From 60ebf7886f7ff89436d36460879d0adc3c3a5754 Mon Sep 17 00:00:00 2001
From: sheaf <sam.derbyshire@gmail.com>
Date: Mon, 11 Mar 2024 14:09:54 +0100
Subject: [PATCH] Split up succFP etc into separate module

---
 brush-strokes/brush-strokes.cabal          |  1 +
 brush-strokes/src/lib/Math/Float/Utils.hs  | 76 ++++++++++++++++++++++
 brush-strokes/src/lib/Math/Interval/FMA.hs | 72 ++------------------
 3 files changed, 83 insertions(+), 66 deletions(-)
 create mode 100644 brush-strokes/src/lib/Math/Float/Utils.hs

diff --git a/brush-strokes/brush-strokes.cabal b/brush-strokes/brush-strokes.cabal
index 08bf574..6362515 100644
--- a/brush-strokes/brush-strokes.cabal
+++ b/brush-strokes/brush-strokes.cabal
@@ -115,6 +115,7 @@ library
       , Math.Bezier.Stroke.EnvelopeEquation
       , Math.Differentiable
       , Math.Epsilon
+      , Math.Float.Utils
       , Math.Interval
       , Math.Linear
       , Math.Linear.Solve
diff --git a/brush-strokes/src/lib/Math/Float/Utils.hs b/brush-strokes/src/lib/Math/Float/Utils.hs
new file mode 100644
index 0000000..e99c9d6
--- /dev/null
+++ b/brush-strokes/src/lib/Math/Float/Utils.hs
@@ -0,0 +1,76 @@
+{-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+module Math.Float.Utils
+  ( FPBits(..)
+  , nextAfter, succFP, prevFP
+  )
+  where
+
+-- base
+import Data.Bits
+  ( Bits((.&.), shiftL) )
+import Data.Word
+  ( Word32, Word64 )
+import GHC.Float
+  ( castFloatToWord32 , castWord32ToFloat
+  , castDoubleToWord64, castWord64ToDouble
+  )
+
+--------------------------------------------------------------------------------
+
+class ( RealFloat f, Num b, Bits b ) => FPBits f b | f -> b, b -> f where
+  toBits   :: f -> b
+  fromBits :: b -> f
+  -- | Size in bytes.
+  sizeOf   :: Int
+
+instance FPBits Float Word32 where
+  toBits   = castFloatToWord32
+  fromBits = castWord32ToFloat
+  sizeOf   = 4
+
+instance FPBits Double Word64 where
+  toBits   = castDoubleToWord64
+  fromBits = castWord64ToDouble
+  sizeOf   = 8
+
+
+{-# SPECIALISE nextAfter :: Float -> Float -> Float #-}
+{-# SPECIALISE nextAfter :: Double -> Double -> Double #-}
+{-# INLINEABLE nextAfter #-}
+-- | @nextAfter a b@ computes the next floating-point value after @a@
+-- in the direction of @b@.
+nextAfter :: forall f b. FPBits f b => f -> f -> f
+nextAfter a b
+  | isNaN a
+  = a
+  | isNaN b
+  = b
+  | a == b
+  = b
+  | otherwise
+  = let !res_bits
+          | a == 0
+          , let !sgn_mask = 1 `shiftL` ( sizeOf @f * 8 - 1 )
+          = ( toBits b .&. sgn_mask ) + 1
+          | ( a < b ) == ( a > 0 )
+          = toBits a + 1
+          | otherwise
+          = toBits a - 1
+    in fromBits res_bits
+
+{-# SPECIALISE succFP :: Float -> Float #-}
+{-# SPECIALISE succFP :: Double -> Double #-}
+{-# INLINEABLE succFP #-}
+-- | The next floating-point number.
+succFP :: forall f b. FPBits f b => f -> f
+succFP x = nextAfter x (1/0)
+
+
+{-# SPECIALISE prevFP :: Float -> Float #-}
+{-# SPECIALISE prevFP :: Double -> Double #-}
+{-# INLINEABLE prevFP #-}
+-- | The previous floating-point number.
+prevFP :: forall f b. FPBits f b => f -> f
+prevFP x = nextAfter x (-1/0)
diff --git a/brush-strokes/src/lib/Math/Interval/FMA.hs b/brush-strokes/src/lib/Math/Interval/FMA.hs
index eea05f6..d5ca39d 100644
--- a/brush-strokes/src/lib/Math/Interval/FMA.hs
+++ b/brush-strokes/src/lib/Math/Interval/FMA.hs
@@ -1,77 +1,17 @@
 {-# LANGUAGE AllowAmbiguousTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 
-module Math.Interval.FMA ( addI, subI, prodI, divI, posPowI ) where
+module Math.Interval.FMA
+  ( addI, subI, prodI, divI, posPowI )
+  where
 
 -- base
-import Data.Bits
-  ( Bits((.&.), shiftL) )
-import Data.Word
-  ( Word32, Word64 )
 import GHC.Exts
   ( Double(D#), fmsubDouble#, fnmaddDouble# )
-import GHC.Float
-  ( castFloatToWord32 , castWord32ToFloat
-  , castDoubleToWord64, castWord64ToDouble
-  )
 
---------------------------------------------------------------------------------
-
-class ( RealFloat f, Num b, Bits b ) => FPBits f b | f -> b, b -> f where
-  toBits   :: f -> b
-  fromBits :: b -> f
-  -- | Size in bytes.
-  sizeOf   :: Int
-
-instance FPBits Float Word32 where
-  toBits   = castFloatToWord32
-  fromBits = castWord32ToFloat
-  sizeOf   = 4
-
-instance FPBits Double Word64 where
-  toBits   = castDoubleToWord64
-  fromBits = castWord64ToDouble
-  sizeOf   = 8
-
-
-{-# SPECIALISE nextAfter :: Float -> Float -> Float #-}
-{-# SPECIALISE nextAfter :: Double -> Double -> Double #-}
-{-# INLINEABLE nextAfter #-}
--- | @nextAfter a b@ computes the next floating-point value after @a@
--- in the direction of @b@.
-nextAfter :: forall f b. FPBits f b => f -> f -> f
-nextAfter a b
-  | isNaN a
-  = a
-  | isNaN b
-  = b
-  | a == b
-  = b
-  | otherwise
-  = let !res_bits
-          | a == 0
-          , let !sgn_mask = 1 `shiftL` ( sizeOf @f * 8 - 1 )
-          = ( toBits b .&. sgn_mask ) + 1
-          | ( a < b ) == ( a > 0 )
-          = toBits a + 1
-          | otherwise
-          = toBits a - 1
-    in fromBits res_bits
-
-{-# SPECIALISE succFP :: Float -> Float #-}
-{-# SPECIALISE succFP :: Double -> Double #-}
-{-# INLINEABLE succFP #-}
--- | The next floating-point number.
-succFP :: forall f b. FPBits f b => f -> f
-succFP x = nextAfter x (1/0)
-
-
-{-# SPECIALISE prevFP :: Float -> Float #-}
-{-# SPECIALISE prevFP :: Double -> Double #-}
-{-# INLINEABLE prevFP #-}
--- | The previous floating-point number.
-prevFP :: forall f b. FPBits f b => f -> f
-prevFP x = nextAfter x (-1/0)
+-- brush-strokes
+import Math.Float.Utils
+  ( prevFP, succFP )
 
 --------------------------------------------------------------------------------