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improved YM2612 DAC/accumulator accuracy

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ekeeke31 2010-11-01 18:00:43 +00:00
parent 7d04780880
commit 31d476948b
1 changed files with 18 additions and 27 deletions
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45
source/sound/ym2612.c
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@ -1731,8 +1731,8 @@ INLINE void OPNWriteReg(int r, int v)
CH->ams = lfo_ams_depth_shift[(v>>4) & 0x03];
/* PAN : b7 = L, b6 = R */
ym2612.OPN.pan[ c*2 ] = (v & 0x80) ? ~((1 << (14 - config.dac_bits)) - 1) : 0;
ym2612.OPN.pan[ c*2+1 ] = (v & 0x40) ? ~((1 << (14 - config.dac_bits)) - 1) : 0;
ym2612.OPN.pan[ c*2 ] = (v & 0x80) ? ~0 : 0;
ym2612.OPN.pan[ c*2+1 ] = (v & 0x40) ? ~0 : 0;
break;
}
break;
@ -1826,11 +1826,14 @@ static void init_tables(void)
signed int i,x;
signed int n;
double o,m;
#ifdef NGC
u32 level = IRQ_Disable();
#endif
/* DAC precision */
unsigned int mask = ~((1 << (14 - config.dac_bits)) - 1);
/* build Linear Power Table */
for (x=0; x<TL_RES_LEN; x++)
{
@ -1850,8 +1853,8 @@ static void init_tables(void)
n <<= 2; /* 13 bits here (as in real chip) */
/* 14 bits (with sign bit) */
tl_tab[ x*2 + 0 ] = n;
tl_tab[ x*2 + 1 ] = -tl_tab[ x*2 + 0 ];
tl_tab[ x*2 + 0 ] = n & mask;
tl_tab[ x*2 + 1 ] = -tl_tab[ x*2 + 0 ] & mask;
/* one entry in the 'Power' table use the following format, xxxxxyyyyyyyys with: */
/* s = sign bit */
@ -1860,8 +1863,8 @@ static void init_tables(void)
/* any value above 13 (included) would be discarded. */
for (i=1; i<13; i++)
{
tl_tab[ x*2+0 + i*2*TL_RES_LEN ] = tl_tab[ x*2+0 ]>>i;
tl_tab[ x*2+1 + i*2*TL_RES_LEN ] = -tl_tab[ x*2+0 + i*2*TL_RES_LEN ];
tl_tab[ x*2+0 + i*2*TL_RES_LEN ] = (tl_tab[ x*2+0 ]>>i) & mask;
tl_tab[ x*2+1 + i*2*TL_RES_LEN ] = -tl_tab[ x*2+0 + i*2*TL_RES_LEN ] & mask;
}
}
@ -2113,17 +2116,17 @@ void YM2612Update(long int *buffer, int length)
}
/* 14-bit channel output */
if (out_fm[0] > 8191) out_fm[0] = 8191;
if (out_fm[0] > 8191) out_fm[0] = 8192;
else if (out_fm[0] < -8192) out_fm[0] = -8192;
if (out_fm[1] > 8191) out_fm[1] = 8191;
if (out_fm[1] > 8191) out_fm[1] = 8192;
else if (out_fm[1] < -8192) out_fm[1] = -8192;
if (out_fm[2] > 8191) out_fm[2] = 8191;
if (out_fm[2] > 8191) out_fm[2] = 8192;
else if (out_fm[2] < -8192) out_fm[2] = -8192;
if (out_fm[3] > 8191) out_fm[3] = 8191;
if (out_fm[3] > 8191) out_fm[3] = 8192;
else if (out_fm[3] < -8192) out_fm[3] = -8192;
if (out_fm[4] > 8191) out_fm[4] = 8191;
if (out_fm[4] > 8191) out_fm[4] = 8192;
else if (out_fm[4] < -8192) out_fm[4] = -8192;
if (out_fm[5] > 8191) out_fm[5] = 8191;
if (out_fm[5] > 8191) out_fm[5] = 8192;
else if (out_fm[5] < -8192) out_fm[5] = -8192;
/* 6-channels mixing */
@ -2199,18 +2202,6 @@ void YM2612Restore(unsigned char *buffer)
setup_connection(&ym2612.CH[4],4);
setup_connection(&ym2612.CH[5],5);
/* update channels mask */
unsigned int mask = ~((1 << (14 - config.dac_bits)) - 1);
ym2612.OPN.pan[0] = ym2612.OPN.pan[0] ? mask : 0;
ym2612.OPN.pan[1] = ym2612.OPN.pan[1] ? mask : 0;
ym2612.OPN.pan[2] = ym2612.OPN.pan[2] ? mask : 0;
ym2612.OPN.pan[3] = ym2612.OPN.pan[3] ? mask : 0;
ym2612.OPN.pan[4] = ym2612.OPN.pan[4] ? mask : 0;
ym2612.OPN.pan[5] = ym2612.OPN.pan[5] ? mask : 0;
ym2612.OPN.pan[6] = ym2612.OPN.pan[6] ? mask : 0;
ym2612.OPN.pan[7] = ym2612.OPN.pan[7] ? mask : 0;
ym2612.OPN.pan[8] = ym2612.OPN.pan[8] ? mask : 0;
ym2612.OPN.pan[9] = ym2612.OPN.pan[9] ? mask : 0;
ym2612.OPN.pan[10] = ym2612.OPN.pan[10] ? mask : 0;
ym2612.OPN.pan[11] = ym2612.OPN.pan[11] ? mask : 0;
/* restore TL table (in case DAC precision has changed) */
init_tables();
}