Tables::Tables() {
int lf;
for (lf = 0; lf <= 100; lf++) {
// CONFIRMED:KG: This matches a ROM table found by Mok
float fVal = (2.0f - LOG10F((float)lf + 1.0f)) * 128.0f;
int val = (int)(fVal + 1.0);
if (val > 255) {
val = 255;
}
levelToAmpSubtraction[lf] = (Bit8u)val;
}
envLogarithmicTime[0] = 64;
for (lf = 1; lf <= 255; lf++) {
// CONFIRMED:KG: This matches a ROM table found by Mok
envLogarithmicTime[lf] = (Bit8u)ceil(64.0f + LOG2F((float)lf) * 8.0f);
}
#ifdef EMULATE_LAPC_I // Dummy #ifdef - we'll have runtime emulation mode selection in future.
// CONFIRMED: Based on a table found by Mok in the LAPC-I control ROM
// Note that this matches the MT-32 table, but with the values clamped to a maximum of 8.
memset(masterVolToAmpSubtraction, 8, 71);
memset(masterVolToAmpSubtraction + 71, 7, 3);
memset(masterVolToAmpSubtraction + 74, 6, 4);
memset(masterVolToAmpSubtraction + 78, 5, 3);
memset(masterVolToAmpSubtraction + 81, 4, 4);
memset(masterVolToAmpSubtraction + 85, 3, 3);
memset(masterVolToAmpSubtraction + 88, 2, 4);
memset(masterVolToAmpSubtraction + 92, 1, 4);
memset(masterVolToAmpSubtraction + 96, 0, 5);
#else
// CONFIRMED: Based on a table found by Mok in the MT-32 control ROM
masterVolToAmpSubtraction[0] = 255;
for (int masterVol = 1; masterVol <= 100; masterVol++) {
masterVolToAmpSubtraction[masterVol] = (int)(106.31 - 16.0f * LOG2F((float)masterVol));
}
#endif
for (int i = 0; i <= 100; i++) {
pulseWidth100To255[i] = (int)(i * 255 / 100.0f + 0.5f);
//synth->printDebug("%d: %d", i, pulseWidth100To255[i]);
}
// The LA32 chip presumably has such a table inside as the internal computaions seem to be performed using fixed point math with 12-bit fractions
for (int i = 0; i < 4096; i++) {
exp2[i] = EXP2F(i / 4096.0f);
}
// found from sample analysis
resAmpFadeFactor[7] = 1.0f / 8.0f;
resAmpFadeFactor[6] = 2.0f / 8.0f;
resAmpFadeFactor[5] = 3.0f / 8.0f;
resAmpFadeFactor[4] = 5.0f / 8.0f;
resAmpFadeFactor[3] = 8.0f / 8.0f;
resAmpFadeFactor[2] = 12.0f / 8.0f;
resAmpFadeFactor[1] = 16.0f / 8.0f;
resAmpFadeFactor[0] = 31.0f / 8.0f;
for (int i = 0; i < 5120; i++) {
sinf10[i] = sin(FLOAT_PI * i / 2048.0f);
}
}
Tables::Tables() {
for (int lf = 0; lf <= 100; lf++) {
// CONFIRMED:KG: This matches a ROM table found by Mok
float fVal = (2.0f - LOG10F(float(lf) + 1.0f)) * 128.0f;
int val = int(fVal + 1.0);
if (val > 255) {
val = 255;
}
levelToAmpSubtraction[lf] = Bit8u(val);
}
envLogarithmicTime[0] = 64;
for (int lf = 1; lf <= 255; lf++) {
// CONFIRMED:KG: This matches a ROM table found by Mok
envLogarithmicTime[lf] = Bit8u(ceil(64.0f + LOG2F(float(lf)) * 8.0f));
}
#if 0
// The table below is to be used in conjunction with emulation of VCA of newer generation units which is currently missing.
// These relatively small values are rather intended to fine-tune the overall amplification of the VCA.
// CONFIRMED: Based on a table found by Mok in the LAPC-I control ROM
// Note that this matches the MT-32 table, but with the values clamped to a maximum of 8.
memset(masterVolToAmpSubtraction, 8, 71);
memset(masterVolToAmpSubtraction + 71, 7, 3);
memset(masterVolToAmpSubtraction + 74, 6, 4);
memset(masterVolToAmpSubtraction + 78, 5, 3);
memset(masterVolToAmpSubtraction + 81, 4, 4);
memset(masterVolToAmpSubtraction + 85, 3, 3);
memset(masterVolToAmpSubtraction + 88, 2, 4);
memset(masterVolToAmpSubtraction + 92, 1, 4);
memset(masterVolToAmpSubtraction + 96, 0, 5);
#else
// CONFIRMED: Based on a table found by Mok in the MT-32 control ROM
masterVolToAmpSubtraction[0] = 255;
for (int masterVol = 1; masterVol <= 100; masterVol++) {
masterVolToAmpSubtraction[masterVol] = Bit8u(106.31 - 16.0f * LOG2F(float(masterVol)));
}
#endif
for (int i = 0; i <= 100; i++) {
pulseWidth100To255[i] = Bit8u(i * 255 / 100.0f + 0.5f);
//synth->printDebug("%d: %d", i, pulseWidth100To255[i]);
}
// The LA32 chip contains an exponent table inside. The table contains 12-bit integer values.
// The actual table size is 512 rows. The 9 higher bits of the fractional part of the argument are used as a lookup address.
// To improve the precision of computations, the lower bits are supposed to be used for interpolation as the LA32 chip also
// contains another 512-row table with inverted differences between the main table values.
for (int i = 0; i < 512; i++) {
exp9[i] = Bit16u(8191.5f - EXP2F(13.0f + ~i / 512.0f));
}
// There is a logarithmic sine table inside the LA32 chip. The table contains 13-bit integer values.
for (int i = 1; i < 512; i++) {
logsin9[i] = Bit16u(0.5f - LOG2F(sin((i + 0.5f) / 1024.0f * FLOAT_PI)) * 1024.0f);
}
// The very first value is clamped to the maximum possible 13-bit integer
logsin9[0] = 8191;
// found from sample analysis
static const Bit8u resAmpDecayFactorTable[] = {31, 16, 12, 8, 5, 3, 2, 1};
resAmpDecayFactor = resAmpDecayFactorTable;
}