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CMSIS-DSP: Added MVE version of stage_rfft_f32

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pull/19/head
Christophe Favergeon 6 years ago
parent 0c8bacd043
commit 266d88ba4a
4 changed files with 227 additions and 4 deletions
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225
Source/TransformFunctions/arm_rfft_fast_f32.c
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@ -28,6 +28,226 @@
#include "arm_math.h"
#if defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE)
void stage_rfft_f32(
const arm_rfft_fast_instance_f32 * S,
float32_t * p,
float32_t * pOut)
{
uint32_t k; /* Loop Counter */
float32_t twR, twI; /* RFFT Twiddle coefficients */
const float32_t * pCoeff = S->pTwiddleRFFT; /* Points to RFFT Twiddle factors */
float32_t *pA = p; /* increasing pointer */
float32_t *pB = p; /* decreasing pointer */
float32_t xAR, xAI, xBR, xBI; /* temporary variables */
float32_t t1a, t1b; /* temporary variables */
float32_t p0, p1, p2, p3; /* temporary variables */
float32x4x2_t tw,xA,xB;
float32x4x2_t tmp1, tmp2, res;
uint32x4_t vecStridesFwd, vecStridesBkwd;
vecStridesFwd = vidupq_u32(0, 2);
vecStridesBkwd = -vecStridesFwd;
int blockCnt;
k = (S->Sint).fftLen - 1;
/* Pack first and last sample of the frequency domain together */
xBR = pB[0];
xBI = pB[1];
xAR = pA[0];
xAI = pA[1];
twR = *pCoeff++ ;
twI = *pCoeff++ ;
// U1 = XA(1) + XB(1); % It is real
t1a = xBR + xAR ;
// U2 = XB(1) - XA(1); % It is imaginary
t1b = xBI + xAI ;
// real(tw * (xB - xA)) = twR * (xBR - xAR) - twI * (xBI - xAI);
// imag(tw * (xB - xA)) = twI * (xBR - xAR) + twR * (xBI - xAI);
*pOut++ = 0.5f * ( t1a + t1b );
*pOut++ = 0.5f * ( t1a - t1b );
// XA(1) = 1/2*( U1 - imag(U2) + i*( U1 +imag(U2) ));
pB = p + 2*k;
pA += 2;
blockCnt = k >> 2;
while (blockCnt > 0)
{
/*
function X = my_split_rfft(X, ifftFlag)
% X is a series of real numbers
L = length(X);
XC = X(1:2:end) +i*X(2:2:end);
XA = fft(XC);
XB = conj(XA([1 end:-1:2]));
TW = i*exp(-2*pi*i*[0:L/2-1]/L).';
for l = 2:L/2
XA(l) = 1/2 * (XA(l) + XB(l) + TW(l) * (XB(l) - XA(l)));
end
XA(1) = 1/2* (XA(1) + XB(1) + TW(1) * (XB(1) - XA(1))) + i*( 1/2*( XA(1) + XB(1) + i*( XA(1) - XB(1))));
X = XA;
*/
xA = vld2q_f32(pA);
pA += 8;
xB = vld2q_f32(pB);
xB.val[0] = vldrwq_gather_shifted_offset_f32(pB, vecStridesBkwd);
xB.val[1] = vldrwq_gather_shifted_offset_f32(&pB[1], vecStridesBkwd);
xB.val[1] = vnegq_f32(xB.val[1]);
pB -= 8;
tw = vld2q_f32(pCoeff);
pCoeff += 8;
tmp1.val[0] = vaddq_f32(xA.val[0],xB.val[0]);
tmp1.val[1] = vaddq_f32(xA.val[1],xB.val[1]);
tmp2.val[0] = vsubq_f32(xB.val[0],xA.val[0]);
tmp2.val[1] = vsubq_f32(xB.val[1],xA.val[1]);
res.val[0] = vmulq(tw.val[0], tmp2.val[0]);
res.val[0] = vfmsq(res.val[0],tw.val[1], tmp2.val[1]);
res.val[1] = vmulq(tw.val[0], tmp2.val[1]);
res.val[1] = vfmaq(res.val[1], tw.val[1], tmp2.val[0]);
res.val[0] = vaddq_f32(res.val[0],tmp1.val[0] );
res.val[1] = vaddq_f32(res.val[1],tmp1.val[1] );
res.val[0] = vmulq_n_f32(res.val[0], 0.5f);
res.val[1] = vmulq_n_f32(res.val[1], 0.5f);
vst2q_f32(pOut, res);
pOut += 8;
blockCnt--;
}
blockCnt = k & 3;
while (blockCnt > 0)
{
/*
function X = my_split_rfft(X, ifftFlag)
% X is a series of real numbers
L = length(X);
XC = X(1:2:end) +i*X(2:2:end);
XA = fft(XC);
XB = conj(XA([1 end:-1:2]));
TW = i*exp(-2*pi*i*[0:L/2-1]/L).';
for l = 2:L/2
XA(l) = 1/2 * (XA(l) + XB(l) + TW(l) * (XB(l) - XA(l)));
end
XA(1) = 1/2* (XA(1) + XB(1) + TW(1) * (XB(1) - XA(1))) + i*( 1/2*( XA(1) + XB(1) + i*( XA(1) - XB(1))));
X = XA;
*/
xBI = pB[1];
xBR = pB[0];
xAR = pA[0];
xAI = pA[1];
twR = *pCoeff++;
twI = *pCoeff++;
t1a = xBR - xAR ;
t1b = xBI + xAI ;
// real(tw * (xB - xA)) = twR * (xBR - xAR) - twI * (xBI - xAI);
// imag(tw * (xB - xA)) = twI * (xBR - xAR) + twR * (xBI - xAI);
p0 = twR * t1a;
p1 = twI * t1a;
p2 = twR * t1b;
p3 = twI * t1b;
*pOut++ = 0.5f * (xAR + xBR + p0 + p3 ); //xAR
*pOut++ = 0.5f * (xAI - xBI + p1 - p2 ); //xAI
pA += 2;
pB -= 2;
blockCnt--;
}
}
/* Prepares data for inverse cfft */
void merge_rfft_f32(
const arm_rfft_fast_instance_f32 * S,
float32_t * p,
float32_t * pOut)
{
uint32_t k; /* Loop Counter */
float32_t twR, twI; /* RFFT Twiddle coefficients */
const float32_t *pCoeff = S->pTwiddleRFFT; /* Points to RFFT Twiddle factors */
float32_t *pA = p; /* increasing pointer */
float32_t *pB = p; /* decreasing pointer */
float32_t xAR, xAI, xBR, xBI; /* temporary variables */
float32_t t1a, t1b, r, s, t, u; /* temporary variables */
k = (S->Sint).fftLen - 1;
xAR = pA[0];
xAI = pA[1];
pCoeff += 2 ;
*pOut++ = 0.5f * ( xAR + xAI );
*pOut++ = 0.5f * ( xAR - xAI );
pB = p + 2*k ;
pA += 2 ;
while (k > 0U)
{
/* G is half of the frequency complex spectrum */
//for k = 2:N
// Xk(k) = 1/2 * (G(k) + conj(G(N-k+2)) + Tw(k)*( G(k) - conj(G(N-k+2))));
xBI = pB[1] ;
xBR = pB[0] ;
xAR = pA[0];
xAI = pA[1];
twR = *pCoeff++;
twI = *pCoeff++;
t1a = xAR - xBR ;
t1b = xAI + xBI ;
r = twR * t1a;
s = twI * t1b;
t = twI * t1a;
u = twR * t1b;
// real(tw * (xA - xB)) = twR * (xAR - xBR) - twI * (xAI - xBI);
// imag(tw * (xA - xB)) = twI * (xAR - xBR) + twR * (xAI - xBI);
*pOut++ = 0.5f * (xAR + xBR - r - s ); //xAR
*pOut++ = 0.5f * (xAI - xBI + t - u ); //xAI
pA += 2;
pB -= 2;
k--;
}
}
#else
void stage_rfft_f32(
const arm_rfft_fast_instance_f32 * S,
float32_t * p,
@ -55,6 +275,7 @@ void stage_rfft_f32(
twR = *pCoeff++ ;
twI = *pCoeff++ ;
// U1 = XA(1) + XB(1); % It is real
t1a = xBR + xAR ;
@ -108,6 +329,7 @@ void stage_rfft_f32(
*pOut++ = 0.5f * (xAR + xBR + p0 + p3 ); //xAR
*pOut++ = 0.5f * (xAI - xBI + p1 - p2 ); //xAI
pA += 2;
pB -= 2;
k--;
@ -174,6 +396,8 @@ void merge_rfft_f32(
}
#endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */
/**
@ingroup groupTransforms
*/
@ -303,7 +527,6 @@ void arm_rfft_fast_f32(
{
/* Real FFT compression */
merge_rfft_f32(S, p, pOut);
/* Complex radix-4 IFFT process */
arm_cfft_f32( Sint, pOut, ifftFlag, 1);
}

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