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/* _______ ____ __ ___ ___
* \ _ \ \ / \ / \ \ / / ' ' '
* | | \ \ | | || | \/ | . .
* | | | | | | || ||\ /| |
* | | | | | | || || \/ | | ' ' '
* | | | | | | || || | | . .
* | |_/ / \ \__// || | |
* /_______/ynamic \____/niversal /__\ /____\usic /| . . ibliotheque
* / \
* / . \
* resamp2.inc - Resampling helper template. / / \ \
* | < / \_
* By Bob and entheh. | \/ /\ /
* \_ / > /
* In order to find a good trade-off between | \ / /
* speed and accuracy in this code, some tests | ' /
* were carried out regarding the behaviour of \__/
* long long ints with gcc. The following code
* was tested:
*
* int a, b, c;
* c = ((long long)a * b) >> 16;
*
* DJGPP GCC Version 3.0.3 generated the following assembly language code for
* the multiplication and scaling, leaving the 32-bit result in EAX.
*
* movl -8(%ebp), %eax ; read one int into EAX
* imull -4(%ebp) ; multiply by the other; result goes in EDX:EAX
* shrdl $16, %edx, %eax ; shift EAX right 16, shifting bits in from EDX
*
* Note that a 32*32->64 multiplication is performed, allowing for high
* accuracy. On the Pentium 2 and above, shrdl takes two cycles (generally),
* so it is a minor concern when four multiplications are being performed
* (the cubic resampler). On the Pentium MMX and earlier, it takes four or
* more cycles, so this method is unsuitable for use in the low-quality
* resamplers.
*
* Since "long long" is a gcc-specific extension, we use LONG_LONG instead,
* defined in dumb.h. We may investigate later what code MSVC generates, but
* if it seems too slow then we suggest you use a good compiler.
*
* FIXME: these comments are somewhat out of date now.
*/
#define SUFFIX3 _1
/* For convenience, returns nonzero on stop. */
static int process_pickup(DUMB_RESAMPLER *resampler)
{
if (resampler->overshot < 0) {
resampler->overshot = 0;
dumb_resample(resampler, NULL, 2, MONO_DEST_VOLUME_ZEROS, 1.0f); /* Doesn't matter which SUFFIX3. */
COPYSRC(resampler->X, 0, resampler->X, 1);
}
for (;;) {
SRCTYPE *src = resampler->src;
if (resampler->dir < 0) {
if (resampler->overshot >= 3 && resampler->pos+3 >= resampler->start) COPYSRC(resampler->X, 0, src, resampler->pos+3);
if (resampler->overshot >= 2 && resampler->pos+2 >= resampler->start) COPYSRC(resampler->X, 1, src, resampler->pos+2);
if (resampler->overshot >= 1 && resampler->pos+1 >= resampler->start) COPYSRC(resampler->X, 2, src, resampler->pos+1);
resampler->overshot = resampler->start - resampler->pos - 1;
} else {
if (resampler->overshot >= 3 && resampler->pos-3 < resampler->end) COPYSRC(resampler->X, 0, src, resampler->pos-3);
if (resampler->overshot >= 2 && resampler->pos-2 < resampler->end) COPYSRC(resampler->X, 1, src, resampler->pos-2);
if (resampler->overshot >= 1 && resampler->pos-1 < resampler->end) COPYSRC(resampler->X, 2, src, resampler->pos-1);
resampler->overshot = resampler->pos - resampler->end;
}
if (resampler->overshot < 0) {
resampler->overshot = 0;
return 0;
}
if (!resampler->pickup) {
resampler->dir = 0;
return 1;
}
(*resampler->pickup)(resampler, resampler->pickup_data);
if (resampler->dir == 0) return 1;
ASSERT(resampler->dir == -1 || resampler->dir == 1);
}
}
/* Create mono destination resampler. */
/* SUFFIX3 was set above. */
#define VOLUME_PARAMETERS MONO_DEST_VOLUME_PARAMETERS
#define VOLUME_VARIABLES MONO_DEST_VOLUME_VARIABLES
#define SET_VOLUME_VARIABLES SET_MONO_DEST_VOLUME_VARIABLES
#define VOLUMES_ARE_ZERO MONO_DEST_VOLUMES_ARE_ZERO
#define MIX_ALIAS(op, offset) MONO_DEST_MIX_ALIAS(op, offset)
#define MIX_LINEAR(op, o0, o1) MONO_DEST_MIX_LINEAR(op, o0, o1)
#define MIX_CUBIC(op, x0, x3, o0, o1, o2, o3) MONO_DEST_MIX_CUBIC(op, x0, x3, o0, o1, o2, o3)
#define MIX_ZEROS(op) *dst++ op 0
#include "resamp3.inc"
/* Create stereo destination resampler. */
#define SUFFIX3 _2
#define VOLUME_PARAMETERS float volume_left, float volume_right
#define VOLUME_VARIABLES lvol, rvol
#define SET_VOLUME_VARIABLES { \
lvol = (int)floor(volume_left * 65536.0 + 0.5); \
rvol = (int)floor(volume_right * 65536.0 + 0.5); \
}
#define VOLUMES_ARE_ZERO (lvol == 0 && rvol == 0)
#define MIX_ALIAS(op, offset) STEREO_DEST_MIX_ALIAS(op, offset)
#define MIX_LINEAR(op, o0, o1) STEREO_DEST_MIX_LINEAR(op, o0, o1)
#define MIX_CUBIC(op, x0, x3, o0, o1, o2, o3) STEREO_DEST_MIX_CUBIC(op, x0, x3, o0, o1, o2, o3)
#define MIX_ZEROS(op) { *dst++ op 0; *dst++ op 0; }
#include "resamp3.inc"
#undef STEREO_DEST_MIX_CUBIC
#undef MONO_DEST_MIX_CUBIC
#undef STEREO_DEST_MIX_LINEAR
#undef MONO_DEST_MIX_LINEAR
#undef STEREO_DEST_MIX_ALIAS
#undef MONO_DEST_MIX_ALIAS
#undef MONO_DEST_VOLUMES_ARE_ZERO
#undef SET_MONO_DEST_VOLUME_VARIABLES
#undef MONO_DEST_VOLUME_ZEROS
#undef MONO_DEST_VOLUME_VARIABLES
#undef MONO_DEST_VOLUME_PARAMETERS
#undef COPYSRC2
#undef COPYSRC
#undef DIVIDE_BY_SRC_CHANNELS
#undef SRC_CHANNELS
#undef SUFFIX2
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