/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/StringBuilder.h>
#include <AK/Types.h>
#include <Kernel/Arch/x86/CPUID.h>
#include <Kernel/Arch/x86/Processor.h>
#include <Kernel/Arch/x86/ProcessorInfo.h>

namespace Kernel {

ProcessorInfo::ProcessorInfo(Processor& processor)
    : m_processor(processor)
{
    u32 max_leaf;
    {
        CPUID cpuid(0);
        StringBuilder builder;
        auto emit_u32 = [&](u32 value) {
            builder.appendff("{:c}{:c}{:c}{:c}",
                value & 0xff,
                (value >> 8) & 0xff,
                (value >> 16) & 0xff,
                (value >> 24) & 0xff);
        };
        max_leaf = cpuid.eax();
        emit_u32(cpuid.ebx());
        emit_u32(cpuid.edx());
        emit_u32(cpuid.ecx());
        m_cpuid = builder.build();
    }
    {
        VERIFY(max_leaf >= 1);
        CPUID cpuid(1);
        m_stepping = cpuid.eax() & 0xf;
        u32 model = (cpuid.eax() >> 4) & 0xf;
        u32 family = (cpuid.eax() >> 8) & 0xf;
        m_type = (cpuid.eax() >> 12) & 0x3;
        u32 extended_model = (cpuid.eax() >> 16) & 0xf;
        u32 extended_family = (cpuid.eax() >> 20) & 0xff;
        if (family == 15) {
            m_display_family = family + extended_family;
            m_display_model = model + (extended_model << 4);
        } else if (family == 6) {
            m_display_family = family;
            m_display_model = model + (extended_model << 4);
        } else {
            m_display_family = family;
            m_display_model = model;
        }
    }

    u32 max_extended_leaf = CPUID(0x80000000).eax();

    if (max_extended_leaf >= 0x80000004) {
        alignas(u32) char buffer[48];
        u32* bufptr = reinterpret_cast<u32*>(buffer);
        auto copy_brand_string_part_to_buffer = [&](u32 i) {
            CPUID cpuid(0x80000002 + i);
            *bufptr++ = cpuid.eax();
            *bufptr++ = cpuid.ebx();
            *bufptr++ = cpuid.ecx();
            *bufptr++ = cpuid.edx();
        };
        copy_brand_string_part_to_buffer(0);
        copy_brand_string_part_to_buffer(1);
        copy_brand_string_part_to_buffer(2);
        m_brandstr = buffer;
    }

    // Cache the CPU feature string
    m_features = m_processor.features_string();
}

}