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