time-to-botec

README.md (5207B)

---

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 # Serialize Meta Data
 
 > Serialize [ndarray][@stdlib/ndarray/ctor] meta data.
 
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 <section class="intro">
 
 </section>
 
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 <!-- Package usage documentation. -->
 
 <section class="usage">
 
 ## Usage
 
 ```javascript
 var serialize = require( '@stdlib/ndarray/base/serialize-meta-data' );
 ```
 
 #### serialize( x )
 
 Serializes [ndarray][@stdlib/ndarray/ctor] meta data.
 
 ```javascript
 var array = require( '@stdlib/ndarray/array' );
 
 var arr = array( [ [ 1, 2 ], [ 3, 4 ] ] );
 var dv = serialize( arr );
 // returns <DataView>
 ```
 
 </section>
 
 <!-- /.usage -->
 
 <!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
 
 <section class="notes">
 
 ## Notes
 
 -   Serialization is performed according to host byte order (endianness).
 
 -   Meta data format:
 
     ```text
     | endianness (1 byte) | <dtype> (2 bytes) | <ndims> (8 bytes) | <shape> (ndims*8 bytes) | <strides> (ndims*8 bytes) | <offset> (8 bytes) | <order> (1 byte) | <mode> (1 byte) | <nsubmodes> (8 bytes) | <submodes> (nsubmodes*1 bytes) |
     ```
 
     which translates to the following `ArrayBuffer` layout:
 
     ```text
     ArrayBuffer[
         <endianness>[int8],
         <dtype>[int16],
         <ndims>[int64],
         <shape>[ndims*int64],
         <strides>[ndims*int64],
         <offset>[int64],
         <order>[int8],
         <mode>[int8],
         <nsubmodes>[int64],
         <submodes>[nsubmodes*int8]
     ]
     ```
 
     where `strides` and `offset` are in units of bytes.
 
 -   If the endianness is `1`, the byte order is little endian. If the endianness is `0`, the byte order is big endian.
 
 -   Buffer length:
 
     ```text
     1 + 2 + 8 + (ndims*8) + (ndims*8) + 8 + 1 + 1 + 8 + (nsubmodes*1) = 29 + (ndims*16) + nsubmodes
     ```
 
     For example, consider a three-dimensional [ndarray][@stdlib/ndarray/ctor] with one subscript index mode (submode):
 
     ```text
     29 + (3*16) + 1 = 78 bytes
     ```
 
 </section>
 
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 <section class="examples">
 
 ## Examples
 
 <!-- eslint no-undef: "error" -->
 
 ```javascript
 var IS_LITTLE_ENDIAN = require( '@stdlib/assert/is-little-endian' );
 var array = require( '@stdlib/ndarray/array' );
 var Uint8Array = require( '@stdlib/array/uint8' );
 var fromInt64Bytes = require( '@stdlib/number/float64/base/from-int64-bytes' );
 var serialize = require( '@stdlib/ndarray/base/serialize-meta-data' );
 
 // Create an ndarray:
 var x = array( [ [ 1, 2 ], [ 3, 4 ] ] );
 
 // Print various properties:
 console.log( 'dtype: %s', x.dtype );
 console.log( 'ndims: %d', x.ndims );
 console.log( 'shape: [ %s ]', x.shape.join( ', ' ) );
 console.log( 'strides: [ %s ]', x.strides.join( ', ' ) );
 console.log( 'offset: %d', x.offset );
 console.log( 'order: %s', x.order );
 
 // Serialize ndarray meta data to a DataView:
 var dv = serialize( x );
 // returns <DataView>
 
 // Create a Uint8Array view:
 var bytes = new Uint8Array( dv.buffer );
 
 // Extract the data type (enum):
 var dtype = dv.getInt16( 1, IS_LITTLE_ENDIAN );
 console.log( 'dtype (enum): %d', dtype );
 
 // Extract the number of dimensions:
 var ndims = fromInt64Bytes( bytes, 1, 3 );
 console.log( 'ndims: %d', ndims );
 
 // Extract the shape:
 var shape = [];
 var i;
 for ( i = 0; i < ndims; i++ ) {
     shape.push( fromInt64Bytes( bytes, 1, 11+(i*8) ) );
 }
 console.log( 'shape: [ %s ]', shape.join( ', ' ) );
 
 // Extract the strides (in units of bytes):
 var strides = [];
 for ( i = 0; i < ndims; i++ ) {
     strides.push( fromInt64Bytes( bytes, 1, 11+(ndims*8)+(i*8) ) );
 }
 console.log( 'strides (bytes): [ %s ]', strides.join( ', ' ) );
 
 // Extract the index offset (in bytes):
 var offset = fromInt64Bytes( bytes, 1, 11+(ndims*16) );
 console.log( 'offset (bytes): %d', offset );
 
 // Extract the order (enum):
 var order = dv.getInt8( 19+(ndims*16) );
 console.log( 'order (enum): %d', order );
 ```
 
 </section>
 
 <!-- /.examples -->
 
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 </section>
 
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 <section class="links">
 
 [@stdlib/ndarray/ctor]: https://www.npmjs.com/package/@stdlib/ndarray/tree/main/ctor
 
 </section>
 
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