Hi Stephen, The third input signal of rdtable is the read index. In your case it should be an integer signal with values in the interval [0..2047]. But in your example cnt will generate reads outside the boundaries of the table causing segfaults. In other words you should use a phasor as read index. You can have a look at osc in music.lib...
Cheers Yann Le 13/05/2014 18:08, Stephen Sinclair a écrit : > Hello, > > I've been struggling a bit with the semantics of rdtable(). I'm using > the plot.cpp architecture for testing my functions, and piping the > data into python/matplotlib for visualization. I'm not sure if I've > encountered a bug or if it is my misunderstanding of how rdtable() > works. > > Trying to create a simple "sin" wavetable oscillator, starting with > the following definitions, > > phasor = ((+(1) : %(2048)) ~_); > cnt = int(+(1) ~ _ : -(1)); > func = (_/2048*2*PI - PI) : sin; > tab = rdtable(2048, func, cnt); > > then the following process generates the phasor just fine: > > process = phasor; > result: http://imgur.com/CWPsWsw > > However, if I try to index the table, I get: > > process = phasor : tab; > result: http://imgur.com/bOokZNF > > So... it starts outputting zeros instead of the sine values, and then > segfaults after just over 2500 samples. I don't understand why, since > the definition of the phasor contains a modulo 2048. The same thing > happens if I replace the % with fmod(). > > Looking into the generated code, in the first process I get the > following compute(): > > FAUSTFLOAT* output0 = output[0]; > for (int i=0; i<count; i++) { > iRec0[0] = ((1 + iRec0[1]) % 2048); > output0[i] = (FAUSTFLOAT)iRec0[0]; > // post processing > iRec0[1] = iRec0[0]; > } > > In the second case, when the table is involved, I get: > > FAUSTFLOAT* output0 = output[0]; > for (int i=0; i<count; i++) { > iRec1[0] = (1 + iRec1[1]); > output0[i] = (FAUSTFLOAT)ftbl0[int((iRec1[0] - 1))]; > // post processing > iRec1[1] = iRec1[0]; > } > > You can see that the modulo appears to have disappeared and the table > is accessed beyond the end. I assume the compiler is trying to > optimise the modulo out of the compute() function since it is trying > to guarantee the range at compile time, but it seems wrong, and is > causing segfaults. I tried using max() and min() to guarantee the > range but these mysteriously don't appear in the compute() function > either, however they do appear in the fill() function. > > Any idea what is going on here? > > I'm working with faust/master. Wanted to try faust2 but couldn't get > it to compile. (During stage, "Linking CXX executable faust") > > thanks, > Steve > > ------------------------------------------------------------------------------ > "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE > Instantly run your Selenium tests across 300+ browser/OS combos. > Get unparalleled scalability from the best Selenium testing platform available > Simple to use. Nothing to install. Get started now for free." > http://p.sf.net/sfu/SauceLabs > _______________________________________________ > Faudiostream-devel mailing list > Faudiostream-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/faudiostream-devel > ------------------------------------------------------------------------------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE Instantly run your Selenium tests across 300+ browser/OS combos. Get unparalleled scalability from the best Selenium testing platform available Simple to use. Nothing to install. Get started now for free." http://p.sf.net/sfu/SauceLabs _______________________________________________ Faudiostream-devel mailing list Faudiostream-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/faudiostream-devel
