[Python-checkins] r71681 - python/branches/py3k-short-float-repr/Objects/floatobject.c

[mark.dickinson]

Author: mark.dickinson
Date: Fri Apr 17 17:48:44 2009
New Revision: 71681

Log:
Undo accidental commit of Objects/floatobject.c changes.


Modified:
   python/branches/py3k-short-float-repr/Objects/floatobject.c

Modified: python/branches/py3k-short-float-repr/Objects/floatobject.c
==============================================================================
--- python/branches/py3k-short-float-repr/Objects/floatobject.c	(original)
+++ python/branches/py3k-short-float-repr/Objects/floatobject.c	Fri Apr 17 17:48:44 2009
@@ -899,62 +899,13 @@
 	return PyLong_FromDouble(wholepart);
 }
 
-/* round a C double x to the closest multiple of 10**-ndigits */
-
-static double
-double_round(double x, int ndigits) {
-	char *buf, *buf_end, shortbuf[20];
-	char *mybuf = shortbuf;
-	int decpt, sign, buflen, mybuflen = 20;
-	double rounded = -1.0;
-
-	mybuf = shortbuf;
-
-	/* first convert to decimal, as a string; then add sign, exp, and
-	extra '0 to avoid trouble when buf_end == buf, then convert back. */
-	buf = _Py_dg_dtoa(x, 3, ndigits, &decpt, &sign, &buf_end);
-	printf("buf is %p\n", buf);
-	if (buf == NULL) {
-		PyErr_NoMemory();
-		goto exit1;
-	}
-	buflen = buf_end - buf;
-
-	printf("result is %s\n", buf);
-
-	/* total buffer space needed <= (buf_end - buf) + 8: (1 extra for '0',
-	   1 for the sign, 5 for exponent, 1 for '\0') */
-	if (buflen + 8 > mybuflen) {
-		mybuflen = buflen+8;
-		mybuf = (char *)PyMem_Malloc(mybuflen);
-		if (mybuf == NULL) {
-			PyErr_NoMemory();
-			goto exit2;
-		}
-	}
-	PyOS_snprintf(mybuf, mybuflen, "%s0%se%d", (sign ? "-" : ""),
-		      buf, decpt - buflen);
-	printf("Checkpoint 1!\n");
-	rounded = _Py_dg_strtod(mybuf, NULL);
-	printf("Checkpoint 2!\n");
-
-	/* done computing value;  now clean up */
-	if (mybuf != shortbuf)
-		PyMem_Free(mybuf);
-  exit2:
-	printf("Checkpoint 3!\n");
-	printf("buf is %p\n", buf);
-	_Py_dg_freedtoa(buf);
-	printf("Checkpoint 4!\n");
-  exit1:
-	return rounded;
-}
-
 static PyObject *
 float_round(PyObject *v, PyObject *args)
 {
 #define UNDEF_NDIGITS (-0x7fffffff) /* Unlikely ndigits value */
 	double x;
+	double f = 1.0;
+	double flr, cil;
 	double rounded;
 	int ndigits = UNDEF_NDIGITS;
 
@@ -962,13 +913,28 @@
 		return NULL;
 
 	x = PyFloat_AsDouble(v);
-	if (ndigits == UNDEF_NDIGITS) {
-		rounded = round(x);
-		if (fabs(x-rounded) == 0.5)
-			rounded = 2.0*round(x/2.0);
-		return PyLong_FromDouble(rounded);
+
+	if (ndigits != UNDEF_NDIGITS) {
+		f = pow(10.0, ndigits);
+		x *= f;
 	}
-	return PyFloat_FromDouble(double_round(x, ndigits));
+
+	flr = floor(x);
+	cil = ceil(x);
+
+	if (x-flr > 0.5)
+		rounded = cil;
+	else if (x-flr == 0.5)
+		rounded = fmod(flr, 2) == 0 ? flr : cil;
+	else
+		rounded = flr;
+
+	if (ndigits != UNDEF_NDIGITS) {
+		rounded /= f;
+		return PyFloat_FromDouble(rounded);
+	}
+
+	return PyLong_FromDouble(rounded);
 #undef UNDEF_NDIGITS
 }