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Fix some arithmetic primops #13

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Fix some arithmetic primops #13

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13 changes: 9 additions & 4 deletions Clear/PrimOps.lean
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Original file line number Diff line number Diff line change
Expand Up @@ -12,23 +12,28 @@ abbrev fromBool := Bool.toUInt256

def evmAddMod (a b c : UInt256) : UInt256 :=
if c = 0 then 0 else
Fin.mod (a + b) c
-- "All intermediate calculations of this operation are **not** subject to the 2^256 modulo."
Fin.mod (a.val + b.val) c

def evmMulMod (a b c : UInt256) : UInt256 :=
if c = 0 then 0 else
Fin.mod (a * b) c
-- "All intermediate calculations of this operation are **not** subject to the 2^256 modulo."
Fin.mod (a.val * b.val) c

def evmExp (a b : UInt256) : UInt256 :=
a ^ b.val

def evmMod (x y : UInt256) : UInt256 :=
if y == 0 then 0 else x % y

set_option linter.unusedVariables false in
def primCall (s : State) : PrimOp → List Literal → State × List Literal
| .Add, [a,b] => (s, [a + b])
| .Sub, [a,b] => (s, [a - b])
| .Mul, [a,b] => (s, [a * b])
| .Div, [a,b] => (s, [a / b])
| .Sdiv, [a,b] => (s, [UInt256.sdiv a b])
| .Mod, [a,b] => (s, [Fin.mod a b])
| .Mod, [a,b] => (s, [evmMod a b])
| .Smod, [a,b] => (s, [UInt256.smod a b])
| .Addmod, [a,b,c] => (s, [evmAddMod a b c])
| .Mulmod, [a,b,c] => (s, [evmMulMod a b c])
Expand Down Expand Up @@ -109,7 +114,7 @@ lemma EVMSub' : primCall s .Sub [a,b] = (s, [a -
lemma EVMMul' : primCall s .Mul [a,b] = (s, [a * b]) := rfl
lemma EVMDiv' : primCall s .Div [a,b] = (s, [a / b]) := rfl
lemma EVMSdiv' : primCall s .Sdiv [a,b] = (s, [UInt256.sdiv a b]) := rfl
lemma EVMMod' : primCall s .Mod [a,b] = (s, [Fin.mod a b]) := rfl
lemma EVMMod' : primCall s .Mod [a,b] = (s, [evmMod a b]) := rfl
lemma EVMSmod' : primCall s .Smod [a,b] = (s, [UInt256.smod a b]) := rfl
lemma EVMAddmod' : primCall s .Addmod [a,b,c] = (s, [evmAddMod a b c]) := rfl
lemma EVMMulmod' : primCall s .Mulmod [a,b,c] = (s, [evmMulMod a b c]) := rfl
Expand Down
17 changes: 9 additions & 8 deletions Clear/UInt256.lean
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Expand Up @@ -54,7 +54,7 @@ def eq0 (a : UInt256) : Bool := a = 0
def lnot (a : UInt256) : UInt256 := (UInt256.size - 1) - a

def byteAt (a b : UInt256) : UInt256 :=
b >>> (31 - a) * 8 <<< 248
b >>> (.ofNat ((31 - a.val) * 8)) &&& 0xFF

def sgn (a : UInt256) : UInt256 :=
if a ≥ 2 ^ 255 then -1
Expand All @@ -76,14 +76,15 @@ def sdiv (a b : UInt256) : UInt256 :=
else a / b

def smod (a b : UInt256) : UInt256 :=
if a ≥ 2 ^ 255 then
if b ≥ 2 ^ 255 then
Fin.mod (abs a) (abs b)
else (-1) * Fin.mod (abs a) b
if b == 0 then 0
else
if b ≥ 2 ^ 255 then
(-1) * Fin.mod a (abs b)
else Fin.mod a b
let sgnA := if 2 ^ 255 <= a then -1 else 1
let sgnB := if 2 ^ 255 <= b then -1 else 1
let mask : UInt256 := .ofNat (2 ^ 256 - 1 : ℕ)
let absA := if sgnA == 1 then a else - (.xor a mask + 1)
let absB := if sgnB == 1 then b else - (.xor b mask + 1)
sgnA * (absA % absB)


def slt (a b : UInt256) : Bool :=
if a ≥ 2 ^ 255 then
Expand Down