;
; jidctflt.asm - floating-point IDCT (64-bit SSE & SSE2)
;
; Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
; Copyright 2009 D. R. Commander
;
; Based on
; x86 SIMD extension for IJG JPEG library
; Copyright (C) 1999-2006, MIYASAKA Masaru.
; For conditions of distribution and use, see copyright notice in jsimdext.inc
;
; This file should be assembled with NASM (Netwide Assembler),
; can *not* be assembled with Microsoft's MASM or any compatible
; assembler (including Borland's Turbo Assembler).
; NASM is available from http://nasm.sourceforge.net/ or
; http://sourceforge.net/project/showfiles.php?group_id=6208
;
; This file contains a floating-point implementation of the inverse DCT
; (Discrete Cosine Transform). The following code is based directly on
; the IJG's original jidctflt.c; see the jidctflt.c for more details.
;
; [TAB8]

%include "jsimdext.inc"
%include "jdct.inc"

; --------------------------------------------------------------------------

%macro  unpcklps2 2     ; %1=(0 1 2 3) / %2=(4 5 6 7) => %1=(0 1 4 5)
        shufps  %1,%2,0x44
%endmacro

%macro  unpckhps2 2     ; %1=(0 1 2 3) / %2=(4 5 6 7) => %1=(2 3 6 7)
        shufps  %1,%2,0xEE
%endmacro

; --------------------------------------------------------------------------
        SECTION SEG_CONST

        alignz  16
        global  EXTN(jconst_idct_float_sse2)

EXTN(jconst_idct_float_sse2):

PD_1_414        times 4 dd  1.414213562373095048801689
PD_1_847        times 4 dd  1.847759065022573512256366
PD_1_082        times 4 dd  1.082392200292393968799446
PD_M2_613       times 4 dd -2.613125929752753055713286
PD_RNDINT_MAGIC times 4 dd  100663296.0 ; (float)(0x00C00000 << 3)
PB_CENTERJSAMP  times 16 db CENTERJSAMPLE

        alignz  16

; --------------------------------------------------------------------------
        SECTION SEG_TEXT
        BITS    64
;
; Perform dequantization and inverse DCT on one block of coefficients.
;
; GLOBAL(void)
; jsimd_idct_float_sse2 (void * dct_table, JCOEFPTR coef_block,
;                        JSAMPARRAY output_buf, JDIMENSION output_col)
;

; r10 = void * dct_table
; r11 = JCOEFPTR coef_block
; r12 = JSAMPARRAY output_buf
; r13 = JDIMENSION output_col

%define original_rbp    rbp+0
%define wk(i)           rbp-(WK_NUM-(i))*SIZEOF_XMMWORD ; xmmword wk[WK_NUM]
%define WK_NUM          2
%define workspace       wk(0)-DCTSIZE2*SIZEOF_FAST_FLOAT
                                        ; FAST_FLOAT workspace[DCTSIZE2]

        align   16
        global  EXTN(jsimd_idct_float_sse2)

EXTN(jsimd_idct_float_sse2):
        push    rbp
        mov     rax,rsp                         ; rax = original rbp
        sub     rsp, byte 4
        and     rsp, byte (-SIZEOF_XMMWORD)     ; align to 128 bits
        mov     [rsp],rax
        mov     rbp,rsp                         ; rbp = aligned rbp
        lea     rsp, [workspace]
        collect_args
        push    rbx

        ; ---- Pass 1: process columns from input, store into work array.

        mov     rdx, r10                ; quantptr
        mov     rsi, r11                ; inptr
        lea     rdi, [workspace]                        ; FAST_FLOAT * wsptr
        mov     rcx, DCTSIZE/4                          ; ctr
.columnloop:
%ifndef NO_ZERO_COLUMN_TEST_FLOAT_SSE
        mov     eax, DWORD [DWBLOCK(1,0,rsi,SIZEOF_JCOEF)]
        or      eax, DWORD [DWBLOCK(2,0,rsi,SIZEOF_JCOEF)]
        jnz     near .columnDCT

        movq    xmm1, XMM_MMWORD [MMBLOCK(1,0,rsi,SIZEOF_JCOEF)]
        movq    xmm2, XMM_MMWORD [MMBLOCK(2,0,rsi,SIZEOF_JCOEF)]
        movq    xmm3, XMM_MMWORD [MMBLOCK(3,0,rsi,SIZEOF_JCOEF)]
        movq    xmm4, XMM_MMWORD [MMBLOCK(4,0,rsi,SIZEOF_JCOEF)]
        movq    xmm5, XMM_MMWORD [MMBLOCK(5,0,rsi,SIZEOF_JCOEF)]
        movq    xmm6, XMM_MMWORD [MMBLOCK(6,0,rsi,SIZEOF_JCOEF)]
        movq    xmm7, XMM_MMWORD [MMBLOCK(7,0,rsi,SIZEOF_JCOEF)]
        por     xmm1,xmm2
        por     xmm3,xmm4
        por     xmm5,xmm6
        por     xmm1,xmm3
        por     xmm5,xmm7
        por     xmm1,xmm5
        packsswb xmm1,xmm1
        movd    eax,xmm1
        test    rax,rax
        jnz     short .columnDCT

        ; -- AC terms all zero

        movq      xmm0, XMM_MMWORD [MMBLOCK(0,0,rsi,SIZEOF_JCOEF)]

        punpcklwd xmm0,xmm0             ; xmm0=(00 00 01 01 02 02 03 03)
        psrad     xmm0,(DWORD_BIT-WORD_BIT)     ; xmm0=in0=(00 01 02 03)
        cvtdq2ps  xmm0,xmm0                     ; xmm0=in0=(00 01 02 03)

        mulps   xmm0, XMMWORD [XMMBLOCK(0,0,rdx,SIZEOF_FLOAT_MULT_TYPE)]

        movaps  xmm1,xmm0
        movaps  xmm2,xmm0
        movaps  xmm3,xmm0

        shufps  xmm0,xmm0,0x00                  ; xmm0=(00 00 00 00)
        shufps  xmm1,xmm1,0x55                  ; xmm1=(01 01 01 01)
        shufps  xmm2,xmm2,0xAA                  ; xmm2=(02 02 02 02)
        shufps  xmm3,xmm3,0xFF                  ; xmm3=(03 03 03 03)

        movaps  XMMWORD [XMMBLOCK(0,0,rdi,SIZEOF_FAST_FLOAT)], xmm0
        movaps  XMMWORD [XMMBLOCK(0,1,rdi,SIZEOF_FAST_FLOAT)], xmm0
        movaps  XMMWORD [XMMBLOCK(1,0,rdi,SIZEOF_FAST_FLOAT)], xmm1
        movaps  XMMWORD [XMMBLOCK(1,1,rdi,SIZEOF_FAST_FLOAT)], xmm1
        movaps  XMMWORD [XMMBLOCK(2,0,rdi,SIZEOF_FAST_FLOAT)], xmm2
        movaps  XMMWORD [XMMBLOCK(2,1,rdi,SIZEOF_FAST_FLOAT)], xmm2
        movaps  XMMWORD [XMMBLOCK(3,0,rdi,SIZEOF_FAST_FLOAT)], xmm3
        movaps  XMMWORD [XMMBLOCK(3,1,rdi,SIZEOF_FAST_FLOAT)], xmm3
        jmp     near .nextcolumn
%endif
.columnDCT:

        ; -- Even part

        movq      xmm0, XMM_MMWORD [MMBLOCK(0,0,rsi,SIZEOF_JCOEF)]
        movq      xmm1, XMM_MMWORD [MMBLOCK(2,0,rsi,SIZEOF_JCOEF)]
        movq      xmm2, XMM_MMWORD [MMBLOCK(4,0,rsi,SIZEOF_JCOEF)]
        movq      xmm3, XMM_MMWORD [MMBLOCK(6,0,rsi,SIZEOF_JCOEF)]

        punpcklwd xmm0,xmm0             ; xmm0=(00 00 01 01 02 02 03 03)
        punpcklwd xmm1,xmm1             ; xmm1=(20 20 21 21 22 22 23 23)
        psrad     xmm0,(DWORD_BIT-WORD_BIT)     ; xmm0=in0=(00 01 02 03)
        psrad     xmm1,(DWORD_BIT-WORD_BIT)     ; xmm1=in2=(20 21 22 23)
        cvtdq2ps  xmm0,xmm0                     ; xmm0=in0=(00 01 02 03)
        cvtdq2ps  xmm1,xmm1                     ; xmm1=in2=(20 21 22 23)

        punpcklwd xmm2,xmm2             ; xmm2=(40 40 41 41 42 42 43 43)
        punpcklwd xmm3,xmm3             ; xmm3=(60 60 61 61 62 62 63 63)
        psrad     xmm2,(DWORD_BIT-WORD_BIT)     ; xmm2=in4=(40 41 42 43)
        psrad     xmm3,(DWORD_BIT-WORD_BIT)     ; xmm3=in6=(60 61 62 63)
        cvtdq2ps  xmm2,xmm2                     ; xmm2=in4=(40 41 42 43)
        cvtdq2ps  xmm3,xmm3                     ; xmm3=in6=(60 61 62 63)

        mulps     xmm0, XMMWORD [XMMBLOCK(0,0,rdx,SIZEOF_FLOAT_MULT_TYPE)]
        mulps     xmm1, XMMWORD [XMMBLOCK(2,0,rdx,SIZEOF_FLOAT_MULT_TYPE)]
        mulps     xmm2, XMMWORD [XMMBLOCK(4,0,rdx,SIZEOF_FLOAT_MULT_TYPE)]
        mulps     xmm3, XMMWORD [XMMBLOCK(6,0,rdx,SIZEOF_FLOAT_MULT_TYPE)]

        movaps  xmm4,xmm0
        movaps  xmm5,xmm1
        subps   xmm0,xmm2               ; xmm0=tmp11
        subps   xmm1,xmm3
        addps   xmm4,xmm2               ; xmm4=tmp10
        addps   xmm5,xmm3               ; xmm5=tmp13

        mulps   xmm1,[rel PD_1_414]
        subps   xmm1,xmm5               ; xmm1=tmp12

        movaps  xmm6,xmm4
        movaps  xmm7,xmm0
        subps   xmm4,xmm5               ; xmm4=tmp3
        subps   xmm0,xmm1               ; xmm0=tmp2
        addps   xmm6,xmm5               ; xmm6=tmp0
        addps   xmm7,xmm1               ; xmm7=tmp1

        movaps  XMMWORD [wk(1)], xmm4   ; tmp3
        movaps  XMMWORD [wk(0)], xmm0   ; tmp2

        ; -- Odd part

        movq      xmm2, XMM_MMWORD [MMBLOCK(1,0,rsi,SIZEOF_JCOEF)]
        movq      xmm3, XMM_MMWORD [MMBLOCK(3,0,rsi,SIZEOF_JCOEF)]
        movq      xmm5, XMM_MMWORD [MMBLOCK(5,0,rsi,SIZEOF_JCOEF)]
        movq      xmm1, XMM_MMWORD [MMBLOCK(7,0,rsi,SIZEOF_JCOEF)]

        punpcklwd xmm2,xmm2             ; xmm2=(10 10 11 11 12 12 13 13)
        punpcklwd xmm3,xmm3             ; xmm3=(30 30 31 31 32 32 33 33)
        psrad     xmm2,(DWORD_BIT-WORD_BIT)     ; xmm2=in1=(10 11 12 13)
        psrad     xmm3,(DWORD_BIT-WORD_BIT)     ; xmm3=in3=(30 31 32 33)
        cvtdq2ps  xmm2,xmm2                     ; xmm2=in1=(10 11 12 13)
        cvtdq2ps  xmm3,xmm3                     ; xmm3=in3=(30 31 32 33)

        punpcklwd xmm5,xmm5             ; xmm5=(50 50 51 51 52 52 53 53)
        punpcklwd xmm1,xmm1             ; xmm1=(70 70 71 71 72 72 73 73)
        psrad     xmm5,(DWORD_BIT-WORD_BIT)     ; xmm5=in5=(50 51 52 53)
        psrad     xmm1,(DWORD_BIT-WORD_BIT)     ; xmm1=in7=(70 71 72 73)
        cvtdq2ps  xmm5,xmm5                     ; xmm5=in5=(50 51 52 53)
        cvtdq2ps  xmm1,xmm1                     ; xmm1=in7=(70 71 72 73)

        mulps     xmm2, XMMWORD [XMMBLOCK(1,0,rdx,SIZEOF_FLOAT_MULT_TYPE)]
        mulps     xmm3, XMMWORD [XMMBLOCK(3,0,rdx,SIZEOF_FLOAT_MULT_TYPE)]
        mulps     xmm5, XMMWORD [XMMBLOCK(5,0,rdx,SIZEOF_FLOAT_MULT_TYPE)]
        mulps     xmm1, XMMWORD [XMMBLOCK(7,0,rdx,SIZEOF_FLOAT_MULT_TYPE)]

        movaps  xmm4,xmm2
        movaps  xmm0,xmm5
        addps   xmm2,xmm1               ; xmm2=z11
        addps   xmm5,xmm3               ; xmm5=z13
        subps   xmm4,xmm1               ; xmm4=z12
        subps   xmm0,xmm3               ; xmm0=z10

        movaps  xmm1,xmm2
        subps   xmm2,xmm5
        addps   xmm1,xmm5               ; xmm1=tmp7

        mulps   xmm2,[rel PD_1_414]     ; xmm2=tmp11

        movaps  xmm3,xmm0
        addps   xmm0,xmm4
        mulps   xmm0,[rel PD_1_847]     ; xmm0=z5
        mulps   xmm3,[rel PD_M2_613]    ; xmm3=(z10 * -2.613125930)
        mulps   xmm4,[rel PD_1_082]     ; xmm4=(z12 * 1.082392200)
        addps   xmm3,xmm0               ; xmm3=tmp12
        subps   xmm4,xmm0               ; xmm4=tmp10

        ; -- Final output stage

        subps   xmm3,xmm1               ; xmm3=tmp6
        movaps  xmm5,xmm6
        movaps  xmm0,xmm7
        addps   xmm6,xmm1               ; xmm6=data0=(00 01 02 03)
        addps   xmm7,xmm3               ; xmm7=data1=(10 11 12 13)
        subps   xmm5,xmm1               ; xmm5=data7=(70 71 72 73)
        subps   xmm0,xmm3               ; xmm0=data6=(60 61 62 63)
        subps   xmm2,xmm3               ; xmm2=tmp5

        movaps    xmm1,xmm6             ; transpose coefficients(phase 1)
        unpcklps  xmm6,xmm7             ; xmm6=(00 10 01 11)
        unpckhps  xmm1,xmm7             ; xmm1=(02 12 03 13)
        movaps    xmm3,xmm0             ; transpose coefficients(phase 1)
        unpcklps  xmm0,xmm5             ; xmm0=(60 70 61 71)
        unpckhps  xmm3,xmm5             ; xmm3=(62 72 63 73)

        movaps  xmm7, XMMWORD [wk(0)]   ; xmm7=tmp2
        movaps  xmm5, XMMWORD [wk(1)]   ; xmm5=tmp3

        movaps  XMMWORD [wk(0)], xmm0   ; wk(0)=(60 70 61 71)
        movaps  XMMWORD [wk(1)], xmm3   ; wk(1)=(62 72 63 73)

        addps   xmm4,xmm2               ; xmm4=tmp4
        movaps  xmm0,xmm7
        movaps  xmm3,xmm5
        addps   xmm7,xmm2               ; xmm7=data2=(20 21 22 23)
        addps   xmm5,xmm4               ; xmm5=data4=(40 41 42 43)
        subps   xmm0,xmm2               ; xmm0=data5=(50 51 52 53)
        subps   xmm3,xmm4               ; xmm3=data3=(30 31 32 33)

        movaps    xmm2,xmm7             ; transpose coefficients(phase 1)
        unpcklps  xmm7,xmm3             ; xmm7=(20 30 21 31)
        unpckhps  xmm2,xmm3             ; xmm2=(22 32 23 33)
        movaps    xmm4,xmm5             ; transpose coefficients(phase 1)
        unpcklps  xmm5,xmm0             ; xmm5=(40 50 41 51)
        unpckhps  xmm4,xmm0             ; xmm4=(42 52 43 53)

        movaps    xmm3,xmm6             ; transpose coefficients(phase 2)
        unpcklps2 xmm6,xmm7             ; xmm6=(00 10 20 30)
        unpckhps2 xmm3,xmm7             ; xmm3=(01 11 21 31)
        movaps    xmm0,xmm1             ; transpose coefficients(phase 2)
        unpcklps2 xmm1,xmm2             ; xmm1=(02 12 22 32)
        unpckhps2 xmm0,xmm2             ; xmm0=(03 13 23 33)

        movaps  xmm7, XMMWORD [wk(0)]   ; xmm7=(60 70 61 71)
        movaps  xmm2, XMMWORD [wk(1)]   ; xmm2=(62 72 63 73)

        movaps  XMMWORD [XMMBLOCK(0,0,rdi,SIZEOF_FAST_FLOAT)], xmm6
        movaps  XMMWORD [XMMBLOCK(1,0,rdi,SIZEOF_FAST_FLOAT)], xmm3
        movaps  XMMWORD [XMMBLOCK(2,0,rdi,SIZEOF_FAST_FLOAT)], xmm1
        movaps  XMMWORD [XMMBLOCK(3,0,rdi,SIZEOF_FAST_FLOAT)], xmm0

        movaps    xmm6,xmm5             ; transpose coefficients(phase 2)
        unpcklps2 xmm5,xmm7             ; xmm5=(40 50 60 70)
        unpckhps2 xmm6,xmm7             ; xmm6=(41 51 61 71)
        movaps    xmm3,xmm4             ; transpose coefficients(phase 2)
        unpcklps2 xmm4,xmm2             ; xmm4=(42 52 62 72)
        unpckhps2 xmm3,xmm2             ; xmm3=(43 53 63 73)

        movaps  XMMWORD [XMMBLOCK(0,1,rdi,SIZEOF_FAST_FLOAT)], xmm5
        movaps  XMMWORD [XMMBLOCK(1,1,rdi,SIZEOF_FAST_FLOAT)], xmm6
        movaps  XMMWORD [XMMBLOCK(2,1,rdi,SIZEOF_FAST_FLOAT)], xmm4
        movaps  XMMWORD [XMMBLOCK(3,1,rdi,SIZEOF_FAST_FLOAT)], xmm3

.nextcolumn:
        add     rsi, byte 4*SIZEOF_JCOEF                ; coef_block
        add     rdx, byte 4*SIZEOF_FLOAT_MULT_TYPE      ; quantptr
        add     rdi,      4*DCTSIZE*SIZEOF_FAST_FLOAT   ; wsptr
        dec     rcx                                     ; ctr
        jnz     near .columnloop

        ; -- Prefetch the next coefficient block

        prefetchnta [rsi + (DCTSIZE2-8)*SIZEOF_JCOEF + 0*32]
        prefetchnta [rsi + (DCTSIZE2-8)*SIZEOF_JCOEF + 1*32]
        prefetchnta [rsi + (DCTSIZE2-8)*SIZEOF_JCOEF + 2*32]
        prefetchnta [rsi + (DCTSIZE2-8)*SIZEOF_JCOEF + 3*32]

        ; ---- Pass 2: process rows from work array, store into output array.

        mov     rax, [original_rbp]
        lea     rsi, [workspace]                        ; FAST_FLOAT * wsptr
        mov     rdi, r12        ; (JSAMPROW *)
        mov     eax, r13d
        mov     rcx, DCTSIZE/4                          ; ctr
.rowloop:

        ; -- Even part

        movaps  xmm0, XMMWORD [XMMBLOCK(0,0,rsi,SIZEOF_FAST_FLOAT)]
        movaps  xmm1, XMMWORD [XMMBLOCK(2,0,rsi,SIZEOF_FAST_FLOAT)]
        movaps  xmm2, XMMWORD [XMMBLOCK(4,0,rsi,SIZEOF_FAST_FLOAT)]
        movaps  xmm3, XMMWORD [XMMBLOCK(6,0,rsi,SIZEOF_FAST_FLOAT)]

        movaps  xmm4,xmm0
        movaps  xmm5,xmm1
        subps   xmm0,xmm2               ; xmm0=tmp11
        subps   xmm1,xmm3
        addps   xmm4,xmm2               ; xmm4=tmp10
        addps   xmm5,xmm3               ; xmm5=tmp13

        mulps   xmm1,[rel PD_1_414]
        subps   xmm1,xmm5               ; xmm1=tmp12

        movaps  xmm6,xmm4
        movaps  xmm7,xmm0
        subps   xmm4,xmm5               ; xmm4=tmp3
        subps   xmm0,xmm1               ; xmm0=tmp2
        addps   xmm6,xmm5               ; xmm6=tmp0
        addps   xmm7,xmm1               ; xmm7=tmp1

        movaps  XMMWORD [wk(1)], xmm4   ; tmp3
        movaps  XMMWORD [wk(0)], xmm0   ; tmp2

        ; -- Odd part

        movaps  xmm2, XMMWORD [XMMBLOCK(1,0,rsi,SIZEOF_FAST_FLOAT)]
        movaps  xmm3, XMMWORD [XMMBLOCK(3,0,rsi,SIZEOF_FAST_FLOAT)]
        movaps  xmm5, XMMWORD [XMMBLOCK(5,0,rsi,SIZEOF_FAST_FLOAT)]
        movaps  xmm1, XMMWORD [XMMBLOCK(7,0,rsi,SIZEOF_FAST_FLOAT)]

        movaps  xmm4,xmm2
        movaps  xmm0,xmm5
        addps   xmm2,xmm1               ; xmm2=z11
        addps   xmm5,xmm3               ; xmm5=z13
        subps   xmm4,xmm1               ; xmm4=z12
        subps   xmm0,xmm3               ; xmm0=z10

        movaps  xmm1,xmm2
        subps   xmm2,xmm5
        addps   xmm1,xmm5               ; xmm1=tmp7

        mulps   xmm2,[rel PD_1_414]     ; xmm2=tmp11

        movaps  xmm3,xmm0
        addps   xmm0,xmm4
        mulps   xmm0,[rel PD_1_847]     ; xmm0=z5
        mulps   xmm3,[rel PD_M2_613]    ; xmm3=(z10 * -2.613125930)
        mulps   xmm4,[rel PD_1_082]     ; xmm4=(z12 * 1.082392200)
        addps   xmm3,xmm0               ; xmm3=tmp12
        subps   xmm4,xmm0               ; xmm4=tmp10

        ; -- Final output stage

        subps   xmm3,xmm1               ; xmm3=tmp6
        movaps  xmm5,xmm6
        movaps  xmm0,xmm7
        addps   xmm6,xmm1               ; xmm6=data0=(00 10 20 30)
        addps   xmm7,xmm3               ; xmm7=data1=(01 11 21 31)
        subps   xmm5,xmm1               ; xmm5=data7=(07 17 27 37)
        subps   xmm0,xmm3               ; xmm0=data6=(06 16 26 36)
        subps   xmm2,xmm3               ; xmm2=tmp5

        movaps  xmm1,[rel PD_RNDINT_MAGIC]      ; xmm1=[rel PD_RNDINT_MAGIC]
        pcmpeqd xmm3,xmm3
        psrld   xmm3,WORD_BIT           ; xmm3={0xFFFF 0x0000 0xFFFF 0x0000 ..}

        addps   xmm6,xmm1       ; xmm6=roundint(data0/8)=(00 ** 10 ** 20 ** 30 **)
        addps   xmm7,xmm1       ; xmm7=roundint(data1/8)=(01 ** 11 ** 21 ** 31 **)
        addps   xmm0,xmm1       ; xmm0=roundint(data6/8)=(06 ** 16 ** 26 ** 36 **)
        addps   xmm5,xmm1       ; xmm5=roundint(data7/8)=(07 ** 17 ** 27 ** 37 **)

        pand    xmm6,xmm3               ; xmm6=(00 -- 10 -- 20 -- 30 --)
        pslld   xmm7,WORD_BIT           ; xmm7=(-- 01 -- 11 -- 21 -- 31)
        pand    xmm0,xmm3               ; xmm0=(06 -- 16 -- 26 -- 36 --)
        pslld   xmm5,WORD_BIT           ; xmm5=(-- 07 -- 17 -- 27 -- 37)
        por     xmm6,xmm7               ; xmm6=(00 01 10 11 20 21 30 31)
        por     xmm0,xmm5               ; xmm0=(06 07 16 17 26 27 36 37)

        movaps  xmm1, XMMWORD [wk(0)]   ; xmm1=tmp2
        movaps  xmm3, XMMWORD [wk(1)]   ; xmm3=tmp3

        addps   xmm4,xmm2               ; xmm4=tmp4
        movaps  xmm7,xmm1
        movaps  xmm5,xmm3
        addps   xmm1,xmm2               ; xmm1=data2=(02 12 22 32)
        addps   xmm3,xmm4               ; xmm3=data4=(04 14 24 34)
        subps   xmm7,xmm2               ; xmm7=data5=(05 15 25 35)
        subps   xmm5,xmm4               ; xmm5=data3=(03 13 23 33)

        movaps  xmm2,[rel PD_RNDINT_MAGIC]      ; xmm2=[rel PD_RNDINT_MAGIC]
        pcmpeqd xmm4,xmm4
        psrld   xmm4,WORD_BIT           ; xmm4={0xFFFF 0x0000 0xFFFF 0x0000 ..}

        addps   xmm3,xmm2       ; xmm3=roundint(data4/8)=(04 ** 14 ** 24 ** 34 **)
        addps   xmm7,xmm2       ; xmm7=roundint(data5/8)=(05 ** 15 ** 25 ** 35 **)
        addps   xmm1,xmm2       ; xmm1=roundint(data2/8)=(02 ** 12 ** 22 ** 32 **)
        addps   xmm5,xmm2       ; xmm5=roundint(data3/8)=(03 ** 13 ** 23 ** 33 **)

        pand    xmm3,xmm4               ; xmm3=(04 -- 14 -- 24 -- 34 --)
        pslld   xmm7,WORD_BIT           ; xmm7=(-- 05 -- 15 -- 25 -- 35)
        pand    xmm1,xmm4               ; xmm1=(02 -- 12 -- 22 -- 32 --)
        pslld   xmm5,WORD_BIT           ; xmm5=(-- 03 -- 13 -- 23 -- 33)
        por     xmm3,xmm7               ; xmm3=(04 05 14 15 24 25 34 35)
        por     xmm1,xmm5               ; xmm1=(02 03 12 13 22 23 32 33)

        movdqa    xmm2,[rel PB_CENTERJSAMP]     ; xmm2=[rel PB_CENTERJSAMP]

        packsswb  xmm6,xmm3     ; xmm6=(00 01 10 11 20 21 30 31 04 05 14 15 24 25 34 35)
        packsswb  xmm1,xmm0     ; xmm1=(02 03 12 13 22 23 32 33 06 07 16 17 26 27 36 37)
        paddb     xmm6,xmm2
        paddb     xmm1,xmm2

        movdqa    xmm4,xmm6     ; transpose coefficients(phase 2)
        punpcklwd xmm6,xmm1     ; xmm6=(00 01 02 03 10 11 12 13 20 21 22 23 30 31 32 33)
        punpckhwd xmm4,xmm1     ; xmm4=(04 05 06 07 14 15 16 17 24 25 26 27 34 35 36 37)

        movdqa    xmm7,xmm6     ; transpose coefficients(phase 3)
        punpckldq xmm6,xmm4     ; xmm6=(00 01 02 03 04 05 06 07 10 11 12 13 14 15 16 17)
        punpckhdq xmm7,xmm4     ; xmm7=(20 21 22 23 24 25 26 27 30 31 32 33 34 35 36 37)

        pshufd  xmm5,xmm6,0x4E  ; xmm5=(10 11 12 13 14 15 16 17 00 01 02 03 04 05 06 07)
        pshufd  xmm3,xmm7,0x4E  ; xmm3=(30 31 32 33 34 35 36 37 20 21 22 23 24 25 26 27)

        mov     rdx, JSAMPROW [rdi+0*SIZEOF_JSAMPROW]
        mov     rbx, JSAMPROW [rdi+2*SIZEOF_JSAMPROW]
        movq    XMM_MMWORD [rdx+rax*SIZEOF_JSAMPLE], xmm6
        movq    XMM_MMWORD [rbx+rax*SIZEOF_JSAMPLE], xmm7
        mov     rdx, JSAMPROW [rdi+1*SIZEOF_JSAMPROW]
        mov     rbx, JSAMPROW [rdi+3*SIZEOF_JSAMPROW]
        movq    XMM_MMWORD [rdx+rax*SIZEOF_JSAMPLE], xmm5
        movq    XMM_MMWORD [rbx+rax*SIZEOF_JSAMPLE], xmm3

        add     rsi, byte 4*SIZEOF_FAST_FLOAT   ; wsptr
        add     rdi, byte 4*SIZEOF_JSAMPROW
        dec     rcx                             ; ctr
        jnz     near .rowloop

        pop     rbx
        uncollect_args
        mov     rsp,rbp         ; rsp <- aligned rbp
        pop     rsp             ; rsp <- original rbp
        pop     rbp
        ret

; For some reason, the OS X linker does not honor the request to align the
; segment unless we do this.
        align   16