[linux-audio-dev] How hard is it to write a pitch shifter?

Im new to audio dev and to linux and am using SoundTracker as my Fruiyloops replacement. I have done a _little_ bit of dsp programming, but really want to learn more - hence this question! I love trackers, and use them to nut out ideas. I record loops in to soundtracker from my record player, and if it works in the song then I record them agin with Rezound to do necessary processing from there. But ST doesnt support plugins, and I need to be able to do a "quick and dirty" pitchshift on the samples to see if it's gunna fit musically in the track. I tracked down a bit of code in ST that does a simple fade of the currently selected data. I want to change this to do a basic pitchshift. p = current_sample->sample.data; p += ss; for(i = 0; i < se - ss; i++) { //ss = selection start, se= selection end. double q = *p; q *= THE PITCH SHIFTED SAMPLE MAGIC! *p++ = CLAMP((int)q, -32768, +32767); } I found and implemented this bit of code for resampling, which changes the pitch, but also the time for(i=0; i <= MaxSamples; i++) { processed_buf[i]= unprocessed_buf[(int) j]; j = j + pitch; if (j > MaxSamples) break; } But I cant find out how to deal with the missing data that is removed - to keep the original length. Is there a (n easy) way to do this? I really dont care too much about artifacts as it is just to get an idea of the loop at that pitch. or should I skip pitchshifters until I learn the basics?!