mirror of
https://github.com/cookiengineer/audacity
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27 lines
1.1 KiB
Plaintext
27 lines
1.1 KiB
Plaintext
(FMFB-ALG
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(NAME "fmfb")
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(ARGUMENTS ("time_type" "t0") ("double" "hz") ("rate_type" "sr")
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("double" "index") ("time_type" "d"))
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(TERMINATE (AFTER "d"))
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(STATE ("double" "yy" "0.0")
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("double" "sin_y" "0.0")
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("double" "xx" "0.0")
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("double" "x_incr"
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"hz * SINE_TABLE_LEN / sr")
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("double" "index" "index * SINE_TABLE_LEN / PI2"))
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(INNER-LOOP "xx += x_incr;
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if (xx > SINE_TABLE_LEN) xx -= SINE_TABLE_LEN;
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/* xx incremented and index scaled to table index, and
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sin_y is a signal (-1 to +1) */
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yy = xx + index * sin_y;
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/* so yy is a table index */
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while (yy > SINE_TABLE_LEN) yy -= SINE_TABLE_LEN;
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while (yy < 0) yy += SINE_TABLE_LEN;
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sin_y = sine_table[(int) yy]; /* truncation gets valid index */
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/* sin_y is now a signal not ready for table lookup */
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output = sin_y")
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(CONSTANT "x_incr")
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(SAMPLE-RATE "sr")
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(SUPPORT-HEADER "#include \"sine.h\" /* sine_table and SINE_TABLE_LEN */\n")
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)
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