示例#1
1
void AMDemod::update(void)
{
  if (!pass) return;

  audio_block_t *blocki, *blockq;
  int16_t *pi, *pq, *end;
  int32_t sum;
	
  blocki = receiveWritable(0); // receives I, end result is written in channel 0
  blockq = receiveReadOnly(1); // receives Q
  
  if (!blocki) {
    if (blockq) release(blockq);
    return;
  }
  
  if (!blockq) {
    release(blocki);
    return;
  }
  
  pi = (int16_t *)(blocki->data);
  pq = (int16_t *)(blockq->data);
  end = pi + AUDIO_BLOCK_SAMPLES;

  while (pi < end) {
    // square and sum I and Q
    sum = *pi * *pi;
    sum += *pq * *pq;
    // The result of squaring a 1.15 is 2.30.
    // Shift the sum up one bit to make it 1.31 (Q31)
    // and then that becomes the input to the arm sqrt function
    sum <<= 1;
    arm_sqrt_q31((q31_t)sum,(q31_t *) &sum);
    // The result is in the high order 16 bits of sum
    *pi++ = sum >> 16;
    pq++;    
  }
  transmit(blocki);
  release(blocki);
  release(blockq);
}
示例#2
0
void arm_rms_q31(
  q31_t * pSrc,
  uint32_t blockSize,
  q31_t * pResult)
{
  q63_t sum = 0;                                 /* accumulator */
  q31_t in;                                      /* Temporary variable to store the input */
  uint32_t blkCnt;                               /* loop counter */

#ifndef ARM_MATH_CM0

  /* Run the below code for Cortex-M4 and Cortex-M3 */

  q31_t in1, in2, in3, in4;                      /* Temporary input variables */

  /*loop Unrolling */
  blkCnt = blockSize >> 2u;

  /* 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)
  {
    /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
    /* Compute sum of the squares and then store the result in a temporary variable, sum */
    /* read two samples from source buffer */
    in1 = pSrc[0];
    in2 = pSrc[1];

    /* calculate power and accumulate to accumulator */
    sum += (q63_t) in1 *in1;
    sum += (q63_t) in2 *in2;

    /* read two samples from source buffer */
    in3 = pSrc[2];
    in4 = pSrc[3];

    /* calculate power and accumulate to accumulator */
    sum += (q63_t) in3 *in3;
    sum += (q63_t) in4 *in4;


    /* update source buffer to process next samples */
    pSrc += 4u;

    /* Decrement the loop counter */
    blkCnt--;
  }

  /* If the blockSize is not a multiple of 8, compute any remaining output samples here.        
   ** No loop unrolling is used. */
  blkCnt = blockSize % 0x4u;

#else

  /* Run the below code for Cortex-M0 */
  blkCnt = blockSize;

#endif /* #ifndef ARM_MATH_CM0 */

  while(blkCnt > 0u)
  {
    /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
    /* Compute sum of the squares and then store the results in a temporary variable, sum */
    in = *pSrc++;
    sum += (q63_t) in *in;

    /* Decrement the loop counter */
    blkCnt--;
  }

  /* Convert data in 2.62 to 1.31 by 31 right shifts and saturate */

  sum = __SSAT(sum >> 31, 31);


  /* Compute Rms and store the result in the destination vector */
  arm_sqrt_q31((q31_t) ((q31_t) sum / (int32_t) blockSize), pResult);
}