CMSISDSP
Version 1.5.2
CMSIS DSP Software Library

Functions  
void  arm_fir_f32 (const arm_fir_instance_f32 *S, float32_t *pSrc, float32_t *pDst, uint32_t blockSize) 
Processing function for the floatingpoint FIR filter. More...  
void  arm_fir_fast_q15 (const arm_fir_instance_q15 *S, q15_t *pSrc, q15_t *pDst, uint32_t blockSize) 
Processing function for the fast Q15 FIR filter for CortexM3 and CortexM4. More...  
IAR_ONLY_LOW_OPTIMIZATION_ENTER void  arm_fir_fast_q31 (const arm_fir_instance_q31 *S, q31_t *pSrc, q31_t *pDst, uint32_t blockSize) 
Processing function for the fast Q31 FIR filter for CortexM3 and CortexM4. More...  
void  arm_fir_init_f32 (arm_fir_instance_f32 *S, uint16_t numTaps, float32_t *pCoeffs, float32_t *pState, uint32_t blockSize) 
Initialization function for the floatingpoint FIR filter. More...  
arm_status  arm_fir_init_q15 (arm_fir_instance_q15 *S, uint16_t numTaps, q15_t *pCoeffs, q15_t *pState, uint32_t blockSize) 
Initialization function for the Q15 FIR filter. More...  
void  arm_fir_init_q31 (arm_fir_instance_q31 *S, uint16_t numTaps, q31_t *pCoeffs, q31_t *pState, uint32_t blockSize) 
Initialization function for the Q31 FIR filter. More...  
void  arm_fir_init_q7 (arm_fir_instance_q7 *S, uint16_t numTaps, q7_t *pCoeffs, q7_t *pState, uint32_t blockSize) 
Initialization function for the Q7 FIR filter. More...  
void  arm_fir_q15 (const arm_fir_instance_q15 *S, q15_t *pSrc, q15_t *pDst, uint32_t blockSize) 
Processing function for the Q15 FIR filter. More...  
void  arm_fir_q31 (const arm_fir_instance_q31 *S, q31_t *pSrc, q31_t *pDst, uint32_t blockSize) 
Processing function for the Q31 FIR filter. More...  
void  arm_fir_q7 (const arm_fir_instance_q7 *S, q7_t *pSrc, q7_t *pDst, uint32_t blockSize) 
Processing function for the Q7 FIR filter. More...  
This set of functions implements Finite Impulse Response (FIR) filters for Q7, Q15, Q31, and floatingpoint data types. Fast versions of Q15 and Q31 are also provided. The functions operate on blocks of input and output data and each call to the function processes blockSize
samples through the filter. pSrc
and pDst
points to input and output arrays containing blockSize
values.
b[n]
is multiplied by a state variable which equals a previous input sample x[n]
. y[n] = b[0] * x[n] + b[1] * x[n1] + b[2] * x[n2] + ...+ b[numTaps1] * x[nnumTaps+1]
pCoeffs
points to a coefficient array of size numTaps
. Coefficients are stored in time reversed order. {b[numTaps1], b[numTaps2], b[N2], ..., b[1], b[0]}
pState
points to a state array of size numTaps + blockSize  1
. Samples in the state buffer are stored in the following order. {x[nnumTaps+1], x[nnumTaps], x[nnumTaps1], x[nnumTaps2]....x[0], x[1], ..., x[blockSize1]}
blockSize1
. The increased state buffer length allows circular addressing, which is traditionally used in the FIR filters, to be avoided and yields a significant speed improvement. The state variables are updated after each block of data is processed; the coefficients are untouched. arm_fir_instance_f32 S = {numTaps, pState, pCoeffs}; arm_fir_instance_q31 S = {numTaps, pState, pCoeffs}; arm_fir_instance_q15 S = {numTaps, pState, pCoeffs}; arm_fir_instance_q7 S = {numTaps, pState, pCoeffs};
where numTaps
is the number of filter coefficients in the filter; pState
is the address of the state buffer; pCoeffs
is the address of the coefficient buffer.
void arm_fir_f32  (  const arm_fir_instance_f32 *  S, 
float32_t *  pSrc,  
float32_t *  pDst,  
uint32_t  blockSize  
) 
[in]  *S  points to an instance of the floatingpoint FIR filter structure. 
[in]  *pSrc  points to the block of input data. 
[out]  *pDst  points to the block of output data. 
[in]  blockSize  number of samples to process per call. 
References arm_fir_instance_f32::numTaps, arm_fir_instance_f32::pCoeffs, and arm_fir_instance_f32::pState.
Referenced by main().
void arm_fir_fast_q15  (  const arm_fir_instance_q15 *  S, 
q15_t *  pSrc,  
q15_t *  pDst,  
uint32_t  blockSize  
) 
[in]  *S  points to an instance of the Q15 FIR filter structure. 
[in]  *pSrc  points to the block of input data. 
[out]  *pDst  points to the block of output data. 
[in]  blockSize  number of samples to process per call. 
Scaling and Overflow Behavior:
arm_fir_q15()
for a slower implementation of this function which uses 64bit accumulation to avoid wrap around distortion. Both the slow and the fast versions use the same instance structure. Use the function arm_fir_init_q15()
to initialize the filter structure. References __PKHBT, __SIMD32, __SMLAD(), __SMLADX(), _SIMD32_OFFSET, arm_fir_instance_q15::numTaps, arm_fir_instance_q15::pCoeffs, and arm_fir_instance_q15::pState.
IAR_ONLY_LOW_OPTIMIZATION_ENTER void arm_fir_fast_q31  (  const arm_fir_instance_q31 *  S, 
q31_t *  pSrc,  
q31_t *  pDst,  
uint32_t  blockSize  
) 
[in]  *S  points to an instance of the Q31 structure. 
[in]  *pSrc  points to the block of input data. 
[out]  *pDst  points to the block output data. 
[in]  blockSize  number of samples to process per call. 
Scaling and Overflow Behavior:
arm_fir_q31()
for a slower implementation of this function which uses a 64bit accumulator to provide higher precision. Both the slow and the fast versions use the same instance structure. Use the function arm_fir_init_q31()
to initialize the filter structure. References multAcc_32x32_keep32_R, arm_fir_instance_q31::numTaps, arm_fir_instance_q31::pCoeffs, and arm_fir_instance_q31::pState.
void arm_fir_init_f32  (  arm_fir_instance_f32 *  S, 
uint16_t  numTaps,  
float32_t *  pCoeffs,  
float32_t *  pState,  
uint32_t  blockSize  
) 
[in,out]  *S  points to an instance of the floatingpoint FIR filter structure. 
[in]  numTaps  Number of filter coefficients in the filter. 
[in]  *pCoeffs  points to the filter coefficients buffer. 
[in]  *pState  points to the state buffer. 
[in]  blockSize  number of samples that are processed per call. 
Description:
pCoeffs
points to the array of filter coefficients stored in time reversed order: {b[numTaps1], b[numTaps2], b[N2], ..., b[1], b[0]}
pState
points to the array of state variables. pState
is of length numTaps+blockSize1
samples, where blockSize
is the number of input samples processed by each call to arm_fir_f32()
. References arm_fir_instance_f32::numTaps, arm_fir_instance_f32::pCoeffs, and arm_fir_instance_f32::pState.
Referenced by main().
arm_status arm_fir_init_q15  (  arm_fir_instance_q15 *  S, 
uint16_t  numTaps,  
q15_t *  pCoeffs,  
q15_t *  pState,  
uint32_t  blockSize  
) 
[in,out]  *S  points to an instance of the Q15 FIR filter structure. 
[in]  numTaps  Number of filter coefficients in the filter. Must be even and greater than or equal to 4. 
[in]  *pCoeffs  points to the filter coefficients buffer. 
[in]  *pState  points to the state buffer. 
[in]  blockSize  is number of samples processed per call. 
numTaps
is not greater than or equal to 4 and even.Description:
pCoeffs
points to the array of filter coefficients stored in time reversed order: {b[numTaps1], b[numTaps2], b[N2], ..., b[1], b[0]}Note that
numTaps
must be even and greater than or equal to 4. To implement an odd length filter simply increase numTaps
by 1 and set the last coefficient to zero. For example, to implement a filter with numTaps=3
and coefficients {0.3, 0.8, 0.3}set
numTaps=4
and use the coefficients: {0.3, 0.8, 0.3, 0}.Similarly, to implement a two point filter
{0.3, 0.3}set
numTaps=4
and use the coefficients: {0.3, 0.3, 0, 0}.
pState
points to the array of state variables. pState
is of length numTaps+blockSize
, when running on CortexM4 and CortexM3 and is of length numTaps+blockSize1
, when running on CortexM0 where blockSize
is the number of input samples processed by each call to arm_fir_q15()
. References ARM_MATH_ARGUMENT_ERROR, ARM_MATH_SUCCESS, arm_fir_instance_q15::numTaps, arm_fir_instance_q15::pCoeffs, arm_fir_instance_q15::pState, and status.
void arm_fir_init_q31  (  arm_fir_instance_q31 *  S, 
uint16_t  numTaps,  
q31_t *  pCoeffs,  
q31_t *  pState,  
uint32_t  blockSize  
) 
[in,out]  *S  points to an instance of the Q31 FIR filter structure. 
[in]  numTaps  Number of filter coefficients in the filter. 
[in]  *pCoeffs  points to the filter coefficients buffer. 
[in]  *pState  points to the state buffer. 
[in]  blockSize  number of samples that are processed per call. 
Description:
pCoeffs
points to the array of filter coefficients stored in time reversed order: {b[numTaps1], b[numTaps2], b[N2], ..., b[1], b[0]}
pState
points to the array of state variables. pState
is of length numTaps+blockSize1
samples, where blockSize
is the number of input samples processed by each call to arm_fir_q31()
. References arm_fir_instance_q31::numTaps, arm_fir_instance_q31::pCoeffs, and arm_fir_instance_q31::pState.
void arm_fir_init_q7  (  arm_fir_instance_q7 *  S, 
uint16_t  numTaps,  
q7_t *  pCoeffs,  
q7_t *  pState,  
uint32_t  blockSize  
) 
[in,out]  *S  points to an instance of the Q7 FIR filter structure. 
[in]  numTaps  Number of filter coefficients in the filter. 
[in]  *pCoeffs  points to the filter coefficients buffer. 
[in]  *pState  points to the state buffer. 
[in]  blockSize  number of samples that are processed per call. 
Description:
pCoeffs
points to the array of filter coefficients stored in time reversed order: {b[numTaps1], b[numTaps2], b[N2], ..., b[1], b[0]}
pState
points to the array of state variables. pState
is of length numTaps+blockSize1
samples, where blockSize
is the number of input samples processed by each call to arm_fir_q7()
. References arm_fir_instance_q7::numTaps, arm_fir_instance_q7::pCoeffs, and arm_fir_instance_q7::pState.
void arm_fir_q15  (  const arm_fir_instance_q15 *  S, 
q15_t *  pSrc,  
q15_t *  pDst,  
uint32_t  blockSize  
) 
[in]  *S  points to an instance of the Q15 FIR structure. 
[in]  *pSrc  points to the block of input data. 
[out]  *pDst  points to the block of output data. 
[in]  blockSize  number of samples to process per call. 
Scaling and Overflow Behavior:
arm_fir_fast_q15()
for a faster but less precise implementation of this function. References blockSize, arm_fir_instance_q15::numTaps, arm_fir_instance_q15::pCoeffs, and arm_fir_instance_q15::pState.
void arm_fir_q31  (  const arm_fir_instance_q31 *  S, 
q31_t *  pSrc,  
q31_t *  pDst,  
uint32_t  blockSize  
) 
[in]  *S  points to an instance of the Q31 FIR filter structure. 
[in]  *pSrc  points to the block of input data. 
[out]  *pDst  points to the block of output data. 
[in]  blockSize  number of samples to process per call. 
Scaling and Overflow Behavior:
arm_fir_fast_q31()
for a faster but less precise implementation of this filter for CortexM3 and CortexM4. References blockSize, arm_fir_instance_q31::numTaps, arm_fir_instance_q31::pCoeffs, and arm_fir_instance_q31::pState.
void arm_fir_q7  (  const arm_fir_instance_q7 *  S, 
q7_t *  pSrc,  
q7_t *  pDst,  
uint32_t  blockSize  
) 
[in]  *S  points to an instance of the Q7 FIR filter structure. 
[in]  *pSrc  points to the block of input data. 
[out]  *pDst  points to the block of output data. 
[in]  blockSize  number of samples to process per call. 
Scaling and Overflow Behavior:
References blockSize, arm_fir_instance_q7::numTaps, arm_fir_instance_q7::pCoeffs, and arm_fir_instance_q7::pState.