mirror of https://github.com/zachjs/sv2v.git
58 lines
1.9 KiB
Haskell
58 lines
1.9 KiB
Haskell
{- sv2v
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- Author: Zachary Snow <zach@zachjs.com>
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-
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- Conversion for `casez` and `casex`
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-
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- Note that this conversion does not completely replicate the behavior of
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- `casex` and `casez` in cases where that case expression itself (rather than
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- just the case item patterns) contains wildcard values. This is apparently
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- rarely ever intentionally done.
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-}
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module Convert.CaseKW (convert) where
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import Convert.Traverse
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import Language.SystemVerilog.AST
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convert :: AST -> AST
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convert = traverseDescriptions (traverseModuleItems (traverseStmts convertStmt))
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-- Conversions:
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-- `casez` -> `case` with wildcards (?, z) expanded
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-- `casex` -> `case` with wildcards (?, z, x) expanded
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-- to be either 0 or 1
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wildcards :: CaseKW -> [Char]
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wildcards CaseN = [] -- CaseN == `case`
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wildcards CaseZ = ['?', 'z', 'Z']
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wildcards CaseX = ['?', 'z', 'Z', 'x', 'X']
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possibilities :: [Char]
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possibilities = ['0', '1']
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explodeBy :: [Char] -> String -> [String]
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explodeBy _ "" = [""]
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explodeBy wilds (x : xs) =
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(map (:) chars) <*> (explodeBy wilds xs)
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where chars = if elem x wilds then possibilities else [x]
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expandExpr :: [Char] -> Expr -> [Expr]
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expandExpr wilds (Number s) = map Number $ explodeBy wilds s
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expandExpr [] other = [other]
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-- TODO: Hopefully they only give us constant expressions...
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-- TODO: We could be given a constant identifier...
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expandExpr _ other = error $ "CaseKW conversion encountered case that was not a number, which is dubious..." ++ (show other)
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-- Note that we don't have to convert the statements within the cases, as the
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-- conversion template takes care of that for us.
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convertStmt :: Stmt -> Stmt
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convertStmt (Case kw expr cases def) =
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Case CaseN expr cases' def
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where
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wilds = wildcards kw
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cases' = map convertCase cases
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convertCase :: Case -> Case
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convertCase (exprs, stmt) = (exprs', stmt)
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where exprs' = concat $ map (expandExpr wilds) exprs
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convertStmt other = other
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