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#include "fmdriver/fmdriver_common.h"
uint8_t fmdriver_fm_freq2key(uint16_t freq) {
int block = freq >> (8+3);
int f_num = freq & ((1<<(8+3))-1);
if (!f_num) return 0x00;
while (!(f_num & (1<<(8+3-1)))) {
f_num <<= 1;
block--;
}
static const uint16_t freqtab[0xc] = {
0x042e, // < 9 (a)
0x046e,
0x04b1,
0x04f9,
0x0544,
0x0595,
0x05ea,
0x0644,
0x06a3,
0x0708,
0x0773,
0x07e4,
};
int note = 0;
for (; note < 12; note++) {
if (f_num < freqtab[note]) break;
}
note += 9;
block += (note/12);
note %= 12;
if (block < 0) return 0x00;
if (block > 8) return 0x8b;
return (block << 4) | note;
}
uint8_t fmdriver_ssg_freq2key(uint16_t freq) {
if (!freq) return 0x00;
int octave = -5;
while (!(freq & 0x8000)) {
freq <<= 1;
octave++;
}
// 7987200.0 / (64*440*(2**((i+2+0.5)/12))/(1<<8))
static const uint16_t freqtab[0xc] = {
0xf57f, // > 0 (c)
0xe7b8,
0xdab7,
0xce70,
0xc2da,
0xb7ea,
0xad98,
0xa3da,
0x9aa7,
0x91f9,
0x89c8,
0x820c,
};
int note = 0;
for (; note < 12; note++) {
if (freq > freqtab[note]) break;
}
note += 11;
octave += (note/12);
note %= 12;
if (octave < 0) return 0x00;
if (octave > 8) return 0x8b;
return (octave << 4) | note;
}
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