mirror of https://github.com/python/cpython
Merged revisions 69634 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk ........ r69634 | mark.dickinson | 2009-02-15 10:13:41 +0000 (Sun, 15 Feb 2009) | 6 lines Issue #5260: Various portability and standards compliance fixes, optimizations and cleanups in Objects/longobject.c. The most significant change is that longs now use less memory: average savings are 2 bytes per long on 32-bit systems and 6 bytes per long on 64-bit systems. (This memory saving already exists in py3k.) ........
This commit is contained in:
Mark Dickinson
parent
32732e3fbd
commit
5a74bf6354
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@ -19,14 +19,13 @@ extern "C" {
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long_pow() requires that SHIFT be divisible by 5. */
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typedef unsigned short digit;
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typedef unsigned int wdigit; /* digit widened to parameter size */
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#define BASE_TWODIGITS_TYPE long
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typedef unsigned BASE_TWODIGITS_TYPE twodigits;
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typedef BASE_TWODIGITS_TYPE stwodigits; /* signed variant of twodigits */
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#define PyLong_SHIFT 15
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#define PyLong_BASE ((digit)1 << PyLong_SHIFT)
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#define PyLong_MASK ((int)(PyLong_BASE - 1))
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#define PyLong_MASK ((digit)(PyLong_BASE - 1))
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#if PyLong_SHIFT % 5 != 0
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#error "longobject.c requires that SHIFT be divisible by 5"
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@ -6,6 +6,7 @@
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#include "longintrepr.h"
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#include <ctype.h>
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#include <stddef.h>
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#ifndef NSMALLPOSINTS
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#define NSMALLPOSINTS 257
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@ -90,12 +91,6 @@ maybe_small_long(PyLongObject *v)
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#define MAX(x, y) ((x) < (y) ? (y) : (x))
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#define MIN(x, y) ((x) > (y) ? (y) : (x))
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/* Forward */
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static PyLongObject *long_normalize(PyLongObject *);
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static PyLongObject *mul1(PyLongObject *, wdigit);
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static PyLongObject *muladd1(PyLongObject *, wdigit, wdigit);
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static PyLongObject *divrem1(PyLongObject *, digit, digit *);
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#define SIGCHECK(PyTryBlock) \
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if (--_Py_Ticker < 0) { \
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_Py_Ticker = _Py_CheckInterval; \
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@ -122,25 +117,29 @@ long_normalize(register PyLongObject *v)
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/* Allocate a new long int object with size digits.
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Return NULL and set exception if we run out of memory. */
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#define MAX_LONG_DIGITS \
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((PY_SSIZE_T_MAX - offsetof(PyLongObject, ob_digit))/sizeof(digit))
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PyLongObject *
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_PyLong_New(Py_ssize_t size)
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{
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PyLongObject *result;
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/* Can't use sizeof(PyLongObject) here, since the
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compiler takes padding at the end into account.
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As the consequence, this would waste 2 bytes on
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a 32-bit system, and 6 bytes on a 64-bit system.
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This computation would be incorrect on systems
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which have padding before the digits; with 16-bit
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digits this should not happen. */
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result = PyObject_MALLOC(sizeof(PyVarObject) +
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/* Number of bytes needed is: offsetof(PyLongObject, ob_digit) +
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sizeof(digit)*size. Previous incarnations of this code used
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sizeof(PyVarObject) instead of the offsetof, but this risks being
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incorrect in the presence of padding between the PyVarObject header
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and the digits. */
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if (size > MAX_LONG_DIGITS) {
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PyErr_SetString(PyExc_OverflowError,
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"too many digits in integer");
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return NULL;
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}
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result = PyObject_MALLOC(offsetof(PyLongObject, ob_digit) +
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size*sizeof(digit));
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if (!result) {
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PyErr_NoMemory();
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return NULL;
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}
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/* XXX(nnorwitz): This can overflow --
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PyObject_NEW_VAR / _PyObject_VAR_SIZE need to detect overflow */
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return (PyLongObject*)PyObject_INIT_VAR(result, &PyLong_Type, size);
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}
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@ -297,8 +296,8 @@ PyLong_FromDouble(double dval)
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return NULL;
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frac = ldexp(frac, (expo-1) % PyLong_SHIFT + 1);
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for (i = ndig; --i >= 0; ) {
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long bits = (long)frac;
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v->ob_digit[i] = (digit) bits;
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digit bits = (digit)frac;
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v->ob_digit[i] = bits;
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frac = frac - (double)bits;
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frac = ldexp(frac, PyLong_SHIFT);
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}
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@ -667,9 +666,9 @@ _PyLong_FromByteArray(const unsigned char* bytes, size_t n,
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int incr; /* direction to move pstartbyte */
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const unsigned char* pendbyte; /* MSB of bytes */
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size_t numsignificantbytes; /* number of bytes that matter */
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size_t ndigits; /* number of Python long digits */
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Py_ssize_t ndigits; /* number of Python long digits */
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PyLongObject* v; /* result */
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int idigit = 0; /* next free index in v->ob_digit */
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Py_ssize_t idigit = 0; /* next free index in v->ob_digit */
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if (n == 0)
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return PyLong_FromLong(0L);
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@ -712,12 +711,16 @@ _PyLong_FromByteArray(const unsigned char* bytes, size_t n,
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}
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/* How many Python long digits do we need? We have
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8*numsignificantbytes bits, and each Python long digit has PyLong_SHIFT
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bits, so it's the ceiling of the quotient. */
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8*numsignificantbytes bits, and each Python long digit has
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PyLong_SHIFT bits, so it's the ceiling of the quotient. */
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/* catch overflow before it happens */
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if (numsignificantbytes > (PY_SSIZE_T_MAX - PyLong_SHIFT) / 8) {
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PyErr_SetString(PyExc_OverflowError,
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"byte array too long to convert to int");
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return NULL;
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}
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ndigits = (numsignificantbytes * 8 + PyLong_SHIFT - 1) / PyLong_SHIFT;
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if (ndigits > (size_t)INT_MAX)
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return PyErr_NoMemory();
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v = _PyLong_New((int)ndigits);
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v = _PyLong_New(ndigits);
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if (v == NULL)
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return NULL;
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@ -746,8 +749,9 @@ _PyLong_FromByteArray(const unsigned char* bytes, size_t n,
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accumbits += 8;
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if (accumbits >= PyLong_SHIFT) {
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/* There's enough to fill a Python digit. */
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assert(idigit < (int)ndigits);
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v->ob_digit[idigit] = (digit)(accum & PyLong_MASK);
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assert(idigit < ndigits);
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v->ob_digit[idigit] = (digit)(accum &
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PyLong_MASK);
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++idigit;
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accum >>= PyLong_SHIFT;
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accumbits -= PyLong_SHIFT;
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@ -756,7 +760,7 @@ _PyLong_FromByteArray(const unsigned char* bytes, size_t n,
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}
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assert(accumbits < PyLong_SHIFT);
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if (accumbits) {
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assert(idigit < (int)ndigits);
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assert(idigit < ndigits);
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v->ob_digit[idigit] = (digit)accum;
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++idigit;
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}
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@ -1409,19 +1413,11 @@ v_isub(digit *x, Py_ssize_t m, digit *y, Py_ssize_t n)
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/* Multiply by a single digit, ignoring the sign. */
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static PyLongObject *
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mul1(PyLongObject *a, wdigit n)
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{
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return muladd1(a, n, (digit)0);
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}
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/* Multiply by a single digit and add a single digit, ignoring the sign. */
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static PyLongObject *
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muladd1(PyLongObject *a, wdigit n, wdigit extra)
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mul1(PyLongObject *a, digit n)
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{
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Py_ssize_t size_a = ABS(Py_SIZE(a));
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PyLongObject *z = _PyLong_New(size_a+1);
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twodigits carry = extra;
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twodigits carry = 0;
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Py_ssize_t i;
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if (z == NULL)
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@ -2034,8 +2030,6 @@ PyLong_FromUnicode(Py_UNICODE *u, Py_ssize_t length, int base)
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static PyLongObject *x_divrem
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(PyLongObject *, PyLongObject *, PyLongObject **);
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static PyObject *long_long(PyObject *v);
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static int long_divrem(PyLongObject *, PyLongObject *,
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PyLongObject **, PyLongObject **);
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/* Long division with remainder, top-level routine */
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@ -2293,14 +2287,12 @@ long_hash(PyLongObject *v)
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sign = -1;
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i = -(i);
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}
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#define LONG_BIT_PyLong_SHIFT (8*sizeof(long) - PyLong_SHIFT)
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/* The following loop produces a C unsigned long x such that x is
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congruent to the absolute value of v modulo ULONG_MAX. The
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resulting x is nonzero if and only if v is. */
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while (--i >= 0) {
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/* Force a native long #-bits (32 or 64) circular shift */
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x = ((x << PyLong_SHIFT) & ~PyLong_MASK) |
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((x >> LONG_BIT_PyLong_SHIFT) & PyLong_MASK);
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x = (x >> (8*SIZEOF_LONG-PyLong_SHIFT)) | (x << PyLong_SHIFT);
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x += v->ob_digit[i];
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/* If the addition above overflowed we compensate by
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incrementing. This preserves the value modulo
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@ -2308,11 +2300,10 @@ long_hash(PyLongObject *v)
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if (x < v->ob_digit[i])
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x++;
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}
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#undef LONG_BIT_PyLong_SHIFT
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x = x * sign;
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if (x == -1)
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x = -2;
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return x;
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if (x == (unsigned long)-1)
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x = (unsigned long)-2;
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return (long)x;
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}
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@ -3566,12 +3557,12 @@ long_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
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/* Since PyLong_FromString doesn't have a length parameter,
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* check here for possible NULs in the string. */
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char *string;
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int size = Py_SIZE(x);
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Py_ssize_t size = Py_SIZE(x);
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if (PyByteArray_Check(x))
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string = PyByteArray_AS_STRING(x);
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else
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string = PyBytes_AS_STRING(x);
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if (strlen(string) != size) {
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if (strlen(string) != (size_t)size) {
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/* We only see this if there's a null byte in x,
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x is a bytes or buffer, *and* a base is given. */
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PyErr_Format(PyExc_ValueError,
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@ -3784,7 +3775,7 @@ long_sizeof(PyLongObject *v)
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{
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Py_ssize_t res;
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res = sizeof(PyVarObject) + abs(Py_SIZE(v))*sizeof(digit);
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res = offsetof(PyLongObject, ob_digit) + ABS(Py_SIZE(v))*sizeof(digit);
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return PyLong_FromSsize_t(res);
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}
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@ -3959,9 +3950,7 @@ static PyNumberMethods long_as_number = {
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PyTypeObject PyLong_Type = {
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PyVarObject_HEAD_INIT(&PyType_Type, 0)
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"int", /* tp_name */
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/* See _PyLong_New for why this isn't
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sizeof(PyLongObject) - sizeof(digit) */
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sizeof(PyVarObject), /* tp_basicsize */
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offsetof(PyLongObject, ob_digit), /* tp_basicsize */
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sizeof(digit), /* tp_itemsize */
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long_dealloc, /* tp_dealloc */
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0, /* tp_print */
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@ -3973,8 +3962,8 @@ PyTypeObject PyLong_Type = {
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0, /* tp_as_sequence */
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0, /* tp_as_mapping */
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(hashfunc)long_hash, /* tp_hash */
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0, /* tp_call */
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long_repr, /* tp_str */
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0, /* tp_call */
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long_repr, /* tp_str */
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PyObject_GenericGetAttr, /* tp_getattro */
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0, /* tp_setattro */
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0, /* tp_as_buffer */
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@ -3998,7 +3987,7 @@ PyTypeObject PyLong_Type = {
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0, /* tp_init */
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0, /* tp_alloc */
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long_new, /* tp_new */
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PyObject_Del, /* tp_free */
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PyObject_Del, /* tp_free */
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};
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int
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