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@//
@// Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
@//
@// Use of this source code is governed by a BSD-style license
@// that can be found in the LICENSE file in the root of the source
@// tree. An additional intellectual property rights grant can be found
@// in the file PATENTS. All contributing project authors may
@// be found in the AUTHORS file in the root of the source tree.
@//
@// This file was originally licensed as follows. It has been
@// relicensed with permission from the copyright holders.
@//
@//
@// File Name: armSP_FFTInv_CCSToR_S32_preTwiddleRadix2_unsafe_s.s
@// OpenMAX DL: v1.0.2
@// Last Modified Revision: 7485
@// Last Modified Date: Fri, 21 Sep 2007
@//
@// (c) Copyright 2007-2008 ARM Limited. All Rights Reserved.
@//
@//
@//
@// Description:
@// Compute the "preTwiddleRadix2" stage prior to the call to the complexFFT
@// It does a Z(k) = Feven(k) + jW^(-k) FOdd(k); k=0,1,2,...N/2-1 computation
@// It implements both "scaled"(by 1/2) and "unsclaed" versions of the above formula
@//
@// Include standard headers
#include "dl/api/armCOMM_s.h"
#include "dl/api/omxtypes_s.h"
@// Import symbols required from other files
@// (For example tables)
@// Set debugging level
@//DEBUG_ON SETL {TRUE}
@// Guarding implementation by the processor name
@// Guarding implementation by the processor name
@//Input Registers
#define pSrc r0
#define pDst r1
#define pFFTSpec r2
#define scale r3
@// Output registers
#define result r0
@//Local Scratch Registers
#define argTwiddle r1
#define argDst r2
#define argScale r4
#define tmpOrder r4
#define pTwiddle r4
#define pOut r5
#define subFFTSize r7
#define subFFTNum r6
#define N r6
#define order r14
#define diff r9
#define count r8 @// Total num of radix stages required to comple the FFT
#define x0r r4
#define x0i r5
#define diffMinusOne r2
#define round r3
#define pOut1 r2
#define size r7
#define step r8
#define step1 r9
#define twStep r10
#define pTwiddleTmp r11
#define argTwiddle1 r12
#define zero r14
@// Neon registers
#define dX0 D0.S32
#define dShift D1.S32
#define dX1 D1.S32
#define dY0 D2.S32
#define dY1 D3.S32
#define dX0r D0.S32
#define dX0i D1.S32
#define dX1r D2.S32
#define dX1i D3.S32
#define dW0r D4.S32
#define dW0i D5.S32
#define dW1r D6.S32
#define dW1i D7.S32
#define dT0 D8.S32
#define dT1 D9.S32
#define dT2 D10.S32
#define dT3 D11.S32
#define qT0 Q6.S64
#define qT1 Q7.S64
#define qT2 Q8.S64
#define qT3 Q9.S64
#define dY0r D4.S32
#define dY0i D5.S32
#define dY1r D6.S32
#define dY1i D7.S32
#define dY2 D4.S32
#define dY3 D5.S32
#define dW0 D6.S32
#define dW1 D7.S32
#define dW0Tmp D10.S32
#define dW1Neg D11.S32
@ Structure offsets for the FFTSpec
.set ARMsFFTSpec_N, 0
.set ARMsFFTSpec_pBitRev, 4
.set ARMsFFTSpec_pTwiddle, 8
.set ARMsFFTSpec_pBuf, 12
.MACRO FFTSTAGE scaled, inverse, name
@// Read the size from structure and take log
LDR N, [pFFTSpec, #ARMsFFTSpec_N]
@// Read other structure parameters
LDR pTwiddle, [pFFTSpec, #ARMsFFTSpec_pTwiddle]
LDR pOut, [pFFTSpec, #ARMsFFTSpec_pBuf]
MOV size,N,ASR #1 @// preserve the contents of N
MOV step,N,LSL #2 @// step = N/2 * 8 bytes
@// Z(k) = 1/2 {[F(k) + F'(N/2-k)] +j*W^(-k) [F(k) - F'(N/2-k)]}
@// Note: W^(k) is stored as negated value and also need to conjugate the values from the table
@// Z(0) : no need of twiddle multiply
@// Z(0) = 1/2 { [F(0) + F'(N/2)] +j [F(0) - F'(N/2)] }
VLD1 dX0,[pSrc],step
ADD pOut1,pOut,step @// pOut1 = pOut+ N/2*8 bytes
VLD1 dX1,[pSrc]!
SUB twStep,step,size,LSL #1 @// twStep = 3N/8 * 8 bytes pointing to W^1
MOV step1,size,LSL #2 @// step1 = N/4 * 8 = N/2*4 bytes
SUB step1,step1,#8 @// (N/4-1)*8 bytes
VHADD dY0,dX0,dX1 @// [b+d | a+c]
VHSUB dY1,dX0,dX1 @// [b-d | a-c]
VZIP dY0,dY1 @// dY0= [a-c | a+c] ;dY1= [b-d | b+d]
.ifeqs "\scaled", "TRUE"
VHSUB dX0,dY0,dY1
SUBS size,size,#2
VHADD dX1,dY0,dY1
.else
VSUB dX0,dY0,dY1
SUBS size,size,#2
VADD dX1,dY0,dY1
.endif
SUB pSrc,pSrc,step
VST1 dX0[0],[pOut1]!
ADD pTwiddleTmp,pTwiddle,#8 @// W^2
VST1 dX1[1],[pOut1]!
ADD argTwiddle1,pTwiddle,twStep @// W^1
BLT decrementScale\name
BEQ lastElement\name
@// Z(k) = 1/2[F(k) + F'(N/2-k)] +j*W^(-k) [F(k) - F'(N/2-k)]
@// Note: W^k is stored as negative values in the table and also need to conjugate the values from the table
@// Process 4 elements at a time. E.g: Z(1),Z(2) and Z(N/2-2),Z(N/2-1) since both of them
@// require F(1),F(2) and F(N/2-2),F(N/2-1)
SUB step,step,#24
evenOddButterflyLoop\name :
VLD1 dW0r,[argTwiddle1],step1
VLD1 dW1r,[argTwiddle1]!
VLD2 {dX0r,dX0i},[pSrc],step
SUB argTwiddle1,argTwiddle1,step1
VLD2 {dX1r,dX1i},[pSrc]!
SUB step1,step1,#8 @// (N/4-2)*8 bytes
VLD1 dW0i,[pTwiddleTmp],step1
VLD1 dW1i,[pTwiddleTmp]!
SUB pSrc,pSrc,step
SUB pTwiddleTmp,pTwiddleTmp,step1
VREV64 dX1r,dX1r
VREV64 dX1i,dX1i
SUBS size,size,#4
VHSUB dT2,dX0r,dX1r @// a-c
VHADD dT3,dX0i,dX1i @// b+d
SUB step1,step1,#8
VHADD dT0,dX0r,dX1r @// a+c
VHSUB dT1,dX0i,dX1i @// b-d
VZIP dW1r,dW1i
VZIP dW0r,dW0i
VMULL qT0,dW1r,dT2
VMLSL qT0,dW1i,dT3
VMULL qT1,dW1r,dT3
VMLAL qT1,dW1i,dT2
VMULL qT2,dW0r,dT2
VMLAL qT2,dW0i,dT3
VMULL qT3,dW0r,dT3
VMLSL qT3,dW0i,dT2
VRSHRN dX1r,qT0,#31
VRSHRN dX1i,qT1,#31
.ifeqs "\scaled", "TRUE"
VHADD dY1r,dT0,dX1i @// F(N/2 -1)
VHSUB dY1i,dX1r,dT1
.else
VADD dY1r,dT0,dX1i @// F(N/2 -1)
VSUB dY1i,dX1r,dT1
.endif
VREV64 dY1r,dY1r
VREV64 dY1i,dY1i
VRSHRN dX0r,qT2,#31
VRSHRN dX0i,qT3,#31
.ifeqs "\scaled", "TRUE"
VHADD dY0r,dT0,dX0i @// F(1)
VHSUB dY0i,dT1,dX0r
.else
VADD dY0r,dT0,dX0i @// F(1)
VSUB dY0i,dT1,dX0r
.endif
VST2 {dY0r,dY0i},[pOut1],step
VST2 {dY1r,dY1i},[pOut1]!
SUB pOut1,pOut1,step
SUB step,step,#32 @// (N/2-4)*8 bytes
BGT evenOddButterflyLoop\name
SUB pSrc,pSrc,#8 @// set both the ptrs to the last element
SUB pOut1,pOut1,#8
@// Last element can be expanded as follows
@// 1/2[Z(k) + Z'(k)] - j w^-k [Z(k) - Z'(k)] (since W^k is stored as -ve)
@// 1/2[(a+jb) + (a-jb)] - j w^-k [(a+jb) - (a-jb)]
@// 1/2[2a+j0] - j (c-jd) [0+j2b]
@// (a+bc, -bd)
@// Since (c,d) = (0,1) for the last element, result is just (a,-b)
lastElement\name :
VLD1 dX0r,[pSrc]
.ifeqs "\scaled", "TRUE"
VSHR dX0r,dX0r,#1
.endif
VST1 dX0r[0],[pOut1]!
VNEG dX0r,dX0r
VST1 dX0r[1],[pOut1]
decrementScale\name :
.ifeqs "\scaled", "TRUE"
SUB scale,scale,#1
.endif
.endm
M_START armSP_FFTInv_CCSToR_S32_preTwiddleRadix2_unsafe,r4
FFTSTAGE "FALSE","TRUE",Inv
M_END
M_START armSP_FFTInv_CCSToR_S32_Sfs_preTwiddleRadix2_unsafe,r4
FFTSTAGE "TRUE","TRUE",InvSfs
M_END
.end
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