Make higher-ord cpu example even shorter

[matthijs/master-project/dsd-paper.git] / cλash.lhs

diff --git a/cλash.lhs b/cλash.lhs
index 2a384a0ed9b9c749a9d5380860021ec76d8b5bec..9fb964773a948b737ee7055d4e86500b3202a3c5 100644 (file)
--- a/cλash.lhs
+++ b/cλash.lhs
@@ -548,9 +548,9 @@ the Haskell code to equivalently behaving synthesizable \VHDL\ code, ready to
 be converted to an actual netlist format by an (optimizing) \VHDL\ synthesis 
 tool.
 
 be converted to an actual netlist format by an (optimizing) \VHDL\ synthesis 
 tool.
 

-Besides trivial circuits such as variants of both the FIR filter and the 
-simple CPU shown in \Cref{sec:usecases}, the \CLaSH\ compiler has also been 
-shown to work for non-trivial descriptions. \CLaSH\ has been able to 
+Besides trivial circuits such as variants of both the \acro{FIR} filter and 
+the simple \acro{CPU} shown in \Cref{sec:usecases}, the \CLaSH\ compiler has 
+also been shown to work for non-trivial descriptions. \CLaSH\ has been able to 

 successfully translate the functional description of a streaming reduction 
 circuit~\cite{reductioncircuit} for floating point numbers.
 
 successfully translate the functional description of a streaming reduction 
 circuit~\cite{reductioncircuit} for floating point numbers.
 


@@ -702,9 +702,9 @@ circuit~\cite{reductioncircuit} for floating point numbers.
     compiler. The \CLaSH\ compiler has generic translation rules to
     translated the user-defined types described below.
 
     compiler. The \CLaSH\ compiler has generic translation rules to
     translated the user-defined types described below.
 

-    The \CLaSH compiler is able to infer unspecified types,
+    The \CLaSH\ compiler is able to infer unspecified types,

     meaning that a developer does not have to annotate every function with a 
     meaning that a developer does not have to annotate every function with a 

-    type signature (though it is good practice to do so anyway).
+    type signature (even if it is good practice to do so).

   
     % Translation of two most basic functional concepts has been
     % discussed: function application and choice. Before looking further
   
     % Translation of two most basic functional concepts has been
     % discussed: function application and choice. Before looking further


@@ -762,7 +762,7 @@ circuit~\cite{reductioncircuit} for floating point numbers.
         the rest of paper is: \hs{[a|n]}. Where the \hs{a} is the element 
         type, and \hs{n} is the length of the vector. Note that this is
         a notation used in this paper only, vectors are slightly more
         the rest of paper is: \hs{[a|n]}. Where the \hs{a} is the element 
         type, and \hs{n} is the length of the vector. Note that this is
         a notation used in this paper only, vectors are slightly more

-        elaborate in real \CLaSH programs.
+        verbose in real \CLaSH\ descriptions.

         % The state type of an 8 element register bank would then for example 
         % be:
 
         % The state type of an 8 element register bank would then for example 
         % be:
 


@@ -1091,7 +1091,7 @@ Haskell language. A description in \emph{Core} can still contain properties
 which have no direct translation to hardware, such as polymorphic types and 
 function-valued arguments. Such a description needs to be transformed to a 
 \emph{normal form}, which only contains properties that have a direct 
 which have no direct translation to hardware, such as polymorphic types and 
 function-valued arguments. Such a description needs to be transformed to a 
 \emph{normal form}, which only contains properties that have a direct 

-translation. The second stage of the compiler, the \emph{normalization} phase 
+translation. The second stage of the compiler, the \emph{normalization} phase, 

 exhaustively applies a set of \emph{meaning-preserving} transformations on the 
 \emph{Core} description until this description is in a \emph{normal form}. 
 This set of transformations includes transformations typically found in 
 exhaustively applies a set of \emph{meaning-preserving} transformations on the 
 \emph{Core} description until this description is in a \emph{normal form}. 
 This set of transformations includes transformations typically found in 


@@ -1107,9 +1107,8 @@ end-product of the \CLaSH\ compiler a \VHDL\ \emph{netlist} as the resulting
 \VHDL\ resembles an actual netlist description and not idiomatic \VHDL.
 
 \section{Use cases}
 \VHDL\ resembles an actual netlist description and not idiomatic \VHDL.
 
 \section{Use cases}

-
-\subsection{FIR Filter}

 \label{sec:usecases}
 \label{sec:usecases}

+\subsection{FIR Filter}

 As an example of a common hardware design where the use of higher-order
 functions leads to a very natural description is a \acro{FIR} filter, which is 
 basically the dot-product of two vectors:
 As an example of a common hardware design where the use of higher-order
 functions leads to a very natural description is a \acro{FIR} filter, which is 
 basically the dot-product of two vectors:


@@ -1169,10 +1168,10 @@ fir (State (xs,hs)) x = (State (x >> xs,hs), xs *+* hs)
 \end{code}
 
 Where the vector \hs{hs} contains the \acro{FIR} coefficients and the vector 
 \end{code}
 
 Where the vector \hs{hs} contains the \acro{FIR} coefficients and the vector 

-\hs{xs} contains the latest input sample in front and older samples behind. 
-The code for the shift (\hs{>>}) operator that adds the new input sample 
+\hs{xs} contains the previous input sample in front and older samples behind. 
+The code for the shift (\hs{>>}) operator, that adds the new input sample 

 (\hs{x}) to the list of previous input samples (\hs{xs}) and removes the 
 (\hs{x}) to the list of previous input samples (\hs{xs}) and removes the 

-oldest sample is shown below:
+oldest sample, is shown below:

 
 \begin{code}
 x >> xs = x +> init xs  
 
 \begin{code}
 x >> xs = x +> init xs  


@@ -1193,40 +1192,32 @@ the vectors of the \acro{FIR} code to a length of 4, is depicted in
 \subsection{Higher order CPU}
 
 \begin{code}
 \subsection{Higher order CPU}
 
 \begin{code}

-type FuState = State Word
-fu :: (a -> a -> a)
-      -> [a]:n
-      -> (RangedWord n, RangedWord n)
-      -> FuState
-      -> (FuState, a)
-fu op inputs (addr1, addr2) (State out) =
-  (State out', out)
+fu op inputs (addr1, addr2) = regIn

   where
   where

-    in1  = inputs!addr1
-    in2  = inputs!addr2
-    out' = op in1 in2
+    in1     = inputs!addr1
+    in2     = inputs!addr2
+    regIn   = op in1 in2

 \end{code}
 
 \begin{code}
 \end{code}
 
 \begin{code}

-type CpuState = State [FuState]:4
-cpu :: Word 
-       -> [(RangedWord 7, RangedWord 7)]:4
-       -> CpuState
-       -> (CpuState, Word)
-cpu input addrs (State fuss) =
-  (State fuss', out)
+cpu :: Word -> [(Index 6, Index 6) | 4] 
+  -> State [Word | 4] -> (State [Word | 4], Word)
+cpu input addrs (State fuss) = (State fuss', out)

   where
   where

-    fures = [ fu const inputs!0 fuss!0
-            , fu (+)   inputs!1 fuss!1
-            , fu (-)   inputs!2 fuss!2
-            , fu (*)   inputs!3 fuss!3
-            ]
-    (fuss', outputs) = unzip fures
-    inputs = 0 +> 1 +> input +> outputs
-    out = head outputs
+    fuss' =   [ fu const  inputs (addrs!0) (fuss!0)
+              , fu (+)    inputs (addrs!1) (fuss!1)
+              , fu (-)    inputs (addrs!2) (fuss!2)
+              , fu (*)    inputs (addrs!3) (fuss!3)
+              ]
+    inputs    = 0 +> (1 +> (input +> fuss))
+    out       = head fuss

 \end{code}
 
 \section{Related work}
 \end{code}
 
 \section{Related work}

+This section describes the features of existing (functional) hardware 
+description languages and highlights the advantages that this research has 
+over existing work.
+

 Many functional hardware description languages have been developed over the 
 years. Early work includes such languages as $\mu$\acro{FP}~\cite{muFP}, an 
 extension of Backus' \acro{FP} language to synchronous streams, designed 
 Many functional hardware description languages have been developed over the 
 years. Early work includes such languages as $\mu$\acro{FP}~\cite{muFP}, an 
 extension of Backus' \acro{FP} language to synchronous streams, designed 


@@ -1238,7 +1229,7 @@ circuits, and has a particular focus on layout.
 functional language \acro{ML}, and has support for polymorphic types and 
 higher-order functions. Published work suggests that there is no direct 
 simulation support for \acro{HML}, but that a description in \acro{HML} has to 
 functional language \acro{ML}, and has support for polymorphic types and 
 higher-order functions. Published work suggests that there is no direct 
 simulation support for \acro{HML}, but that a description in \acro{HML} has to 

-be translated to \VHDL\ and that the translated description can than be 
+be translated to \VHDL\ and that the translated description can then be 

 simulated in a \VHDL\ simulator. Also not all of the mentioned language 
 features of \acro{HML} could be translated to hardware. The \CLaSH\ compiler 
 on the other hand can correctly translate all of the language constructs 
 simulated in a \VHDL\ simulator. Also not all of the mentioned language 
 features of \acro{HML} could be translated to hardware. The \CLaSH\ compiler 
 on the other hand can correctly translate all of the language constructs 


@@ -1280,9 +1271,12 @@ mentioned in this section.
 
 The merits of polymorphic typing, combined with higher-order functions, are 
 now also recognized in the `main-stream' hardware description languages, 
 
 The merits of polymorphic typing, combined with higher-order functions, are 
 now also recognized in the `main-stream' hardware description languages, 

-exemplified by the new \VHDL-2008 standard~\cite{VHDL2008}. \VHDL-2008 support for generics has been extended to types, allowing a developer to describe 
+exemplified by the new \VHDL-2008 standard~\cite{VHDL2008}. \VHDL-2008 support 
+for generics has been extended to types, allowing a developer to describe 

 polymorphic components. Note that those types still require an explicit 
 polymorphic components. Note that those types still require an explicit 

-generic map, whereas types can be automatically inferred in \CLaSH.
+generic map, whereas types can be automatically inferred in \CLaSH. There are 
+also no (generally available) \VHDL\ synthesis tools that currently support 
+the \VHDL-2008 standard, and thus the synthesis of polymorphic types.

 
 % Wired~\cite{Wired},, T-Ruby~\cite{T-Ruby}, Hydra~\cite{Hydra}. 
 % 
 
 % Wired~\cite{Wired},, T-Ruby~\cite{T-Ruby}, Hydra~\cite{Hydra}. 
 % 


@@ -1384,14 +1378,9 @@ The conclusion goes here.
 
 
 % use section* for acknowledgement
 
 
 % use section* for acknowledgement

-\section*{Acknowledgment}
-
-
-The authors would like to thank...
-
-
-
-
+% \section*{Acknowledgment}
+% 
+% The authors would like to thank...

 
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