-- | Bits and pieces on the bottom of the module dependency tree.
--	Also import the required constants, so we know what we're using.
--	
--	In the interests of cross-compilation, we want to free ourselves
--	from the autoconf generated modules like main/Constants
--
{-# OPTIONS -fno-warn-tabs #-}
-- The above warning supression flag is a temporary kludge.
-- While working on this module you are encouraged to remove it and
-- detab the module (please do the detabbing in a separate patch). See
--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces
-- for details

module SPARC.Base (
	wordLength,
	wordLengthInBits,
	spillAreaLength,
	spillSlotSize,
	extraStackArgsHere,
	fits13Bits,
	is32BitInteger,
	largeOffsetError
)

where

import qualified Constants
import Panic

import Data.Int


-- On 32 bit SPARC, pointers are 32 bits.
wordLength :: Int
wordLength = 4

wordLengthInBits :: Int
wordLengthInBits 
	= wordLength * 8

-- Size of the available spill area
spillAreaLength :: Int
spillAreaLength
	= Constants.rESERVED_C_STACK_BYTES

-- | We need 8 bytes because our largest registers are 64 bit.
spillSlotSize :: Int
spillSlotSize = 8


-- | We (allegedly) put the first six C-call arguments in registers;
-- 	where do we start putting the rest of them?
extraStackArgsHere :: Int
extraStackArgsHere = 23


{-# SPECIALIZE fits13Bits :: Int -> Bool, Integer -> Bool #-}
-- | Check whether an offset is representable with 13 bits.
fits13Bits :: Integral a => a -> Bool
fits13Bits x = x >= -4096 && x < 4096

-- | Check whether an integer will fit in 32 bits.
--	A CmmInt is intended to be truncated to the appropriate 
-- 	number of bits, so here we truncate it to Int64.  This is
-- 	important because e.g. -1 as a CmmInt might be either
-- 	-1 or 18446744073709551615.
--
is32BitInteger :: Integer -> Bool
is32BitInteger i 
	= i64 <= 0x7fffffff && i64 >= -0x80000000
  	where i64 = fromIntegral i :: Int64


-- | Sadness.
largeOffsetError :: (Integral a, Show a) => a -> b
largeOffsetError i
  = panic ("ERROR: SPARC native-code generator cannot handle large offset ("
		++ show i ++ ");\nprobably because of large constant data structures;" ++ 
		"\nworkaround: use -fvia-C on this module.\n")