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//===--- StableHasher.cpp - Stable Hasher ---------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2021 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
#include "swift/Basic/StableHasher.h"
using namespace swift;
#define ROTATE_LEFT(ROTAND, DISTANCE) \
(uint64_t)((ROTAND) << (DISTANCE)) | ((ROTAND) >> (64 - (DISTANCE)))
namespace {
static inline void sip_round(uint64_t &v0, uint64_t &v1, uint64_t &v2,
uint64_t &v3) {
v0 += v1;
v1 = ROTATE_LEFT(v1, 13);
v1 ^= v0;
v0 = ROTATE_LEFT(v0, 32);
v2 += v3;
v3 = ROTATE_LEFT(v3, 16);
v3 ^= v2;
v0 += v3;
v3 = ROTATE_LEFT(v3, 21);
v3 ^= v0;
v2 += v1;
v1 = ROTATE_LEFT(v1, 17);
v1 ^= v2;
v2 = ROTATE_LEFT(v2, 32);
}
} // end anonymous namespace
void StableHasher::compress(uint64_t value) {
state.v3 ^= value;
for (unsigned i = 0; i < 2; ++i) {
::sip_round(state.v0, state.v1, state.v2, state.v3);
}
state.v0 ^= value;
}
std::pair<uint64_t, uint64_t> StableHasher::finalize() && {
auto fillBitsFromBuffer = [](uint64_t fill, uint8_t *bits) {
uint64_t head = 0;
switch (fill) {
case 7:
head |= uint64_t(bits[6]) << 48;
LLVM_FALLTHROUGH;
case 6:
head |= uint64_t(bits[5]) << 40;
LLVM_FALLTHROUGH;
case 5:
head |= uint64_t(bits[4]) << 32;
LLVM_FALLTHROUGH;
case 4:
head |= uint64_t(bits[3]) << 24;
LLVM_FALLTHROUGH;
case 3:
head |= uint64_t(bits[2]) << 16;
LLVM_FALLTHROUGH;
case 2:
head |= uint64_t(bits[1]) << 8;
LLVM_FALLTHROUGH;
case 1:
head |= uint64_t(bits[0]);
break;
case 0:
break;
default:
break;
}
return head;
};
const uint64_t b = fillBitsFromBuffer(getBufferLength(), byteBuffer);
compress(((getDigestLength() & 0xFF) << 56) | b);
state.v2 ^= 0xEE;
for (unsigned i = 0; i < 4; ++i) {
::sip_round(state.v0, state.v1, state.v2, state.v3);
}
const uint64_t h1 = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
state.v1 ^= 0xDD;
for (unsigned i = 0; i < 4; ++i) {
::sip_round(state.v0, state.v1, state.v2, state.v3);
}
const uint64_t h2 = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
return std::make_pair(h1, h2);
}
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