********************************
* 周期和频率: *
********************************
PatternNote = 0..95 (0 = C-0, 95 = B-7)
<< Blah: Note = 1..96, 1 = C-0, 97 = key off >>
FineTune = -128..+127 (-128 = -1 halftone, +127 = +127/128 halftones)
RelativeTone = -96..95 (0 => C-4 = C-4)
RealNote = PatternNote + RelativeTone; (0..118, 0 = C-0, 118 = A#9)
线性频率表：
Period = 10*12*16*4 - Note*16*4 - FineTune/2;
Frequency = 8363*2^((6*12*16*4 - Period) / (12*16*4));
Amiga频率表：
Period = (PeriodTab[(Note MOD 12)*8 + FineTune/16]*(1-Frac(FineTune/16)) +
PeriodTab[(Note MOD 12)*8 + FineTune/16]*(Frac(FineTune/16)))
*16/2^(Note DIV 12);
(The period is interpolated for finer finetune values)
Frequency = 8363*1712/Period;
<<由于以下原因，上面的插值代码不起作用几个原因：
1.它不插值（尝试将1添加到第二行的PeriodTab索引）
2.它可能会从表开始变成负数微调值 写你自己的插值程序-没那么难。>>
PeriodTab = Array[0..12*8-1] of Word = (
907,900,894,887,881,875,868,862,856,850,844,838,832,826,820,814,
808,802,796,791,785,779,774,768,762,757,752,746,741,736,730,725,
720,715,709,704,699,694,689,684,678,675,670,665,660,655,651,646,
640,636,632,628,623,619,614,610,604,601,597,592,588,584,580,575,
570,567,563,559,555,551,547,543,538,535,532,528,524,520,516,513,
508,505,502,498,494,491,487,484,480,477,474,470,467,463,460,457);