utils: API: Add multiplication and addition functions for fractions

gst_util_fraction_add()
gst_util_fraction_multiply()

These work on plain integers instead of GValues to
keep the overhead as low as possible.

5 files changed, 108 insertions, 25 deletions

diff --git a/docs/gst/gstreamer-sections.txt b/docs/gst/gstreamer-sections.txt
index 40c4069c62..6ee8dbccd1 100644
--- a/docs/gst/gstreamer-sections.txt
+++ b/docs/gst/gstreamer-sections.txt
@@ -2528,6 +2528,8 @@ gst_util_uint64_scale_int_ceil
 gst_util_greatest_common_divisor
 gst_util_fraction_to_double
 gst_util_double_to_fraction
+gst_util_fraction_multiply
+gst_util_fraction_add
 gst_util_seqnum_next
 gst_util_seqnum_compare
 gst_util_set_object_arg
diff --git a/gst/gstutils.c b/gst/gstutils.c
index d12aa9fe6b..ef7b9757a8 100644
--- a/gst/gstutils.c
+++ b/gst/gstutils.c
@@ -3950,3 +3950,96 @@ gst_util_double_to_fraction (gdouble src, gint * dest_n, gint * dest_d)
   *dest_n = N;
   *dest_d = D;
 }
+
+/** gst_util_fraction_multiply:
+ * @a_n: Numerator of first value
+ * @a_d: Denominator of first value
+ * @b_n: Numerator of second value
+ * @b_d: Denominator of second value
+ * @res_n: Pointer to #gint to hold the result numerator
+ * @res_d: Pointer to #gint to hold the result denominator
+ *
+ * Multiplies the fractions @a_n/@a_d and @b_n/@b_d and stores
+ * the result in @res_n and @res_d.
+ *
+ * Returns: %FALSE on overflow, %TRUE otherwise.
+ *
+ * Since: 0.10.26
+ */
+gboolean
+gst_util_fraction_multiply (gint a_n, gint a_d, gint b_n, gint b_d,
+    gint * res_n, gint * res_d)
+{
+  gint gcd;
+
+  g_return_val_if_fail (res_n != NULL, FALSE);
+  g_return_val_if_fail (res_d != NULL, FALSE);
+  g_return_val_if_fail (a_d != 0, FALSE);
+  g_return_val_if_fail (b_d != 0, FALSE);
+
+  gcd = gst_util_greatest_common_divisor (a_n, b_d);
+  a_n /= gcd;
+  b_d /= gcd;
+  gcd = gst_util_greatest_common_divisor (a_d, b_n);
+  a_d /= gcd;
+  b_n /= gcd;
+
+  g_return_val_if_fail (a_n == 0 || G_MAXINT / ABS (a_n) >= ABS (b_n), FALSE);
+  g_return_val_if_fail (G_MAXINT / ABS (a_d) >= ABS (b_d), FALSE);
+
+  *res_n = a_n * b_n;
+  *res_d = a_d * b_d;
+
+  return TRUE;
+}
+
+/** gst_util_fraction_add:
+ * @a_n: Numerator of first value
+ * @a_d: Denominator of first value
+ * @b_n: Numerator of second value
+ * @b_d: Denominator of second value
+ * @res_n: Pointer to #gint to hold the result numerator
+ * @res_d: Pointer to #gint to hold the result denominator
+ *
+ * Adds the fractions @a_n/@a_d and @b_n/@b_d and stores
+ * the result in @res_n and @res_d.
+ *
+ * Returns: %FALSE on overflow, %TRUE otherwise.
+ *
+ * Since: 0.10.26
+ */
+gboolean
+gst_util_fraction_add (gint a_n, gint a_d, gint b_n, gint b_d, gint * res_n,
+    gint * res_d)
+{
+  gint gcd;
+
+  g_return_val_if_fail (res_n != NULL, FALSE);
+  g_return_val_if_fail (res_d != NULL, FALSE);
+  g_return_val_if_fail (a_d != 0, FALSE);
+  g_return_val_if_fail (b_d != 0, FALSE);
+
+  if (a_n == 0) {
+    *res_n = b_n;
+    *res_d = b_d;
+    return TRUE;
+  }
+  if (b_n == 0) {
+    *res_n = a_n;
+    *res_d = a_d;
+    return TRUE;
+  }
+
+  g_return_val_if_fail (a_n == 0 || G_MAXINT / ABS (a_n) >= ABS (b_n), FALSE);
+  g_return_val_if_fail (G_MAXINT / ABS (a_d) >= ABS (b_d), FALSE);
+  g_return_val_if_fail (G_MAXINT / ABS (a_d) >= ABS (b_d), FALSE);
+
+  *res_n = (a_n * b_d) + (a_d * b_n);
+  *res_d = a_d * b_d;
+
+  gcd = gst_util_greatest_common_divisor (*res_n, *res_d);
+  *res_n /= gcd;
+  *res_d /= gcd;
+
+  return TRUE;
+}
diff --git a/gst/gstutils.h b/gst/gstutils.h
index 4fa4c02c04..af4e33d021 100644
--- a/gst/gstutils.h
+++ b/gst/gstutils.h
@@ -1169,6 +1169,8 @@ gpointer                gst_util_array_binary_search      (gpointer array, guint
 gint gst_util_greatest_common_divisor (gint a, gint b);
 void gst_util_fraction_to_double (gint src_n, gint src_d, gdouble *dest);
 void gst_util_double_to_fraction (gdouble src, gint *dest_n, gint *dest_d);
+gboolean gst_util_fraction_multiply (gint a_n, gint a_d, gint b_n, gint b_d, gint *res_n, gint *res_d);
+gboolean gst_util_fraction_add (gint a_n, gint a_d, gint b_n, gint b_d, gint *res_n, gint *res_d);
 
 G_END_DECLS
 
diff --git a/gst/gstvalue.c b/gst/gstvalue.c
index 257cff3bd8..f307345deb 100644
--- a/gst/gstvalue.c
+++ b/gst/gstvalue.c
@@ -3606,7 +3606,8 @@ gboolean
 gst_value_fraction_multiply (GValue * product, const GValue * factor1,
     const GValue * factor2)
 {
-  gint gcd, n1, n2, d1, d2;
+  gint n1, n2, d1, d2;
+  gint res_n, res_d;
 
   g_return_val_if_fail (GST_VALUE_HOLDS_FRACTION (factor1), FALSE);
   g_return_val_if_fail (GST_VALUE_HOLDS_FRACTION (factor2), FALSE);
@@ -3616,17 +3617,10 @@ gst_value_fraction_multiply (GValue * product, const GValue * factor1,
   d1 = factor1->data[1].v_int;
   d2 = factor2->data[1].v_int;
 
-  gcd = gst_util_greatest_common_divisor (n1, d2);
-  n1 /= gcd;
-  d2 /= gcd;
-  gcd = gst_util_greatest_common_divisor (n2, d1);
-  n2 /= gcd;
-  d1 /= gcd;
-
-  g_return_val_if_fail (n1 == 0 || G_MAXINT / ABS (n1) >= ABS (n2), FALSE);
-  g_return_val_if_fail (G_MAXINT / ABS (d1) >= ABS (d2), FALSE);
+  if (!gst_util_fraction_multiply (n1, d1, n2, d2, &res_n, &res_d))
+    return FALSE;
 
-  gst_value_set_fraction (product, n1 * n2, d1 * d2);
+  gst_value_set_fraction (product, res_n, res_d);
 
   return TRUE;
 }
@@ -3646,6 +3640,7 @@ gst_value_fraction_subtract (GValue * dest,
     const GValue * minuend, const GValue * subtrahend)
 {
   gint n1, n2, d1, d2;
+  gint res_n, res_d;
 
   g_return_val_if_fail (GST_VALUE_HOLDS_FRACTION (minuend), FALSE);
   g_return_val_if_fail (GST_VALUE_HOLDS_FRACTION (subtrahend), FALSE);
@@ -3655,20 +3650,9 @@ gst_value_fraction_subtract (GValue * dest,
   d1 = minuend->data[1].v_int;
   d2 = subtrahend->data[1].v_int;
 
-  if (n1 == 0) {
-    gst_value_set_fraction (dest, -n2, d2);
-    return TRUE;
-  }
-  if (n2 == 0) {
-    gst_value_set_fraction (dest, n1, d1);
-    return TRUE;
-  }
-
-  g_return_val_if_fail (n1 == 0 || G_MAXINT / ABS (n1) >= ABS (d2), FALSE);
-  g_return_val_if_fail (G_MAXINT / ABS (d1) >= ABS (n2), FALSE);
-  g_return_val_if_fail (G_MAXINT / ABS (d1) >= ABS (d2), FALSE);
-
-  gst_value_set_fraction (dest, (n1 * d2) - (n2 * d1), d1 * d2);
+  if (!gst_util_fraction_add (n1, d1, -n2, d2, &res_n, &res_d))
+    return FALSE;
+  gst_value_set_fraction (dest, res_n, res_d);
 
   return TRUE;
 }
diff --git a/win32/common/libgstreamer.def b/win32/common/libgstreamer.def
index 6e8ede0487..d03e866336 100644
--- a/win32/common/libgstreamer.def
+++ b/win32/common/libgstreamer.def
@@ -1058,6 +1058,8 @@ EXPORTS
 	gst_util_array_binary_search
 	gst_util_double_to_fraction
 	gst_util_dump_mem
+	gst_util_fraction_add
+	gst_util_fraction_multiply
 	gst_util_fraction_to_double
 	gst_util_gdouble_to_guint64
 	gst_util_get_timestamp