X-Git-Url: https://git.stderr.nl/gitweb?p=matthijs%2Fmaster-project%2Freport.git;a=blobdiff_plain;f=Chapters%2FHardwareDescription.tex;h=f5e2615a5b404e17920cd3779e88539df9db4be9;hp=479dd400640b5dfa38de5a2c929d41ef79f75a54;hb=f2d45a8c05c4fff4eb9574e8514b213fbfc8fb84;hpb=d196e984e8b30373485e136ac763b669d21c4751 diff --git a/Chapters/HardwareDescription.tex b/Chapters/HardwareDescription.tex index 479dd40..f5e2615 100644 --- a/Chapters/HardwareDescription.tex +++ b/Chapters/HardwareDescription.tex @@ -152,7 +152,8 @@ and3 a b c = and (and a b) c In Haskell, there is no sharp distinction between a variable and a function: a function is just a variable (binder) with a function type. This means that a top level function is just any top level - binder with a function type. + binder with a function type. This also means that sometimes top level + function will be used when top level binder is really meant. As an example, consider the following Haskell snippet: @@ -193,13 +194,16 @@ and3 a b c = and (and a b) c simply be translated to a conditional assignment, where the conditions use equality comparisons against the constructors in the \hs{case} expressions. - In \in{example}[ex:CaseInv] a simple \hs{case} expression is shown, - scrutinizing a boolean value. The corresponding architecture has a - comparator to determine which of the constructors is on the \hs{in} - input. There is a multiplexer to select the output signal. The two options - for the output signals are just constants, but these could have been more - complex expressions (in which case also both of them would be working in - parallel, regardless of which output would be chosen eventually). + In \in{example}[ex:Inv] two versions of an inverter are shown. The first + uses a simple \hs{case} expression, scrutinizing a boolean value. The + corresponding architecture has a comparator to determine which of the + constructors is on the \hs{in} input. There is a multiplexer to select the + output signal (which is just a conditional assignment in the generated + \VHDL). The two options for the output signals are just constants, + but these could have been more complex expressions (in which case also + both of them would be working in parallel, regardless of which output + would be chosen eventually). The \VHDL\ generated for (both versions of) + this inverter is shown in \in{example}[ex:InvVHDL]. If we would translate a Boolean to a bit value, we could of course remove the comparator and directly feed 'in' into the multiplexer (or even use an @@ -233,8 +237,9 @@ and3 a b c = and (and a b) c specifies a pattern. When the arguments match the pattern, the corresponding clause will be used. - The architecture described by \in{example}[ex:PatternInv] is of course the - same one as the one in \in{example}[ex:CaseInv]. The general interpretation + \in{Example}[ex:Inv] also shows an inverter that uses pattern matching. + The architecture it describes is of course the + same one as the description with a case expression. The general interpretation of pattern matching is also similar to that of \hs{case} expressions: generate hardware for each of the clauses (like each of the clauses of a \hs{case} expression) and connect them to the function output through (a number of @@ -253,7 +258,13 @@ and3 a b c = and (and a b) c False -> True \stopbuffer - \startuseMPgraphic{CaseInv} + \startbuffer[PatternInv] + inv :: Bool -> Bool + inv True = False + inv False = True + \stopbuffer + + \startuseMPgraphic{Inv} save in, truecmp, falseout, trueout, out, cmp, mux; % I/O ports @@ -287,7 +298,7 @@ and3 a b c = and (and a b) c ncline(mux)(out) "posA(out)"; \stopuseMPgraphic - \startbuffer[CaseInvVHDL] + \startbuffer[InvVHDL] entity invComponent_0 is port (\xzAMo2\ : in boolean; \reszAMuzAMu2\ : out boolean; @@ -303,25 +314,34 @@ and3 a b c = and (and a b) c end architecture structural; \stopbuffer - \placeexample[][ex:CaseInv]{Simple inverter.} - \startcombination[2*1] - {\typebufferhs{CaseInv}}{Haskell description using a Case expression.} - {\boxedgraphic{CaseInv}}{The architecture described by the Haskell description.} - \stopcombination - - \placeexample[][ex:CaseInvVHDL]{\VHDL\ generated for \hs{inv} from - \in{example}[ex:CaseInv] and \in{example}[ex:PatternInv]} - {\typebuffervhdl{CaseInvVHDL}} - - \startbuffer[PatternInv] - inv :: Bool -> Bool - inv True = False - inv False = True - \stopbuffer + \placeexample[][ex:Inv]{Simple inverter.}{ + % Use placesidebyside, since nesting combinations doesn't seem to work + % here. This does break centering, but well... + \placesidebyside + % Use 2*2 instead of 1*2 to insert some extra space (\placesidebyside + % places stuff very close together) + {\startcombination[2*2] + {\typebufferhs{CaseInv}}{Haskell description using a Case expression.} + {}{} + {\typebufferhs{PatternInv}}{Haskell description using Pattern matching expression.} + {}{} + \stopcombination} + % Use a 1*1 combination to add a caption + {\startcombination[1*1] + {\boxedgraphic{Inv}}{The architecture described by the Haskell descriptions.} + \stopcombination} + } - \placeexample[][ex:PatternInv]{Simple inverter using pattern matching. - Describes the same architecture as \in{example}[ex:CaseInv].} - {\typebufferhs{PatternInv}} +% \placeexample[][ex:Inv]{Simple inverter.}{ +% \startcombination[2*2] +% {\typebufferhs{CaseInv}}{Haskell description using a Case expression.} +% {}{} +% {\typebufferhs{PatternInv}}{Haskell description using Pattern matching expression.} +% {\boxedgraphic{Inv}}{The architecture described by the Haskell description.} +% \stopcombination +% } + \placeexample[][ex:InvVHDL]{\VHDL\ generated for (both versions of) \hs{inv} from \in{example}[ex:Inv]} + {\typebuffervhdl{InvVHDL}} \section{Types} Translation of two most basic functional concepts has been