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(.module: [lux #- and or not])
(def: #export width Nat +64)
## [Values]
(do-template [<name> <type> <op> <doc>]
[(def: #export (<name> param subject)
{#.doc <doc>}
(-> Nat <type> <type>)
(<op> subject param))]
[and Nat "lux bit and" "Bitwise and."]
[or Nat "lux bit or" "Bitwise or."]
[xor Nat "lux bit xor" "Bitwise xor."]
[left-shift Nat "lux bit left-shift" "Bitwise left-shift."]
[logical-right-shift Nat "lux bit logical-right-shift" "Unsigned bitwise logical-right-shift."]
[arithmetic-right-shift Int "lux bit arithmetic-right-shift" "Signed bitwise arithmetic-right-shift."]
)
(def: (add-shift shift value)
(-> Nat Nat Nat)
(|> value (logical-right-shift shift) (n/+ value)))
(def: #export (count subject)
{#.doc "Count the number of 1s in a bit-map."}
(-> Nat Nat)
(let [count' (n/- (|> subject (logical-right-shift +1) (and +6148914691236517205))
subject)]
(|> count'
(logical-right-shift +2) (and +3689348814741910323) (n/+ (and +3689348814741910323 count'))
(add-shift +4) (and +1085102592571150095)
(add-shift +8)
(add-shift +16)
(add-shift +32)
(and +127))))
(def: #export not
{#.doc "Bitwise negation."}
(-> Nat Nat)
(let [mask (int-to-nat -1)]
(xor mask)))
(def: #export (clear idx input)
{#.doc "Clear bit at given index."}
(-> Nat Nat Nat)
(..and (..not (left-shift idx +1))
input))
(do-template [<name> <op> <doc>]
[(def: #export (<name> idx input)
{#.doc <doc>}
(-> Nat Nat Nat)
(<op> (left-shift idx +1) input))]
[set ..or "Set bit at given index."]
[flip ..xor "Flip bit at given index."]
)
(def: #export (set? idx input)
(-> Nat Nat Bool)
(|> input (..and (left-shift idx +1)) (n/= +0) .not))
(do-template [<name> <main> <comp>]
[(def: #export (<name> distance input)
(-> Nat Nat Nat)
(..or (<main> distance input)
(<comp> (n/- (n/% width distance)
width)
input)))]
[rotate-left left-shift logical-right-shift]
[rotate-right logical-right-shift left-shift]
)
(def: #export (region-mask size offset)
(-> Nat Nat Nat)
(let [pattern (|> +1 (left-shift size) n/dec)]
(left-shift offset pattern)))
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