/* vim: set ts=4 sw=4 tw=99 et:

 *

 * Copyright (C) 2012 David Anderson

 *

 * This file is part of JITCraft.

 *

 * JITCraft is free software: you can redistribute it and/or modify it under

 * the terms of the GNU General Public License as published by the Free

 * Software Foundation, either version 3 of the License, or (at your option)

 * any later version.

 * 

 * Foobar is distributed in the hope that it will be useful, but WITHOUT ANY

 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License along with

 * JITCraft. If not, see http://www.gnu.org/licenses/.

 */

#include <sys/mman.h>

#include "Platform.h"

using namespace jc;

static inline int

ToProtBits(OS::Protection prot)

{

    switch (prot) {

      case OS::Prot_ReadWrite:

        return PROT_READ | PROT_WRITE;

      case OS::Prot_ReadWriteExecute:

        return PROT_READ | PROT_WRITE | PROT_EXEC;

      default:

        assert(prot == OS::Prot_ReadExecute);

        return PROT_READ | PROT_EXEC;

    }

}

Address

OS::MapMemory(size_t amount, MapMode mode, Protection prot_)

{

    int prot = ToProtBits(prot_);

    void *addr = mmap(NULL, amount, prot, MAP_ANON | MAP_PRIVATE, -1, 0);

    if (addr == MAP_FAILED)

        return NULL;

    return Address(addr);

}

bool

OS::CommitMemory(Address address, size_t amount, Protection prot_)

{

    return true;

}

void

OS::UnmapMemory(Address address, size_t size)

{

    munmap(address, size);

}

OS::AlignableMapping

OS::MapAlignedMemory(size_t amount, size_t alignment, MapMode mode)

{

    assert(amount >= alignment);

    assert(IsPowerOfTwo(alignment));

    if (alignment == kPageAlignment) {

        Address address = MapMemory(amount, mode, Prot_ReadWrite);

        if (!address)

            return AlignableMapping();

        return AlignableMapping(address, alignment, amount);

    }

    size_t requested = Min(amount * 2, amount + 2 * alignment);

    Address address = MapMemory(amount, mode, Prot_ReadWrite);

    if (!address)

        return AlignableMapping();

    size_t begin = 0;

    Address aligned = AlignedBase(address, alignment);

    if (!IsAligned(address, alignment)) {

        // Shave off the first part of the unaligned region.

        aligned += alignment;

        begin = size_t(aligned - address);

        UnmapAlignedMemory(address, begin);

    }

    if (requested - begin > amount) {

        // Shave off the last part of the unaligned region.

        UnmapAlignedMemory(address + amount, requested - amount - begin);

    }

    return AlignableMapping(aligned, alignment, amount);

}

void

OS::UnmapAlignedMemory(Address address, size_t size)

{

    OS::UnmapMemory(address, size);

}