Contract 0x6e6012f66e8d...5f1dece95640
UtilityThe Etheria hex bounds check with the absolute value missing its else branch
Context
Frontier era deployment by Cyrus Adkisson, the author of Etheria.
Key Facts
Description
The second of four standalone blockHexCoordsValid deployments on 14 October 2015. It uses the integer form of the diagonal test, (absx2) + (absy3) <= 198, which needs uint8 rather than int8 because 198 will not fit in a signed byte. The absolute values are computed with an if and no else, so any non negative coordinate is treated as zero and passes the diagonal test unconditionally. The next deployment 23 minutes later adds the else branch.
Source Verified
Heuristic Analysis
The following characteristics were detected through bytecode analysis and may not be accurate.
Frontier Era
The initial release of Ethereum. A bare-bones implementation for technical users.
Bytecode Overview
Verified Source Available
Source verified through compiler archaeology and exact bytecode matching.
View Verification ProofShow source code (Solidity)
// Submitted by EthereumHistory (ethereumhistory.com)
contract HexValidator
{
function blockHexCoordsValid(int8 x, int8 y) constant returns (bool)
{
if(-33 <= y && y <= 33)
{
if(y % 2 != 0 ) // odd
{
if(-50 <= x && x <= 49)
return true;
}
else // even
{
if(-49 <= x && x <= 49)
return true;
}
}
else
{
uint8 absx;
uint8 absy;
if(x < 0)
absx = uint8(x*-1);
if(y < 0)
absy = uint8(y*-1);
if((y >= 0 && x >= 0) || (y < 0 && x > 0)) // first or 4th quadrants
{
if(y % 2 != 0 ) // odd
{
if (((absx*2) + (absy*3)) <= 198)
return true;
}
else // even
{
if ((((absx+1)*2) + ((absy-1)*3)) <= 198)
return true;
}
}
else
{
if(y % 2 == 0 ) // even
{
if (((absx*2) + (absy*3)) <= 198)
return true;
}
else // odd
{
if ((((absx+1)*2) + ((absy-1)*3)) <= 198)
return true;
}
}
}
return false;
}
}External Links
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