        fprintf(stderr, "\x1b[0m");
#endif
    }
}

/* Deallocate a tree */
static void destroy_func_tree(CheckasmFunc *const f) {
    if (f) {
        CheckasmFuncVersion *v = f->versions.next;
        while (v) {
            CheckasmFuncVersion *next = v->next;
            free(v);
            v = next;
        }

        destroy_func_tree(f->child[0]);
        destroy_func_tree(f->child[1]);
        free(f);
    }
}

/* Allocate a zero-initialized block, clean up and exit on failure */
static void *checkasm_malloc(const size_t size) {
    void *const ptr = calloc(1, size);
    if (!ptr) {
        fprintf(stderr, "checkasm: malloc failed\n");
        destroy_func_tree(state.funcs);
        exit(1);
    }
    return ptr;
}

/* Get the suffix of the specified cpu flag */
static const char *cpu_suffix(const unsigned cpu) {
    for (int i = (int)(sizeof(cpus) / sizeof(*cpus)) - 2; i >= 0; i--)
        if (cpu & cpus[i].flag)
            return cpus[i].suffix;

    return "c";
}

#ifdef readtime
static int cmp_nop(const void *a, const void *b) {
    return *(const uint16_t*)a - *(const uint16_t*)b;
}

/* Measure the overhead of the timing code (in decicycles) */
static int measure_nop_time(void) {
    uint16_t nops[10000];
    int i, nop_sum = 0;

    for (i = 0; i < 10000; i++) {
        uint64_t t = readtime();
        nops[i] = readtime() - t;
    }

    qsort(nops, 10000, sizeof(uint16_t), cmp_nop);
    for (i = 2500; i < 7500; i++)
        nop_sum += nops[i];

    return nop_sum / 500;
}

/* Print benchmark results */
static void print_benchs(const CheckasmFunc *const f) {
    if (f) {
        print_benchs(f->child[0]);

        /* Only print functions with at least one assembly version */
        if (f->versions.cpu || f->versions.next) {
            const CheckasmFuncVersion *v = &f->versions;
            do {
                if (v->iterations) {
                    int decicycles = (10*v->cycles/v->iterations -
                                      state.nop_time) / 4;
                    printf("%s_%s: %d.%d\n", f->name, cpu_suffix(v->cpu),
                           decicycles/10, decicycles%10);
                }
            } while ((v = v->next));
        }

        print_benchs(f->child[1]);
    }
}
#endif

#define is_digit(x) ((x) >= '0' && (x) <= '9')

/* ASCIIbetical sort except preserving natural order for numbers */
static int cmp_func_names(const char *a, const char *b) {
    const char *const start = a;
    int ascii_diff, digit_diff;

    for (; !(ascii_diff = *(const unsigned char*)a -
                          *(const unsigned char*)b) && *a; a++, b++);
    for (; is_digit(*a) && is_digit(*b); a++, b++);

    if (a > start && is_digit(a[-1]) &&
        (digit_diff = is_digit(*a) - is_digit(*b)))
    {
        return digit_diff;
    }

    return ascii_diff;
}

/* Perform a tree rotation in the specified direction and return the new root */
static CheckasmFunc *rotate_tree(CheckasmFunc *const f, const int dir) {
    CheckasmFunc *const r = f->child[dir^1];
    f->child[dir^1] = r->child[dir];
    r->child[dir] = f;
    r->color = f->color;
    f->color = 0;
    return r;
}

#define is_red(f) ((f) && !(f)->color)

/* Balance a left-leaning red-black tree at the specified node */
static void balance_tree(CheckasmFunc **root) {
    CheckasmFunc *const f = *root;

    if (is_red(f->child[0]) && is_red(f->child[1])) {
        f->color ^= 1;
        f->child[0]->color = f->child[1]->color = 1;
    }
    else if (!is_red(f->child[0]) && is_red(f->child[1]))
        *root = rotate_tree(f, 0); /* Rotate left */
    else if (is_red(f->child[0]) && is_red(f->child[0]->child[0]))
        *root = rotate_tree(f, 1); /* Rotate right */
}

/* Get a node with the specified name, creating it if it doesn't exist */
static CheckasmFunc *get_func(CheckasmFunc **root, const char *const name) {
    CheckasmFunc *f = *root;

    if (f) {
        /* Search the tree for a matching node */
        int cmp = cmp_func_names(name, f->name);
        if (cmp) {
            f = get_func(&f->child[cmp > 0], name);

            /* Rebalance the tree on the way up if a new node was inserted */
            if (!f->versions.func)
                balance_tree(root);
        }
    } else {
        /* Allocate and insert a new node into the tree */
        const int name_length = strlen(name);
        f = *root = checkasm_malloc(sizeof(CheckasmFunc) + name_length);
        memcpy(f->name, name, name_length + 1);
    }

    return f;
}

/* Perform tests and benchmarks for the specified
 * cpu flag if supported by the host */
static void check_cpu_flag(const char *const name, unsigned flag) {
    const unsigned old_cpu_flag = state.cpu_flag;

    flag |= old_cpu_flag;
    dav1d_set_cpu_flags_mask(flag);
    state.cpu_flag = dav1d_get_cpu_flags();

    if (!flag || state.cpu_flag != old_cpu_flag) {
        state.cpu_flag_name = name;
        for (int i = 0; tests[i].func; i++) {
            if (state.test_name && strcmp(tests[i].name, state.test_name))
                continue;
            state.current_test_name = tests[i].name;
            tests[i].func();
        }
    }
}

/* Print the name of the current CPU flag, but only do it once */
static void print_cpu_name(void) {
    if (state.cpu_flag_name) {
        color_printf(COLOR_YELLOW, "%s:\n", state.cpu_flag_name);
        state.cpu_flag_name = NULL;
    }
}

int main(int argc, char *argv[]) {
#ifdef readtime
    unsigned int seed = readtime();
#else
    unsigned int seed = time(NULL);
#endif
    int ret = 0;

    while (argc > 1) {
        if (!strncmp(argv[1], "--bench", 7)) {
#ifndef readtime
            fprintf(stderr,
                    "checkasm: --bench is not supported on your system\n");
            return 1;
#endif
            if (argv[1][7] == '=') {
                state.bench_pattern = argv[1] + 8;
                state.bench_pattern_len = strlen(state.bench_pattern);
            } else
                state.bench_pattern = "";
        } else if (!strncmp(argv[1], "--test=", 7)) {
            state.test_name = argv[1] + 7;
        } else {
            seed = strtoul(argv[1], NULL, 10);
        }

        argc--;
        argv++;
    }

    fprintf(stderr, "checkasm: using random seed %u\n", seed);
    srand(seed);

    check_cpu_flag(NULL, 0);
    for (int i = 0; cpus[i].flag; i++)
        check_cpu_flag(cpus[i].name, cpus[i].flag);

    if (!state.num_checked) {
        fprintf(stderr, "checkasm: no tests to perform\n");
    } else if (state.num_failed) {
        fprintf(stderr, "checkasm: %d of %d tests have failed\n",
                state.num_failed, state.num_checked);
        ret = 1;
    } else {
        fprintf(stderr, "checkasm: all %d tests passed\n", state.num_checked);
#ifdef readtime
        if (state.bench_pattern) {
            state.nop_time = measure_nop_time();
            printf("nop: %d.%d\n", state.nop_time/10, state.nop_time%10);
            print_benchs(state.funcs);
        }
#endif
    }

    destroy_func_tree(state.funcs);
    return ret;
}

/* Decide whether or not the specified function needs to be tested and
 * allocate/initialize data structures if needed. Returns a pointer to a
 * reference function if the function should be tested, otherwise NULL */
void *checkasm_check_func(void *const func, const char *const name, ...) {
    char name_buf[256];
    va_list arg;

    va_start(arg, name);
    const int name_length = vsnprintf(name_buf, sizeof(name_buf), name, arg);
    va_end(arg);

    if (!func || name_length <= 0 || (size_t)name_length >= sizeof(name_buf))
        return NULL;

    state.current_func = get_func(&state.funcs, name_buf);
    state.funcs->color = 1;
    CheckasmFuncVersion *v = &state.current_func->versions;
    void *ref = func;

    if (v->func) {
        CheckasmFuncVersion *prev;
        do {
            /* Only test functions that haven't already been tested */
            if (v->func == func)
                return NULL;

            if (v->ok)
                ref = v->func;

            prev = v;
        } while ((v = v->next));

        v = prev->next = checkasm_malloc(sizeof(CheckasmFuncVersion));
    }

    v->func = func;
    v->ok = 1;
    v->cpu = state.cpu_flag;
    state.current_func_ver = v;

    if (state.cpu_flag)
        state.num_checked++;

    return ref;
}

/* Decide whether or not the current function needs to be benchmarked */
int checkasm_bench_func(void) {
    return !state.num_failed && state.bench_pattern &&
           !strncmp(state.current_func->name, state.bench_pattern,
                    state.bench_pattern_len);
}

/* Indicate that the current test has failed */
void checkasm_fail_func(const char *const msg, ...) {
    if (state.current_func_ver->cpu && state.current_func_ver->ok) {
        va_list arg;

        print_cpu_name();
        fprintf(stderr, "   %s_%s (", state.current_func->name,
                cpu_suffix(state.current_func_ver->cpu));
        va_start(arg, msg);
        vfprintf(stderr, msg, arg);
        va_end(arg);
        fprintf(stderr, ")\n");

        state.current_func_ver->ok = 0;
        state.num_failed++;
    }
}

/* Update benchmark results of the current function */
void checkasm_update_bench(const int iterations, const uint64_t cycles) {
    state.current_func_ver->iterations += iterations;
    state.current_func_ver->cycles += cycles;
}

/* Print the outcome of all tests performed since
 * the last time this function was called */
void checkasm_report(const char *const name, ...) {
    static int prev_checked, prev_failed, max_length;

    if (state.num_checked > prev_checked) {
        int pad_length = max_length + 4;
        va_list arg;

        print_cpu_name();
        pad_length -= fprintf(stderr, " - %s.", state.current_test_name);
        va_start(arg, name);
        pad_length -= vfprintf(stderr, name, arg);
        va_end(arg);
        fprintf(stderr, "%*c", imax(pad_length, 0) + 2, '[');

        if (state.num_failed == prev_failed)
            color_printf(COLOR_GREEN, "OK");
        else
            color_printf(COLOR_RED, "FAILED");
        fprintf(stderr, "]\n");

        prev_checked = state.num_checked;
        prev_failed  = state.num_failed;
    } else if (!state.cpu_flag) {
        /* Calculate the amount of padding required
         * to make the output vertically aligned */
        int length = strlen(state.current_test_name);
        va_list arg;

        va_start(arg, name);
        length += vsnprintf(NULL, 0, name, arg);
        va_end(arg);

        if (length > max_length)
            max_length = length;
    }
}