Add openmax dl routines for review. MUST NOT BE LANDED

third_party/openmax_dl/dl/sp/src/omxSP_FFTInv_CToC_SC16_Sfs_s.S

+@//
+@//  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:  omxSP_FFTInv_CToC_SC16_Sfs_s.s
+@// OpenMAX DL: v1.0.2
+@// Last Modified Revision:   6729
+@// Last Modified Date:       Tue, 17 Jul 2007
+@//
+@// (c) Copyright 2007-2008 ARM Limited. All Rights Reserved.
+@//
+@//
+@//
+@// Description:
+@// Compute an inverse FFT for a complex signal
+@//
+@//
+
+
+@// Include standard headers
+
+#include "dl/api/armCOMM_s.h"
+#include "dl/api/omxtypes_s.h"
+
+@// Import symbols required from other files
+@// (For example tables)
+
+        .extern  armSP_FFTInv_CToC_SC16_Sfs_Radix2_fs_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Radix2_fs_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Radix4_fs_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Radix4_ls_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Radix8_fs_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Radix4_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Sfs_Radix4_fs_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Sfs_Radix4_ls_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Sfs_Radix8_fs_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Sfs_Radix4_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Sfs_Radix2_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Radix2_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Sfs_Radix2_ls_OutOfPlace_unsafe
+        .extern  armSP_FFTInv_CToC_SC16_Radix2_ls_OutOfPlace_unsafe
+
+@// Set debugging level
+@//DEBUG_ON    SETL {TRUE}
+
+
+
+@// Guarding implementation by the processor name
+
+
+
+@// Guarding implementation by the processor name
+
+
+    .extern  armSP_FFTInv_CToC_SC16_Radix2_ps_OutOfPlace_unsafe
+    .extern  armSP_FFTInv_CToC_SC16_Sfs_Radix2_ps_OutOfPlace_unsafe
+
+@//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 pTwiddle        r4
+#define tmpOrder        r4
+#define pOut    r5
+#define subFFTSize      r7
+#define subFFTNum       r6
+#define N       r6
+#define order   r14
+#define diff    r9
+@// Total num of radix stages required to comple the FFT
+#define count   r8
+#define x0r     r4
+#define x0i     r5
+#define diffMinusOne    r2
+#define round   r3
+
+@// Neon registers
+
+#define dX0  D0.S16
+#define dShift  D1.S16
+#define dX0S32  D0.S32
+
+
+    @// Allocate stack memory required by the function
+        M_ALLOC4        diffOnStack, 4
+
+    @// Write function header
+        M_START     omxSP_FFTInv_CToC_SC16_Sfs,r11,d15
+
+@ Structure offsets for the 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
+
+        ADD     scale,scale,order                   @// FFTInverse has a final scaling factor by N

[aedla, 2013/06/28 11:47:06]

Documentation in api/omxSP.h says:
 scaleFactor - scale factor of the output. Valid value is 0 only.

So scale will always equal order after this ADD. Most of the code below is for
handling cases where scale is from 0 to order - 1 and will be unreachable. Maybe
delete it? I think only order < 4 and scaleEqualsOrder cases are reachable.

+
+        CMP     order,#3
+        BGT     orderGreaterthan3                   @// order > 3
+
+        CMP     order,#1
+        BGE     orderGreaterthan0                   @// order > 0
+        M_STR   scale, diffOnStack,LT               @// order = 0
+        LDRLT   x0r,[pSrc]
+        STRLT   x0r,[pDst]
+        MOVLT   pSrc,pDst
+        BLT     FFTEnd
+
+orderGreaterthan0:
+        @// set the buffers appropriately for various orders
+        CMP     order,#2
+        MOVNE   argDst,pDst
+        MOVEQ   argDst,pOut
+        MOVEQ   pOut,pDst                           @// Pass the first stage destination in RN5
+        MOV     argTwiddle,pTwiddle
+        @// Store the scale factor and scale at the end
+        SUB     diff,scale,order
+        M_STR   diff, diffOnStack
+        BGE     orderGreaterthan1
+        BLLT    armSP_FFTInv_CToC_SC16_Sfs_Radix2_fs_OutOfPlace_unsafe  @// order = 1
+        B       FFTEnd
+
+
+orderGreaterthan1:
+        MOV     tmpOrder,order                          @// tmpOrder = RN 4
+        BL      armSP_FFTInv_CToC_SC16_Sfs_Radix2_fs_OutOfPlace_unsafe
+        CMP     tmpOrder,#2
+        BLGT    armSP_FFTInv_CToC_SC16_Sfs_Radix2_ps_OutOfPlace_unsafe
+        BL      armSP_FFTInv_CToC_SC16_Sfs_Radix2_ls_OutOfPlace_unsafe
+        B       FFTEnd
+
+
+
+
+orderGreaterthan3:
+        @// check scale = 0 or scale = order
+        SUBS    diff, scale, order                 @// scale > order
+        MOVGT   scale,order
+        BGE     specialScaleCase                   @// scale = 0 or scale = order
+        CMP     scale,#0
+        BEQ     specialScaleCase
+        B       generalScaleCase
+
+specialScaleCase:                                           @//  scale = 0 or scale = order  and order > 3
+
+        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
+
+        CMP      diff,#0
+        M_STR    diff, diffOnStack
+        BGE      scaleEqualsOrder
+
+        @//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_FFTInv_CToC_SC16_Radix4_fs_OutOfPlace_unsafe sets the Z flag to EQ
+
+        TST     order,#0x00000001
+        BLEQ    armSP_FFTInv_CToC_SC16_Radix4_fs_OutOfPlace_unsafe
+        BLNE    armSP_FFTInv_CToC_SC16_Radix8_fs_OutOfPlace_unsafe
+
+        CMP        subFFTNum,#4
+        BLT     FFTEnd
+
+unscaledRadix4Loop:
+        BEQ        lastStageUnscaledRadix4
+        BL        armSP_FFTInv_CToC_SC16_Radix4_OutOfPlace_unsafe
+         CMP        subFFTNum,#4
+         B        unscaledRadix4Loop
+
+lastStageUnscaledRadix4:
+        BL      armSP_FFTInv_CToC_SC16_Radix4_ls_OutOfPlace_unsafe
+        B        FFTEnd
+
+scaleEqualsOrder:
+        @//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_FFTInv_CToC_SC32_Radix4_fs_OutOfPlace_unsafe sets the Z flag to EQ
+
+        TST     order,#0x00000001
+        BLEQ    armSP_FFTInv_CToC_SC16_Sfs_Radix4_fs_OutOfPlace_unsafe
+        BLNE    armSP_FFTInv_CToC_SC16_Sfs_Radix8_fs_OutOfPlace_unsafe
+
+        CMP        subFFTNum,#4
+        BLT     FFTEnd
+
+scaledRadix4Loop:
+        BEQ        lastStageScaledRadix4
+        BL        armSP_FFTInv_CToC_SC16_Sfs_Radix4_OutOfPlace_unsafe
+         CMP        subFFTNum,#4
+         B        scaledRadix4Loop
+
+lastStageScaledRadix4:
+        BL      armSP_FFTInv_CToC_SC16_Sfs_Radix4_ls_OutOfPlace_unsafe
+        B        FFTEnd
+
+
+
+generalScaleCase:                                        @// 0 < scale < order and order > 3
+        @// Determine the correct destination buffer
+        SUB     diff,order,scale
+        TST     diff,#0x01
+        ADDEQ   count,scale,diff,LSR #1         @// count = scale + (order - scale)/2
+        MOVNE   count,order
+        TST     count,#0x01                     @// Is count even or odd ?
+
+        MOVNE   argDst,pDst                     @// Set input args to fft stages
+        MOVEQ   argDst,pOut
+        MOVEQ   pOut,pDst                       @// Pass the first stage destination in RN5
+        MOV     argTwiddle,pTwiddle
+
+        CMP     diff,#1
+        M_STR   diff, diffOnStack
+        BEQ     scaleps                         @// scaling including a radix2_ps stage
+
+        MOV     argScale,scale                  @// Put scale in RN4 so as to save and restore
+        BL      armSP_FFTInv_CToC_SC16_Sfs_Radix2_fs_OutOfPlace_unsafe     @// scaled first stage
+        SUBS    argScale,argScale,#1
+
+scaledRadix2Loop:
+        BLGT    armSP_FFTInv_CToC_SC16_Sfs_Radix2_OutOfPlace_unsafe
+        SUBS    argScale,argScale,#1            @// save and restore scale (RN4) in the scaled stages
+        BGT     scaledRadix2Loop
+        B       outScale
+
+scaleps:
+        SUB     argScale,scale,#1                   @// order>3 and diff=1 => scale >= 3
+        BL      armSP_FFTInv_CToC_SC16_Sfs_Radix2_fs_OutOfPlace_unsafe     @// scaled first stage
+        SUBS    argScale,argScale,#1
+
+scaledRadix2psLoop:
+        BEQ     scaledRadix2psStage
+        BLGT    armSP_FFTInv_CToC_SC16_Sfs_Radix2_OutOfPlace_unsafe
+        SUBS    argScale,argScale,#1            @// save and restore scale (RN4) in the scaled stages
+        BGE     scaledRadix2psLoop
+
+scaledRadix2psStage:
+        BL      armSP_FFTInv_CToC_SC16_Sfs_Radix2_ps_OutOfPlace_unsafe
+        B       generalLastStageUnscaledRadix2
+
+
+outScale:
+        M_LDR   diff, diffOnStack
+        @//check for even or odd order
+        TST     diff,#0x00000001
+        BEQ     generalUnscaledRadix4Loop
+        B       unscaledRadix2Loop
+
+generalUnscaledRadix4Loop:
+        CMP        subFFTNum,#4
+         BEQ        generalLastStageUnscaledRadix4
+         BL        armSP_FFTInv_CToC_SC16_Radix4_OutOfPlace_unsafe
+         B        generalUnscaledRadix4Loop
+
+generalLastStageUnscaledRadix4:
+        BL      armSP_FFTInv_CToC_SC16_Radix4_ls_OutOfPlace_unsafe
+        B        End
+
+unscaledRadix2Loop:
+        CMP        subFFTNum,#4
+         BEQ        generalLastTwoStagesUnscaledRadix2
+         BL        armSP_FFTInv_CToC_SC16_Radix2_OutOfPlace_unsafe
+         B        unscaledRadix2Loop
+
+generalLastTwoStagesUnscaledRadix2:
+        BL      armSP_FFTInv_CToC_SC16_Radix2_ps_OutOfPlace_unsafe
+generalLastStageUnscaledRadix2:
+        BL      armSP_FFTInv_CToC_SC16_Radix2_ls_OutOfPlace_unsafe
+        B        End
+
+
+FFTEnd:                                              @// Does only the scaling
+
+        M_LDR   diff, diffOnStack
+        CMP     diff,#0
+        BLE     End
+
+        RSB     diff,diff,#0                        @// to use VRSHL for right shift by a variable
+        VDUP    dShift,diff
+
+scaleFFTData:                                        @// N = subFFTSize  ; dataptr = pDst  ; scale = diff
+        VLD1    {dX0S32[0]},[pSrc]                        @// pSrc contains pDst pointer
+        SUBS    subFFTSize,subFFTSize,#1
+        VRSHL   dX0,dShift
+        VST1    {dX0S32[0]},[pSrc]!
+
+        BGT     scaleFFTData
+
+
+End:
+        @// Set return value
+        MOV     result, #OMX_Sts_NoErr
+
+        @// Write function tail
+        M_END
+
+
+
+
+
+
+    .END