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#include "nw4r/snd/snd_adpcm.h"
/* Original source:
* kiwi515/ogws
* src/nw4r/snd/snd_adpcm.cpp
*/
/*******************************************************************************
* headers
*/
#include <climits>
#include "common.h"
#include <rvl/AX/AXVPB.h> // AXPBADPCM
/*******************************************************************************
* functions
*/
namespace nw4r { namespace snd { namespace detail {
s16 DecodeDspAdpcm(AXPBADPCM *adpcm, byte_t bits)
{
s16 yn1 = static_cast<s16>(adpcm->yn1);
s16 yn2 = static_cast<s16>(adpcm->yn2);
s16 scale = 1 << (adpcm->pred_scale & 0x0f);
s16 bits2 = bits << 12;
u16 index = adpcm->pred_scale >> 4;
s16 coef0 = adpcm->a[index][0];
s16 coef1 = adpcm->a[index][1];
s32 sample = coef0 * yn1;
sample += coef1 * yn2;
sample += scale * (bits2 >> 1);
sample >>= 10;
sample += 1;
sample >>= 1;
if (sample > SHRT_MAX)
sample = SHRT_MAX;
else if (sample < SHRT_MIN)
sample = SHRT_MIN;
adpcm->yn2 = adpcm->yn1;
adpcm->yn1 = sample;
return sample;
}
}}} // namespace nw4r::snd::detail
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