Function Descriptions
3.9 Real Fast Fourier Transform (Unaligned)
Description:
This module computes a 32-bit floating-point real 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 RFFT_f32 function for improved performance.
Header File:
FPU.h
Declaration:
void RFFT_f32u (RFFT_F32_STRUCT
*
)
Usage:
A pointer to the following structure is passed to the RFFT_f32u function. It is the same structure
described in the RFFT_f32 section:
typedef struct {
float32
*
InBuf;
float32
*
OutBuf;
float32
*
CosSinBuf;
float32
*
MagBuf;
float32
*
PhaseBuf;
Uint16 FFTSize;
Uint16 FFTStages;
} RFFT_F32_STRUCT;
Table 3.11 describes each element with the exception that the input buffer does not require
alignment.
Alignment Requirements:
None
Notes:
1. If you can align the input buffer to a 2*FFTSize, then consider using the RFFT_f32
function which has input buffer alignment requirements, but it is more cycle efficient
2. All buffers and stack are placed in internal memory (zero-wait states in data space).
Sep 10, 2012 31
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