X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=time.c;h=e0f6c756e21ae87d553c7a3a3e4a99e04e34e977;hp=1fd7b0981584fc4557079ee62a87fbd713554f3a;hb=d0d27cfa56d05eaa0e5567c75adfe606eab2957e;hpb=97727c2e95cce064e03f495e97119cae447397d7

diff --git a/time.c b/time.c
index 1fd7b098..e0f6c756 100644
--- a/time.c
+++ b/time.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2005-2008 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2005-2012 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -12,7 +12,7 @@
  *
  * \param tv The time value value to convert.
  *
- * \return The number off milliseconds in \a tv.
+ * \return The number of milliseconds in \a tv.
  */
 long unsigned tv2ms(const struct timeval *tv)
 {
@@ -82,7 +82,7 @@ int tv_diff(const struct timeval *b, const struct timeval *a, struct timeval *di
  *
  * \param a First addend.
  * \param b Second addend.
- * \param sum Contains the sum \a + \a b on return.
+ * \param sum Contains the sum \a a + \a b on return.
  */
 void tv_add(const struct timeval *a, const struct timeval *b,
 	struct timeval *sum)
@@ -106,9 +106,10 @@ void tv_add(const struct timeval *a, const struct timeval *b,
 void tv_scale(const unsigned long mult, const struct timeval *tv,
 	struct timeval *result)
 {
-	result->tv_sec = mult * tv->tv_sec;
-	result->tv_sec += tv->tv_usec * mult / 1000 / 1000;
-	result->tv_usec = tv->tv_usec * mult % (1000 * 1000);
+	uint64_t x = ((uint64_t)tv->tv_sec * 1000 * 1000 + tv->tv_usec) * mult;
+
+	result->tv_sec = x / 1000 / 1000;
+	result->tv_usec = x % (1000 * 1000);
 }
 
 /**
@@ -130,46 +131,57 @@ void tv_divide(const unsigned long divisor, const struct timeval *tv,
 /**
  * Compute a convex combination of two time values.
  *
- * \param a The first coefiicent.
+ * \param a The first coefficient.
  * \param tv1 The first time value.
- * \param b The second coefiicent.
+ * \param b The second coefficient.
  * \param tv2 The second time value.
  * \param result Contains the convex combination upon return.
  *
- * compute x := (a * tv1 + b * tv2) / (|a| + |b|) and store |x| in \a result.
+ * Compute x := (a * tv1 + b * tv2) / (|a| + |b|) and store |x| in \a result.
  * Both \a a and \a b may be negative.
  *
- * \return One if \a x is positive, -1 otherwise.
+ * \return Zero, 1 or -1, if \a x is zero, positive or negative, respectively.
  */
 int tv_convex_combination(const long a, const struct timeval *tv1,
 		const long b, const struct timeval *tv2,
 		struct timeval *result)
 {
 	struct timeval tmp1, tmp2, tmp3;
-	int ret = 1, subtract = ((a > 0 && b < 0) || (a < 0 && b > 0));
-	unsigned long a1 = PARA_ABS(a), b1 = PARA_ABS(b);
+	int ret = 1;
+	unsigned long a1, b1;
 
+	if (a == 0 && b == 0) {
+		result->tv_sec = 0;
+		result->tv_usec = 0;
+		return 0;
+	}
+	a1 = PARA_ABS(a);
+	b1 = PARA_ABS(b);
 	tv_scale(a1, tv1, &tmp1);
 	tv_scale(b1, tv2, &tmp2);
-	if (subtract)
+	if ((a > 0 && b < 0) || (a < 0 && b > 0)) /* subtract */
 		ret = tv_diff(&tmp1, &tmp2, &tmp3);
 	else
 		tv_add(&tmp1, &tmp2, &tmp3);
-	if (a1 + b1)
-		tv_divide(a1 + b1, &tmp3, result);
-	else {
-		result->tv_sec = 0;
-		result->tv_usec = 0;
-	}
+	tv_divide(a1 + b1, &tmp3, result);
 	if (!a || !b) {
 		if (a + b < 0)
 			ret = -1;
-	} else
-		if (a < 0)
-			ret = -ret;
+	} else if (a < 0)
+		ret = -ret;
 	return ret;
 }
 
+/**
+ * Compute when to send a chunk of an audio file.
+ *
+ * \param chunk_num The number of the chunk.
+ * \param chunk_tv The duration of one chunk.
+ * \param stream_start When the first chunk was sent.
+ * \param result The time when to send chunk number \a chunk_num.
+ *
+ * This function computes \a stream_start + \a chunk_num * \a chunk_time.
+ */
 void compute_chunk_time(long unsigned chunk_num,
 		struct timeval *chunk_tv, struct timeval *stream_start,
 		struct timeval *result)