From cfe5b6ca04a14ef1ba42e78bf6da05cfa9c0b66b Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Mon, 20 Jul 2015 00:25:50 -0400 Subject: Divisions-by-two for a positive Py_ssize_t compile more cleanly with >>1 than /2. --- Modules/_collectionsmodule.c | 2 +- Modules/_heapqmodule.c | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c index c1fd8b9d9b..47db46f86b 100644 --- a/Modules/_collectionsmodule.c +++ b/Modules/_collectionsmodule.c @@ -788,7 +788,7 @@ deque_reverse(dequeobject *deque, PyObject *unused) block *rightblock = deque->rightblock; Py_ssize_t leftindex = deque->leftindex; Py_ssize_t rightindex = deque->rightindex; - Py_ssize_t n = Py_SIZE(deque) / 2; + Py_ssize_t n = Py_SIZE(deque) >> 1; Py_ssize_t i; PyObject *tmp; diff --git a/Modules/_heapqmodule.c b/Modules/_heapqmodule.c index c343862b8c..28604afee9 100644 --- a/Modules/_heapqmodule.c +++ b/Modules/_heapqmodule.c @@ -66,7 +66,7 @@ siftup(PyListObject *heap, Py_ssize_t pos) /* Bubble up the smaller child until hitting a leaf. */ arr = _PyList_ITEMS(heap); - limit = endpos / 2; /* smallest pos that has no child */ + limit = endpos >> 1; /* smallest pos that has no child */ while (pos < limit) { /* Set childpos to index of smaller child. */ childpos = 2*pos + 1; /* leftmost child position */ @@ -347,7 +347,7 @@ heapify_internal(PyObject *heap, int siftup_func(PyListObject *, Py_ssize_t)) n is odd = 2*j+1, this is (2*j+1-1)/2 = j so j-1 is the largest, and that's again n//2-1. */ - for (i = n/2 - 1 ; i >= 0 ; i--) + for (i = (n >> 1) - 1 ; i >= 0 ; i--) if (siftup_func((PyListObject *)heap, i)) return NULL; Py_RETURN_NONE; @@ -420,7 +420,7 @@ siftup_max(PyListObject *heap, Py_ssize_t pos) /* Bubble up the smaller child until hitting a leaf. */ arr = _PyList_ITEMS(heap); - limit = endpos / 2; /* smallest pos that has no child */ + limit = endpos >> 1; /* smallest pos that has no child */ while (pos < limit) { /* Set childpos to index of smaller child. */ childpos = 2*pos + 1; /* leftmost child position */ -- cgit v1.2.1