260 lines
10 KiB
C++
260 lines
10 KiB
C++
/* _______ ____ __ ___ ___
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* \ _ \ \ / \ / \ \ / / ' ' '
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* | | \ \ | | || | \/ | . .
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* | | | | | | || ||\ /| |
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* | | | | | | || || \/ | | ' ' '
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* | | | | | | || || | | . .
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* | |_/ / \ \__// || | |
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* /_______/ynamic \____/niversal /__\ /____\usic /| . . ibliotheque
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* / \
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* / . \
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* resamp3.inc - Resampling helper template. / / \ \
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* | < / \_
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* By Bob and entheh. | \/ /\ /
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* \_ / > /
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* In order to find a good trade-off between | \ / /
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* speed and accuracy in this code, some tests | ' /
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* were carried out regarding the behaviour of \__/
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* long long ints with gcc. The following code
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* was tested:
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*
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* int a, b, c;
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* c = ((long long)a * b) >> 16;
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*
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* DJGPP GCC Version 3.0.3 generated the following assembly language code for
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* the multiplication and scaling, leaving the 32-bit result in EAX.
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*
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* movl -8(%ebp), %eax ; read one int into EAX
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* imull -4(%ebp) ; multiply by the other; result goes in EDX:EAX
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* shrdl $16, %edx, %eax ; shift EAX right 16, shifting bits in from EDX
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*
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* Note that a 32*32->64 multiplication is performed, allowing for high
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* accuracy. On the Pentium 2 and above, shrdl takes two cycles (generally),
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* so it is a minor concern when four multiplications are being performed
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* (the cubic resampler). On the Pentium MMX and earlier, it takes four or
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* more cycles, so this method is unsuitable for use in the low-quality
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* resamplers.
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*
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* Since "long long" is a gcc-specific extension, we use LONG_LONG instead,
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* defined in dumb.h. We may investigate later what code MSVC generates, but
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* if it seems too slow then we suggest you use a good compiler.
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*
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* FIXME: these comments are somewhat out of date now.
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*/
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long dumb_resample(DUMB_RESAMPLER *resampler, sample_t *dst, long dst_size, VOLUME_PARAMETERS, float delta)
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{
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int dt, inv_dt;
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int VOLUME_VARIABLES;
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long done;
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long todo;
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LONG_LONG todo64;
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int quality;
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/*int check;*/
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if (!resampler || resampler->dir == 0) return 0;
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ASSERT(resampler->dir == -1 || resampler->dir == 1);
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done = 0;
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dt = (int)(delta * 65536.0 + 0.5);
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if (dt == 0 || dt == (int)-0x80000000) return 0;
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inv_dt = (int)(1.0 / delta * 65536.0 + 0.5);
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SET_VOLUME_VARIABLES;
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if (VOLUMES_ARE_ZERO) dst = NULL;
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_dumb_init_cubic();
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quality = resampler->quality;
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while (done < dst_size) {
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if (process_pickup(resampler)) {
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RETURN_VOLUME_VARIABLES;
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return done;
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}
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if ((resampler->dir ^ dt) < 0)
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dt = -dt;
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if (resampler->dir < 0)
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todo64 = ((((LONG_LONG)(resampler->pos - resampler->start) << 16) + resampler->subpos - dt) / -dt);
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else
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todo64 = ((((LONG_LONG)(resampler->end - resampler->pos) << 16) - resampler->subpos - 1 + dt) / dt);
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if (todo64 < 0)
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todo = 0;
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else if (todo64 > dst_size - done)
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todo = dst_size - done;
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else
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todo = (long) todo64;
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done += todo;
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{
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SRCTYPE *src = resampler->src;
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long pos = resampler->pos;
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int subpos = resampler->subpos;
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long diff = pos;
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long overshot;
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if (resampler->dir < 0) {
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if (!dst) {
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/* Silence or simulation */
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LONG_LONG new_subpos = subpos + (LONG_LONG)dt * todo;
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pos += (long)(new_subpos >> 16);
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subpos = (long)new_subpos & 65535;
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} else {
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/* FIR resampling, backwards */
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SRCTYPE *x;
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if ( resampler->fir_resampler_ratio != delta ) {
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resampler_set_rate( resampler->fir_resampler[0], delta );
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resampler_set_rate( resampler->fir_resampler[1], delta );
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resampler->fir_resampler_ratio = delta;
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}
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x = &src[pos*SRC_CHANNELS];
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while ( todo ) {
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while ( ( resampler_get_free_count( resampler->fir_resampler[0] ) ||
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(!resampler_get_sample_count( resampler->fir_resampler[0] )
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#if SRC_CHANNELS == 2
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&& !resampler_get_sample_count( resampler->fir_resampler[1] )
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#endif
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) ) && pos >= resampler->start )
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{
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POKE_FIR(0);
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pos--;
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x -= SRC_CHANNELS;
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}
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if ( !resampler_get_sample_count( resampler->fir_resampler[0] ) ) break;
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MIX_FIR;
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ADVANCE_FIR;
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--todo;
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}
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done -= todo;
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}
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diff = diff - pos;
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overshot = resampler->start - pos - 1;
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if (diff >= 3) {
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COPYSRC2(resampler->X, 0, overshot < 3, src, pos+3);
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COPYSRC2(resampler->X, 1, overshot < 2, src, pos+2);
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COPYSRC2(resampler->X, 2, overshot < 1, src, pos+1);
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} else if (diff >= 2) {
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COPYSRC(resampler->X, 0, resampler->X, 2);
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COPYSRC2(resampler->X, 1, overshot < 2, src, pos+2);
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COPYSRC2(resampler->X, 2, overshot < 1, src, pos+1);
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} else if (diff >= 1) {
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COPYSRC(resampler->X, 0, resampler->X, 1);
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COPYSRC(resampler->X, 1, resampler->X, 2);
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COPYSRC2(resampler->X, 2, overshot < 1, src, pos+1);
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}
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} else {
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if (!dst) {
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/* Silence or simulation */
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LONG_LONG new_subpos = subpos + (LONG_LONG)dt * todo;
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pos += (long)(new_subpos >> 16);
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subpos = (long)new_subpos & 65535;
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} else {
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/* FIR resampling, forwards */
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SRCTYPE *x;
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if ( resampler->fir_resampler_ratio != delta ) {
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resampler_set_rate( resampler->fir_resampler[0], delta );
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resampler_set_rate( resampler->fir_resampler[1], delta );
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resampler->fir_resampler_ratio = delta;
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}
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x = &src[pos*SRC_CHANNELS];
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while ( todo ) {
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while ( ( resampler_get_free_count( resampler->fir_resampler[0] ) ||
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(!resampler_get_sample_count( resampler->fir_resampler[0] )
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#if SRC_CHANNELS == 2
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&& !resampler_get_sample_count( resampler->fir_resampler[1] )
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#endif
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) ) && pos < resampler->end )
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{
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POKE_FIR(0);
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pos++;
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x += SRC_CHANNELS;
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}
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if ( !resampler_get_sample_count( resampler->fir_resampler[0] ) ) break;
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MIX_FIR;
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ADVANCE_FIR;
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--todo;
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}
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done -= todo;
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}
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diff = pos - diff;
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overshot = pos - resampler->end;
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if (diff >= 3) {
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COPYSRC2(resampler->X, 0, overshot < 3, src, pos-3);
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COPYSRC2(resampler->X, 1, overshot < 2, src, pos-2);
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COPYSRC2(resampler->X, 2, overshot < 1, src, pos-1);
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} else if (diff >= 2) {
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COPYSRC(resampler->X, 0, resampler->X, 2);
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COPYSRC2(resampler->X, 1, overshot < 2, src, pos-2);
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COPYSRC2(resampler->X, 2, overshot < 1, src, pos-1);
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} else if (diff >= 1) {
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COPYSRC(resampler->X, 0, resampler->X, 1);
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COPYSRC(resampler->X, 1, resampler->X, 2);
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COPYSRC2(resampler->X, 2, overshot < 1, src, pos-1);
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}
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}
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resampler->pos = pos;
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resampler->subpos = subpos;
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}
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}
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RETURN_VOLUME_VARIABLES;
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return done;
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}
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void dumb_resample_get_current_sample(DUMB_RESAMPLER *resampler, VOLUME_PARAMETERS, sample_t *dst)
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{
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int VOLUME_VARIABLES;
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SRCTYPE *src;
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long pos;
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int subpos;
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int quality;
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SRCTYPE *x;
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if (!resampler || resampler->dir == 0) { MIX_ZEROS(=); return; }
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ASSERT(resampler->dir == -1 || resampler->dir == 1);
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if (process_pickup(resampler)) { MIX_ZEROS(=); return; }
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SET_VOLUME_VARIABLES;
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if (VOLUMES_ARE_ZERO) { MIX_ZEROS(=); return; }
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_dumb_init_cubic();
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quality = resampler->quality;
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src = resampler->src;
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pos = resampler->pos;
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subpos = resampler->subpos;
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x = resampler->X;
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if (resampler->dir < 0) {
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HEAVYASSERT(pos >= resampler->start);
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/* FIR resampling, backwards */
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PEEK_FIR;
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} else {
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HEAVYASSERT(pos < resampler->end);
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/* FIR resampling, forwards */
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PEEK_FIR;
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}
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}
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#undef MIX_ZEROS
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#undef MIX_FIR
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#undef PEEK_FIR
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#undef VOLUMES_ARE_ZERO
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#undef SET_VOLUME_VARIABLES
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#undef RETURN_VOLUME_VARIABLES
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#undef VOLUME_VARIABLES
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#undef VOLUME_PARAMETERS
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#undef SUFFIX3
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