/* 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 ke;

 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(requested, 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(aligned + amount, requested - amount - begin);

     }

     return AlignableMapping(aligned, alignment, amount);

 }

 void

 OS::UnmapAlignedMemory(Address address, size_t size)

 {

     OS::UnmapMemory(address, size);

 }