1 files changed, 49 insertions, 0 deletions
diff --git a/tran/tapf.alg b/tran/tapf.alg
new file mode 100644
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+++ b/tran/tapf.alg
@@ -0,0 +1,49 @@
+(TAPF-ALG
+(NAME "tapf")
+(ARGUMENTS ("sound_type" "s1") ("double" "offset") ("sound_type" "vardelay")
+           ("double" "maxdelay"))
+(INLINE-INTERPOLATION T)
+(STEP-FUNCTION "vardelay")
+(INTERNAL-SCALING vardelay)
+(ALWAYS-SCALE s1)
+(START (MAX s1 vardelay))
+(TERMINATE (MIN s1 vardelay))
+(LOGICAL-STOP (MIN s1))
+(STATE ("double" "offset" "offset * s1->sr")
+       ("double" "vdscale" "vardelay->scale * s1->sr")
+       ("long" "maxdelay" "(long)(maxdelay * s1->sr)")
+       ("long" "bufflen" "max(2, (long) (susp->maxdelay + 0.5))")
+       ("long" "index" "susp->bufflen")
+       ("sample_type *" "buffer" 
+        "(sample_type *) calloc(susp->bufflen + 1, sizeof(sample_type))"))
+(SAMPLE-RATE (MAX s1))
+(CONSTANT "maxdelay" "offset" "vdscale" "buffer")
+(INNER-LOOP-LOCALS "            long phase;
+")
+(INNER-LOOP "        phase = (long) (vardelay * vdscale + offset);
+        /* now phase should give number of samples of delay */
+        if (phase < 0) phase = 0;
+        else if (phase > maxdelay) phase = maxdelay;
+        phase = index - phase;
+        /* now phase is a location in the buffer (before modulo) */
+
+        /* Time out to update the buffer:
+         * this is a tricky buffer: buffer[0] == buffer[bufflen]
+         * the logical length is bufflen, but the actual length
+         * is bufflen + 1 to allow for a repeated sample at the
+         * end. This allows for efficient interpolation.
+         */ 
+        buffer[index++] = s1;
+        if (index >= bufflen) {
+            index = 0;
+        }
+
+        /* back to the phase calculation: 
+         * use conditional instead of modulo
+         */
+        if (phase < 0) phase += bufflen;
+        output = (sample_type) (buffer[phase]);")
+(FINALIZATION "    free(susp->buffer);
+")
+)
+