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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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gstutils: API: Add rounding to nearest and next integer versions of the 64 bit integer scaling functions
The new functions are gst_util_uint64_scale_int_round() gst_util_uint64_scale_int_ceil() gst_util_uint64_scale_round() gst_util_uint64_scale_ceil() Fixes bug #590919.
This commit is contained in:
Kipp Cannon
Sebastian Dröge
parent
61481c1b79
commit
9cfd9f9374
2 changed files with 243 additions and 34 deletions
273
gst/gstutils.c
273
gst/gstutils.c
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@ -204,6 +204,14 @@ typedef union
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} l;
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} GstUInt64;
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/* used internally by muldiv functions to control rounding mode */
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typedef enum
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{
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GST_ROUND_TONEAREST,
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GST_ROUND_UP,
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GST_ROUND_DOWN,
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} GstRoundingMode;
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/* multiply two 64-bit unsigned ints into a 128-bit unsigned int. the high
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* and low 64 bits of the product are placed in c1 and c0 respectively.
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* this operation cannot overflow. */
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@ -342,13 +350,43 @@ gst_util_div96_32 (guint64 c1, guint64 c0, guint32 denom)
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}
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static guint64
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gst_util_uint64_scale_uint64_unchecked (guint64 val, guint64 num, guint64 denom)
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gst_util_uint64_scale_uint64_unchecked (guint64 val, guint64 num,
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guint64 denom, GstRoundingMode mode)
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{
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GstUInt64 c1, c0;
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/* compute 128-bit numerator product */
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gst_util_uint64_mul_uint64 (&c1, &c0, val, num);
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/* condition numerator based on rounding mode */
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switch (mode) {
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case GST_ROUND_TONEAREST:
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/* add 1/2 the denominator to the numerator with carry */
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if (G_MAXUINT64 - c0.ll < denom / 2) {
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if (G_UNLIKELY (c1.ll == G_MAXUINT64))
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/* overflow */
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return G_MAXUINT64;
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c1.ll++;
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}
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c0.ll += denom / 2;
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break;
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case GST_ROUND_UP:
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/* add denominator - 1 to the numerator with carry */
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if (G_MAXUINT64 - c0.ll < denom - 1) {
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if (G_UNLIKELY (c1.ll == G_MAXUINT64))
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/* overflow */
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return G_MAXUINT64;
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c1.ll++;
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}
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c0.ll += denom - 1;
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break;
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case GST_ROUND_DOWN:
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/* natural behaviour */
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break;
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}
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/* high word as big as or bigger than denom --> overflow */
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if (G_UNLIKELY (c1.ll >= denom))
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return G_MAXUINT64;
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@ -358,13 +396,43 @@ gst_util_uint64_scale_uint64_unchecked (guint64 val, guint64 num, guint64 denom)
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}
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static inline guint64
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gst_util_uint64_scale_uint32_unchecked (guint64 val, guint32 num, guint32 denom)
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gst_util_uint64_scale_uint32_unchecked (guint64 val, guint32 num,
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guint32 denom, GstRoundingMode mode)
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{
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GstUInt64 c1, c0;
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/* compute 96-bit numerator product */
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gst_util_uint64_mul_uint32 (&c1, &c0, val, num);
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/* condition numerator based on rounding mode */
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switch (mode) {
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case GST_ROUND_TONEAREST:
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/* add 1/2 the denominator to the numerator with carry */
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if (G_MAXUINT64 - c0.ll < denom / 2) {
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if (G_UNLIKELY (c1.ll == G_MAXUINT64))
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/* overflow */
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return G_MAXUINT64;
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c1.ll++;
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}
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c0.ll += denom / 2;
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break;
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case GST_ROUND_UP:
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/* add denominator - 1 to the numerator with carry */
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if (G_MAXUINT64 - c0.ll < denom - 1) {
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if (G_UNLIKELY (c1.ll == G_MAXUINT64))
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/* overflow */
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return G_MAXUINT64;
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c1.ll++;
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}
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c0.ll += denom - 1;
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break;
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case GST_ROUND_DOWN:
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/* natural behaviour */
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break;
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}
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/* high 32 bits as big as or bigger than denom --> overflow */
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if (G_UNLIKELY (c1.l.high >= denom))
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return G_MAXUINT64;
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@ -373,6 +441,36 @@ gst_util_uint64_scale_uint32_unchecked (guint64 val, guint32 num, guint32 denom)
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return gst_util_div96_32 (c1.ll, c0.ll, denom);
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}
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/* the guts of the gst_util_uint64_scale() variants */
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static guint64
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_gst_util_uint64_scale (guint64 val, guint64 num, guint64 denom,
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GstRoundingMode mode)
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{
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g_return_val_if_fail (denom != 0, G_MAXUINT64);
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if (G_UNLIKELY (num == 0))
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return 0;
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if (G_UNLIKELY (num == denom))
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return val;
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/* denom is low --> try to use 96 bit muldiv */
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if (G_LIKELY (denom <= G_MAXUINT32)) {
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/* num is low --> use 96 bit muldiv */
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if (G_LIKELY (num <= G_MAXUINT32))
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return gst_util_uint64_scale_uint32_unchecked (val, (guint32) num,
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(guint32) denom, mode);
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/* num is high but val is low --> swap and use 96-bit muldiv */
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if (G_LIKELY (val <= G_MAXUINT32))
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return gst_util_uint64_scale_uint32_unchecked (num, (guint32) val,
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(guint32) denom, mode);
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}
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/* val is high and num is high --> use 128-bit muldiv */
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return gst_util_uint64_scale_uint64_unchecked (val, num, denom, mode);
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}
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/**
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* gst_util_uint64_scale:
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* @val: the number to scale
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@ -386,12 +484,75 @@ gst_util_uint64_scale_uint32_unchecked (guint64 val, guint32 num, guint32 denom)
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* greater than G_MAXUINT32.
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*
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* Returns: @val * @num / @denom. In the case of an overflow, this
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* function returns G_MAXUINT64.
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* function returns G_MAXUINT64. If the result is not exactly
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* representable as an integer it is truncated. See also
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* gst_util_uint64_scale_round(), gst_util_uint64_scale_ceil(),
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* gst_util_uint64_scale_int(), gst_util_uint64_scale_int_round(),
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* gst_util_uint64_scale_int_ceil().
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*/
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guint64
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gst_util_uint64_scale (guint64 val, guint64 num, guint64 denom)
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{
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g_return_val_if_fail (denom != 0, G_MAXUINT64);
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return _gst_util_uint64_scale (val, num, denom, GST_ROUND_DOWN);
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}
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/**
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* gst_util_uint64_scale_round:
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* @val: the number to scale
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* @num: the numerator of the scale ratio
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* @denom: the denominator of the scale ratio
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*
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* Scale @val by the rational number @num / @denom, avoiding overflows and
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* underflows and without loss of precision.
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*
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* This function can potentially be very slow if val and num are both
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* greater than G_MAXUINT32.
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*
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* Returns: @val * @num / @denom. In the case of an overflow, this
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* function returns G_MAXUINT64. If the result is not exactly
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* representable as an integer, it is rounded to the nearest integer
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* (half-way cases are rounded up). See also gst_util_uint64_scale(),
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* gst_util_uint64_scale_ceil(), gst_util_uint64_scale_int(),
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* gst_util_uint64_scale_int_round(), gst_util_uint64_scale_int_ceil().
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*/
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guint64
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gst_util_uint64_scale_round (guint64 val, guint64 num, guint64 denom)
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{
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return _gst_util_uint64_scale (val, num, denom, GST_ROUND_TONEAREST);
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}
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/**
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* gst_util_uint64_scale_ceil:
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* @val: the number to scale
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* @num: the numerator of the scale ratio
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* @denom: the denominator of the scale ratio
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*
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* Scale @val by the rational number @num / @denom, avoiding overflows and
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* underflows and without loss of precision.
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*
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* This function can potentially be very slow if val and num are both
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* greater than G_MAXUINT32.
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*
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* Returns: @val * @num / @denom. In the case of an overflow, this
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* function returns G_MAXUINT64. If the result is not exactly
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* representable as an integer, it is rounded up. See also
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* gst_util_uint64_scale(), gst_util_uint64_scale_round(),
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* gst_util_uint64_scale_int(), gst_util_uint64_scale_int_round(),
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* gst_util_uint64_scale_int_ceil().
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*/
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guint64
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gst_util_uint64_scale_ceil (guint64 val, guint64 num, guint64 denom)
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{
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return _gst_util_uint64_scale (val, num, denom, GST_ROUND_UP);
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}
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/* the guts of the gst_util_uint64_scale_int() variants */
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static guint64
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_gst_util_uint64_scale_int (guint64 val, gint num, gint denom,
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GstRoundingMode mode)
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{
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g_return_val_if_fail (denom > 0, G_MAXUINT64);
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g_return_val_if_fail (num >= 0, G_MAXUINT64);
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if (G_UNLIKELY (num == 0))
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return 0;
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@ -399,21 +560,33 @@ gst_util_uint64_scale (guint64 val, guint64 num, guint64 denom)
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if (G_UNLIKELY (num == denom))
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return val;
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/* denom is low --> try to use 96 bit muldiv */
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if (G_LIKELY (denom <= G_MAXUINT32)) {
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/* num is low --> use 96 bit muldiv */
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if (G_LIKELY (num <= G_MAXUINT32))
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return gst_util_uint64_scale_uint32_unchecked (val, (guint32) num,
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(guint32) denom);
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if (val <= G_MAXUINT32) {
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/* simple case. num and denom are not negative so casts are OK. when
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* not truncating, the additions to the numerator cannot overflow
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* because val*num <= G_MAXUINT32 * G_MAXINT32 < G_MAXUINT64 -
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* G_MAXINT32, so there's room to add another gint32. */
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val *= (guint64) num;
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switch (mode) {
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case GST_ROUND_TONEAREST:
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/* add 1/2 the denominator to the numerator. */
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val += denom / 2;
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break;
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/* num is high but val is low --> swap and use 96-bit muldiv */
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if (G_LIKELY (val <= G_MAXUINT32))
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return gst_util_uint64_scale_uint32_unchecked (num, (guint32) val,
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(guint32) denom);
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case GST_ROUND_UP:
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/* add denominator - 1 to the numerator. */
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val += denom - 1;
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break;
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case GST_ROUND_DOWN:
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/* natural behaviour */
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break;
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}
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return val / (guint64) denom;
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}
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/* val is high and num is high --> use 128-bit muldiv */
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return gst_util_uint64_scale_uint64_unchecked (val, num, denom);
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/* num and denom are not negative so casts are OK */
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return gst_util_uint64_scale_uint32_unchecked (val, (guint32) num,
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(guint32) denom, mode);
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}
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/**
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@ -427,30 +600,62 @@ gst_util_uint64_scale (guint64 val, guint64 num, guint64 denom)
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* @denom must be positive.
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*
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* Returns: @val * @num / @denom. In the case of an overflow, this
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* function returns G_MAXUINT64.
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* function returns G_MAXUINT64. If the result is not exactly
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* representable as an integer, it is truncated. See also
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* gst_util_uint64_scale_int_round(), gst_util_uint64_scale_int_ceil(),
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* gst_util_uint64_scale(), gst_util_uint64_scale_round(),
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* gst_util_uint64_scale_ceil().
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*/
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guint64
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gst_util_uint64_scale_int (guint64 val, gint num, gint denom)
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{
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g_return_val_if_fail (denom > 0, G_MAXUINT64);
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g_return_val_if_fail (num >= 0, G_MAXUINT64);
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return _gst_util_uint64_scale_int (val, num, denom, GST_ROUND_DOWN);
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}
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if (G_UNLIKELY (num == 0))
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return 0;
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/**
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* gst_util_uint64_scale_int_round:
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* @val: guint64 (such as a #GstClockTime) to scale.
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* @num: numerator of the scale factor.
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* @denom: denominator of the scale factor.
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*
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* Scale @val by the rational number @num / @denom, avoiding overflows and
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* underflows and without loss of precision. @num must be non-negative and
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* @denom must be positive.
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*
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* Returns: @val * @num / @denom. In the case of an overflow, this
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* function returns G_MAXUINT64. If the result is not exactly
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* representable as an integer, it is rounded to the nearest integer
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* (half-way cases are rounded up). See also gst_util_uint64_scale_int(),
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* gst_util_uint64_scale_int_ceil(), gst_util_uint64_scale(),
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* gst_util_uint64_scale_round(), gst_util_uint64_scale_ceil().
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*/
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guint64
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gst_util_uint64_scale_int_round (guint64 val, gint num, gint denom)
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{
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return _gst_util_uint64_scale_int (val, num, denom, GST_ROUND_TONEAREST);
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}
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if (G_UNLIKELY (num == denom))
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return val;
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if (val <= G_MAXUINT32) {
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/* simple case, use two statements to prevent optimizer from screwing
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* up result. num and denom are not negative so casts are OK */
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val *= (guint64) num;
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return val / (guint64) denom;
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}
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/* num and denom are not negative so casts are OK */
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return gst_util_uint64_scale_uint32_unchecked (val, (guint32) num,
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(guint32) denom);
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/**
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* gst_util_uint64_scale_int_ceil:
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* @val: guint64 (such as a #GstClockTime) to scale.
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* @num: numerator of the scale factor.
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* @denom: denominator of the scale factor.
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*
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* Scale @val by the rational number @num / @denom, avoiding overflows and
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* underflows and without loss of precision. @num must be non-negative and
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* @denom must be positive.
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*
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* Returns: @val * @num / @denom. In the case of an overflow, this
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* function returns G_MAXUINT64. If the result is not exactly
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* representable as an integer, it is rounded up. See also
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* gst_util_uint64_scale_int(), gst_util_uint64_scale_int_round(),
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* gst_util_uint64_scale(), gst_util_uint64_scale_round(),
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* gst_util_uint64_scale_ceil().
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*/
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guint64
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gst_util_uint64_scale_int_ceil (guint64 val, gint num, gint denom)
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{
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return _gst_util_uint64_scale_int (val, num, denom, GST_ROUND_UP);
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}
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/**
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@ -64,8 +64,12 @@ gdouble gst_util_guint64_to_gdouble (guint64 value) G_GNUC_PURE;
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#endif
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guint64 gst_util_uint64_scale (guint64 val, guint64 num, guint64 denom) G_GNUC_PURE;
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guint64 gst_util_uint64_scale_round (guint64 val, guint64 num, guint64 denom) G_GNUC_PURE;
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guint64 gst_util_uint64_scale_ceil (guint64 val, guint64 num, guint64 denom) G_GNUC_PURE;
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guint64 gst_util_uint64_scale_int (guint64 val, gint num, gint denom) G_GNUC_PURE;
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guint64 gst_util_uint64_scale_int_round (guint64 val, gint num, gint denom) G_GNUC_PURE;
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guint64 gst_util_uint64_scale_int_ceil (guint64 val, gint num, gint denom) G_GNUC_PURE;
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guint32 gst_util_seqnum_next (void);
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gint32 gst_util_seqnum_compare (guint32 s1, guint32 s2);
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