/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser General Public
** License version 2.1 as published by the Free Software Foundation and
** appearing in the file LICENSE.LGPL included in the packaging of this
** file. Please review the following information to ensure the GNU Lesser
** General Public License version 2.1 requirements will be met:
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of this
** file. Please review the following information to ensure the GNU General
** Public License version 3.0 requirements will be met:
** http://www.gnu.org/copyleft/gpl.html.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms and
** conditions contained in a signed written agreement between you and Nokia.
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qsimd_p.h"
#include <QByteArray>
#include <stdio.h>

#if defined(Q_OS_WIN)
#  if defined(Q_OS_WINCE)
#    include <qt_windows.h>
#  endif
#  if !defined(Q_CC_GNU)
#    include <intrin.h>
#  endif
#elif defined(Q_OS_LINUX) && defined(__arm__)
#include "private/qcore_unix_p.h"

// the kernel header definitions for HWCAP_*
// (the ones we need/may need anyway)

// copied from <asm/hwcap.h> (ARM)
#define HWCAP_IWMMXT    512
#define HWCAP_CRUNCH    1024
#define HWCAP_THUMBEE   2048
#define HWCAP_NEON      4096
#define HWCAP_VFPv3     8192
#define HWCAP_VFPv3D16  16384

// copied from <linux/auxvec.h>
#define AT_HWCAP  16    /* arch dependent hints at CPU capabilities */

#endif

QT_BEGIN_NAMESPACE

#if defined (Q_OS_NACL)
static inline uint detectProcessorFeatures()
{
    return 0;
}
#elif defined (Q_OS_WINCE)
static inline uint detectProcessorFeatures()
{
    uint features = 0;

#if defined (ARM)
    if (IsProcessorFeaturePresent(PF_ARM_INTEL_WMMX)) {
        features = IWMMXT;
        return features;
    }
#elif defined(_X86_)
    features = 0;
    if (IsProcessorFeaturePresent(PF_XMMI64_INSTRUCTIONS_AVAILABLE))
        features |= SSE2;
    if (IsProcessorFeaturePresent(PF_SSE3_INSTRUCTIONS_AVAILABLE))
        features |= SSE3;
    return features;
#endif
    features = 0;
    return features;
}

#elif defined(__arm__) || defined(__arm) || defined(QT_HAVE_IWMMXT) || defined(QT_HAVE_NEON)
static inline uint detectProcessorFeatures()
{
    uint features = 0;

#if defined(Q_OS_LINUX)
    int auxv = qt_safe_open("/proc/self/auxv", O_RDONLY);
    if (auxv != -1) {
        unsigned long vector[64];
        int nread;
        while (features == 0) {
            nread = qt_safe_read(auxv, (char *)vector, sizeof vector);
            if (nread <= 0) {
                // EOF or error
                break;
            }

            int max = nread / (sizeof vector[0]);
            for (int i = 0; i < max; i += 2)
                if (vector[i] == AT_HWCAP) {
                    if (vector[i+1] & HWCAP_IWMMXT)
                        features |= IWMMXT;
                    if (vector[i+1] & HWCAP_NEON)
                        features |= NEON;
                    break;
                }
        }

        qt_safe_close(auxv);
        return features;
    }
    // fall back if /proc/self/auxv wasn't found
#endif

#if defined(QT_HAVE_IWMMXT)
    // runtime detection only available when running as a previlegied process
    features = IWMMXT;
#elif defined(QT_ALWAYS_HAVE_NEON)
    features = NEON;
#endif

    return features;
}

#elif defined(__i386__) || defined(_M_IX86)
static inline uint detectProcessorFeatures()
{
    uint features = 0;

    unsigned int extended_result = 0;
    unsigned int feature_result = 0;
    uint result = 0;
    /* see p. 118 of amd64 instruction set manual Vol3 */
#if defined(Q_CC_GNU)
    long cpuid_supported, tmp1;
    asm ("pushf\n"
         "pop %0\n"
         "mov %0, %1\n"
         "xor $0x00200000, %0\n"
         "push %0\n"
         "popf\n"
         "pushf\n"
         "pop %0\n"
         "xor %1, %0\n" // %eax is now 0 if CPUID is not supported
         : "=a" (cpuid_supported), "=r" (tmp1)
         );
    if (cpuid_supported) {
        asm ("xchg %%ebx, %2\n"
             "cpuid\n"
             "xchg %%ebx, %2\n"
            : "=c" (feature_result), "=d" (result), "=&r" (tmp1)
            : "a" (1));

        asm ("xchg %%ebx, %1\n"
             "cpuid\n"
             "cmp $0x80000000, %%eax\n"
             "jnbe 1f\n"
             "xor %0, %0\n"
             "jmp 2f\n"
             "1:\n"
             "mov $0x80000001, %%eax\n"
             "cpuid\n"
             "2:\n"
             "xchg %%ebx, %1\n"
            : "=d" (extended_result), "=&r" (tmp1)
            : "a" (0x80000000)
            : "%ecx"
            );
    }

#elif defined (Q_OS_WIN)
    _asm {
        push eax
        push ebx
        push ecx
        push edx
        pushfd
        pop eax
        mov ebx, eax
        xor eax, 00200000h
        push eax
        popfd
        pushfd
        pop eax
        mov edx, 0
        xor eax, ebx
        jz skip

        mov eax, 1
        cpuid
        mov result, edx
        mov feature_result, ecx
    skip:
        pop edx
        pop ecx
        pop ebx
        pop eax
    }

    _asm {
        push eax
        push ebx
        push ecx
        push edx
        pushfd
        pop eax
        mov ebx, eax
        xor eax, 00200000h
        push eax
        popfd
        pushfd
        pop eax
        mov edx, 0
        xor eax, ebx
        jz skip2

        mov eax, 80000000h
        cpuid
        cmp eax, 80000000h
        jbe skip2
        mov eax, 80000001h
        cpuid
        mov extended_result, edx
    skip2:
        pop edx
        pop ecx
        pop ebx
        pop eax
    }
#endif


    // result now contains the standard feature bits
    if (result & (1u << 26))
        features |= SSE2;
    if (feature_result & (1u))
        features |= SSE3;
    if (feature_result & (1u << 9))
        features |= SSSE3;
    if (feature_result & (1u << 19))
        features |= SSE4_1;
    if (feature_result & (1u << 20))
        features |= SSE4_2;
    if (feature_result & (1u << 28))
        features |= AVX;

    return features;
}

#elif defined(__x86_64) || defined(Q_OS_WIN64)
static inline uint detectProcessorFeatures()
{
    uint features = SSE2;
    uint feature_result = 0;

#if defined (Q_OS_WIN64)
    {
       int info[4];
       __cpuid(info, 1);
       feature_result = info[2];
    }
#elif defined(Q_CC_GNU)
    quint64 tmp;
    asm ("xchg %%rbx, %1\n"
         "cpuid\n"
         "xchg %%rbx, %1\n"
        : "=c" (feature_result), "=&r" (tmp)
        : "a" (1)
        : "%edx"
        );
#endif

    if (feature_result & (1u))
        features |= SSE3;
    if (feature_result & (1u << 9))
        features |= SSSE3;
    if (feature_result & (1u << 19))
        features |= SSE4_1;
    if (feature_result & (1u << 20))
        features |= SSE4_2;
    if (feature_result & (1u << 28))
        features |= AVX;

    return features;
}

#else
static inline uint detectProcessorFeatures()
{
    return 0;
}
#endif

/*
 * Use kdesdk/scripts/generate_string_table.pl to update the table below.
 * Here's the data (don't forget the ONE leading space):
 iwmmxt
 neon
 sse2
 sse3
 ssse3
 sse4.1
 sse4.2
 avx
  */

// begin generated
static const char features_string[] =
    " iwmmxt\0"
    " neon\0"
    " sse2\0"
    " sse3\0"
    " ssse3\0"
    " sse4.1\0"
    " sse4.2\0"
    " avx\0"
    "\0";

static const int features_indices[] = {
    0,    8,   14,   20,   26,   33,   41,   49,
    -1
};
// end generated

static const int features_count = (sizeof features_indices - 1) / (sizeof features_indices[0]);

static const uint minFeature = None
#if defined __RTM__
                               | RTM
#endif
// don't define for HLE, since the HLE prefix can be run on older CPUs
#if defined __AVX2__
                               | AVX2
#endif
#if defined __AVX__
                               | AVX
#endif
#if defined __SSE4_2__
                               | SSE4_2
#endif
#if defined __SSE4_1__
                               | SSE4_1
#endif
#if defined __SSSE3__
                               | SSSE3
#endif
#if defined __SSE3__
                               | SSE3
#endif
#if defined __SSE2__
                               | SSE2
#endif
#if defined __ARM_NEON__
                               | NEON
#endif
#if defined __IWMMXT__
                               | IWMMXT
#endif
                               ;

#ifdef Q_OS_WIN
#if defined(Q_CC_GNU)
#  define ffs __builtin_ffs
#else
int ffs(int i)
{
    unsigned long result;
    return _BitScanForward(&result, i) ? result : 0;
}
#endif
#endif // Q_OS_WIN

uint qDetectCPUFeatures()
{
    static QBasicAtomicInt features = Q_BASIC_ATOMIC_INITIALIZER(-1);
    if (features.load() != -1)
        return features.load();

    uint f = detectProcessorFeatures();
    QByteArray disable = qgetenv("QT_NO_CPU_FEATURE");
    if (!disable.isEmpty()) {
        disable.prepend(' ');
        for (int i = 0; i < features_count; ++i) {
            if (disable.contains(features_string + features_indices[i]))
                f &= ~(1 << i);
        }
    }

    if (minFeature != 0 && (f & minFeature) != minFeature) {
        uint missing = minFeature & ~f;
        fprintf(stderr, "Incompatible processor. This Qt build requires the following features:\n   ");
        for (int i = 0; i < features_count; ++i) {
            if (missing & (1 << i))
                fprintf(stderr, "%s", features_string + features_indices[i]);
        }
        fprintf(stderr, "\n");
        fflush(stderr);
        qFatal("Aborted. Incompatible processor: missing feature 0x%x -%s.", missing,
               features_string + features_indices[ffs(missing) - 1]);
    }

    features.store(f);
    return f;
}

void qDumpCPUFeatures()
{
    uint features = qDetectCPUFeatures();
    printf("Processor features: ");
    for (int i = 0; i < features_count; ++i) {
        if (features & (1 << i))
            printf("%s%s", features_string + features_indices[i],
                   minFeature & (1 << i) ? "[required]" : "");
    }
    puts("");
}

QT_END_NAMESPACE