ptablei — Accesses table values by direct indexing with linear interpolation.
ares ptablei andx, ifn [, ixmode] [, ixoff] [, iwrap]
ires ptablei indx, ifn [, ixmode] [, ixoff] [, iwrap]
kres ptablei kndx, ifn [, ixmode] [, ixoff] [, iwrap]
ifn -- function table number. The table need not be a power of 2 long.
ixmode (optional) -- index data mode. The default value is 0.
0 = raw index
1 = normalized (0 to 1)
ixoff (optional) -- amount by which index is to be offset. For a table with origin at center, use tablesize/2 (raw) or .5 (normalized). The default value is 0.
iwrap (optional) -- wraparound index flag. The default value is 0.
0 = nowrap (index < 0 treated as index=0; index > tablesize sticks at index=size)
1 = wraparound.
ptablei is a interpolating unit in which the fractional part of index is used to interpolate between adjacent table entries. The smoothness gained by interpolation is at some small cost in execution time (see also oscili, etc.), but the interpolating and non-interpolating units are otherwise interchangeable.
Here is an example of the ptablei opcode. It uses the file ptablei.csd.
Example 1338. Example of the ptablei opcode.
See the sections Real-time Audio and Command Line Flags for more information on using command line flags.
<CsoundSynthesizer> <CsOptions> ; Select audio/midi flags here according to platform -odac ;;;realtime audio out ;-iadc ;;;uncomment -iadc if realtime audio input is needed too ; For Non-realtime ouput leave only the line below: ; -o tablei.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> sr = 44100 ksmps = 32 nchnls = 2 0dbfs = 1 seed 0 ;generate new values every time the instr is played instr 1 ifn = p4 isize = p5 ithresh = 0.5 itemp ftgen ifn, 0, isize, 21, 2 iwrite_value = 0 i_index = 0 loop_start: iread_value ptablei i_index, ifn if iread_value > ithresh then iwrite_value = 1 else iwrite_value = -1 endif ptableiw iwrite_value, i_index, ifn loop_lt i_index, 1, isize, loop_start turnoff endin instr 2 ifn = p4 isize = ftlen(ifn) prints "Index\tValue\n" i_index = 0 loop_start: ivalue tablei i_index, ifn prints "%d:\t%f\n", i_index, ivalue loop_lt i_index, 1, isize, loop_start ;read table 1 with our index aout oscili .5, 100, ifn ;use table to play the polypulse outs aout, aout endin </CsInstruments> <CsScore> i 1 0 1 100 16 i 2 0 2 100 e </CsScore> </CsoundSynthesizer>