Class: WordArray

• Inheritance
• Description
• Class protocol
  • queries
• Instance protocol
  • accessing

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:

 elementByteSize

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

 literalTokenPrefix

 maxVal

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

 minVal

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

Instance protocol:

 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