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/* Copyright (C) 2025 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.
*/
/*
* OS-specific support functions relating to CPU and memory
*/
#ifndef INCLUDED_OS_CPU
#define INCLUDED_OS_CPU
#include "lib/status.h"
#include <climits>
#include <cstddef>
#include <cstdint>
namespace ERR
{
const Status OS_CPU_RESTRICTED_AFFINITY = -130100;
}
//-----------------------------------------------------------------------------
// processor topology
// processor ID = [0, os_cpu_NumProcessors())
// they are a numbering of the bits of the process affinity mask where the
// least significant nonzero bit corresponds to ID 0.
// rationale: this spares users from having to deal with noncontiguous IDs,
// e.g. when administrative tools are used to restrict process affinity.
/**
* maximum number of processors supported by the OS (determined by the
* number of bits in an affinity mask)
**/
static const size_t os_cpu_MaxProcessors = sizeof(uintptr_t)*CHAR_BIT;
/**
* @return bit mask of processors that exist and are available to
* this process.
* its population count is by definition equal to os_cpu_NumProcessors().
**/
uintptr_t os_cpu_ProcessorMask();
/**
* @return the number of processors available to this process.
*
* note: this function is necessary because POSIX sysconf _SC_NPROCESSORS_CONF
* is not suppored on MacOSX, else we would use that.
**/
size_t os_cpu_NumProcessors();
//-----------------------------------------------------------------------------
// CPU and memory characteristics
/**
* @return a rough estimate of the CPU clock frequency.
* this is usually accurate to a few MHz and is faster than measurement loops.
**/
double os_cpu_ClockFrequency();
/**
* @return the size [bytes] of a MMU page (4096 on most IA-32 systems)
**/
size_t os_cpu_PageSize();
/**
* @return the size [bytes] of a large MMU page (4 MiB on most IA-32 systems)
* or zero if they are not supported.
**/
size_t os_cpu_LargePageSize();
/**
* @return the size [MB] of physical memory as reported by the OS;
* no caching/validation is performed.
**/
size_t os_cpu_QueryMemorySize();
/**
* @return the size [MB] of physical memory; caches the result of
* os_cpu_QueryMemorySize and overrides it with a more exact value
* if SMBIOS information is available.
**/
size_t os_cpu_MemorySize();
/**
* @return the current amount [MB] of available memory.
**/
size_t os_cpu_MemoryAvailable();
//-----------------------------------------------------------------------------
// scheduling
/**
* restrict the current thread to a set of processors.
*
* @param processorMask a bit mask of acceptable processors
* (bit index i corresponds to processor i)
* @return the previous mask
**/
uintptr_t os_cpu_SetThreadAffinityMask(uintptr_t processorMask);
class os_cpu_ScopedSetThreadAffinityMask
{
public:
os_cpu_ScopedSetThreadAffinityMask(uintptr_t processorMask)
: m_previousProcessorMask(os_cpu_SetThreadAffinityMask(processorMask))
{
}
~os_cpu_ScopedSetThreadAffinityMask()
{
(void)os_cpu_SetThreadAffinityMask(m_previousProcessorMask);
}
private:
uintptr_t m_previousProcessorMask;
};
/**
* called by os_cpu_CallByEachCPU.
* @param processor ID of processor running the current thread for the
* duration of this function.
* @param cbData user-specified data passed through os_cpu_CallByEachCPU.
**/
typedef void (*OsCpuCallback)(size_t processor, uintptr_t cbData);
/**
* execute the specified function once on each processor.
* this proceeds serially (the callback is never reentered) in increasing
* order of processor ID.
* fails if process affinity prevents running on all processors.
**/
Status os_cpu_CallByEachCPU(OsCpuCallback cb, uintptr_t cbData);
#endif // #ifndef INCLUDED_OS_CPU
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