SDDBlock handles the IO and value extraction from SDD records (blocks). More...

#include <SDDBlock.h>

Public Types
enum	{ STANDARD_RECORD_SIZE }
	SDD files have traditionally been composed of 512 byte records, but they are not not really required to be. More...
Public Member Functions
	SDDBlock (uInt n=1, uInt bytesPerRecord=STANDARD_RECORD_SIZE)
	An SDDBlock with the indicated number of SDD records, each record having the indicated size in bytes, the whole thing filled with zeros.
	SDDBlock (const SDDBlock &other)
	copy constructor, this makes a true copy.
	~SDDBlock ()
SDDBlock &	operator= (const SDDBlock &other)
	assignment operator, this makes a true copy
uInt	nRecords () const
	return the size in SDD records
uInt	nbytes () const
	return the number of bytes
uInt	bytesPerRecord () const
	return the number of bytes per record
void	resize (uInt nRecords, Bool forceSmaller=False, Bool copyElements=False)
	resize this block to the indicated number of SDD records forceSmaller and copyElements work as with the Block class
void	reshape (uInt nRecords, uInt bytesPerRecord, Bool forceSmaller=False, Bool copyElements=False)
	reshape is like resize, except that the number of bytes per record can also change.
uInt	read (istream &in)
	read from istream and fill until this SDDBlock is full or istream is exhausted return the number of records actually read
uInt	read (istream &in, uInt nrecord, uInt startRecord=0)
	read nrecord records from istream, filling starting at the indicated record stop if istream is exhausted, return the number of records actually read
uInt	readBytes (istream &in, uInt nbytes, uInt startOffset=0)
	read the indicated number of bytes from in, starting at the optionally indicated starting bytes offset, returns the number of bytes actually read
uInt	write (ostream &out) const
	write the entire SDDBlock to ostream, return the number of records written
uInt	write (ostream &out, uInt nrecord, uInt startRecord=0) const
	write nrecord records to ostream, starting at the indicated record return the number of records written
uInt	writeBytes (ostream &out, uInt nbytes, uInt startOffset=0) const
	write the indicated number of bytes to out, starting at the optionally indicated starting byte offset, returns the number of bytes actually written
void	copy (SDDBlock &outBlock, uInt ncopy, uInt outStart=0, uInt inStart=0) const
	copy ncopy character to another SDDBlock starting at outStart (characters) offset into and starting at inStart (characters) offset into this blcck
Char &	operator[] (uInt index)
	index into the block
const Char &	operator[] (uInt index) const
Short &	asShort (uInt index)
	Index into the block as Shorts (0-based)
const Short &	asShort (uInt index) const
Int &	asInt (uInt location)
	Index into the block as Ints (0-based)
const Int &	asInt (uInt location) const
float &	asfloat (uInt location)
	Index into the block as floats (0-based)
const float &	asfloat (uInt location) const
double &	asdouble (uInt location)
	Index into the block as doubles (0-based)
const double &	asdouble (uInt location) const
Private Member Functions
void	set_pointers ()
Private Attributes
Block< Char > *	cblk_p
Short *	sarray
Int *	iarray
float *	farray
double *	darray
uInt	bytesPerRecord_p

Detailed Description

SDDBlock handles the IO and value extraction from SDD records (blocks).

Intended use:

Internal

Prerequisite

SDDFile
Block
iostreams
The SDD file format.

Etymology

SDD stands for Single Dish Data. It is the data format that UniPOPS understands. It is also the on-line data format at the NRAO 12m. SDD files are organized in records or blocks. This class handles the io to and from those blocks. it is used by the other SDD classes.

Synopsis

SDDBlock is used primarily to handle the IO to and from an SDD file in units of an SDD record size. The standard rccord size if 512 bytes although this class can handle arbitrarily sized records so long as the size is an integer multiple of 8 bytes (the size of and IEEE double precision floating point number). The total size of an SDDBlock is an integer multiple of the record size (i.e. no fractional records are allowed). This class also aids in extracting values of different types from the block. This is not likely to be immediately portable. However, by isolating that conversion here, it should make any future ports easier. Since SDD files will only ever be written on Suns, its unlikely that this issue will be a problem.

The IO only involves iostreams and not fstream. It is intended that the public SDD classes handle all of the fstream specific operations and that this class does not need to do any seeks.

An SDDBlock is always at least 1 SDD record in size.

Example

This is a somewhat contrived example.

    // This istream would be initialized appropriately
    istream in;
    // construct an SDDBlock of 1 SDD record using the standard record size
    SDDBlock block;
    block.read(in, 1);
    // Extract the 5th double from the record, which indicates the size
    // of the full record to read in bytes, convert that to SDD records
    // read it in.   This would need some additional checks if partial
    // records might be indicated.
    double fullSize = block.asdouble(4);
    uInt nrecs = uInt(fullSize/block.bytesPerRecord());
    // read the remaining records
    block.read(in, (nrecs-1));

Motivation

SDD files are organized into units that are integer number of records (always of 512 bytes at this point in history, but they could theoretically be of a different size). It makes sense to have a class that the other SDD classes could use to deal with the data in those chunks.

Thrown Exceptions

indexError - by the asT functions but only when AIPS_ARRAY_INDEX_CHECK is on.
AllocError - during construction
AipsError - by read/write indicates an IO error
AipsError - by copy and write if the indicated size is invalid

Definition at line 121 of file SDDBlock.h.

Member Enumeration Documentation

anonymous enum

SDD files have traditionally been composed of 512 byte records, but they are not not really required to be.

Enumerator:

STANDARD_RECORD_SIZE

Definition at line 126 of file SDDBlock.h.

Constructor & Destructor Documentation

SDDBlock::SDDBlock	(	uInt	n = `1`,
		uInt	bytesPerRecord = `STANDARD_RECORD_SIZE`
	)

An SDDBlock with the indicated number of SDD records, each record having the indicated size in bytes, the whole thing filled with zeros.

SDDBlock::SDDBlock ( const SDDBlock & other )

copy constructor, this makes a true copy.

SDDBlock::~SDDBlock ( )

Member Function Documentation

double & SDDBlock::asdouble ( uInt location ) [inline]

Index into the block as doubles (0-based)

Definition at line 284 of file SDDBlock.h.

References cblk_p, and darray.

const double & SDDBlock::asdouble ( uInt location ) const [inline]

Definition at line 296 of file SDDBlock.h.

References cblk_p, and darray.

float & SDDBlock::asfloat ( uInt location ) [inline]

Index into the block as floats (0-based)

Definition at line 260 of file SDDBlock.h.

References cblk_p, and farray.

const float & SDDBlock::asfloat ( uInt location ) const [inline]

Definition at line 272 of file SDDBlock.h.

References cblk_p, and farray.

Int & SDDBlock::asInt ( uInt location ) [inline]

Index into the block as Ints (0-based)

Definition at line 235 of file SDDBlock.h.

References cblk_p, and iarray.

const Int & SDDBlock::asInt ( uInt location ) const [inline]

Definition at line 247 of file SDDBlock.h.

References cblk_p, and iarray.

Short & SDDBlock::asShort ( uInt index ) [inline]

Index into the block as Shorts (0-based)

Definition at line 211 of file SDDBlock.h.

References cblk_p, and sarray.

const Short & SDDBlock::asShort ( uInt index ) const [inline]

Definition at line 223 of file SDDBlock.h.

References cblk_p, and sarray.

uInt SDDBlock::bytesPerRecord ( ) const [inline]

return the number of bytes per record

Definition at line 144 of file SDDBlock.h.

References bytesPerRecord_p.

void SDDBlock::copy	(	SDDBlock &	outBlock,
		uInt	ncopy,
		uInt	outStart = `0`,
		uInt	inStart = `0`
	)		const `[inline]`

copy ncopy character to another SDDBlock starting at outStart (characters) offset into and starting at inStart (characters) offset into this blcck

Definition at line 363 of file SDDBlock.h.

References cblk_p, and nbytes().

uInt SDDBlock::nbytes ( ) const [inline]

return the number of bytes

Definition at line 142 of file SDDBlock.h.

References cblk_p.

Referenced by copy(), and writeBytes().

uInt SDDBlock::nRecords ( ) const [inline]

return the size in SDD records

Definition at line 140 of file SDDBlock.h.

References bytesPerRecord_p, and cblk_p.

SDDBlock& SDDBlock::operator= ( const SDDBlock & other )

assignment operator, this makes a true copy

Char& SDDBlock::operator[] ( uInt index ) [inline]

index into the block

Definition at line 183 of file SDDBlock.h.

References cblk_p.

const Char& SDDBlock::operator[] ( uInt index ) const [inline]

Definition at line 184 of file SDDBlock.h.

References cblk_p.

uInt SDDBlock::read ( istream & in ) [inline]

read from istream and fill until this SDDBlock is full or istream is exhausted return the number of records actually read

attempt to read from istream until Block is full

Definition at line 319 of file SDDBlock.h.

References bytesPerRecord_p, cblk_p, and readBytes().

uInt SDDBlock::read	(	istream &	in,
		uInt	nrecord,
		uInt	startRecord = `0`
	)		`[inline]`

read nrecord records from istream, filling starting at the indicated record stop if istream is exhausted, return the number of records actually read

Definition at line 329 of file SDDBlock.h.

References bytesPerRecord_p, and readBytes().

uInt SDDBlock::readBytes	(	istream &	in,
		uInt	nbytes,
		uInt	startOffset = `0`
	)		`[inline]`

read the indicated number of bytes from in, starting at the optionally indicated starting bytes offset, returns the number of bytes actually read

is a resize necessary, copy elements if it is necessary this may be wastefull, if so, use SDDBlock::resize() first without copying

Definition at line 308 of file SDDBlock.h.

References cblk_p, casa::False, resize(), and casa::True.

Referenced by read().

void SDDBlock::reshape	(	uInt	nRecords,
		uInt	bytesPerRecord,
		Bool	forceSmaller = `False`,
		Bool	copyElements = `False`
	)

reshape is like resize, except that the number of bytes per record can also change.

The number of bytesPerRecord must be a multiple of 8.

void SDDBlock::resize	(	uInt	nRecords,
		Bool	forceSmaller = `False`,
		Bool	copyElements = `False`
	)

resize this block to the indicated number of SDD records forceSmaller and copyElements work as with the Block class

Referenced by readBytes().

void SDDBlock::set_pointers ( ) [private]

uInt SDDBlock::write ( ostream & out ) const [inline]

write the entire SDDBlock to ostream, return the number of records written

write all of Block to ostream

Definition at line 351 of file SDDBlock.h.

References bytesPerRecord_p, cblk_p, and writeBytes().

uInt SDDBlock::write	(	ostream &	out,
		uInt	nrecord,
		uInt	startRecord = `0`
	)		const `[inline]`

write nrecord records to ostream, starting at the indicated record return the number of records written

Definition at line 357 of file SDDBlock.h.

References bytesPerRecord_p, and writeBytes().

uInt SDDBlock::writeBytes	(	ostream &	out,
		uInt	nbytes,
		uInt	startOffset = `0`
	)		const `[inline]`

write the indicated number of bytes to out, starting at the optionally indicated starting byte offset, returns the number of bytes actually written

make sure we have what has been requested

Definition at line 341 of file SDDBlock.h.

References cblk_p, and nbytes().

Referenced by write().

Member Data Documentation

uInt SDDBlock::bytesPerRecord_p [private]

Definition at line 206 of file SDDBlock.h.

Referenced by bytesPerRecord(), nRecords(), read(), and write().

Block<Char>* SDDBlock::cblk_p [private]

Definition at line 200 of file SDDBlock.h.

Referenced by asdouble(), asfloat(), asInt(), asShort(), copy(), nbytes(), nRecords(), operator[](), read(), readBytes(), write(), and writeBytes().

double* SDDBlock::darray [private]

Definition at line 204 of file SDDBlock.h.

Referenced by asdouble().

float* SDDBlock::farray [private]

Definition at line 203 of file SDDBlock.h.

Referenced by asfloat().

Int* SDDBlock::iarray [private]

Definition at line 202 of file SDDBlock.h.

Referenced by asInt().

Short* SDDBlock::sarray [private]

Definition at line 201 of file SDDBlock.h.

Referenced by asShort().

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

code/nrao/SDD/SDDBlock.h

Public Types

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Intended use:

Prerequisite

Etymology

Synopsis

Example

Motivation

Thrown Exceptions

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation