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utils: gst_util_uint64_scale*() micro-optimisations

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Sprinkle G_LIKELY/G_UNLIKELY; add inlined _scale_int_unchecked()
so we don't do some checks twice when calling it from _scale().
This commit is contained in:
Tim-Philipp Müller 2009-06-08 15:39:59 +01:00
parent 998b2392d3
commit f44204c8fa
1 changed files with 43 additions and 36 deletions
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79
gst/gstutils.c
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@ -264,7 +264,7 @@ gst_util_div128_64 (GstUInt64 c1, GstUInt64 c0, guint64 denom)
}
static guint64
gst_util_uint64_scale_int64 (guint64 val, guint64 num, guint64 denom)
gst_util_uint64_scale_int64_unchecked (guint64 val, guint64 num, guint64 denom)
{
GstUInt64 a0, a1, b0, b1, c0, ct, c1, result;
GstUInt64 v, n;
@ -296,7 +296,7 @@ gst_util_uint64_scale_int64 (guint64 val, guint64 num, guint64 denom)
c1.ll = (guint64) a1.l.high + b0.l.high + ct.l.high + b1.ll;
/* if high bits bigger than denom, we overflow */
if (c1.ll >= denom)
if (G_UNLIKELY (c1.ll >= denom))
goto overflow;
/* shortcut for division by 1, c1.ll should be 0 because of the
@ -326,6 +326,36 @@ overflow:
}
}
static inline guint64
gst_util_uint64_scale_int_unchecked (guint64 val, gint num, gint denom)
{
GstUInt64 result;
GstUInt64 low, high;
/* do 96 bits mult/div */
low.ll = val;
result.ll = ((guint64) low.l.low) * num;
high.ll = ((guint64) low.l.high) * num + (result.l.high);
low.ll = high.ll / denom;
result.l.high = high.ll % denom;
result.ll /= denom;
/* avoid overflow */
if (G_UNLIKELY (low.ll + result.l.high > G_MAXUINT32))
goto overflow;
result.l.high += low.l.low;
return result.ll;
overflow:
{
return G_MAXUINT64;
}
}
/**
* gst_util_uint64_scale:
* @val: the number to scale
@ -344,33 +374,33 @@ gst_util_uint64_scale (guint64 val, guint64 num, guint64 denom)
{
g_return_val_if_fail (denom != 0, G_MAXUINT64);
if (num == 0)
if (G_UNLIKELY (num == 0))
return 0;
if (num == 1 && denom == 1)
if (G_UNLIKELY (num == denom))
return val;
/* if the denom is high, we need to do a 64 muldiv */
if (denom > G_MAXINT32)
if (G_UNLIKELY (denom > G_MAXINT32))
goto do_int64;
/* if num and denom are low we can do a 32 bit muldiv */
if (num <= G_MAXINT32)
if (G_LIKELY (num <= G_MAXINT32))
goto do_int32;
/* val and num are high, we need 64 muldiv */
if (val > G_MAXINT32)
if (G_UNLIKELY (val > G_MAXINT32))
goto do_int64;
/* val is low and num is high, we can swap them and do 32 muldiv */
return gst_util_uint64_scale_int (num, (gint) val, (gint) denom);
return gst_util_uint64_scale_int_unchecked (num, (gint) val, (gint) denom);
do_int32:
return gst_util_uint64_scale_int (val, (gint) num, (gint) denom);
return gst_util_uint64_scale_int_unchecked (val, (gint) num, (gint) denom);
do_int64:
/* to the more heavy implementations... */
return gst_util_uint64_scale_int64 (val, num, denom);
return gst_util_uint64_scale_int64_unchecked (val, num, denom);
}
/**
@ -390,43 +420,20 @@ do_int64:
guint64
gst_util_uint64_scale_int (guint64 val, gint num, gint denom)
{
GstUInt64 result;
GstUInt64 low, high;
g_return_val_if_fail (denom > 0, G_MAXUINT64);
g_return_val_if_fail (num >= 0, G_MAXUINT64);
if (num == 0)
if (G_UNLIKELY (num == 0))
return 0;
if (num == 1 && denom == 1)
if (G_UNLIKELY (num == denom))
return val;
if (val <= G_MAXUINT32)
/* simple case */
return val * num / denom;
/* do 96 bits mult/div */
low.ll = val;
result.ll = ((guint64) low.l.low) * num;
high.ll = ((guint64) low.l.high) * num + (result.l.high);
low.ll = high.ll / denom;
result.l.high = high.ll % denom;
result.ll /= denom;
/* avoid overflow */
if (low.ll + result.l.high > G_MAXUINT32)
goto overflow;
result.l.high += low.l.low;
return result.ll;
overflow:
{
return G_MAXUINT64;
}
return gst_util_uint64_scale_int_unchecked (val, num, denom);
}
/**