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CDROM: Shift instead of divide in ZigZagInterpolate

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Stenzek 2024-07-23 22:10:04 +10:00
parent 5ec9c8a397
commit 68575d15a4
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1 changed files with 3 additions and 2 deletions
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5
src/core/cdrom.cpp
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@ -353,6 +353,7 @@ template<bool IS_STEREO, bool IS_8BIT>
static void DecodeXAADPCMChunks(const u8* chunk_ptr, s16* samples);
template<bool STEREO, bool SAMPLE_RATE>
static void ResampleXAADPCM(const s16* frames_in, u32 num_frames_in);
static s16 ZigZagInterpolate(const s16* ringbuf, const s16* table, u8 p);
static TinyString LBAToMSFString(CDImage::LBA lba);
@ -3137,11 +3138,11 @@ static std::array<std::array<s16, 29>, 7> s_zigzag_table = {
0x3C07, 0x53E0, -0x16FA, 0x0AFA, -0x0548, 0x027B, -0x00EB, 0x001A, 0x002B, -0x0023,
0x0010, -0x0008, 0x0002, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}}};
static s16 ZigZagInterpolate(const s16* ringbuf, const s16* table, u8 p)
ALWAYS_INLINE_RELEASE s16 CDROM::ZigZagInterpolate(const s16* ringbuf, const s16* table, u8 p)
{
s32 sum = 0;
for (u8 i = 0; i < 29; i++)
sum += (s32(ringbuf[(p - i) & 0x1F]) * s32(table[i])) / 0x8000;
sum += (static_cast<s32>(ringbuf[(p - i) & 0x1F]) * static_cast<s32>(table[i])) >> 15;
return static_cast<s16>(std::clamp<s32>(sum, -0x8000, 0x7FFF));
}