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check/gst/gstutils.c: Updated check, add some scaling accuracy checking code.

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Original commit message from CVS:
* check/gst/gstutils.c: (GST_START_TEST):
Updated check, add some scaling accuracy checking code.

* gst/gstutils.c: (gst_util_div128_64),
(gst_util_uint64_scale_int64), (gst_util_uint64_scale),
(gst_util_uint64_scale_int):
Fix 6 times faster division code. Optimize for common
1/1 and less common X/1 cases.
This commit is contained in:
Wim Taymans 2005-11-28 18:44:11 +00:00
parent 597335c574
commit 2dc0ef57fd
4 changed files with 65 additions and 42 deletions
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11
ChangeLog
View file

@ -1,3 +1,14 @@
2005-11-28 Wim Taymans <wim@fluendo.com>
* check/gst/gstutils.c: (GST_START_TEST):
Updated check, add some scaling accuracy checking code.
* gst/gstutils.c: (gst_util_div128_64),
(gst_util_uint64_scale_int64), (gst_util_uint64_scale),
(gst_util_uint64_scale_int):
Fix 6 times faster division code. Optimize for common
1/1 and less common X/1 cases.
2005-11-28 Wim Taymans <wim@fluendo.com>
* check/gst/gstutils.c: (GST_START_TEST), (gst_utils_suite):

20
check/gst/gstutils.c
View file

@ -236,19 +236,35 @@ GST_START_TEST (test_math_scale_uint64)
GST_START_TEST (test_math_scale_random)
{
guint64 val, num, denom, res;;
guint64 val, num, denom, res;
GRand *rand;
gint i;
rand = g_rand_new ();
i = 1000;
i = 1000000;
while (i--) {
guint64 check, diff;
val = ((guint64) g_rand_int (rand)) << 32 | g_rand_int (rand);
num = ((guint64) g_rand_int (rand)) << 32 | g_rand_int (rand);
denom = ((guint64) g_rand_int (rand)) << 32 | g_rand_int (rand);
res = gst_util_uint64_scale (val, num, denom);
check = gst_gdouble_to_guint64 (gst_guint64_to_gdouble (val) *
gst_guint64_to_gdouble (num) / gst_guint64_to_gdouble (denom));
if (res < G_MAXUINT64 && check < G_MAXUINT64) {
if (res > check)
diff = res - check;
else
diff = check - res;
/* some arbitrary value, really.. someone do the proper math to get
* the upper bound */
if (diff > 20000)
fail_if (diff > 20000);
}
}
g_rand_free (rand);

56
gst/gstutils.c
View file

@ -356,36 +356,6 @@ typedef union
} l;
} GstUInt64;
static guint64
gst_util_div128_64_iterate (GstUInt64 c1, GstUInt64 c0, guint64 denom)
{
gint i;
gint64 mask;
GstUInt64 a0;
/* full 128/64 case, very slow... */
/* quotient is c1, c0 */
a0.ll = 0; /* remainder a0 */
/* This can be done faster, inspiration in Hacker's Delight p152 */
for (i = 0; i < 128; i++) {
/* shift 192 bits remainder:quotient, we only need to
* check the top bit since denom is only 64 bits. */
/* sign extend top bit into mask */
mask = ((gint32) a0.l.high) >> 31;
mask |= (a0.ll = (a0.ll << 1) | (c1.l.high >> 31));
c1.ll = (c1.ll << 1) | (c0.l.high >> 31);
c0.ll <<= 1;
/* if remainder >= denom or top bit was set */
if (mask >= denom) {
a0.ll -= denom;
c0.ll += 1;
}
}
return c0.ll;
}
/* based on Hacker's Delight p152 */
static guint64
gst_util_div128_64 (GstUInt64 c1, GstUInt64 c0, guint64 denom)
@ -409,10 +379,12 @@ gst_util_div128_64 (GstUInt64 c1, GstUInt64 c0, guint64 denom)
s += (s >> 8);
s = (s + (s >> 16)) & 0x3f;
/* normalize divisor and dividend */
v.ll <<= s;
c1.ll = (c1.ll << s) | ((c0.l.high >> (32 - s)) & (-s >> 31));
c0.ll <<= s;
if (s > 0) {
/* normalize divisor and dividend */
v.ll <<= s;
c1.ll = (c1.ll << s) | (c0.l.high >> (32 - s));
c0.ll <<= s;
}
q1.ll = c1.ll / v.l.high;
rhat.ll = c1.ll - q1.ll * v.l.high;
@ -489,6 +461,11 @@ gst_util_uint64_scale_int64 (guint64 val, guint64 num, guint64 denom)
if (c1.ll >= denom)
goto overflow;
/* shortcut for division by 1, c1.ll should be 0 because of the
* overflow check above. */
if (denom == 1)
return c0.ll;
/* and 128/64 bits division, result fits 64 bits */
if (denom <= G_MAXUINT32) {
guint32 den = (guint32) denom;
@ -501,10 +478,7 @@ gst_util_uint64_scale_int64 (guint64 val, guint64 num, guint64 denom)
result.l.high = c1.ll / den;
result.l.low = c0.ll / den;
} else {
if (TRUE)
result.ll = gst_util_div128_64_iterate (c1, c0, denom);
else
result.ll = gst_util_div128_64 (c1, c0, denom);
result.ll = gst_util_div128_64 (c1, c0, denom);
}
return result.ll;
@ -534,6 +508,9 @@ gst_util_uint64_scale (guint64 val, guint64 num, guint64 denom)
if (num == 0)
return 0;
if (num == 1 && denom == 1)
return val;
/* if the denom is high, we need to do a 64 muldiv */
if (denom > G_MAXINT32)
goto do_int64;
@ -581,6 +558,9 @@ gst_util_uint64_scale_int (guint64 val, gint num, gint denom)
if (num == 0)
return 0;
if (num == 1 && denom == 1)
return val;
if (val <= G_MAXUINT32) {
/* simple case */
result.ll = val * num / denom;

20
tests/check/gst/gstutils.c
View file

@ -236,19 +236,35 @@ GST_START_TEST (test_math_scale_uint64)
GST_START_TEST (test_math_scale_random)
{
guint64 val, num, denom, res;;
guint64 val, num, denom, res;
GRand *rand;
gint i;
rand = g_rand_new ();
i = 1000;
i = 1000000;
while (i--) {
guint64 check, diff;
val = ((guint64) g_rand_int (rand)) << 32 | g_rand_int (rand);
num = ((guint64) g_rand_int (rand)) << 32 | g_rand_int (rand);
denom = ((guint64) g_rand_int (rand)) << 32 | g_rand_int (rand);
res = gst_util_uint64_scale (val, num, denom);
check = gst_gdouble_to_guint64 (gst_guint64_to_gdouble (val) *
gst_guint64_to_gdouble (num) / gst_guint64_to_gdouble (denom));
if (res < G_MAXUINT64 && check < G_MAXUINT64) {
if (res > check)
diff = res - check;
else
diff = check - res;
/* some arbitrary value, really.. someone do the proper math to get
* the upper bound */
if (diff > 20000)
fail_if (diff > 20000);
}
}
g_rand_free (rand);