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Class: WordArray


Inheritance:

   Object
   |
   +--Collection
      |
      +--SequenceableCollection
         |
         +--ArrayedCollection
            |
            +--UninterpretedBytes
               |
               +--AbstractNumberVector
                  |
                  +--UnboxedIntegerArray
                     |
                     +--WordArray

Package:
stx:libbasic
Category:
Collections-Arrayed
Version:
rev: 1.11 date: 2022/08/10 10:07:47
user: cg
file: WordArray.st directory: libbasic
module: stx stc-classLibrary: libbasic

Description:


WordArrays store 16bit unsigned integers in the range 0..16rFFFF.
In contrast to normal arrays (which store pointers to their elements),
wordArrays store the values in a dense & compact way. 
Since the representation fits the underlying C-language systems representation
of unsigned int16's, this is also useful to pass bulk data to c primitive code.

WordArrays can be used to hold bulk integer data in a more compact way.
    For example:
        Array new:100000 withAll:1
    requires 400k of object memory;

    in contrast,
        WordArray new:100000 withAll:1
    only requires half of it.

WordArrays can be used as literals i.e. you can enter WordArray-constants as: 
    #u16( element1 element2 .... elementN ) 
    #s16( element1 element2 .... elementN ) 
for example:
    #u16(1 10 128 127 0x7FFF 0x8000 0xFFFF)
    #s16(-1 1 10 128 127 0x7FFF -0x7FFF -0x8000)

Aliased as UInt16Array.

[memory requirements:]
    OBJ-HEADER + (size * 2)


[caveat:]
    should probably be renamed to UInt16Array
    (there is an alias named 'UInt16Array', but when inspected,
    it presents itself as WordArray)

copyright

COPYRIGHT (c) 1989 by Claus Gittinger All Rights Reserved This software is furnished under a license and may be used only in accordance with the terms of that license and with the inclusion of the above copyright notice. This software may not be provided or otherwise made available to, or used by, any other person. No title to or ownership of the software is hereby transferred.

Class protocol:

queries
o  elementByteSize
for bit-like containers, return the number of bytes stored per element.
Here, 2 is returned

o  literalTokenPrefix

o  maxVal
the maximum value which can be stored in instances of me.
For WordArrays, this is 16rFFFF (largest 16bit unsigned int)

o  minVal
the minimum value which can be stored in instances of me.
For WordArrays, this is 0


Instance protocol:

accessing
o  unsignedInt16At: index MSB: msb
return the 2-bytes starting at index as an (unsigned) Integer.
The index is a smalltalk index (i.e. 1-based).
The value is retrieved MSB (high 8 bits at lower index) if msb is true;
LSB-first (i.e. low 8-bits at lower byte index) if it's false.
Notice:
the index is a byte index; thus, this allows for unaligned access to
words on any boundary



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