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utils: API: Add multiplication and addition functions for fractions

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gst_util_fraction_add()
gst_util_fraction_multiply()

These work on plain integers instead of GValues to
keep the overhead as low as possible.
This commit is contained in:
Sebastian Dröge 2009-11-16 09:49:46 +01:00
parent e4257e8d5f
commit 0ed24bc50e
5 changed files with 108 additions and 25 deletions
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2
docs/gst/gstreamer-sections.txt
View file

@ -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

93
gst/gstutils.c
View file

@ -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;
}

2
gst/gstutils.h
View file

@ -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

34
gst/gstvalue.c
View file

@ -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;
if (!gst_util_fraction_multiply (n1, d1, n2, d2, &res_n, &res_d))
return FALSE;
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);
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;
}

2
win32/common/libgstreamer.def
View file

@ -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