lsp2poly

static void lsp2poly(float *lsp, float *f) {    int i, j;    f[-1] = 0.0;    f[ 0] = 1.0;#if 0    for(i=0; i<5; i++) {        int idx_lsp = 2*i;        f[i+1] = -lsp[idx_lsp]*f[i] + 2.0*f[i-1];        for(j=i; j>0; j--) {            f[j] += -lsp[idx_lsp]*f[j-1] + f[j-2];        }    }#else    f[1] = -2*lsp[0];    for(i=1; i<5; i++) {        float b = -2*lsp[2*i];        f[i+1] = b*f[i] + 2.0*f[i-1];        for(j=i; j>1; j--) {            f[j] += b*f[j-1] + f[j-2];        }	f[1]+=b;    }#endif}