View source for ELLA (programming language)

{{Infobox software
|name = ELLA
|logo = <!-- File name only -->
|logo alt = 
|logo caption = 
|screenshot = <!-- File name only -->
|screenshot alt = 
|caption = 
|author = 
|developer = [[Engineering:Royal Signals and Radar Establishment|Royal Signals and Radar Establishment]]
|released = {{Start date and age|1986}}<!-- If known, add |mm|dd|df=yes -->
|latest release version = 
|latest release date = <!--{{Start date and age|20yy}} If known, add |mm|dd|df=yes -->
|programming language = ALGOL 68RS
|operating system = [[Software:OpenVMS|VMS]]
|platform = [[ICL 2900 Series]], [[Software:Multics|Multics]], [[VAX]]
|size = <!-- ? K words -->
|language = English
|genre = [[Hardware description language]]
|license = [[Social:Public domain|public domain]] (parts)
|website = <!--{{URL|www.example.com}}-->
}}
'''ELLA''' is a [[Hardware description language|hardware description language]] and support toolset, developed in the United Kingdom by the [[Engineering:Royal Signals and Radar Establishment|Royal Signals and Radar Establishment]] (RSRE) during the 1980s and 1990s, which also developed the [[Compiler|compiler]] for the [[Programming language|programming language]], ALGOL 68RS, used to write ELLA.

ELLA has tools to perform:
* Design transformation
* [[Symbolic simulation]]s
* [[Formal verification]]

ELLA is a winner of the 1989 Queen's Award for Technological Achievement.

== Sample ==
Sample originally from ftp://ftp.dra.hmg.gb/pub/ella{{dead link|date=May 2015}}, public release.

Code for matrix multiplication hardware design verification:
<pre>
MAC ZIP = ([INT n]TYPE t: vector1 vector2) -> [n][2]t:
  [INT k = 1..n](vector1[k], vector2[k]).
     
MAC TRANSPOSE = ([INT n][INT m]TYPE t: matrix) -> [m][n]t:
  [INT i = 1..m] [INT j = 1..n] matrix[j][i].

MAC INNER_PRODUCT{FN * = [2]TYPE t -> TYPE s, FN + = [2]s -> s}
                 = ([INT n][2]t: vector) -> s:
  IF n = 1 THEN *vector[1]
  ELSE *vector[1] + INNER_PRODUCT {*,+} vector[2..n]
  FI.

MAC MATRIX_MULT {FN * = [2]TYPE t->TYPE s, FN + = [2]s->s} =
([INT n][INT m]t: matrix1, [m][INT p]t: matrix2) -> [n][p]s:
BEGIN
  LET transposed_matrix2 = TRANSPOSE matrix2.
OUTPUT [INT i = 1..n][INT j = 1..p]
       INNER_PRODUCT{*,+}ZIP(matrix1[i],transposed_matrix2[j])
END.

TYPE element = NEW elt/(1..20),
     product = NEW prd/(1..1200).

FN PLUS = (product: integer1 integer2) -> product:
  ARITH integer1 + integer2.

FN MULT = (element: integer1 integer2) -> product:
  ARITH integer1 * integer2.

FN MULT_234 = ([2][3]element:matrix1, [3][4]element:matrix2) ->
             [2][4]product:  
  MATRIX_MULT{MULT,PLUS}(matrix1, matrix2).

FN TEST = () -> [2][4]product:
( LET m1 = ((elt/2, elt/1, elt/1),
            (elt/3, elt/6, elt/9)), 
      m2 = ((elt/6, elt/1, elt/3, elt/4), 
            (elt/9, elt/2, elt/8, elt/3),
            (elt/6, elt/4, elt/1, elt/2)).
  OUTPUT
    MULT_234 (m1, m2)
).

COM test: just displaysignal MOC
</pre>

== References ==
{{Refbegin}}
*{{cite book |last1=Morison |first1=J. D. |last2=Clarke |first2=A. S. |date=1 October 1993 |title=Ella 2000: A Language for Electronic System Design |publisher=McGraw Hill |isbn=978-0077078218}}
*{{Cite conference |last1=Barringer |first1=H. |last2=Gough |first2=G. |last3=Monahan |first3=B. |last4=Williams |first4=A. |last5=Arcus |first5=M. |last6=Armstrong |first6=A. |last7=Hill |first7=M. |year=1995 |doi=10.1109/ASPDAC.1995.486387 |title=A design and verification environment for ELLA |work=Proceedings of ASP-DAC '95, CHDL '95, VLSI '95 with EDA Technofair |conference=Design Automation Conference (DAC) 1995 |pages=685–690 |isbn=4-930813-67-0}}
*{{Cite conference |last1=Morison |first1=J. D. |last2=Peeling |first2=N. E. |last3=Thorp |first3=T. L. |last4=Whiting |first4=E. V. |year=1987 |doi=10.1145/37888.38006 |title=EASE: A Design Support Environment for the HDDL ELLA |work=24th Conference on Design Automation |conference=Design Automation Conference (DAC) 1987 |pages=741–749 |isbn=0-8186-0781-5}}
{{Refend}}

==External links==
* [http://cs.nyu.edu/courses/spring02/G22.3130-001/ella/ ELLA source code] including the ALGOL 68RS translator

{{Programmable Logic}}
{{ALGOL programming}}

[[Category:Hardware description languages]]


{{Sourceattribution|ELLA (programming language)}}