Hashing without memory allocations #2
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| uint256 constant scratchSpacePtr = 0x00; | ||
| /** | ||
| * @dev We call word the typical unit size for operands of EVM instructions: 32 bytes. | ||
| */ | ||
| uint256 constant wordSize = 32; |
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We typically CAPITALIZE constants, don't we?
| ) internal pure returns (bytes32 hash) { | ||
| assembly ("memory-safe") { | ||
| // The length of the bytes type `length` field is that of a word in memory | ||
| let data := add(add(encoded, offset), 0x20) |
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Should use the word size constant.
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I was actually about to use the memoryWord (or MEMORY_WORD?) constant instead since this refers to size of a type in memory while the other one is about the typical size of an operand. The distinction is very small but it could bite us in the future if we're not careful with these constants 🤔
Ah, in any case, I ended up not including that constant because it was defined by the pay function which I didn't include here but I could just add that constant by itself instead.
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I mean, at some point the memory could be accessed in sizes other than 32 bytes; in fact, you can access it byte by byte, although I don't think the compiler ever does that.
This adds a few functions that allow the user to hash without extra memory allocations.