Reduce the size of the _PyLong_DigitValue table.

rhettinger · rhettinger · commit 356315379362 · 2009-01-09T03:58:09.000Z
diff --git a/Include/longobject.h b/Include/longobject.h
@@ -41,7 +41,7 @@ PyAPI_FUNC(unsigned long) PyLong_AsUnsignedLongMask(PyObject *);
 #endif
 
 /* For use by intobject.c only */
-PyAPI_DATA(int) _PyLong_DigitValue[256];
+PyAPI_DATA(unsigned char) _PyLong_DigitValue[256];
 
 /* _PyLong_AsScaledDouble returns a double x and an exponent e such that
    the true value is approximately equal to x * 2**(SHIFT*e).  e is >= 0.
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -12,6 +12,10 @@ What's New in Python 3.1 alpha 0
 Core and Builtins
 -----------------
 
+- The internal table, _PyLong_DigitValue, is now an array of unsigned chars
+  instead of ints (reducing its size from 4 to 8 times thereby reducing
+  Python's overall memory).
+
 - Issue #1180193: When importing a module from a .pyc (or .pyo) file with
   an existing .py counterpart, override the co_filename attributes of all
   code objects if the original filename is obsolete (which can happen if the
diff --git a/Objects/longobject.c b/Objects/longobject.c
@@ -1646,7 +1646,7 @@ _PyLong_Format(PyObject *aa, int base)
  * Note that when converting a base B string, a char c is a legitimate
  * base B digit iff _PyLong_DigitValue[Py_CHARPyLong_MASK(c)] < B.
  */
-int _PyLong_DigitValue[256] = {
+unsigned char _PyLong_DigitValue[256] = {
 	37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37,
 	37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37,
 	37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37,
@@ -1710,7 +1710,7 @@ long_from_binary_base(char **str, int base)
 	bits_in_accum = 0;
 	pdigit = z->ob_digit;
 	while (--p >= start) {
-		int k = _PyLong_DigitValue[Py_CHARMASK(*p)];
+		int k = (int)_PyLong_DigitValue[Py_CHARMASK(*p)];
 		assert(k >= 0 && k < base);
 		accum |= (twodigits)(k << bits_in_accum);
 		bits_in_accum += bits_per_char;
@@ -1926,7 +1926,7 @@ digit beyond the first.
 			c = (digit)_PyLong_DigitValue[Py_CHARMASK(*str++)];
 			for (i = 1; i < convwidth && str != scan; ++i, ++str) {
 				c = (twodigits)(c *  base +
-					_PyLong_DigitValue[Py_CHARMASK(*str)]);
+					(int)_PyLong_DigitValue[Py_CHARMASK(*str)]);
 				assert(c < PyLong_BASE);
 			}
 
