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3292 lines (2832 loc) · 89.9 KB
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/*
Copyright (c) 2008 - 2019, Ilan Schnell
bitarray is published under the PSF license.
This file is the C part of the bitarray package.
All functionality is implemented here.
Author: Ilan Schnell
*/
#define PY_SSIZE_T_CLEAN
#include "Python.h"
#if PY_MAJOR_VERSION >= 3
#define IS_PY3K
#endif
#ifdef IS_PY3K
#define Py_TPFLAGS_HAVE_WEAKREFS 0
#endif
#if PY_MAJOR_VERSION == 3 || (PY_MAJOR_VERSION == 2 && PY_MINOR_VERSION == 7)
/* (new) buffer protocol */
#define WITH_BUFFER
#endif
#ifdef STDC_HEADERS
#include <stddef.h>
#else /* !STDC_HEADERS */
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h> /* For size_t */
#endif /* HAVE_SYS_TYPES_H */
#endif /* !STDC_HEADERS */
typedef long long int idx_t;
/* throughout: 0 = little endian 1 = big endian */
#define DEFAULT_ENDIAN 1
/* Unlike the normal convention, ob_size is the byte count, not the number
of elements. The reason for doing this is that we can use our own
special idx_t for the number of bits (which can exceed 2^32 on a 32 bit
machine. */
typedef struct {
PyObject_VAR_HEAD
char *ob_item;
Py_ssize_t allocated; /* how many bytes allocated */
idx_t nbits; /* length of bitarray, i.e. elements */
int endian; /* bit endianness of bitarray */
int ob_exports; /* how many buffer exports */
PyObject *weakreflist; /* list of weak references */
} bitarrayobject;
static PyTypeObject Bitarraytype;
#define bitarray_Check(obj) PyObject_TypeCheck(obj, &Bitarraytype)
#define BITS(bytes) ((idx_t) (bytes) << 3)
/* number of bytes necessary to store given bits */
#define BYTES(bits) (((bits) == 0) ? 0 : (((bits) - 1) / 8 + 1))
#define BITMASK(endian, i) (((char) 1) << ((endian) ? (7 - (i)%8) : (i)%8))
/* ------------ low level access to bits in bitarrayobject ------------- */
#ifndef NDEBUG
static int GETBIT(bitarrayobject *self, idx_t i) {
assert(0 <= i && i < self->nbits);
return ((self)->ob_item[(i) / 8] & BITMASK((self)->endian, i) ? 1 : 0);
}
#else
#define GETBIT(self, i) \
((self)->ob_item[(i) / 8] & BITMASK((self)->endian, i) ? 1 : 0)
#endif
static void
setbit(bitarrayobject *self, idx_t i, int bit)
{
char *cp, mask;
assert(0 <= i && i < BITS(Py_SIZE(self)));
mask = BITMASK(self->endian, i);
cp = self->ob_item + i / 8;
if (bit)
*cp |= mask;
else
*cp &= ~mask;
}
static int
check_overflow(idx_t nbits)
{
assert(nbits >= 0);
if (sizeof(void *) == 4) { /* 32bit system */
const idx_t max_bits = ((idx_t) 1) << 34; /* 2^34 = 16 Gbits*/
if (nbits > max_bits) {
char buff[256];
sprintf(buff, "cannot create bitarray of size %lld, "
"max size is %lld", nbits, max_bits);
PyErr_SetString(PyExc_OverflowError, buff);
return -1;
}
}
return 0;
}
static int
resize(bitarrayobject *self, idx_t nbits)
{
Py_ssize_t newsize;
size_t new_allocated;
Py_ssize_t allocated = self->allocated;
if (check_overflow(nbits) < 0)
return -1;
newsize = (Py_ssize_t) BYTES(nbits);
/* Bypass realloc() when a previous overallocation is large enough
to accommodate the newsize. If the newsize falls lower than half
the allocated size, then proceed with the realloc() to shrink.
*/
if (allocated >= newsize && newsize >= (allocated >> 1)) {
assert(self->ob_item != NULL || newsize == 0);
Py_SIZE(self) = newsize;
self->nbits = nbits;
return 0;
}
new_allocated = (size_t) newsize;
if (newsize < Py_SIZE(self) + 65536)
/* Over-allocate unless the size increase is very large.
This over-allocates proportional to the bitarray size, making
room for additional growth.
The growth pattern is: 0, 4, 8, 16, 25, 34, 44, 54, 65, 77, ...
Note, the pattern starts out the same as for lists but then
grows at a smaller rate so that larger bitarrays only overallocate
by about 1/16th -- this is done because bitarrays are assumed
to be memory critical.
*/
new_allocated += (newsize >> 4) + (newsize < 8 ? 3 : 7);
if (newsize == 0)
new_allocated = 0;
self->ob_item = PyMem_Realloc(self->ob_item, new_allocated);
if (self->ob_item == NULL) {
PyErr_NoMemory();
return -1;
}
Py_SIZE(self) = newsize;
self->allocated = new_allocated;
self->nbits = nbits;
return 0;
}
/* create new bitarray object without initialization of buffer */
static PyObject *
newbitarrayobject(PyTypeObject *type, idx_t nbits, int endian)
{
bitarrayobject *obj;
Py_ssize_t nbytes;
if (check_overflow(nbits) < 0)
return NULL;
obj = (bitarrayobject *) type->tp_alloc(type, 0);
if (obj == NULL)
return NULL;
nbytes = (Py_ssize_t) BYTES(nbits);
Py_SIZE(obj) = nbytes;
obj->nbits = nbits;
obj->endian = endian;
if (nbytes == 0) {
obj->ob_item = NULL;
}
else {
obj->ob_item = (char *) PyMem_Malloc((size_t) nbytes);
if (obj->ob_item == NULL) {
PyObject_Del(obj);
PyErr_NoMemory();
return NULL;
}
}
obj->allocated = nbytes;
obj->weakreflist = NULL;
return (PyObject *) obj;
}
static void
bitarray_dealloc(bitarrayobject *self)
{
if (self->weakreflist != NULL)
PyObject_ClearWeakRefs((PyObject *) self);
if (self->ob_item != NULL)
PyMem_Free((void *) self->ob_item);
Py_TYPE(self)->tp_free((PyObject *) self);
}
/* copy n bits from other (starting at b) onto self (starting at a) */
static void
copy_n(bitarrayobject *self, idx_t a,
bitarrayobject *other, idx_t b, idx_t n)
{
idx_t i;
assert(0 <= n && n <= self->nbits && n <= other->nbits);
assert(0 <= a && a <= self->nbits - n);
assert(0 <= b && b <= other->nbits - n);
if (n == 0)
return;
/* When the start positions are at byte positions, we can copy whole
bytes using memmove, and copy the remaining few bits individually.
Note that the order of these two operations matters when copying
self to self. */
if (self->endian == other->endian && a % 8 == 0 && b % 8 == 0 && n >= 8)
{
const Py_ssize_t bytes = (Py_ssize_t) n / 8;
const idx_t bits = BITS(bytes);
assert(bits <= n && n < bits + 8);
if (a <= b)
memmove(self->ob_item + a / 8, other->ob_item + b / 8, bytes);
if (n != bits)
copy_n(self, bits + a, other, bits + b, n - bits);
if (a > b)
memmove(self->ob_item + a / 8, other->ob_item + b / 8, bytes);
return;
}
/* The two different types of looping are only relevant when copying
self to self, i.e. when copying a piece of an bitarrayobject onto
itself. */
if (a <= b) {
for (i = 0; i < n; i++) /* loop forward (delete) */
setbit(self, i + a, GETBIT(other, i + b));
}
else {
for (i = n - 1; i >= 0; i--) /* loop backwards (insert) */
setbit(self, i + a, GETBIT(other, i + b));
}
}
/* starting at start, delete n bits from self */
static int
delete_n(bitarrayobject *self, idx_t start, idx_t n)
{
assert(0 <= start && start <= self->nbits);
assert(0 <= n && n <= self->nbits - start);
if (n == 0)
return 0;
copy_n(self, start, self, start + n, self->nbits - start - n);
return resize(self, self->nbits - n);
}
/* starting at start, insert n (uninitialized) bits into self */
static int
insert_n(bitarrayobject *self, idx_t start, idx_t n)
{
assert(0 <= start && start <= self->nbits);
assert(n >= 0);
if (n == 0)
return 0;
if (resize(self, self->nbits + n) < 0)
return -1;
copy_n(self, start + n, self, start, self->nbits - start - n);
return 0;
}
/* sets ususet bits to 0, i.e. the ones in the last byte (if any),
and return the number of bits set -- self->nbits is unchanged */
static int
setunused(bitarrayobject *self)
{
const idx_t n = BITS(Py_SIZE(self));
idx_t i;
int res = 0;
for (i = self->nbits; i < n; i++) {
setbit(self, i, 0);
res++;
}
assert(res < 8);
return res;
}
/* repeat self n times */
static int
repeat(bitarrayobject *self, idx_t n)
{
idx_t nbits, i;
if (n <= 0) {
if (resize(self, 0) < 0)
return -1;
}
if (n > 1) {
nbits = self->nbits;
if (resize(self, nbits * n) < 0)
return -1;
for (i = 1; i < n; i++)
copy_n(self, i * nbits, self, 0, nbits);
}
return 0;
}
enum op_type {
OP_and,
OP_or,
OP_xor,
};
/* perform bitwise in-place operation */
static int
bitwise(bitarrayobject *self, PyObject *arg, enum op_type oper)
{
bitarrayobject *other;
Py_ssize_t i;
if (!bitarray_Check(arg)) {
PyErr_SetString(PyExc_TypeError,
"bitarray object expected for bitwise operation");
return -1;
}
other = (bitarrayobject *) arg;
if (self->nbits != other->nbits) {
PyErr_SetString(PyExc_ValueError,
"bitarrays of equal length expected for bitwise operation");
return -1;
}
setunused(self);
setunused(other);
switch (oper) {
case OP_and:
for (i = 0; i < Py_SIZE(self); i++)
self->ob_item[i] &= other->ob_item[i];
break;
case OP_or:
for (i = 0; i < Py_SIZE(self); i++)
self->ob_item[i] |= other->ob_item[i];
break;
case OP_xor:
for (i = 0; i < Py_SIZE(self); i++)
self->ob_item[i] ^= other->ob_item[i];
break;
default: /* should never happen */
return -1;
}
return 0;
}
/* set the bits from start to stop (excluding) in self to val */
static void
setrange(bitarrayobject *self, idx_t start, idx_t stop, int val)
{
idx_t i;
assert(0 <= start && start <= self->nbits);
assert(0 <= stop && stop <= self->nbits);
if (self->nbits == 0 || start >= stop)
return;
if (stop >= start + 8) {
const Py_ssize_t byte_start = BYTES(start);
const Py_ssize_t byte_stop = (Py_ssize_t) stop / 8;
for (i = start; i < BITS(byte_start); i++)
setbit(self, i, val);
memset(self->ob_item + byte_start, val ? 0xff : 0x00,
byte_stop - byte_start);
for (i = BITS(byte_stop); i < stop; i++)
setbit(self, i, val);
}
else {
for (i = start; i < stop; i++)
setbit(self, i, val);
}
}
static void
invert(bitarrayobject *self)
{
Py_ssize_t i;
for (i = 0; i < Py_SIZE(self); i++)
self->ob_item[i] = ~self->ob_item[i];
}
/* reverse the order of bits in each byte of the buffer */
static void
bytereverse(bitarrayobject *self)
{
static char trans[256];
static int setup = 0;
Py_ssize_t i;
unsigned char c;
if (!setup) {
/* setup translation table, which maps each byte to it's reversed:
trans = {0, 128, 64, 192, 32, 160, ..., 255} */
int j, k;
for (k = 0; k < 256; k++) {
trans[k] = 0x00;
for (j = 0; j < 8; j++)
if (1 << (7 - j) & k)
trans[k] |= 1 << j;
}
setup = 1;
}
setunused(self);
for (i = 0; i < Py_SIZE(self); i++) {
c = self->ob_item[i];
self->ob_item[i] = trans[c];
}
}
static int bitcount_lookup[256] = {
0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
};
/* returns number of 1 bits */
static idx_t
count(bitarrayobject *self, int vi, idx_t start, idx_t stop)
{
idx_t i, res = 0;
unsigned char c;
assert(0 <= start && start <= self->nbits);
assert(0 <= stop && stop <= self->nbits);
assert(0 <= vi && vi <= 1);
assert(BYTES(stop) <= Py_SIZE(self));
if (self->nbits == 0 || start >= stop)
return 0;
if (stop >= start + 8) {
const Py_ssize_t byte_start = BYTES(start);
const Py_ssize_t byte_stop = (Py_ssize_t) (stop / 8);
Py_ssize_t j;
for (i = start; i < BITS(byte_start); i++)
res += GETBIT(self, i);
for (j = byte_start; j < byte_stop; j++) {
c = self->ob_item[j];
res += bitcount_lookup[c];
}
for (i = BITS(byte_stop); i < stop; i++)
res += GETBIT(self, i);
}
else {
for (i = start; i < stop; i++)
res += GETBIT(self, i);
}
return vi ? res : stop - start - res;
}
/* return index of first occurrence of vi, -1 when x is not in found. */
static idx_t
findfirst(bitarrayobject *self, int vi, idx_t start, idx_t stop)
{
Py_ssize_t j;
idx_t i;
assert(0 <= start && start <= self->nbits);
assert(0 <= stop && stop <= self->nbits);
assert(0 <= vi && vi <= 1);
assert(BYTES(stop) <= Py_SIZE(self));
if (self->nbits == 0 || start >= stop)
return -1;
if (stop >= start + 8) {
/* seraching for 1 means: break when byte is not 0x00
searching for 0 means: break when byte is not 0xff */
const char c = vi ? 0x00 : 0xff;
/* skip ahead by checking whole bytes */
for (j = (Py_ssize_t) (start / 8); j < BYTES(stop); j++)
if (c ^ self->ob_item[j])
break;
if (start < BITS(j))
start = BITS(j);
}
/* fine grained search */
for (i = start; i < stop; i++)
if (GETBIT(self, i) == vi)
return i;
return -1;
}
/* search for the first occurrence of bitarray xa (in self), starting at p,
and return its position (or -1 when not found)
*/
static idx_t
search(bitarrayobject *self, bitarrayobject *xa, idx_t p)
{
idx_t i;
assert(p >= 0);
while (p < self->nbits - xa->nbits + 1) {
for (i = 0; i < xa->nbits; i++)
if (GETBIT(self, p + i) != GETBIT(xa, i))
goto next;
return p;
next:
p++;
}
return -1;
}
static int
set_item(bitarrayobject *self, idx_t i, PyObject *v)
{
long vi;
assert(0 <= i && i < self->nbits);
vi = PyObject_IsTrue(v);
if (vi < 0)
return -1;
setbit(self, i, vi);
return 0;
}
static int
append_item(bitarrayobject *self, PyObject *item)
{
if (resize(self, self->nbits + 1) < 0)
return -1;
return set_item(self, self->nbits - 1, item);
}
static PyObject *
unpack(bitarrayobject *self, char zero, char one)
{
PyObject *result;
Py_ssize_t i;
char *str;
if (self->nbits > PY_SSIZE_T_MAX) {
PyErr_SetString(PyExc_OverflowError, "bitarray too large to unpack");
return NULL;
}
str = (char *) PyMem_Malloc((size_t) self->nbits);
if (str == NULL) {
PyErr_NoMemory();
return NULL;
}
for (i = 0; i < self->nbits; i++) {
*(str + i) = GETBIT(self, i) ? one : zero;
}
result = PyBytes_FromStringAndSize(str, (Py_ssize_t) self->nbits);
PyMem_Free((void *) str);
return result;
}
static int
extend_bitarray(bitarrayobject *self, bitarrayobject *other)
{
idx_t n_sum;
idx_t n_other_bits;
if (other->nbits == 0)
return 0;
/* Note that other may be self. Thus we take the size before we resize,
ensuring we only copy the right parts of the array. */
n_other_bits = other->nbits;
n_sum = self->nbits + other->nbits;
if (resize(self, n_sum) < 0)
return -1;
copy_n(self, n_sum - n_other_bits, other, 0, n_other_bits);
return 0;
}
static int
extend_iter(bitarrayobject *self, PyObject *iter)
{
PyObject *item;
assert(PyIter_Check(iter));
while ((item = PyIter_Next(iter)) != NULL) {
if (append_item(self, item) < 0) {
Py_DECREF(item);
return -1;
}
Py_DECREF(item);
}
if (PyErr_Occurred())
return -1;
return 0;
}
static int
extend_list(bitarrayobject *self, PyObject *list)
{
PyObject *item;
Py_ssize_t n, i;
assert(PyList_Check(list));
n = PyList_Size(list);
if (n == 0)
return 0;
if (resize(self, self->nbits + n) < 0)
return -1;
for (i = 0; i < n; i++) {
item = PyList_GetItem(list, i);
if (item == NULL)
return -1;
if (set_item(self, self->nbits - n + i, item) < 0)
return -1;
}
return 0;
}
static int
extend_tuple(bitarrayobject *self, PyObject *tuple)
{
PyObject *item;
Py_ssize_t n, i;
assert(PyTuple_Check(tuple));
n = PyTuple_Size(tuple);
if (n == 0)
return 0;
if (resize(self, self->nbits + n) < 0)
return -1;
for (i = 0; i < n; i++) {
item = PyTuple_GetItem(tuple, i);
if (item == NULL)
return -1;
if (set_item(self, self->nbits - n + i, item) < 0)
return -1;
}
return 0;
}
/* extend_bytes(): extend the bitarray from a PyBytes object, where each
whole character is converted to a single bit */
enum conv_t {
BYTES_01, /* '0' -> 0 '1' -> 1 no other characters allowed */
BYTES_RAW, /* 0x00 -> 0 other -> 1 */
};
static int
extend_bytes(bitarrayobject *self, PyObject *bytes, enum conv_t conv)
{
Py_ssize_t strlen, i;
char c, *str;
int vi = 0;
assert(PyBytes_Check(bytes));
strlen = PyBytes_Size(bytes);
if (strlen == 0)
return 0;
if (resize(self, self->nbits + strlen) < 0)
return -1;
str = PyBytes_AsString(bytes);
for (i = 0; i < strlen; i++) {
c = *(str + i);
/* depending on conv, map c to bit */
switch (conv) {
case BYTES_01:
switch (c) {
case '0': vi = 0; break;
case '1': vi = 1; break;
default:
PyErr_Format(PyExc_ValueError,
"character must be '0' or '1', found '%c'", c);
return -1;
}
break;
case BYTES_RAW:
vi = c ? 1 : 0;
break;
default: /* should never happen */
return -1;
}
setbit(self, self->nbits - strlen + i, vi);
}
return 0;
}
static int
extend_rawbytes(bitarrayobject *self, PyObject *bytes)
{
Py_ssize_t strlen;
char *str;
assert(PyBytes_Check(bytes) && self->nbits % 8 == 0);
strlen = PyBytes_Size(bytes);
if (strlen == 0)
return 0;
if (resize(self, self->nbits + BITS(strlen)) < 0)
return -1;
str = PyBytes_AsString(bytes);
memcpy(self->ob_item + (Py_SIZE(self) - strlen), str, strlen);
return 0;
}
static int
extend_dispatch(bitarrayobject *self, PyObject *obj)
{
PyObject *iter;
int ret;
/* dispatch on type */
if (bitarray_Check(obj)) /* bitarray */
return extend_bitarray(self, (bitarrayobject *) obj);
if (PyList_Check(obj)) /* list */
return extend_list(self, obj);
if (PyTuple_Check(obj)) /* tuple */
return extend_tuple(self, obj);
if (PyBytes_Check(obj)) /* bytes 01 */
return extend_bytes(self, obj, BYTES_01);
if (PyUnicode_Check(obj)) { /* (unicode) string 01 */
PyObject *bytes;
bytes = PyUnicode_AsEncodedString(obj, NULL, NULL);
ret = extend_bytes(self, bytes, BYTES_01);
Py_DECREF(bytes);
return ret;
}
if (PyIter_Check(obj)) /* iter */
return extend_iter(self, obj);
/* finally, try to get the iterator of the object */
iter = PyObject_GetIter(obj);
if (iter == NULL) {
PyErr_SetString(PyExc_TypeError, "could not extend bitarray");
return -1;
}
ret = extend_iter(self, iter);
Py_DECREF(iter);
return ret;
}
/* --------- helper functions NOT involving bitarrayobjects ------------ */
#define ENDIAN_STR(ba) (((ba)->endian) ? "big" : "little")
#ifdef IS_PY3K
#define IS_INDEX(x) (PyLong_Check(x) || PyIndex_Check(x))
#define IS_INT_OR_BOOL(x) (PyBool_Check(x) || PyLong_Check(x))
#else /* Py 2 */
#define IS_INDEX(x) (PyInt_Check(x) || PyLong_Check(x) || PyIndex_Check(x))
#define IS_INT_OR_BOOL(x) (PyBool_Check(x) || PyInt_Check(x) || \
PyLong_Check(x))
#endif
/* given an PyLong (which must be 0 or 1), or a PyBool, return 0 or 1,
or -1 on error */
static int
IntBool_AsInt(PyObject *v)
{
long x;
if (PyBool_Check(v))
return PyObject_IsTrue(v);
#ifndef IS_PY3K
if (PyInt_Check(v)) {
x = PyInt_AsLong(v);
}
else
#endif
if (PyLong_Check(v)) {
x = PyLong_AsLong(v);
}
else {
PyErr_SetString(PyExc_TypeError, "integer or bool expected");
return -1;
}
if (x < 0 || x > 1) {
PyErr_SetString(PyExc_ValueError,
"integer value between 0 and 1 expected");
return -1;
}
return (int) x;
}
/* Normalize index (which may be negative), such that 0 <= i <= n */
static void
normalize_index(idx_t n, idx_t *i)
{
if (*i < 0) {
*i += n;
if (*i < 0)
*i = 0;
}
if (*i > n)
*i = n;
}
/* Extract a slice index from a PyInt or PyLong or an object with the
nb_index slot defined, and store in *i.
However, this function returns -1 on error and 0 on success.
This is almost _PyEval_SliceIndex() with Py_ssize_t replaced by idx_t
*/
static int
getIndex(PyObject *v, idx_t *i)
{
idx_t x;
#ifndef IS_PY3K
if (PyInt_Check(v)) {
x = PyInt_AS_LONG(v);
}
else
#endif
if (PyLong_Check(v)) {
x = PyLong_AsLongLong(v);
}
else if (PyIndex_Check(v)) {
x = PyNumber_AsSsize_t(v, NULL);
if (x == -1 && PyErr_Occurred())
return -1;
}
else {
PyErr_SetString(PyExc_TypeError, "slice indices must be integers or "
"None or have an __index__ method");
return -1;
}
*i = x;
return 0;
}
/* this is PySlice_GetIndicesEx() with Py_ssize_t replaced by idx_t */
static int
slice_GetIndicesEx(PySliceObject *r, idx_t length,
idx_t *start, idx_t *stop, idx_t *step, idx_t *slicelength)
{
idx_t defstart, defstop;
if (r->step == Py_None) {
*step = 1;
}
else {
if (getIndex(r->step, step) < 0)
return -1;
if (*step == 0) {
PyErr_SetString(PyExc_ValueError, "slice step cannot be zero");
return -1;
}
}
defstart = *step < 0 ? length - 1 : 0;
defstop = *step < 0 ? -1 : length;
if (r->start == Py_None) {
*start = defstart;
}
else {
if (getIndex(r->start, start) < 0)
return -1;
if (*start < 0) *start += length;
if (*start < 0) *start = (*step < 0) ? -1 : 0;
if (*start >= length) *start = (*step < 0) ? length - 1 : length;
}
if (r->stop == Py_None) {
*stop = defstop;
}
else {
if (getIndex(r->stop, stop) < 0)
return -1;
if (*stop < 0) *stop += length;
if (*stop < 0) *stop = -1;
if (*stop > length) *stop = length;
}
if ((*step < 0 && *stop >= *start) || (*step > 0 && *start >= *stop)) {
*slicelength = 0;
}
else if (*step < 0) {
*slicelength = (*stop - *start + 1) / (*step) + 1;
}
else {
*slicelength = (*stop - *start - 1) / (*step) + 1;
}
return 0;
}
/**************************************************************************
Implementation of API methods
**************************************************************************/
static PyObject *
bitarray_length(bitarrayobject *self)
{
return PyLong_FromLongLong(self->nbits);
}
PyDoc_STRVAR(length_doc,
"length() -> int\n\
\n\
Return the length, i.e. number of bits stored in the bitarray.\n\
This method is preferred over `__len__` (used when typing `len(a)`),\n\
since `__len__` will fail for a bitarray object with 2^31 or more elements\n\
on a 32bit machine, whereas this method will return the correct value,\n\
on 32bit and 64bit machines.");
PyDoc_STRVAR(len_doc,
"__len__() -> int\n\
\n\
Return the length, i.e. number of bits stored in the bitarray.\n\
This method will fail for a bitarray object with 2^31 or more elements\n\
on a 32bit machine. Use bitarray.length() instead.");
static PyObject *
bitarray_copy(bitarrayobject *self)
{
PyObject *res;
res = newbitarrayobject(Py_TYPE(self), self->nbits, self->endian);
if (res == NULL)
return NULL;
memcpy(((bitarrayobject *) res)->ob_item, self->ob_item, Py_SIZE(self));
return res;
}
PyDoc_STRVAR(copy_doc,
"copy() -> bitarray\n\
\n\
Return a copy of the bitarray.");
static PyObject *
bitarray_count(bitarrayobject *self, PyObject *args)
{
PyObject *x = Py_True;
idx_t start = 0, stop = self->nbits;
long vi;
if (!PyArg_ParseTuple(args, "|OLL:count", &x, &start, &stop))
return NULL;
vi = PyObject_IsTrue(x);
if (vi < 0)
return NULL;
normalize_index(self->nbits, &start);
normalize_index(self->nbits, &stop);
return PyLong_FromLongLong(count(self, vi, start, stop));
}
PyDoc_STRVAR(count_doc,
"count(value=True, start=0, stop=<end of array>, /) -> int\n\
\n\
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