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GBHawk: Implement obscure audio effects

This commit is contained in:
alyosha-tas 2017-12-04 14:39:41 -05:00
parent 6c1e45963e
commit 3818ecf193
1 changed files with 19 additions and 2 deletions
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21
BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/Audio.cs
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@ -188,11 +188,20 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
SQ1_len_cntr = SQ1_length;
break;
case 0xFF12: // NR12 (envelope)
Audio_Regs[NR12] = value;
SQ1_st_vol = (byte)((value & 0xF0) >> 4);
SQ1_env_add = (value & 8) > 0;
SQ1_per = (byte)(value & 7);
// several glitchy effects happen when writing to NRx2 during audio playing
if (((Audio_Regs[NR12] & 7) == 0) && !SQ1_vol_done) { SQ1_vol_state++; }
else if ((Audio_Regs[NR12] & 8) == 0) { SQ1_vol_state += 2; }
if (((Audio_Regs[NR12] ^ value) & 8) > 0) { SQ1_vol_state = (byte)(0x10 - SQ1_vol_state); }
SQ1_vol_state &= 0xF;
if ((value & 0xF8) == 0) { SQ1_enable = SQ1_swp_enable = false; SQ1_output = 0; }
Audio_Regs[NR12] = value;
break;
case 0xFF13: // NR13 (freq low)
Audio_Regs[NR13] = value;
@ -269,11 +278,19 @@ namespace BizHawk.Emulation.Cores.Nintendo.GBHawk
SQ2_len_cntr = SQ2_length;
break;
case 0xFF17: // NR22 (envelope)
Audio_Regs[NR22] = value;
SQ2_st_vol = (byte)((value & 0xF0) >> 4);
SQ2_env_add = (value & 8) > 0;
SQ2_per = (byte)(value & 7);
// several glitchy effects happen when writing to NRx2 during audio playing
if (((Audio_Regs[NR22] & 7) == 0) && !SQ2_vol_done) { SQ2_vol_state++; }
else if ((Audio_Regs[NR22] & 8) == 0) { SQ2_vol_state += 2; }
if (((Audio_Regs[NR22] ^ value) & 8) > 0) { SQ2_vol_state = (byte)(0x10 - SQ2_vol_state); }
SQ2_vol_state &= 0xF;
if ((value & 0xF8) == 0) { SQ2_enable = false; SQ2_output = 0; }
Audio_Regs[NR22] = value;
break;
case 0xFF18: // NR23 (freq low)
Audio_Regs[NR23] = value;