From 8a4bca986c57062e96f1e58281b3eff52a856ee6 Mon Sep 17 00:00:00 2001
From: rekado <rekado@elephly.net>
Date: Tue, 6 Sep 2016 22:13:03 +0200
Subject: Initial commit.

---
 objects/read-interp-slow.axo | 76 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 objects/read-interp-slow.axo

(limited to 'objects/read-interp-slow.axo')

diff --git a/objects/read-interp-slow.axo b/objects/read-interp-slow.axo
new file mode 100644
index 0000000..2919a1f
--- /dev/null
+++ b/objects/read-interp-slow.axo
@@ -0,0 +1,76 @@
+<objdefs>
+   <obj.normal id="read interp slow" uuid="2c605953453ac59b4f0c9fb67024ec9e61ee3376" sha="4f975ff0db958aff6c52f01f837ad750a823625c">
+      <sDescription>delay read slow, linear interpolated</sDescription>
+      <author>Johannes Taelman</author>
+      <license>BSD</license>
+      <helpPatch>delay.axh</helpPatch>
+      <inlets>
+         <frac32buffer name="time" description="delay time (fraction of total delayline size)"/>
+      </inlets>
+      <outlets>
+         <frac32buffer name="out" description="wave"/>
+      </outlets>
+      <displays/>
+      <params>
+         <frac32.u.map name="time" noLabel="true"/>
+      </params>
+      <attribs>
+         <objref name="delayname"/>
+      </attribs>
+      <code.srate><![CDATA[
+  // delay
+  // saturate the delay sum to bit 27
+  // max is 0x07FFFFF
+
+//(ash (- (ash 1 23) 1) (* -1 (- 27 15)))
+  uint32_t tmp_d =  __USAT(param_time + inlet_time,27);
+
+  // index for delayed input, strictly less than the write position in the delay line.
+  // What happens when writepos is 0?  Is the delay line really a circular buffer?
+
+  /* LENGTHPOW =>
+     256 (5.33ms)  = 8
+     512 (10.66ms) = 9
+    1024 (21.33ms) = 10
+    2048 (42.66ms) = 11
+    4096 (85.33ms) = 12
+    8192 (170ms)   = 13
+   16384 (341ms)   = 14
+   32768 (682ms)   = 15
+(/ 32768.0 48000)
+48000 = 1000ms
+
+  ,*/
+  // Example: set LENGTHPOW to 12
+  // shift tmp_d right by (- 27 12) = 15
+  // This is supposed to give a number of samples in the past, before writepos
+  // As this runs in a loop over the input buffer we have BUFSIZE samples to process.
+  // Hence (- BUFSIZE + buffer_index -1) starts at -BUFSIZE and is the last sample at the end of the srate loop.
+  uint32_t tmp_di = attr_delayname.writepos - (tmp_d>>(27-attr_delayname.LENGTHPOW+1)) - BUFSIZE + buffer_index -1;
+
+  // get delayed value from delay line
+  int32_t tmp_a1 = attr_delayname.array[tmp_di&attr_delayname.LENGTHMASK]<<16;
+  // get next delayed value from delay line
+  int32_t tmp_a2 = attr_delayname.array[(tmp_di+1)&attr_delayname.LENGTHMASK]<<16;
+
+  // ?  what does this value represent?
+  // shift tmp_d left by 18, then mask with max value.
+  uint32_t tmp_w1 = (tmp_d<<(attr_delayname.LENGTHPOW+3)) & 0x3FFFFFFF;
+
+  // ? opposite of w1
+  uint32_t tmp_w2 = (1<<30) - tmp_w1;
+
+  // is this what's happening?
+  // out = (tmp_a2 * tmp_w2) + (tmp_a1 * tmp_w1)
+
+  // multiply value with ...?
+  int32_t tmp_r = ___SMMUL(tmp_a1,tmp_w1);
+
+  // ?
+  // multiply the values from tmp_a2 and tmp_w2, then add the value of
+  // tmp_r to the most significant 32 bits of the product
+  tmp_r = ___SMMLA(tmp_a2,tmp_w2,tmp_r);
+  outlet_out= tmp_a1;//tmp_r;
+]]></code.srate>
+   </obj.normal>
+</objdefs>
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