@//
@//  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 is a modification of omxSP_FFTFwd_CToC_SC32_Sfs_s.S
@//  to support float instead of SC32.
@//

@//
@// Description:
@// Compute an inverse FFT for a complex signal
@// 
@// 

        
@// Include standard headers

#include "dl/api/arm/armCOMM_s.h"
#include "dl/api/arm/omxtypes_s.h"
        
@//        M_VARIANTS ARM1136JS
        
@// Import symbols required from other files
@// (For example tables)
        
        .extern  armSP_FFTFwd_CToC_FC32_Radix2_fs_OutOfPlace_unsafe_vfp
        .extern  armSP_FFTFwd_CToC_FC32_Radix4_fs_OutOfPlace_unsafe_vfp
        .extern  armSP_FFTFwd_CToC_FC32_Radix8_fs_OutOfPlace_unsafe_vfp
        .extern  armSP_FFTFwd_CToC_FC32_Radix4_OutOfPlace_unsafe_vfp
        
@// Set debugging level        
@//DEBUG_ON    SETL {TRUE}


@// Guarding implementation by the processor name
    
@/    IF  ARM1136JS 
    
@//Input Registers

#define pSrc		r0
#define pDst		r1
#define pFFTSpec	r2


@// Output registers
#define result		r0

@//Local Scratch Registers

#define argTwiddle	r1
#define argDst		r2
#define argScale	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
#define diffMinusOne	r2
#define round		r3

#define x0r s0    
#define x0i s1


    @// Allocate stack memory required by the function

    @// Write function header
        M_START     omxSP_FFTFwd_CToC_FC32_Sfs_vfp,r11
        
@ Structure offsets for FFTSpec	
	.set	ARMsFFTSpec_N, 0
	.set	ARMsFFTSpec_pBitRev, 4
	.set	ARMsFFTSpec_pTwiddle, 8
	.set	ARMsFFTSpec_pBuf, 12
        
        @// Define stack arguments
        
        @// 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]
                
        CLZ     order,N			@// N = 2^order 
        RSB     order,order,#31     
        MOV     subFFTSize,#1
        @//MOV     subFFTNum,N
        
        
        CMP     order,#1
        BGT     orderGreaterthan1	@// order > 1
	@// order = 0, 1
	vldmlt.f32 pSrc, {x0r, x0i}
	vstmlt.f32 pDst, {x0r, x0i}
	
        MOVLT   pSrc,pDst
        BLT     End

	@// Handle order = 1
        MOV     argDst,pDst             @// Set input args to fft stages
        MOV     argTwiddle,pTwiddle
        BL    armSP_FFTFwd_CToC_FC32_Radix2_fs_OutOfPlace_unsafe_vfp
        B     End  
        

orderGreaterthan1:       
        
        TST     order, #2               @// Set input args to fft stages
        MOVNE   argDst,pDst        
        MOVEQ   argDst,pOut
        MOVEQ   pOut,pDst               @// Pass the first stage destination in RN5
        MOV     argTwiddle,pTwiddle  

        @//check for even or odd order
	
        @// NOTE: The following combination of BL's would work fine
	@// eventhough the first BL would corrupt the flags. This is
	@// because the end of the "grpZeroSetLoop" loop inside
        @// armSP_FFTFwd_CToC_FC32_Radix4_fs_OutOfPlace_unsafe_vfp
	@// sets the Z flag to EQ
        
        TST     order,#0x00000001
        BLEQ    armSP_FFTFwd_CToC_FC32_Radix4_fs_OutOfPlace_unsafe_vfp 
        BLNE    armSP_FFTFwd_CToC_FC32_Radix8_fs_OutOfPlace_unsafe_vfp 

unscaledRadix4Loop:
        CMP        subFFTNum,#1
         BEQ        End
         BL        armSP_FFTFwd_CToC_FC32_Radix4_OutOfPlace_unsafe_vfp
         B        unscaledRadix4Loop

       
End:                        
        @// Set return value
        MOV     result, #OMX_Sts_NoErr       

        @// Write function tail
        M_END
        
@//    ENDIF                                           @//ARM1136JS    
    
    
    @// Guarding implementation by the processor name
    
    
    .end