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<objdefs>
<obj.normal id="pitch detect 128" uuid="89eda14ecd003f22288812e9843218f2d020b7ad" sha="e1ec4fbea98f37a5be48b1f7d3522ed1f7fe3229">
<sDescription>spectral analyzer display using 128 input points fft</sDescription>
<author>Johannes Taelman, Ricardo Wurmus</author>
<license>BSD</license>
<inlets>
<frac32buffer name="in" description="input"/>
<bool32 name="hold" description="hold"/>
</inlets>
<outlets>
<int32 name="pitch" description="pitch"/>
</outlets>
<params/>
<attribs/>
<code.declaration><![CDATA[
#define N 128
int32_t inbuf[N];
int32_t outbuf[N];
// must be twice as wide because the result is
// stored like {real[0], imag[0], real[1], imag[1]...}
int32_t fftbuf[2*N];
arm_rfft_instance_q31 rfft;
arm_cfft_radix4_instance_q31 cfft;
int32_t state;
int32_t max_val = 0;
uint32_t max_a = 0;
/**
* @brief Maximum value of a Q31 vector.
* @param[in] *pSrc points to the input vector
* @param[in] blockSize length of the input vector
* @param[out] *pResult maximum value returned here
* @param[out] *pIndex index of maximum value returned here
* @return none.
*/
void arm_max_q31(
q31_t * pSrc,
uint32_t blockSize,
q31_t * pResult,
uint32_t * pIndex)
{
#ifndef ARM_MATH_CM0_FAMILY
/* Run the below code for Cortex-M4 and Cortex-M3 */
q31_t maxVal1, maxVal2, out; /* Temporary variables to store the output value. */
uint32_t blkCnt, outIndex, count; /* loop counter */
/* Initialise the count value. */
count = 0u;
/* Initialise the index value to zero. */
outIndex = 0u;
/* Load first input value that act as reference value for comparision */
out = *pSrc++;
/* Loop unrolling */
blkCnt = (blockSize - 1u) >> 2u;
/* Run the below code for Cortex-M4 and Cortex-M3 */
while(blkCnt > 0u)
{
/* Initialize maxVal to the next consecutive values one by one */
maxVal1 = *pSrc++;
maxVal2 = *pSrc++;
/* compare for the maximum value */
if(out < maxVal1)
{
/* Update the maximum value and its index */
out = maxVal1;
outIndex = count + 1u;
}
maxVal1 = *pSrc++;
/* compare for the maximum value */
if(out < maxVal2)
{
/* Update the maximum value and its index */
out = maxVal2;
outIndex = count + 2u;
}
maxVal2 = *pSrc++;
/* compare for the maximum value */
if(out < maxVal1)
{
/* Update the maximum value and its index */
out = maxVal1;
outIndex = count + 3u;
}
/* compare for the maximum value */
if(out < maxVal2)
{
/* Update the maximum value and its index */
out = maxVal2;
outIndex = count + 4u;
}
count += 4u;
/* Decrement the loop counter */
blkCnt--;
}
/* if (blockSize - 1u) is not multiple of 4 */
blkCnt = (blockSize - 1u) % 4u;
#else
/* Run the below code for Cortex-M0 */
q31_t maxVal1, out; /* Temporary variables to store the output value. */
uint32_t blkCnt, outIndex; /* loop counter */
/* Initialise the index value to zero. */
outIndex = 0u;
/* Load first input value that act as reference value for comparision */
out = *pSrc++;
blkCnt = (blockSize - 1u);
#endif /* #ifndef ARM_MATH_CM0_FAMILY */
while(blkCnt > 0u)
{
/* Initialize maxVal to the next consecutive values one by one */
maxVal1 = *pSrc++;
/* compare for the maximum value */
if(out < maxVal1)
{
/* Update the maximum value and it's index */
out = maxVal1;
outIndex = blockSize - blkCnt;
}
/* Decrement the loop counter */
blkCnt--;
}
/* Store the maximum value and its index into destination pointers */
*pResult = out;
*pIndex = outIndex;
}
]]></code.declaration>
<code.init><![CDATA[
int i;
for(i=0;i<N;i++) inbuf[i]=0;
for(i=0;i<N;i++) outbuf[i]=0;
state = 0;
arm_rfft_init_q31(&rfft, &cfft, N,0,1);
]]></code.init>
<code.krate><![CDATA[
if (state<N){
// fill buffer
int i;
for(i=0;i<BUFSIZE;i++) {
inbuf[state++] = inlet_in[i];
}
} else {
// compute FFT
arm_rfft_q31(&rfft, (q31_t *)inbuf, (q31_t *)fftbuf);
// compute magnitude
arm_cmplx_mag_q31(fftbuf, outbuf, N);
// second half is conjugates, so we only look at N/2
arm_max_q31(outbuf, N/2, &max_val, &max_a);
outlet_pitch = max_a;
state = 0;
}
]]></code.krate>
</obj.normal>
</objdefs>
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