/* Copyright (c) 2010 Wildfire Games
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include "precompiled.h"

#include "lib/sysdep/os_cpu.h"
#include "lib/alignment.h"
#include "lib/bits.h"

#if OS_LINUX
#include "valgrind.h"
#endif


size_t os_cpu_NumProcessors()
{
	static size_t numProcessors;

	if(numProcessors == 0)
	{
		// Valgrind reports the number of real CPUs, but only emulates a single CPU.
		// That causes problems when we expect all those CPUs to be distinct, so
		// just pretend there's only one CPU
		if (RUNNING_ON_VALGRIND)
			numProcessors = 1;
		else
		{
			long res = sysconf(_SC_NPROCESSORS_CONF);
			ENSURE(res != -1);
			numProcessors = (size_t)res;
		}
	}

	return numProcessors;
}


uintptr_t os_cpu_ProcessorMask()
{
	static uintptr_t processorMask;

	if(!processorMask)
		processorMask = bit_mask<uintptr_t>(os_cpu_NumProcessors());

	return processorMask;
}


size_t os_cpu_PageSize()
{
	static size_t pageSize;

	if(!pageSize)
		pageSize = (size_t)sysconf(_SC_PAGESIZE);

	return pageSize;
}


size_t os_cpu_LargePageSize()
{
	// assume they're unsupported.
	return 0;
}


size_t os_cpu_QueryMemorySize()
{
	const uint64_t memorySize = (uint64_t)sysconf(_SC_PHYS_PAGES) * os_cpu_PageSize();
	return size_t(memorySize / MiB);
}


size_t os_cpu_MemoryAvailable()
{
	const uint64_t memoryAvailableBytes = (uint64_t)sysconf(_SC_AVPHYS_PAGES) * os_cpu_PageSize();
	const size_t memoryAvailable = size_t(memoryAvailableBytes / MiB);
	return memoryAvailable;
}


uintptr_t os_cpu_SetThreadAffinityMask(uintptr_t processorMask)
{
	// This code is broken on kernels with CONFIG_NR_CPUS >= 1024, since cpu_set_t
	// is too small by default. See <http://trac.wildfiregames.com/ticket/547>.
	// It seems the most reliable solution is to use dynamically-allocated sets
	// (CPU_SET_S etc), and do it in a loop until we've allocated a set large
	// enough to fit all the CPUs.
	// That's a pain and we currently don't actually need this code at all, and on OS X
	// we don't implement this function anyway, so just disable it here.
#if 0
	int ret;
	cpu_set_t set;

	uintptr_t previousProcessorMask = 0;
	{
		ret = sched_getaffinity(0, sizeof(set), &set);
		ENSURE(ret == 0);

		for(size_t processor = 0; processor < os_cpu_NumProcessors(); processor++)
		{
			if(CPU_ISSET(processor, &set))
				previousProcessorMask |= uintptr_t(1) << processor;
		}
	}
	
	CPU_ZERO(&set);
	for(size_t processor = 0; processor < os_cpu_NumProcessors(); processor++)
	{
		if(IsBitSet(processorMask, processor))
			CPU_SET(processor, &set);
	}

	ret = sched_setaffinity(0, sizeof(set), &set);
	ENSURE(ret == 0);
	// (The process gets migrated immediately by the setaffinity call)

	return previousProcessorMask;
#endif

	UNUSED2(processorMask);
	return os_cpu_ProcessorMask();
}


Status os_cpu_CallByEachCPU(OsCpuCallback cb, uintptr_t cbData)
{
	for(size_t processor = 0; processor < os_cpu_NumProcessors(); processor++)
	{
		const uintptr_t processorMask = uintptr_t(1) << processor;
		os_cpu_SetThreadAffinityMask(processorMask);
		cb(processor, cbData);
	}

	return INFO::OK;
}
