vsip_dcorr1d_create_p - Create 1D Correlation Object

Core

This manual is preliminary and incomplete.
While our Core implementation implements all functions given in the standard we are still working on completing this documentation.

Please refer to the VSIPL standard for a complete function reference of the Core profile until we have completed work on this documentation.

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5.2.5 vsip_dcorr1d_create_p - Create 1D Correlation Object

typedef enum _vsip_support_region { 
  VSIP_SUPPORT_FULL = 0, 
  VSIP_SUPPORT_SAME = 1, 
  VSIP_SUPPORT_MIN  = 2, 
} vsip_support_region; 
 
typedef enum _vsip_alg_hint { 
  VSIP_ALG_TIME  = 0, 
  VSIP_ALG_SPACE = 1, 
  VSIP_ALG_NOISE = 2 
} vsip_alg_hint; 
 
vsip_corr1d_f* vsip_corr1d_create_f(vsip_length m, vsip_length n, vsip_support_region support, vsip_length ntimes, vsip_alg_hint hint); 
vsip_ccorr1d_f* vsip_ccorr1d_create_f(vsip_length m, vsip_length n, vsip_support_region support, vsip_length ntimes, vsip_alg_hint hint);

Description

This function creates a one-dimensional correlation object that can be used to compute the correlation between an input signal and a reference signal.

The correlation object is optimized for repeated use, allowing efficient computation of correlations between signals of length $m$ and reference signals of length $n$ .

Parameters

vsip_length m: Length of the input signal.
vsip_length n: Length of the reference signal.
vsip_support_region support: Specifies the support region for the correlation:
- VSIP_SUPPORT_FULL: Compute full correlation. Output length is $n+ m -1$ .
- VSIP_SUPPORT_SAME: Compute correlation with same-length output $n$ .
- VSIP_SUPPORT_MIN: Compute minimum-length correlation. Output length is $|n-m |-1$ .
vsip_length ntimes: Number of times the correlation will be applied.
vsip_alg_hint hint: Algorithm hint for optimization:
- VSIP_ALG_TIME: Optimize for computation time
- VSIP_ALG_SPACE: Optimize for memory usage
- VSIP_ALG_NOHINT: No specific optimization

Return Value

On success: Pointer to the newly created 1D correlation object.
On error (e.g., memory allocation failure): NULL.

Example

vsip_corr1d_f *corr; 
vsip_length m = 1024;  // Input signal length 
vsip_length n = 64;    // Reference signal length 
vsip_length ntimes = 100; // Number of times to reuse object 
 
// Create correlation object for full correlation 
corr = vsip_corr1d_create_f(m, n, VSIP_SUPPORT_FULL, ntimes, VSIP_ALG_TIME); 
if (corr == NULL) { 
    fprintf(stderr, "Error: Could not create correlation object\n"); 
    return -1; 
} 
 
// Use the correlation object for your signal processing 
// vsip_vview_f *input = vsip_vcreate_f(m, VSIP_MEM_NONE); 
// vsip_vview_f *reference = vsip_vcreate_f(n, VSIP_MEM_NONE); 
// vsip_vview_f *result = vsip_vcreate_f(m + n - 1, VSIP_MEM_NONE); 
// 
// vsip_corr1d_f(corr, input, reference, result); 
 
// Clean up when done 
vsip_corr1d_destroy_f(corr);

Notes

The correlation object should be destroyed with vsip_dcorr1d_destroy_p when no longer needed.
The choice of support affects the length of the output correlation vector:
- VSIP_SUPPORT_FULL: Output length is $n+ m -1$
- VSIP_SUPPORT_SAME: Output length is $n$
- VSIP_SUPPORT_MIN: Output length is $|n-m |+1$
The ntimes parameter helps the library optimize memory allocation for repeated use.

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