From 62d1c70eff9498446d2ce3c564fefee7a7e54770 Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@gmail.com>
Date: Wed, 1 Apr 2015 17:47:07 +0200
Subject: Issue #22117, issue #23485: Fix _PyTime_AsMilliseconds() and
 _PyTime_AsMicroseconds() rounding.

Add also unit tests.
---
 Python/pytime.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

(limited to 'Python/pytime.c')

diff --git a/Python/pytime.c b/Python/pytime.c
index 003003bdca..491bbea611 100644
--- a/Python/pytime.c
+++ b/Python/pytime.c
@@ -19,6 +19,10 @@
 #define MS_TO_NS (MS_TO_US * US_TO_NS)
 #define SEC_TO_NS (SEC_TO_MS * MS_TO_NS)
 
+/* Conversion from nanoseconds */
+#define NS_TO_MS (1000 * 1000)
+#define NS_TO_US (1000)
+
 static void
 error_time_t_overflow(void)
 {
@@ -288,33 +292,29 @@ _PyTime_AsNanosecondsObject(_PyTime_t t)
 }
 
 static _PyTime_t
-_PyTime_Multiply(_PyTime_t t, unsigned int multiply, _PyTime_round_t round)
+_PyTime_Divide(_PyTime_t t, _PyTime_t k, _PyTime_round_t round)
 {
-    _PyTime_t k;
-    if (multiply < SEC_TO_NS) {
-        k = SEC_TO_NS / multiply;
-        if (round == _PyTime_ROUND_CEILING)
+    assert(k > 1);
+    if (round == _PyTime_ROUND_CEILING) {
+        if (t >= 0)
             return (t + k - 1) / k;
         else
-            return t / k;
-    }
-    else {
-        k = multiply / SEC_TO_NS;
-        return t * k;
+            return (t - (k - 1)) / k;
     }
+    else
+        return t / k;
 }
 
 _PyTime_t
 _PyTime_AsMilliseconds(_PyTime_t t, _PyTime_round_t round)
 {
-    return _PyTime_Multiply(t, 1000, round);
+    return _PyTime_Divide(t, NS_TO_MS, round);
 }
 
-/* FIXME: write unit tests */
 _PyTime_t
 _PyTime_AsMicroseconds(_PyTime_t t, _PyTime_round_t round)
 {
-    return _PyTime_Multiply(t, 1000 * 1000, round);
+    return _PyTime_Divide(t, NS_TO_US, round);
 }
 
 static int
-- 
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