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AnonymousVoting.sol: avoid jump and jumpi instructions #17

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AnonymousVoting.sol: avoid jump and jumpi instructions #17

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34 changes: 18 additions & 16 deletions AnonymousVoting.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -50,15 +50,14 @@ library ECCMath {
uint bit = 2 ** 255;
bit = bit;
assembly {
loop:
jumpi(end, iszero(bit))
// replaced jump and jumpi by for loop due to compile errors/warnings
for { } not(eq(bit, 0)) { } {
r := mulmod(mulmod(r, r, m), exp(b, iszero(iszero(and(e, bit)))), m)
r := mulmod(mulmod(r, r, m), exp(b, iszero(iszero(and(e, div(bit, 2))))), m)
r := mulmod(mulmod(r, r, m), exp(b, iszero(iszero(and(e, div(bit, 4))))), m)
r := mulmod(mulmod(r, r, m), exp(b, iszero(iszero(and(e, div(bit, 8))))), m)
bit := div(bit, 16)
jump(loop)
end:
}
}
}

Expand Down Expand Up @@ -348,22 +347,25 @@ library Secp256k1 {
// wNAF
assembly
{
let dm := 0
dwPtr := mload(0x40)
mstore(0x40, add(dwPtr, 512)) // Should lower this.
loop:
jumpi(loop_end, iszero(d))
jumpi(even, iszero(and(d, 1)))
let dm := 0
dwPtr := mload(0x40)
mstore(0x40, add(dwPtr, 512)) // Should lower this.

// replaced jumpi and jump by for loop due to compile errors/warnings
for { } not(eq(d, 0)) { } {
// since if is not supported we used the switch statement to replace the conditional jump
switch not(eq(and(d, 1), 0))
case 1 {
dm := mod(d, 32)
mstore8(add(dwPtr, i), dm) // Don"t store as signed - convert when reading.
d := add(sub(d, dm), mul(gt(dm, 16), 32))
even:
d := div(d, 2)
i := add(i, 1)
jump(loop)
loop_end:
}
default { }
d := div(d, 2)
i := add(i, 1)
}
}

dwPtr = dwPtr;

// Pre calculation
Expand Down