先前測試了FFT的使用，接下來進行FIR的測試， 目前已將C6accel程式清空，主程式只保留DSP調用需要的部分， 將測試碼獨立為一個副程式，才不會不小心把主程式搞壞，
測試代碼如下所示: int c6accel_test_FIR(C6accel_Handle hC6accel,unsigned int nr,unsigned int nh) { float fc=(float)8000.0/16000.0; short *xArray16, *hArray16, *yArray16; int i; float j,k,l; unsigned int nx = nr+nh-1; float nWaves=3.5; // C6accel_DSP_fir_gen() test xArray16 = (short *)pSrcBuf_16bpp; hArray16 = (short *)pWorkingBuf_16bpp; yArray16 = (short *)pOutBuf_16bpp; //create nWaves cosine wave with Q.15format in nx point for (i = 0; i < nx; i++ ) { xArray16[i] = (short) (cos(2.0*PI*nWaves*i/nx)*32767);} printf(" %f cosine wave in 120 data are : ",nWaves); showData(xArray16,nx); for (i = 0; i < nh; i++ ) { l=i; if ( nh%2 != 0) { l = l-(nh-1)/2.0; } //add else { l = l-(nh /2.0)+0.5 ; } //even j = sin(l*2.0*PI*fc)/(float)(l*PI); // ideal coefficients k = 0.54+0.46*cos(2.0*PI*l/(float)nh); //Hamming window printf("ideal coeff = %1.4f , Hamming = %1.4f, d=%1.4f ",j,k,j*k); j=j*k*32767; // transfor to Q.15 hArray16[i] = (short) j; } printf(" ideal coefficients * Hamming windows parameter are : "); showData(hArray16,nh); // Clear output arrays before tests begins memset (pOutBuf_16bpp,0x0000, nr); // Call the DSP_fir_gen function in C6Accel C6accel_DSP_fir_gen(hC6accel,xArray16, hArray16, yArray16, nh, nr ); if (C6Accel_readCallType(hC6accel) == ASYNC) { C6accel_waitAsyncCall(hC6accel); } // Now wait for the callback printf(" Data after hamming window are : "); showData(yArray16,nr); // Clear output arrays memset (pOutBuf_16bpp,0x0000, nr); C6accel_DSP_fir_r4(hC6accel,xArray16, hArray16, yArray16, nh, nr ); if (C6Accel_readCallType(hC6accel) == ASYNC) { C6accel_waitAsyncCall(hC6accel); } // Now wait for the callback printf(" Data after hamming window are : "); showData(yArray16,nr); // Clear output arrays memset (pOutBuf_16bpp,0x00, nr*sizeof(short)); C6accel_DSP_fir_r8(hC6accel,xArray16, hArray16, yArray16,nh,nr); if (C6Accel_readCallType(hC6accel) == ASYNC) { C6accel_waitAsyncCall(hC6accel); } // Now wait for the callback printf(" Data after hamming window are : "); showData(yArray16,nr); printf(" END of FIR Filtering functions test "); return (1); }
產生 3.5 個cosine 波型 並且加入 8位的Hamming Windows 的FIR濾波器，此方式可使用較少位數的窗函數進行連續移動的濾波轉換， 或是可改用其他濾波器（高通或低通效果），使用DSP進行（半？）即時的濾波轉換。