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drgn/libdrgn/cityhash.h
Omar Sandoval 87b7292aa5 Relicense drgn from GPLv3+ to LGPLv2.1+ 
drgn is currently licensed as GPLv3+. Part of the long term vision for
drgn is that other projects can use it as a library providing
programmatic interfaces for debugger functionality. A more permissive
license is better suited to this goal. We decided on LGPLv2.1+ as a good
balance between software freedom and permissiveness.

All contributors not employed by Meta were contacted via email and
consented to the license change. The only exception was the author of
commit c4fbf7e589 ("libdrgn: fix for compilation error"), who did not
respond. That commit reverted a single line of code to one originally
written by me in commit 640b1c011d ("libdrgn: embed DWARF index in
DWARF info cache").

Signed-off-by: Omar Sandoval <osandov@osandov.com>
2022-11-01 17:05:16 -07:00

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// Copyright (c) Meta Platforms, Inc. and affiliates.
// SPDX-License-Identifier: LGPL-2.1-or-later
#ifndef DRGN_CITYHASH_H
#define DRGN_CITYHASH_H
#include <byteswap.h>
#include <stddef.h>
#include <stdint.h>
static inline uint32_t cityhash_fetch32(const uint8_t *p)
{
return ((uint32_t)p[0] |
((uint32_t)p[1] << 8) |
((uint32_t)p[2] << 16) |
((uint32_t)p[3] << 24));
}
static inline uint64_t cityhash_fetch64(const uint8_t *p)
{
return ((uint64_t)p[0] |
((uint64_t)p[1] << 8) |
((uint64_t)p[2] << 16) |
((uint64_t)p[3] << 24) |
((uint64_t)p[4] << 32) |
((uint64_t)p[5] << 40) |
((uint64_t)p[6] << 48) |
((uint64_t)p[7] << 56));
}
#define cityhash_c1 UINT32_C(0xcc9e2d51)
#define cityhash_c2 UINT32_C(0x1b873593)
#define cityhash_c3 UINT32_C(0xe6546b64)
static uint32_t cityhash_fmix(uint32_t h)
{
h ^= h >> 16;
h *= UINT32_C(0x85ebca6b);
h ^= h >> 13;
h *= UINT32_C(0xc2b2ae35);
h ^= h >> 16;
return h;
}
static uint32_t cityhash_rotate32(uint32_t x, int b) {
return b == 0 ? x : (x >> b) | (x << (32 - b));
}
static uint32_t cityhash_mur(uint32_t a, uint32_t h) {
a *= cityhash_c1;
a = cityhash_rotate32(a, 17);
a *= cityhash_c2;
h ^= a;
h = cityhash_rotate32(h, 19);
return h * 5 + cityhash_c3;
}
static uint32_t cityhash32_len_13to24(const uint8_t *s, size_t len) {
uint32_t a = cityhash_fetch32(s - 4 + (len >> 1));
uint32_t b = cityhash_fetch32(s + 4);
uint32_t c = cityhash_fetch32(s + len - 8);
uint32_t d = cityhash_fetch32(s + (len >> 1));
uint32_t e = cityhash_fetch32(s);
uint32_t f = cityhash_fetch32(s + len - 4);
uint32_t h = len;
return cityhash_fmix(cityhash_mur(f, cityhash_mur(e, cityhash_mur(d, cityhash_mur(c, cityhash_mur(b, cityhash_mur(a, h)))))));
}
static uint32_t cityhash32_len_0to4(const uint8_t *s, size_t len) {
uint32_t b = 0;
uint32_t c = 9;
for (size_t i = 0; i < len; i++) {
signed char v = s[i];
b = b * cityhash_c1 + v;
c ^= b;
}
return cityhash_fmix(cityhash_mur(b, cityhash_mur(len, c)));
}
static uint32_t cityhash32_len_5to12(const uint8_t *s, size_t len) {
uint32_t a = len, b = len * 5, c = 9, d = b;
a += cityhash_fetch32(s);
b += cityhash_fetch32(s + len - 4);
c += cityhash_fetch32(s + ((len >> 1) & 4));
return cityhash_fmix(cityhash_mur(c, cityhash_mur(b, cityhash_mur(a, d))));
}
__attribute__((__unused__))
static uint32_t cityhash32(const void *data, size_t len) {
const uint8_t *s = data;
if (len <= 4)
return cityhash32_len_0to4(s, len);
else if (len <= 12)
return cityhash32_len_5to12(s, len);
else if (len <= 24)
return cityhash32_len_13to24(s, len);
uint32_t h = len, g = cityhash_c1 * len, f = g;
uint32_t a0 = cityhash_rotate32(cityhash_fetch32(s + len - 4) * cityhash_c1, 17) * cityhash_c2;
uint32_t a1 = cityhash_rotate32(cityhash_fetch32(s + len - 8) * cityhash_c1, 17) * cityhash_c2;
uint32_t a2 = cityhash_rotate32(cityhash_fetch32(s + len - 16) * cityhash_c1, 17) * cityhash_c2;
uint32_t a3 = cityhash_rotate32(cityhash_fetch32(s + len - 12) * cityhash_c1, 17) * cityhash_c2;
uint32_t a4 = cityhash_rotate32(cityhash_fetch32(s + len - 20) * cityhash_c1, 17) * cityhash_c2;
h ^= a0;
h = cityhash_rotate32(h, 19);
h = h * 5 + cityhash_c3;
h ^= a2;
h = cityhash_rotate32(h, 19);
h = h * 5 + cityhash_c3;
g ^= a1;
g = cityhash_rotate32(g, 19);
g = g * 5 + cityhash_c3;
g ^= a3;
g = cityhash_rotate32(g, 19);
g = g * 5 + cityhash_c3;
f += a4;
f = cityhash_rotate32(f, 19);
f = f * 5 + cityhash_c3;
size_t iters = (len - 1) / 20;
do {
uint32_t a0 = cityhash_rotate32(cityhash_fetch32(s) * cityhash_c1, 17) * cityhash_c2;
uint32_t a1 = cityhash_fetch32(s + 4);
uint32_t a2 = cityhash_rotate32(cityhash_fetch32(s + 8) * cityhash_c1, 17) * cityhash_c2;
uint32_t a3 = cityhash_rotate32(cityhash_fetch32(s + 12) * cityhash_c1, 17) * cityhash_c2;
uint32_t a4 = cityhash_fetch32(s + 16);
h ^= a0;
h = cityhash_rotate32(h, 18);
h = h * 5 + cityhash_c3;
f += a1;
f = cityhash_rotate32(f, 19);
f = f * cityhash_c1;
g += a2;
g = cityhash_rotate32(g, 18);
g = g * 5 + cityhash_c3;
h ^= a3 + a1;
h = cityhash_rotate32(h, 19);
h = h * 5 + cityhash_c3;
g ^= a4;
g = bswap_32(g) * 5;
h += a4 * 5;
h = bswap_32(h);
f += a0;
uint32_t tmp;
tmp = f;
f = g;
g = h;
h = tmp;
s += 20;
} while (--iters != 0);
g = cityhash_rotate32(g, 11) * cityhash_c1;
g = cityhash_rotate32(g, 17) * cityhash_c1;
f = cityhash_rotate32(f, 11) * cityhash_c1;
f = cityhash_rotate32(f, 17) * cityhash_c1;
h = cityhash_rotate32(h + g, 19);
h = h * 5 + cityhash_c3;
h = cityhash_rotate32(h, 17) * cityhash_c1;
h = cityhash_rotate32(h + f, 19);
h = h * 5 + cityhash_c3;
h = cityhash_rotate32(h, 17) * cityhash_c1;
return h;
}
struct cityhash_pair {
uint64_t first;
uint64_t second;
};
#define cityhash_k0 UINT64_C(0xc3a5c85c97cb3127)
#define cityhash_k1 UINT64_C(0xb492b66fbe98f273)
#define cityhash_k2 UINT64_C(0x9ae16a3b2f90404f)
static inline uint64_t cityhash_rotate(uint64_t x, int b)
{
return b == 0 ? x : (x >> b) | (x << (64 - b));
}
static inline uint64_t cityhash_shiftmix(uint64_t val)
{
return val ^ (val >> 47);
}
static inline uint64_t cityhash_128_to_64(uint64_t lo, uint64_t hi) {
static const uint64_t mul = UINT64_C(0x9ddfea08eb382d69);
uint64_t a = (lo ^ hi) * mul;
a ^= (a >> 47);
uint64_t b = (hi ^ a) * mul;
b ^= (b >> 47);
b *= mul;
return b;
}
static inline uint64_t cityhash_len_16(uint64_t u, uint64_t v, uint64_t mul)
{
uint64_t a = (u ^ v) * mul;
a ^= (a >> 47);
uint64_t b = (v ^ a) * mul;
b ^= (b >> 47);
b *= mul;
return b;
}
static uint64_t cityhash_len_0to16(const uint8_t *s, size_t len)
{
if (len == 0) {
return cityhash_k2;
} else if (len < 4) {
uint8_t a = s[0];
uint8_t b = s[len >> 1];
uint8_t c = s[len - 1];
uint32_t y = (uint32_t)a + ((uint32_t)b << 8);
uint32_t z = len + ((uint32_t)c << 2);
return cityhash_shiftmix(y * cityhash_k2 ^ z * cityhash_k0) * cityhash_k2;
} else if (len < 8) {
uint64_t mul = cityhash_k2 + len * 2;
uint64_t a = cityhash_fetch32(s);
return cityhash_len_16(len + (a << 3),
cityhash_fetch32(s + len - 4), mul);
} else {
uint64_t mul = cityhash_k2 + len * 2;
uint64_t a = cityhash_fetch64(s) + cityhash_k2;
uint64_t b = cityhash_fetch64(s + len - 8);
uint64_t c = cityhash_rotate(b, 37) * mul + a;
uint64_t d = (cityhash_rotate(a, 25) + b) * mul;
return cityhash_len_16(c, d, mul);
}
}
static uint64_t cityhash_len_17to32(const uint8_t *s, size_t len)
{
uint64_t mul = cityhash_k2 + len * 2;
uint64_t a = cityhash_fetch64(s) * cityhash_k1;
uint64_t b = cityhash_fetch64(s + 8);
uint64_t c = cityhash_fetch64(s + len - 8) * mul;
uint64_t d = cityhash_fetch64(s + len - 16) * cityhash_k2;
return cityhash_len_16(cityhash_rotate(a + b, 43) +
cityhash_rotate(c, 30) + d,
a + cityhash_rotate(b + cityhash_k2, 18) + c,
mul);
}
static struct cityhash_pair cityhash_weak_len_32_with_seeds(const uint8_t *s,
uint64_t a,
uint64_t b)
{
uint64_t w = cityhash_fetch64(s);
uint64_t x = cityhash_fetch64(s + 8);
uint64_t y = cityhash_fetch64(s + 16);
uint64_t z = cityhash_fetch64(s + 24);
a += w;
b = cityhash_rotate(b + a + z, 21);
uint64_t c = a;
a += x;
a += y;
b += cityhash_rotate(a, 44);
return (struct cityhash_pair){a + z, b + c};
}
static uint64_t cityhash_len_33to64(const uint8_t *s, size_t len)
{
uint64_t mul = cityhash_k2 + len * 2;
uint64_t a = cityhash_fetch64(s) * cityhash_k2;
uint64_t b = cityhash_fetch64(s + 8);
uint64_t c = cityhash_fetch64(s + len - 24);
uint64_t d = cityhash_fetch64(s + len - 32);
uint64_t e = cityhash_fetch64(s + 16) * cityhash_k2;
uint64_t f = cityhash_fetch64(s + 24) * 9;
uint64_t g = cityhash_fetch64(s + len - 8);
uint64_t h = cityhash_fetch64(s + len - 16) * mul;
uint64_t u = cityhash_rotate(a + g, 43) + (cityhash_rotate(b, 30) + c) * 9;
uint64_t v = ((a + g) ^ d) + f + 1;
uint64_t w = bswap_64((u + v) * mul) + h;
uint64_t x = cityhash_rotate(e + f, 42) + c;
uint64_t y = (bswap_64((v + w) * mul) + g) * mul;
uint64_t z = e + f + c;
a = bswap_64((x + z) * mul + y) + b;
b = cityhash_shiftmix((z + a) * mul + d + h) * mul;
return b + x;
}
__attribute__((__unused__))
static uint64_t cityhash64(const void *data, size_t len)
{
const uint8_t *s = data;
if (len <= 16)
return cityhash_len_0to16(s, len);
else if (len <= 32)
return cityhash_len_17to32(s, len);
else if (len <= 64)
return cityhash_len_33to64(s, len);
uint64_t x = cityhash_fetch64(s + len - 40);
uint64_t y = (cityhash_fetch64(s + len - 16) +
cityhash_fetch64(s + len - 56));
uint64_t z = cityhash_128_to_64(cityhash_fetch64(s + len - 48) + len,
cityhash_fetch64(s + len - 24));
struct cityhash_pair v =
cityhash_weak_len_32_with_seeds(s + len - 64, len, z);
struct cityhash_pair w =
cityhash_weak_len_32_with_seeds(s + len - 32, y + cityhash_k1,
x);
x = x * cityhash_k1 + cityhash_fetch64(s);
len = (len - 1) & ~(size_t)63;
do {
x = (cityhash_rotate(x + y + v.first +
cityhash_fetch64(s + 8), 37) *
cityhash_k1);
y = (cityhash_rotate(y + v.second +
cityhash_fetch64(s + 48), 42) *
cityhash_k1);
x ^= w.second;
y += v.first + cityhash_fetch64(s + 40);
z = cityhash_rotate(z + w.first, 33) * cityhash_k1;
v = cityhash_weak_len_32_with_seeds(s, v.second * cityhash_k1,
x + w.first);
w = cityhash_weak_len_32_with_seeds(s + 32, z + w.second,
y + cityhash_fetch64(s + 16));
uint64_t tmp = z;
z = x;
x = tmp;
s += 64;
len -= 64;
} while (len != 0);
return cityhash_128_to_64(cityhash_128_to_64(v.first, w.first) + cityhash_shiftmix(y) * cityhash_k1 + z,
cityhash_128_to_64(v.second, w.second) + x);
}
static inline size_t cityhash_size_t(const void *data, size_t len)
{
if (sizeof(size_t) == sizeof(uint32_t))
return cityhash32(data, len);
else
return cityhash64(data, len);
}
#endif /* DRGN_CITYHASH_H */
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