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/* logsin and exponent tables */
The OPL3 uses two look-up tables, each containing 256 entries. [https://g.co/kgs/Da1vEi4 Source]
This is strong evidence that the OPL chip produces the sound without any multiplications, using for frequency modulated (actually phase modulated) synthesis the formula:
out = exp(logsin(phase2 + exp(logsin(phase1) + gain1)) + gain2)
Exponential table:
