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/*
* Postgres hashes for Python.
*/
#define PY_SSIZE_T_CLEAN
#include <Python.h>
#include <stdint.h>
#include <string.h>
typedef uint32_t (*hash_fn_t)(const void *src, Py_ssize_t src_len);
typedef uint8_t uint8;
typedef uint16_t uint16;
typedef uint32_t uint32;
#define rot(x, k) (((x)<<(k)) | ((x)>>(32-(k))))
/*
* Old Postgres hashtext()
*/
#define mix_old(a,b,c) \
{ \
a -= b; a -= c; a ^= ((c)>>13); \
b -= c; b -= a; b ^= ((a)<<8); \
c -= a; c -= b; c ^= ((b)>>13); \
a -= b; a -= c; a ^= ((c)>>12); \
b -= c; b -= a; b ^= ((a)<<16); \
c -= a; c -= b; c ^= ((b)>>5); \
a -= b; a -= c; a ^= ((c)>>3); \
b -= c; b -= a; b ^= ((a)<<10); \
c -= a; c -= b; c ^= ((b)>>15); \
}
static uint32_t hash_old_hashtext(const void *_k, Py_ssize_t keylen)
{
const unsigned char *k = _k;
uint32 a, b, c;
Py_ssize_t len;
/* Set up the internal state */
len = keylen;
a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */
c = 3923095; /* initialize with an arbitrary value */
/* handle most of the key */
while (len >= 12)
{
a += (k[0] + ((uint32) k[1] << 8) + ((uint32) k[2] << 16) + ((uint32) k[3] << 24));
b += (k[4] + ((uint32) k[5] << 8) + ((uint32) k[6] << 16) + ((uint32) k[7] << 24));
c += (k[8] + ((uint32) k[9] << 8) + ((uint32) k[10] << 16) + ((uint32) k[11] << 24));
mix_old(a, b, c);
k += 12;
len -= 12;
}
/* handle the last 11 bytes */
c += (uint32)keylen;
switch (len) /* all the case statements fall through */
{
case 11:
c += ((uint32) k[10] << 24);
case 10:
c += ((uint32) k[9] << 16);
case 9:
c += ((uint32) k[8] << 8);
/* the first byte of c is reserved for the length */
case 8:
b += ((uint32) k[7] << 24);
case 7:
b += ((uint32) k[6] << 16);
case 6:
b += ((uint32) k[5] << 8);
case 5:
b += k[4];
case 4:
a += ((uint32) k[3] << 24);
case 3:
a += ((uint32) k[2] << 16);
case 2:
a += ((uint32) k[1] << 8);
case 1:
a += k[0];
/* case 0: nothing left to add */
}
mix_old(a, b, c);
/* report the result */
return c;
}
/*
* New Postgres hashtext()
*/
#define UINT32_ALIGN_MASK 3
#define mix_new(a,b,c) \
{ \
a -= c; a ^= rot(c, 4); c += b; \
b -= a; b ^= rot(a, 6); a += c; \
c -= b; c ^= rot(b, 8); b += a; \
a -= c; a ^= rot(c,16); c += b; \
b -= a; b ^= rot(a,19); a += c; \
c -= b; c ^= rot(b, 4); b += a; \
}
#define final_new(a,b,c) \
{ \
c ^= b; c -= rot(b,14); \
a ^= c; a -= rot(c,11); \
b ^= a; b -= rot(a,25); \
c ^= b; c -= rot(b,16); \
a ^= c; a -= rot(c, 4); \
b ^= a; b -= rot(a,14); \
c ^= b; c -= rot(b,24); \
}
static uint32_t hash_new_hashtext(const void *_k, Py_ssize_t keylen)
{
const unsigned char *k = _k;
uint32_t a, b, c;
Py_ssize_t len = keylen;
/* Set up the internal state */
a = b = c = 0x9e3779b9 + (uint32)len + 3923095;
/* If the source pointer is word-aligned, we use word-wide fetches */
if (((uintptr_t) k & UINT32_ALIGN_MASK) == 0)
{
/* Code path for aligned source data */
const uint32_t *ka = (const uint32_t *) k;
/* handle most of the key */
while (len >= 12)
{
a += ka[0];
b += ka[1];
c += ka[2];
mix_new(a, b, c);
ka += 3;
len -= 12;
}
/* handle the last 11 bytes */
k = (const unsigned char *) ka;
#ifdef WORDS_BIGENDIAN
switch (len)
{
case 11:
c += ((uint32) k[10] << 8);
/* fall through */
case 10:
c += ((uint32) k[9] << 16);
/* fall through */
case 9:
c += ((uint32) k[8] << 24);
/* the lowest byte of c is reserved for the length */
/* fall through */
case 8:
b += ka[1];
a += ka[0];
break;
case 7:
b += ((uint32) k[6] << 8);
/* fall through */
case 6:
b += ((uint32) k[5] << 16);
/* fall through */
case 5:
b += ((uint32) k[4] << 24);
/* fall through */
case 4:
a += ka[0];
break;
case 3:
a += ((uint32) k[2] << 8);
/* fall through */
case 2:
a += ((uint32) k[1] << 16);
/* fall through */
case 1:
a += ((uint32) k[0] << 24);
/* case 0: nothing left to add */
}
#else /* !WORDS_BIGENDIAN */
switch (len)
{
case 11:
c += ((uint32) k[10] << 24);
/* fall through */
case 10:
c += ((uint32) k[9] << 16);
/* fall through */
case 9:
c += ((uint32) k[8] << 8);
/* the lowest byte of c is reserved for the length */
/* fall through */
case 8:
b += ka[1];
a += ka[0];
break;
case 7:
b += ((uint32) k[6] << 16);
/* fall through */
case 6:
b += ((uint32) k[5] << 8);
/* fall through */
case 5:
b += k[4];
/* fall through */
case 4:
a += ka[0];
break;
case 3:
a += ((uint32) k[2] << 16);
/* fall through */
case 2:
a += ((uint32) k[1] << 8);
/* fall through */
case 1:
a += k[0];
/* case 0: nothing left to add */
}
#endif /* WORDS_BIGENDIAN */
}
else
{
/* Code path for non-aligned source data */
/* handle most of the key */
while (len >= 12)
{
#ifdef WORDS_BIGENDIAN
a += (k[3] + ((uint32) k[2] << 8) + ((uint32) k[1] << 16) + ((uint32) k[0] << 24));
b += (k[7] + ((uint32) k[6] << 8) + ((uint32) k[5] << 16) + ((uint32) k[4] << 24));
c += (k[11] + ((uint32) k[10] << 8) + ((uint32) k[9] << 16) + ((uint32) k[8] << 24));
#else /* !WORDS_BIGENDIAN */
a += (k[0] + ((uint32) k[1] << 8) + ((uint32) k[2] << 16) + ((uint32) k[3] << 24));
b += (k[4] + ((uint32) k[5] << 8) + ((uint32) k[6] << 16) + ((uint32) k[7] << 24));
c += (k[8] + ((uint32) k[9] << 8) + ((uint32) k[10] << 16) + ((uint32) k[11] << 24));
#endif /* WORDS_BIGENDIAN */
mix_new(a, b, c);
k += 12;
len -= 12;
}
/* handle the last 11 bytes */
#ifdef WORDS_BIGENDIAN
switch (len) /* all the case statements fall through */
{
case 11:
c += ((uint32) k[10] << 8);
case 10:
c += ((uint32) k[9] << 16);
case 9:
c += ((uint32) k[8] << 24);
/* the lowest byte of c is reserved for the length */
case 8:
b += k[7];
case 7:
b += ((uint32) k[6] << 8);
case 6:
b += ((uint32) k[5] << 16);
case 5:
b += ((uint32) k[4] << 24);
case 4:
a += k[3];
case 3:
a += ((uint32) k[2] << 8);
case 2:
a += ((uint32) k[1] << 16);
case 1:
a += ((uint32) k[0] << 24);
/* case 0: nothing left to add */
}
#else /* !WORDS_BIGENDIAN */
switch (len) /* all the case statements fall through */
{
case 11:
c += ((uint32) k[10] << 24);
case 10:
c += ((uint32) k[9] << 16);
case 9:
c += ((uint32) k[8] << 8);
/* the lowest byte of c is reserved for the length */
case 8:
b += ((uint32) k[7] << 24);
case 7:
b += ((uint32) k[6] << 16);
case 6:
b += ((uint32) k[5] << 8);
case 5:
b += k[4];
case 4:
a += ((uint32) k[3] << 24);
case 3:
a += ((uint32) k[2] << 16);
case 2:
a += ((uint32) k[1] << 8);
case 1:
a += k[0];
/* case 0: nothing left to add */
}
#endif /* WORDS_BIGENDIAN */
}
final_new(a, b, c);
/* report the result */
return c;
}
/*
* Common argument parsing.
*/
static PyObject *run_hash(PyObject *args, hash_fn_t real_hash)
{
unsigned char *src = NULL;
Py_ssize_t src_len = 0;
int32_t hash;
if (!PyArg_ParseTuple(args, "s#", &src, &src_len))
return NULL;
hash = real_hash(src, src_len);
return PyLong_FromLong(hash);
}
/*
* Python wrappers around actual hash functions.
*/
static PyObject *hashtext_old(PyObject *self, PyObject *args)
{
return run_hash(args, hash_old_hashtext);
}
static PyObject *hashtext_new(PyObject *self, PyObject *args)
{
return run_hash(args, hash_new_hashtext);
}
/*
* Module initialization
*/
static PyMethodDef methods[] = {
{ "hashtext_old", hashtext_old, METH_VARARGS, "Old Postgres hashtext().\n" },
{ "hashtext_new", hashtext_new, METH_VARARGS, "New Postgres hashtext().\n" },
{ NULL }
};
static PyModuleDef_Slot slots[] = {{0, NULL}};
static struct PyModuleDef module = {
PyModuleDef_HEAD_INIT,
.m_name = "_chashtext",
.m_doc = "String hash functions",
.m_size = 0,
.m_methods = methods,
.m_slots = slots
};
PyMODINIT_FUNC PyInit__chashtext(void)
{
return PyModuleDef_Init(&module);
}
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