Function Descriptions
3.2 Complex Fast Fourier Transform (Unaligned)
Description:
This module computes a 32-bit floating-point complex FFT including input bit reversing. This
version of the function does not have any buffer alignment requirements. If you can align the
input buffer, then use the CFFT_f32 function for improved performance
Header File:
FPU.h
Declaration:
void CFFT_f32u (CFFT_F32_STRUCT
*
)
Usage:
A pointer to the following structure is passed to the CFFT_f32 function.It is the same structure
described in the CFFT_f32 section:
typedef struct {
float32
*
InPtr;
float32
*
OutPtr;
float32
*
CoefPtr;
float32
*
CurrentInPtr;
float32
*
CurrentOutPtr;
Uint16 Stages;
Uint16 FFTSize;
} CFFT_F32_STRUCT;
Table 3.2 describes each element describes each element with the exception that the input
buffer does not require alignment.
Alignment Requirements:
None
Notes:
1. This function is not re-entrant as it uses global variables to store arguments; these
will be overwritten if the function is invoked while it is currently processing.
2. If you can align the input buffer to a 4*FFTSize, then consider using the CFFT_f32
function which has input buffer alignment requirements, but it is more cycle efficient
3. All buffers and stack are placed in internal memory (zero-wait states in data space).
Sep 10, 2012 15
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