--- /dev/null
+#include <cstdint>
+using float32_t = float;
+
+typedef struct
+{
+ uint16_t numTaps; /**< number of filter coefficients in the filter. */
+ float32_t *pState; /**< points to the state variable array. The array is of length numTaps+blockSize-1. */
+ float32_t *pCoeffs; /**< points to the coefficient array. The array is of length numTaps. */
+} arm_fir_instance_f32;
+
+static void arm_fir_f32(const arm_fir_instance_f32 * S, float32_t * pSrc, float32_t * pDst, uint32_t blockSize);
+
+adcsample_t *process_data(adcsample_t *samples, unsigned int size)
+{
+ // 1. Define our array sizes (Be sure to set Run > Set buffer size... to below value!)
+ constexpr unsigned int buffer_size = 500;
+ constexpr unsigned int filter_size = 100;
+
+ // 2. Define our filter and the working arrays
+ static float filter[filter_size] = {
+ .01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,
+ .01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,
+ .01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,
+ .01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,
+ .01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,
+ .01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,
+ .01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,
+ .01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,
+ .01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,
+ .01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f,.01f
+ };
+ static float input[buffer_size];
+ static float output[buffer_size];
+ static float working[buffer_size + filter_size];
+
+ // 3. Scale 0-4095 interger sample values to +/- 1.0 floats
+ for (unsigned int i = 0; i < size; i++)
+ input[i] = (samples[i] - 2048) / 2048.f;
+
+ // 4. Compute the FIR
+ arm_fir_instance_f32 fir { filter_size, working, filter };
+ arm_fir_f32(&fir, input, output, size);
+
+ // 5. Convert float results back to 0-4095 range for output
+ for (unsigned int i = 0; i < size; i++)
+ samples[i] = output[i] * 2048.f + 2048;
+
+ return samples;
+}
+
+// Below taken from the CMSIS DSP Library (find it on GitHub)
+void arm_fir_f32(
+ const arm_fir_instance_f32 * S,
+ float32_t * pSrc,
+ float32_t * pDst,
+ uint32_t blockSize)
+{
+ float32_t *pState = S->pState; /* State pointer */
+ float32_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
+ float32_t *pStateCurnt; /* Points to the current sample of the state */
+ float32_t *px, *pb; /* Temporary pointers for state and coefficient buffers */
+ float32_t acc0, acc1, acc2, acc3, acc4, acc5, acc6, acc7; /* Accumulators */
+ float32_t x0, x1, x2, x3, x4, x5, x6, x7, c0; /* Temporary variables to hold state and coefficient values */
+ uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
+ uint32_t i, tapCnt, blkCnt; /* Loop counters */
+ float32_t p0,p1,p2,p3,p4,p5,p6,p7; /* Temporary product values */
+
+ /* S->pState points to state array which contains previous frame (numTaps - 1) samples */
+ /* pStateCurnt points to the location where the new input data should be written */
+ pStateCurnt = &(S->pState[(numTaps - 1u)]);
+
+ /* Apply loop unrolling and compute 8 output values simultaneously.
+ * The variables acc0 ... acc7 hold output values that are being computed:
+ *
+ * acc0 = b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0]
+ * acc1 = b[numTaps-1] * x[n-numTaps] + b[numTaps-2] * x[n-numTaps-1] + b[numTaps-3] * x[n-numTaps-2] +...+ b[0] * x[1]
+ * acc2 = b[numTaps-1] * x[n-numTaps+1] + b[numTaps-2] * x[n-numTaps] + b[numTaps-3] * x[n-numTaps-1] +...+ b[0] * x[2]
+ * acc3 = b[numTaps-1] * x[n-numTaps+2] + b[numTaps-2] * x[n-numTaps+1] + b[numTaps-3] * x[n-numTaps] +...+ b[0] * x[3]
+ */
+ blkCnt = blockSize >> 3;
+
+ /* First part of the processing with loop unrolling. Compute 8 outputs at a time.
+ ** a second loop below computes the remaining 1 to 7 samples. */
+ while(blkCnt > 0u)
+ {
+ /* Copy four new input samples into the state buffer */
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+
+ /* Set all accumulators to zero */
+ acc0 = 0.0f;
+ acc1 = 0.0f;
+ acc2 = 0.0f;
+ acc3 = 0.0f;
+ acc4 = 0.0f;
+ acc5 = 0.0f;
+ acc6 = 0.0f;
+ acc7 = 0.0f;
+
+ /* Initialize state pointer */
+ px = pState;
+
+ /* Initialize coeff pointer */
+ pb = (pCoeffs);
+
+ /* This is separated from the others to avoid
+ * a call to __aeabi_memmove which would be slower
+ */
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+
+ /* Read the first seven samples from the state buffer: x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2] */
+ x0 = *px++;
+ x1 = *px++;
+ x2 = *px++;
+ x3 = *px++;
+ x4 = *px++;
+ x5 = *px++;
+ x6 = *px++;
+
+ /* Loop unrolling. Process 8 taps at a time. */
+ tapCnt = numTaps >> 3u;
+
+ /* Loop over the number of taps. Unroll by a factor of 8.
+ ** Repeat until we've computed numTaps-8 coefficients. */
+ while(tapCnt > 0u)
+ {
+ /* Read the b[numTaps-1] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-3] sample */
+ x7 = *(px++);
+
+ /* acc0 += b[numTaps-1] * x[n-numTaps] */
+ p0 = x0 * c0;
+
+ /* acc1 += b[numTaps-1] * x[n-numTaps-1] */
+ p1 = x1 * c0;
+
+ /* acc2 += b[numTaps-1] * x[n-numTaps-2] */
+ p2 = x2 * c0;
+
+ /* acc3 += b[numTaps-1] * x[n-numTaps-3] */
+ p3 = x3 * c0;
+
+ /* acc4 += b[numTaps-1] * x[n-numTaps-4] */
+ p4 = x4 * c0;
+
+ /* acc1 += b[numTaps-1] * x[n-numTaps-5] */
+ p5 = x5 * c0;
+
+ /* acc2 += b[numTaps-1] * x[n-numTaps-6] */
+ p6 = x6 * c0;
+
+ /* acc3 += b[numTaps-1] * x[n-numTaps-7] */
+ p7 = x7 * c0;
+
+ /* Read the b[numTaps-2] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-4] sample */
+ x0 = *(px++);
+
+ acc0 += p0;
+ acc1 += p1;
+ acc2 += p2;
+ acc3 += p3;
+ acc4 += p4;
+ acc5 += p5;
+ acc6 += p6;
+ acc7 += p7;
+
+
+ /* Perform the multiply-accumulate */
+ p0 = x1 * c0;
+ p1 = x2 * c0;
+ p2 = x3 * c0;
+ p3 = x4 * c0;
+ p4 = x5 * c0;
+ p5 = x6 * c0;
+ p6 = x7 * c0;
+ p7 = x0 * c0;
+
+ /* Read the b[numTaps-3] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-5] sample */
+ x1 = *(px++);
+
+ acc0 += p0;
+ acc1 += p1;
+ acc2 += p2;
+ acc3 += p3;
+ acc4 += p4;
+ acc5 += p5;
+ acc6 += p6;
+ acc7 += p7;
+
+ /* Perform the multiply-accumulates */
+ p0 = x2 * c0;
+ p1 = x3 * c0;
+ p2 = x4 * c0;
+ p3 = x5 * c0;
+ p4 = x6 * c0;
+ p5 = x7 * c0;
+ p6 = x0 * c0;
+ p7 = x1 * c0;
+
+ /* Read the b[numTaps-4] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-6] sample */
+ x2 = *(px++);
+
+ acc0 += p0;
+ acc1 += p1;
+ acc2 += p2;
+ acc3 += p3;
+ acc4 += p4;
+ acc5 += p5;
+ acc6 += p6;
+ acc7 += p7;
+
+ /* Perform the multiply-accumulates */
+ p0 = x3 * c0;
+ p1 = x4 * c0;
+ p2 = x5 * c0;
+ p3 = x6 * c0;
+ p4 = x7 * c0;
+ p5 = x0 * c0;
+ p6 = x1 * c0;
+ p7 = x2 * c0;
+
+ /* Read the b[numTaps-4] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-6] sample */
+ x3 = *(px++);
+
+ acc0 += p0;
+ acc1 += p1;
+ acc2 += p2;
+ acc3 += p3;
+ acc4 += p4;
+ acc5 += p5;
+ acc6 += p6;
+ acc7 += p7;
+
+ /* Perform the multiply-accumulates */
+ p0 = x4 * c0;
+ p1 = x5 * c0;
+ p2 = x6 * c0;
+ p3 = x7 * c0;
+ p4 = x0 * c0;
+ p5 = x1 * c0;
+ p6 = x2 * c0;
+ p7 = x3 * c0;
+
+ /* Read the b[numTaps-4] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-6] sample */
+ x4 = *(px++);
+
+ acc0 += p0;
+ acc1 += p1;
+ acc2 += p2;
+ acc3 += p3;
+ acc4 += p4;
+ acc5 += p5;
+ acc6 += p6;
+ acc7 += p7;
+
+ /* Perform the multiply-accumulates */
+ p0 = x5 * c0;
+ p1 = x6 * c0;
+ p2 = x7 * c0;
+ p3 = x0 * c0;
+ p4 = x1 * c0;
+ p5 = x2 * c0;
+ p6 = x3 * c0;
+ p7 = x4 * c0;
+
+ /* Read the b[numTaps-4] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-6] sample */
+ x5 = *(px++);
+
+ acc0 += p0;
+ acc1 += p1;
+ acc2 += p2;
+ acc3 += p3;
+ acc4 += p4;
+ acc5 += p5;
+ acc6 += p6;
+ acc7 += p7;
+
+ /* Perform the multiply-accumulates */
+ p0 = x6 * c0;
+ p1 = x7 * c0;
+ p2 = x0 * c0;
+ p3 = x1 * c0;
+ p4 = x2 * c0;
+ p5 = x3 * c0;
+ p6 = x4 * c0;
+ p7 = x5 * c0;
+
+ /* Read the b[numTaps-4] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-6] sample */
+ x6 = *(px++);
+
+ acc0 += p0;
+ acc1 += p1;
+ acc2 += p2;
+ acc3 += p3;
+ acc4 += p4;
+ acc5 += p5;
+ acc6 += p6;
+ acc7 += p7;
+
+ /* Perform the multiply-accumulates */
+ p0 = x7 * c0;
+ p1 = x0 * c0;
+ p2 = x1 * c0;
+ p3 = x2 * c0;
+ p4 = x3 * c0;
+ p5 = x4 * c0;
+ p6 = x5 * c0;
+ p7 = x6 * c0;
+
+ tapCnt--;
+
+ acc0 += p0;
+ acc1 += p1;
+ acc2 += p2;
+ acc3 += p3;
+ acc4 += p4;
+ acc5 += p5;
+ acc6 += p6;
+ acc7 += p7;
+ }
+
+ /* If the filter length is not a multiple of 8, compute the remaining filter taps */
+ tapCnt = numTaps % 0x8u;
+
+ while(tapCnt > 0u)
+ {
+ /* Read coefficients */
+ c0 = *(pb++);
+
+ /* Fetch 1 state variable */
+ x7 = *(px++);
+
+ /* Perform the multiply-accumulates */
+ p0 = x0 * c0;
+ p1 = x1 * c0;
+ p2 = x2 * c0;
+ p3 = x3 * c0;
+ p4 = x4 * c0;
+ p5 = x5 * c0;
+ p6 = x6 * c0;
+ p7 = x7 * c0;
+
+ /* Reuse the present sample states for next sample */
+ x0 = x1;
+ x1 = x2;
+ x2 = x3;
+ x3 = x4;
+ x4 = x5;
+ x5 = x6;
+ x6 = x7;
+
+ acc0 += p0;
+ acc1 += p1;
+ acc2 += p2;
+ acc3 += p3;
+ acc4 += p4;
+ acc5 += p5;
+ acc6 += p6;
+ acc7 += p7;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+ /* Advance the state pointer by 8 to process the next group of 8 samples */
+ pState = pState + 8;
+
+ /* The results in the 8 accumulators, store in the destination buffer. */
+ *pDst++ = acc0;
+ *pDst++ = acc1;
+ *pDst++ = acc2;
+ *pDst++ = acc3;
+ *pDst++ = acc4;
+ *pDst++ = acc5;
+ *pDst++ = acc6;
+ *pDst++ = acc7;
+
+ blkCnt--;
+ }
+
+ /* If the blockSize is not a multiple of 8, compute any remaining output samples here.
+ ** No loop unrolling is used. */
+ blkCnt = blockSize % 0x8u;
+
+ while(blkCnt > 0u)
+ {
+ /* Copy one sample at a time into state buffer */
+ *pStateCurnt++ = *pSrc++;
+
+ /* Set the accumulator to zero */
+ acc0 = 0.0f;
+
+ /* Initialize state pointer */
+ px = pState;
+
+ /* Initialize Coefficient pointer */
+ pb = (pCoeffs);
+
+ i = numTaps;
+
+ /* Perform the multiply-accumulates */
+ do
+ {
+ acc0 += *px++ * *pb++;
+ i--;
+
+ } while(i > 0u);
+
+ /* The result is store in the destination buffer. */
+ *pDst++ = acc0;
+
+ /* Advance state pointer by 1 for the next sample */
+ pState = pState + 1;
+
+ blkCnt--;
+ }
+
+ /* Processing is complete.
+ ** Now copy the last numTaps - 1 samples to the start of the state buffer.
+ ** This prepares the state buffer for the next function call. */
+
+ /* Points to the start of the state buffer */
+ pStateCurnt = S->pState;
+
+ tapCnt = (numTaps - 1u) >> 2u;
+
+ /* copy data */
+ while(tapCnt > 0u)
+ {
+ *pStateCurnt++ = *pState++;
+ *pStateCurnt++ = *pState++;
+ *pStateCurnt++ = *pState++;
+ *pStateCurnt++ = *pState++;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+ /* Calculate remaining number of copies */
+ tapCnt = (numTaps - 1u) % 0x4u;
+
+ /* Copy the remaining q31_t data */
+ while(tapCnt > 0u)
+ {
+ *pStateCurnt++ = *pState++;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+}
projects / clyne / stmdsp.git / commitdiff