dolphin/Source/Core/Core/HW/StreamADPCM.cpp
Lioncash 1b3dae918a StreamADPCM: Turn the ADPCM decoder into a class
Migrates the state to be instance-based as opposed to being a flat
namespace. This keeps behavior localized to its own instantiable unit
(and forces uses of the class to also be localized, lest they cart around
an instance all over the place).
2018-04-09 03:49:18 -04:00

73 lines
1.5 KiB
C++

// Copyright 2008 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
// Adapted from in_cube by hcs & destop
#include "Core/HW/StreamADPCM.h"
#include "Common/ChunkFile.h"
#include "Common/CommonTypes.h"
#include "Common/MathUtil.h"
namespace StreamADPCM
{
static s16 ADPDecodeSample(s32 bits, s32 q, s32& hist1, s32& hist2)
{
s32 hist = 0;
switch (q >> 4)
{
case 0:
hist = 0;
break;
case 1:
hist = (hist1 * 0x3c);
break;
case 2:
hist = (hist1 * 0x73) - (hist2 * 0x34);
break;
case 3:
hist = (hist1 * 0x62) - (hist2 * 0x37);
break;
}
hist = MathUtil::Clamp((hist + 0x20) >> 6, -0x200000, 0x1fffff);
s32 cur = (((s16)(bits << 12) >> (q & 0xf)) << 6) + hist;
hist2 = hist1;
hist1 = cur;
cur >>= 6;
cur = MathUtil::Clamp(cur, -0x8000, 0x7fff);
return (s16)cur;
}
void ADPCMDecoder::ResetFilter()
{
m_histl1 = 0;
m_histl2 = 0;
m_histr1 = 0;
m_histr2 = 0;
}
void ADPCMDecoder::DoState(PointerWrap& p)
{
p.Do(m_histl1);
p.Do(m_histl2);
p.Do(m_histr1);
p.Do(m_histr2);
}
void ADPCMDecoder::DecodeBlock(s16* pcm, const u8* adpcm)
{
for (int i = 0; i < SAMPLES_PER_BLOCK; i++)
{
pcm[i * 2] = ADPDecodeSample(adpcm[i + (ONE_BLOCK_SIZE - SAMPLES_PER_BLOCK)] & 0xf, adpcm[0],
m_histl1, m_histl2);
pcm[i * 2 + 1] = ADPDecodeSample(adpcm[i + (ONE_BLOCK_SIZE - SAMPLES_PER_BLOCK)] >> 4, adpcm[1],
m_histr1, m_histr2);
}
}
}