Output saving data to binary data without loss of precision. More...

#include <Output.h>

Inheritance diagram for BinaryOutput:

Public Member Functions
	BinaryOutput (const OutputFile &fileMask, const RunTypeEnum runTypeId=RunTypeEnum::SPH)

virtual Expected< Path >	dump (const Storage &storage, const Statistics &stats) override
	Saves data from particle storage into the file. More...

Public Member Functions inherited from IOutput
	IOutput (const OutputFile &fileMask)
	Constructs output given the file name of the output. More...

Public Member Functions inherited from Polymorphic
virtual	~Polymorphic ()

Friends
class	BinaryInput

Additional Inherited Members
Protected Attributes inherited from IOutput
OutputFile	paths

Detailed Description

Output saving data to binary data without loss of precision.

specification

File format can store values of type int64 (called Size hereafter), double (called Float hereafter), strings encoded as chars with terminating zero and padding (zero bytes). There are no other types currently used. All other types (Vectors, Tensors, enums, ...) are converted to Floats or Sizes. The file is divided as follows: header, quantity info, n x [material info, quantity data] where n is the number of materials.

Header is always 256 bytes, storing the following:

first 4 bytes are file format identifier "SPH" (including terminating zero)
bytes 5-12: time [Float] of the dump (in simulation time)
bytes 13-20: total particle count [Size] in the storage (called particleCnt)
bytes 21-28: number of quantities [Size] in the storage (called quantityCnt)
bytes 29-36: number of materials [Size] (called materialCnt)
bytes 37-44: timestep when the snapshot has been created
bytes 45-52: version of the file format, see enum BinaryOutput::Version.
bytes 53-68: string identifying a run type, see enum RunTypeEnum.
bytes 69-84: string representing the build date
bytes 85-92: wallclock time of the simulation (if present in stats)
bytes 93-256: padding (possibly will be used in the future)

Quantity info (summary) follows the header. It consist of quantityCnt triples of values

ID of quantity [Size casted from QuantityId]
Order of quantity [Size casted from OrderEnum]
Value type of quantity [Size casted from ValueEum]

After than there follows material info and quantity data for every stored material. The material info consist of materialCnt blocks with content:

block identifier "MAT" (4 bytes with terminating zero)
number of material [Size] in increasing order (from 0 up to materialCnt-1)
number of BodySettings entries [Size] of the material (called paramCnt)
paramCnt times: . parameter ID [Size casted from BodySettingsId] . type index of the value type [Size], corresponding to the type in settings variant . entry value itself. The size of the value depends on its type, identified by the index read previously. There is currently no upper limit for the entry size; although the largest one used is a Tensor with 72 bytes, this size can be increased in the future.
quantityCnt times: . Quantity ID of n-th quantity [Size casted from QuantityId] . Range of n-th quantity [2x Float] . minimal value of n-th quantity [Float] for timestepping
Attention
The whole material block can be missing as Storage can exist without a material. This is indicated by materialCnt == 0, but also by identifier "NOMAT" (6 bytes including terminating zero) in place of first "MAT" identifier if the file had material block.
The next two numbers [2x Float] are the first and one-past-last index of the particles corresponding to this material. The first index for the first material is always zero, the second index for the last material is the particleCnt. The first index is always equal to the second index of the previous material. The quantity data are stored immediately afterwards. It consist of quantityCnt blocks. Each block has 1-3 sub-blocks, depending on the order of n-th. Note that the orders and value types of quantities are stored in the quantity info at the beginning of the file and are not repeated here. Each sub-block contains directly serialized value and derivatives of n-th quantity, i.e.
particleCnt times value, representing quantity value of i-th particle
if quantity is of first or second order, then follows particleCnt times value, representing quantity first derivative of i-th particle
if quantity is of second order, then follows particleCnt times values, representing quantity second derivative of i-th particle. The size of a single value depends on the value type, i.e. scalar quantities are stored as Floats, Vector quantities are stored as 4x Float (components X, Y, Z and H), etc. The file ends immediately after the last quantity is saved.

Todo:

Possible todos & fixes:

arbitrary precision: store doubles as floats or halfs and size_t as uint32 or uint16, based on data in header
deserialized materials are created using Factory::getMaterial from loaded settings. This won't be correct if the material was created differently, i.e. if the material doesn't match the information in the settings it holds. This should be enforced somehow.

Definition at line 335 of file Output.h.

Constructor & Destructor Documentation

◆ BinaryOutput()

BinaryOutput::BinaryOutput	(	const OutputFile &	fileMask,
		const RunTypeEnum	runTypeId = `RunTypeEnum::SPH`
	)

explicit

Definition at line 508 of file Output.cpp.

Member Function Documentation

◆ dump()

Expected< Path > BinaryOutput::dump	(	const Storage &	storage,
		const Statistics &	stats
	)

overridevirtual

Saves data from particle storage into the file.

Returns the filename of the dump, generated from file mask given in constructor, or an error message in case writing the output file failed.

Implements IOutput.

Definition at line 512 of file Output.cpp.

Friends And Related Function Documentation

◆ BinaryInput

friend class BinaryInput

friend

Definition at line 336 of file Output.h.

The documentation for this class was generated from the following files:

/home/pavel/projects/astro/sph/src/core/io/Output.h
/home/pavel/projects/astro/sph/src/core/io/Output.cpp

Public Member Functions

Friends

Additional Inherited Members