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(CONVOLVE-ALG
(NAME "convolve")
(SUPPORT-FUNCTIONS "
void h_reverse(sample_type *h, long len)
{
sample_type temp;
int i;
for (i = 0; i < len; i++) {
temp = h[i];
h[i] = h[len - 1];
h[len - 1] = temp;
len--;
}
}
")
(ARGUMENTS ("sound_type" "x_snd") ("sound_type" "h_snd") )
(TABLE "h_snd")
(START (MIN x_snd))
(NOT-IN-INNER-LOOP "h_snd")
(STATE
("table_type" "table" "sound_to_table(h_snd)")
("sample_type *" "h_buf" "susp->table->samples")
("double" "length_of_h" "susp->table->length")
("long" "h_len" "(long) susp->length_of_h;
h_reverse(susp->h_buf, susp->h_len)")
("long" "x_buf_len" "2 * susp->h_len")
("sample_type *" "x_buffer_pointer"
"calloc((2 * (susp->h_len)), sizeof(float))")
("sample_type *" "x_buffer_current" "susp->x_buffer_pointer") )
(ALWAYS-SCALE x_snd)
(TERMINATE (MIN x_snd))
(LOGICAL-STOP (MIN x_snd))
(INNER-LOOP-LOCALS
"long i; double sum;")
(INNER-LOOP "
/* see if we've reached end of x_buffer */
if ((x_buffer_pointer + x_buf_len) <= (x_buffer_current + h_len)) {
/* shift x_buffer from current back to base */
for (i = 1; i < h_len; i++) {
x_buffer_pointer[i-1] = x_buffer_current[i];
}
/* this will be incremented back to x_buffer_pointer below */
x_buffer_current = x_buffer_pointer - 1;
}
x_buffer_current++;
x_buffer_current[h_len - 1] = x_snd;
sum = 0.0;
for (i = 0; i < h_len; i++) {
sum += x_buffer_current[i] * h_buf[i];
}
output = (sample_type) sum;
")
(CONSTANT "h_buf" "h_len" "x_buf_len" "table")
(SAMPLE-RATE "x_snd->sr")
(FINALIZATION " table_unref(susp->table);
free(susp->x_buffer_pointer);")
)
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