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nes: apu: remove unbiasing from apu core. blip_buf already handles a dc bias removal internally, and keeping all of the values to the mixer in their original forms is simpler code and probably reflects the underlying hardware more accurately. should sound about the same as before.

This commit is contained in:
goyuken 2012-12-09 20:39:29 +00:00
parent b9f37d7ed8
commit 4a673e614b
1 changed files with 18 additions and 29 deletions
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47
BizHawk.Emulation/Consoles/Nintendo/NES/APU.cs
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@ -263,17 +263,13 @@ namespace BizHawk.Emulation.Consoles.Nintendo
if (duty_value) //high state of duty cycle
{
newsample = env_output;
if (swp_silence)
newsample = env_output >> 1; //(a little biasing hack here)
if (len_cnt == 0) //length counter is 0
newsample = env_output >> 1; //silenced (a little biasing hack here)
if (swp_silence || len_cnt == 0)
newsample = 0; // silenced
}
else
newsample = env_output >> 1; //duty cycle is 0, silenced.
newsample = 0; //duty cycle is 0, silenced.
newsample -= env_output >> 1; //unbias
//newsample -= env_output >> 1; //unbias
if (newsample != sample)
{
apu.recalculate = true;
@ -428,11 +424,10 @@ namespace BizHawk.Emulation.Consoles.Nintendo
noise_bit = (shift_register & 1) != 0;
}
//unbiasing is rolled in here
int newsample;
if (len_cnt == 0) newsample = 0;
else if (noise_bit) newsample = -env_output;
else newsample = env_output;
else if (noise_bit) newsample = env_output; // switched, was 0?
else newsample = 0;
if (newsample != sample)
{
apu.recalculate = true;
@ -532,7 +527,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
seq = (seq + 1) & 0x1F;
timer = timer_cnt_reload;
}
if(CFG_DECLICK)
if(CFG_DECLICK) // this looks ugly...
newsample = TRIANGLE_TABLE[(seq + 8) & 0x1F];
else
newsample = TRIANGLE_TABLE[seq];
@ -542,7 +537,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
//so we'll emulate it at the digital level
if (timer_cnt_reload == 1) newsample = 8;
newsample -= 8; //unbias
//newsample -= 8; //unbias
if (newsample != sample)
{
apu.recalculate = true;
@ -615,7 +610,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
int out_shift, out_bits_remaining, out_deltacounter;
bool out_silence;
public int sample { get { return out_deltacounter - 64; } }
public int sample { get { return out_deltacounter /* - 64*/; } }
public void SyncState(Serializer ser)
{
@ -1022,11 +1017,6 @@ namespace BizHawk.Emulation.Consoles.Nintendo
}
}
//public void DiscardSamples()
//{
// metaspu.buffer.clear();
//}
int toggle = 0;
public void RunOne()
{
@ -1074,11 +1064,6 @@ namespace BizHawk.Emulation.Consoles.Nintendo
//we want the changes to affect it on the *next* cycle.
}
//int loopy = 0;
//public const int DECIMATIONFACTOR = 20;
//const int QUEUESIZE = 1789773 / DECIMATIONFACTOR; //1 second, should be enough
//public QuickQueue<short> squeue = new QuickQueue<short>(QUEUESIZE);
public struct Delta
{
public uint time;
@ -1114,14 +1099,18 @@ namespace BizHawk.Emulation.Consoles.Nintendo
if (!EnableNoise) s_noise = 0;
if (!EnableDMC) s_dmc = 0;
const float NOISEADJUST = 0.5f;
//const float NOISEADJUST = 0.5f;
//linear approximation
float pulse_out = 0.00752f * (s_pulse0 + s_pulse1);
float tnd_out = 0.00851f * s_tri + 0.00494f * NOISEADJUST * s_noise + 0.00335f * s_dmc;
float output = pulse_out + tnd_out;
//float pulse_out = 0.00752f * (s_pulse0 + s_pulse1);
//float tnd_out = 0.00851f * s_tri + 0.00494f * /*NOISEADJUST * */ s_noise + 0.00335f * s_dmc;
//float output = pulse_out + tnd_out;
//this needs to leave enough headroom for straying DC bias due to the DMC unit getting stuck outputs. smb3 is bad about that.
int mix = (int)(50000 * output);
//int mix = (int)(50000 * output);
int pulse_out = 376 * (s_pulse0 + s_pulse1);
int tnd_out = 426 * s_tri + 247 * s_noise + 167 * s_dmc;
int mix = pulse_out + tnd_out;
dlist.Add(new Delta(sampleclock, mix - oldmix));
oldmix = mix;