Waveshape generator for electronic musical instruments

DETAILED DESCRIPTION We claim: 1.
A waveshape generator for an electronic musical instrument, comprising: address signal generating means for generating a sequence of first address signals, each of said first address signals including an integer part and a fractional part, said integer part being a non-negative integer I and said fractional part being any one of a discrete number of fractional values 0.
ltoreq.
e<1; waveshape memory means for storing a desired waveshape f(x) in the form of m discrete sample values f(i), i=1, 2, .
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, m, each of said sample values f(i) representing the magnitude of said desired waveshape f(x) at a respective discrete location x=i on said waveshape, m being a positive integer; and sum forming means electrically connected to said address signal generator means and to said waveshape memory means, said sum forming means for forming the sum ##EQU6## for each of said first address signals generated by said address signal generating means, A.
sub.
k (e) being the coefficient values for an nth-order interpolation method of calculating the value f(I+e) from n+1 of said discrete sample values f(i) of said waveshape f(x), wherein f(I+e) is the magnitude of the waveshape f(x) at the point x=I+e, f(I+k) being the magnitude of that said discrete sample value f(i) corresponding to the sampling point i=I+k, n being a positive integer.
2.
A waveshape generator according to claim 1, wherein said sum-forming means comprises a coefficient memory means for storing said nth-order interpolation coefficient values A.
sub.
k (e) for each of said fractional values e.
3.
A waveshape generator according to claim 2, wherein said sum-forming means comprises: means for causing said waveshape memory means to sequentially output said n+1 stored sample values f(I+k) (K=0, 1, .
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,n); and multiplier means for sequentially multiplying each of said n+1 values f(I+k) by a respective one of said n+1 coefficient values A.
sub.
k (e) corresponding to said fractional value e.
4.
A waveshape generator according to claim 3, wherein said sum-forming means further comprises accumulator means for adding said n+1 products output by said multiplier means to form said sum