mirror of
https://github.com/cookiengineer/audacity
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31 lines
1.1 KiB
Plaintext
31 lines
1.1 KiB
Plaintext
(FMFBV-ALG
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(NAME "fmfbv") ; FM feedback unit generator
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(ARGUMENTS ("time_type" "t0") ("double" "hz") ("rate_type" "sr")
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("sound_type" "index"))
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(START (MIN index))
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(TERMINATE (MIN index))
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(LOGICAL-STOP (MIN index))
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(STEP-FUNCTION index)
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(STATE ("double" "yy" "0.0")
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("double" "sin_y" "0.0")
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("double" "phase" "0.0")
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("double" "ph_incr" "hz * SINE_TABLE_LEN / sr;
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index->scale *= SINE_TABLE_LEN / PI2
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"))
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(INNER-LOOP "phase += ph_incr;
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if (phase > SINE_TABLE_LEN) phase -= SINE_TABLE_LEN;
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/* PHASE is 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 = phase + 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 ready for table lookup */
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output = sin_y")
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(CONSTANT "ph_incr")
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(SAMPLE-RATE "sr")
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(SUPPORT-HEADER "#include \"sine.h\" /* sine_table and SINE_TABLE_LEN */
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")
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)
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