;
; Fast integer FDCT (32-bit SSE2)
;
; Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
; Copyright (C) 2016, 2024-2025, D. R. Commander.
;
; Based on the 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) or Yasm.
;
; This file contains a fast, not so accurate integer implementation of the
; forward DCT (Discrete Cosine Transform).  The following code is based
; directly on the IJG's original jfdctfst.c; see jfdctfst.c for more details.

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

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

%define CONST_BITS  8  ; 14 is also OK.

%if CONST_BITS == 8
F_0_382 equ  98  ; FIX(0.382683433)
F_0_541 equ 139  ; FIX(0.541196100)
F_0_707 equ 181  ; FIX(0.707106781)
F_1_306 equ 334  ; FIX(1.306562965)
%else
; NASM cannot do compile-time arithmetic on floating-point constants.
%define DESCALE(x, n)  (((x) + (1 << ((n) - 1))) >> (n))
F_0_382 equ DESCALE( 410903207, 30 - CONST_BITS)  ; FIX(0.382683433)
F_0_541 equ DESCALE( 581104887, 30 - CONST_BITS)  ; FIX(0.541196100)
F_0_707 equ DESCALE( 759250124, 30 - CONST_BITS)  ; FIX(0.707106781)
F_1_306 equ DESCALE(1402911301, 30 - CONST_BITS)  ; FIX(1.306562965)
%endif

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

; PRE_MULTIPLY_SCALE_BITS <= 2 (to avoid overflow)
; CONST_BITS + CONST_SHIFT + PRE_MULTIPLY_SCALE_BITS == 16 (for pmulhw)

%define PRE_MULTIPLY_SCALE_BITS  2
%define CONST_SHIFT              (16 - PRE_MULTIPLY_SCALE_BITS - CONST_BITS)

    ALIGNZ      32
    GLOBAL_DATA(jconst_fdct_ifast_sse2)

EXTN(jconst_fdct_ifast_sse2):

PW_F0707 times 8 dw F_0_707 << CONST_SHIFT
PW_F0382 times 8 dw F_0_382 << CONST_SHIFT
PW_F0541 times 8 dw F_0_541 << CONST_SHIFT
PW_F1306 times 8 dw F_1_306 << CONST_SHIFT

    ALIGNZ      32

; --------------------------------------------------------------------------
    SECTION     SEG_TEXT
    BITS        32

; Perform the forward DCT on one block of samples.
;
; GLOBAL(void)
; jsimd_fdct_ifast_sse2(DCTELEM *data)

%define data(b)       (b) + 8           ; DCTELEM *data

%define original_ebp  ebp + 0
%define wk(i)         ebp - (WK_NUM - (i)) * SIZEOF_XMMWORD
                      ; xmmword wk[WK_NUM]
%define WK_NUM        2

    align       32
    GLOBAL_FUNCTION(jsimd_fdct_ifast_sse2)

EXTN(jsimd_fdct_ifast_sse2):
    push        ebp
    mov         eax, esp                ; eax = original ebp
    sub         esp, byte 4
    and         esp, byte (-SIZEOF_XMMWORD)  ; align to 128 bits
    mov         [esp], eax
    mov         ebp, esp                ; ebp = aligned ebp
    lea         esp, [wk(0)]
    PUSHPIC     ebx
;   push        ecx                     ; unused
;   push        edx                     ; need not be preserved
;   push        esi                     ; unused
;   push        edi                     ; unused

    GET_GOT     ebx                     ; get GOT address

    ; ---- Pass 1: process rows.

    mov         edx, POINTER [data(eax)]  ; (DCTELEM *)

    movdqa      xmm0, XMMWORD [XMMBLOCK(0, 0, edx, SIZEOF_DCTELEM)]
    movdqa      xmm1, XMMWORD [XMMBLOCK(1, 0, edx, SIZEOF_DCTELEM)]
    movdqa      xmm2, XMMWORD [XMMBLOCK(2, 0, edx, SIZEOF_DCTELEM)]
    movdqa      xmm3, XMMWORD [XMMBLOCK(3, 0, edx, SIZEOF_DCTELEM)]

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

    movdqa      xmm4, xmm0              ; transpose coefficients(phase 1)
    punpcklwd   xmm0, xmm1              ; xmm0 = (00 10 01 11 02 12 03 13)
    punpckhwd   xmm4, xmm1              ; xmm4 = (04 14 05 15 06 16 07 17)
    movdqa      xmm5, xmm2              ; transpose coefficients(phase 1)
    punpcklwd   xmm2, xmm3              ; xmm2 = (20 30 21 31 22 32 23 33)
    punpckhwd   xmm5, xmm3              ; xmm5 = (24 34 25 35 26 36 27 37)

    movdqa      xmm6, XMMWORD [XMMBLOCK(4, 0, edx, SIZEOF_DCTELEM)]
    movdqa      xmm7, XMMWORD [XMMBLOCK(5, 0, edx, SIZEOF_DCTELEM)]
    movdqa      xmm1, XMMWORD [XMMBLOCK(6, 0, edx, SIZEOF_DCTELEM)]
    movdqa      xmm3, XMMWORD [XMMBLOCK(7, 0, edx, SIZEOF_DCTELEM)]

    ; xmm6 = ( 4 12 20 28 36 44 52 60)
    ; xmm1 = ( 6 14 22 30 38 46 54 62)
    ; xmm7 = ( 5 13 21 29 37 45 53 61)
    ; xmm3 = ( 7 15 23 31 39 47 55 63)

    movdqa      XMMWORD [wk(0)], xmm2   ; wk(0) = (20 30 21 31 22 32 23 33)
    movdqa      XMMWORD [wk(1)], xmm5   ; wk(1) = (24 34 25 35 26 36 27 37)

    movdqa      xmm2, xmm6              ; transpose coefficients(phase 1)
    punpcklwd   xmm6, xmm7              ; xmm6 = (40 50 41 51 42 52 43 53)
    punpckhwd   xmm2, xmm7              ; xmm2 = (44 54 45 55 46 56 47 57)
    movdqa      xmm5, xmm1              ; transpose coefficients(phase 1)
    punpcklwd   xmm1, xmm3              ; xmm1 = (60 70 61 71 62 72 63 73)
    punpckhwd   xmm5, xmm3              ; xmm5 = (64 74 65 75 66 76 67 77)

    movdqa      xmm7, xmm6              ; transpose coefficients(phase 2)
    punpckldq   xmm6, xmm1              ; xmm6 = (40 50 60 70 41 51 61 71)
    punpckhdq   xmm7, xmm1              ; xmm7 = (42 52 62 72 43 53 63 73)
    movdqa      xmm3, xmm2              ; transpose coefficients(phase 2)
    punpckldq   xmm2, xmm5              ; xmm2 = (44 54 64 74 45 55 65 75)
    punpckhdq   xmm3, xmm5              ; xmm3 = (46 56 66 76 47 57 67 77)

    movdqa      xmm1, XMMWORD [wk(0)]   ; xmm1 = (20 30 21 31 22 32 23 33)
    movdqa      xmm5, XMMWORD [wk(1)]   ; xmm5 = (24 34 25 35 26 36 27 37)
    movdqa      XMMWORD [wk(0)], xmm7   ; wk(0) = (42 52 62 72 43 53 63 73)
    movdqa      XMMWORD [wk(1)], xmm2   ; wk(1) = (44 54 64 74 45 55 65 75)

    movdqa      xmm7, xmm0              ; transpose coefficients(phase 2)
    punpckldq   xmm0, xmm1              ; xmm0 = (00 10 20 30 01 11 21 31)
    punpckhdq   xmm7, xmm1              ; xmm7 = (02 12 22 32 03 13 23 33)
    movdqa      xmm2, xmm4              ; transpose coefficients(phase 2)
    punpckldq   xmm4, xmm5              ; xmm4 = (04 14 24 34 05 15 25 35)
    punpckhdq   xmm2, xmm5              ; xmm2 = (06 16 26 36 07 17 27 37)

    movdqa      xmm1, xmm0           ; transpose coefficients(phase 3)
    punpcklqdq  xmm0, xmm6           ; xmm0 = (00 10 20 30 40 50 60 70) = data0
    punpckhqdq  xmm1, xmm6           ; xmm1 = (01 11 21 31 41 51 61 71) = data1
    movdqa      xmm5, xmm2           ; transpose coefficients(phase 3)
    punpcklqdq  xmm2, xmm3           ; xmm2 = (06 16 26 36 46 56 66 76) = data6
    punpckhqdq  xmm5, xmm3           ; xmm5 = (07 17 27 37 47 57 67 77) = data7

    movdqa      xmm6, xmm1
    movdqa      xmm3, xmm0
    psubw       xmm1, xmm2              ; xmm1 = data1 - data6 = tmp6
    psubw       xmm0, xmm5              ; xmm0 = data0 - data7 = tmp7
    paddw       xmm6, xmm2              ; xmm6 = data1 + data6 = tmp1
    paddw       xmm3, xmm5              ; xmm3 = data0 + data7 = tmp0

    movdqa      xmm2, XMMWORD [wk(0)]   ; xmm2 = (42 52 62 72 43 53 63 73)
    movdqa      xmm5, XMMWORD [wk(1)]   ; xmm5 = (44 54 64 74 45 55 65 75)
    movdqa      XMMWORD [wk(0)], xmm1   ; wk(0) = tmp6
    movdqa      XMMWORD [wk(1)], xmm0   ; wk(1) = tmp7

    movdqa      xmm1, xmm7           ; transpose coefficients(phase 3)
    punpcklqdq  xmm7, xmm2           ; xmm7 = (02 12 22 32 42 52 62 72) = data2
    punpckhqdq  xmm1, xmm2           ; xmm1 = (03 13 23 33 43 53 63 73) = data3
    movdqa      xmm0, xmm4           ; transpose coefficients(phase 3)
    punpcklqdq  xmm4, xmm5           ; xmm4 = (04 14 24 34 44 54 64 74) = data4
    punpckhqdq  xmm0, xmm5           ; xmm0 = (05 15 25 35 45 55 65 75) = data5

    movdqa      xmm2, xmm1
    movdqa      xmm5, xmm7
    paddw       xmm1, xmm4              ; xmm1 = data3 + data4 = tmp3
    paddw       xmm7, xmm0              ; xmm7 = data2 + data5 = tmp2
    psubw       xmm2, xmm4              ; xmm2 = data3 - data4 = tmp4
    psubw       xmm5, xmm0              ; xmm5 = data2 - data5 = tmp5

    ; -- Even part

    movdqa      xmm4, xmm3
    movdqa      xmm0, xmm6
    psubw       xmm3, xmm1              ; xmm3 = tmp13
    psubw       xmm6, xmm7              ; xmm6 = tmp12
    paddw       xmm4, xmm1              ; xmm4 = tmp10
    paddw       xmm0, xmm7              ; xmm0 = tmp11

    paddw       xmm6, xmm3
    psllw       xmm6, PRE_MULTIPLY_SCALE_BITS
    pmulhw      xmm6, [GOTOFF(ebx, PW_F0707)]  ; xmm6 = z1

    movdqa      xmm1, xmm4
    movdqa      xmm7, xmm3
    psubw       xmm4, xmm0              ; xmm4 = data4
    psubw       xmm3, xmm6              ; xmm3 = data6
    paddw       xmm1, xmm0              ; xmm1 = data0
    paddw       xmm7, xmm6              ; xmm7 = data2

    movdqa      xmm0, XMMWORD [wk(0)]   ; xmm0 = tmp6
    movdqa      xmm6, XMMWORD [wk(1)]   ; xmm6 = tmp7
    movdqa      XMMWORD [wk(0)], xmm4   ; wk(0) = data4
    movdqa      XMMWORD [wk(1)], xmm3   ; wk(1) = data6

    ; -- Odd part

    paddw       xmm2, xmm5              ; xmm2 = tmp10
    paddw       xmm5, xmm0              ; xmm5 = tmp11
    paddw       xmm0, xmm6              ; xmm0 = tmp12, xmm6 = tmp7

    psllw       xmm2, PRE_MULTIPLY_SCALE_BITS
    psllw       xmm0, PRE_MULTIPLY_SCALE_BITS

    psllw       xmm5, PRE_MULTIPLY_SCALE_BITS
    pmulhw      xmm5, [GOTOFF(ebx, PW_F0707)]  ; xmm5 = z3

    movdqa      xmm4, xmm2              ; xmm4 = tmp10
    psubw       xmm2, xmm0
    pmulhw      xmm2, [GOTOFF(ebx, PW_F0382)]  ; xmm2 = z5
    pmulhw      xmm4, [GOTOFF(ebx, PW_F0541)]
                ; xmm4 = MULTIPLY(tmp10, FIX_0_541196)
    pmulhw      xmm0, [GOTOFF(ebx, PW_F1306)]
                ; xmm0 = MULTIPLY(tmp12, FIX_1_306562)
    paddw       xmm4, xmm2              ; xmm4 = z2
    paddw       xmm0, xmm2              ; xmm0 = z4

    movdqa      xmm3, xmm6
    psubw       xmm6, xmm5              ; xmm6 = z13
    paddw       xmm3, xmm5              ; xmm3 = z11

    movdqa      xmm2, xmm6
    movdqa      xmm5, xmm3
    psubw       xmm6, xmm4              ; xmm6 = data3
    psubw       xmm3, xmm0              ; xmm3 = data7
    paddw       xmm2, xmm4              ; xmm2 = data5
    paddw       xmm5, xmm0              ; xmm5 = data1

    ; ---- Pass 2: process columns.

;   mov         edx, POINTER [data(eax)]  ; (DCTELEM *)

    ; xmm1 = (00 10 20 30 40 50 60 70)
    ; xmm7 = (02 12 22 32 42 52 62 72)
    ; xmm5 = (01 11 21 31 41 51 61 71)
    ; xmm6 = (03 13 23 33 43 53 63 73)

    movdqa      xmm4, xmm1              ; transpose coefficients(phase 1)
    punpcklwd   xmm1, xmm5              ; xmm1 = (00 01 10 11 20 21 30 31)
    punpckhwd   xmm4, xmm5              ; xmm4 = (40 41 50 51 60 61 70 71)
    movdqa      xmm0, xmm7              ; transpose coefficients(phase 1)
    punpcklwd   xmm7, xmm6              ; xmm7 = (02 03 12 13 22 23 32 33)
    punpckhwd   xmm0, xmm6              ; xmm0 = (42 43 52 53 62 63 72 73)

    movdqa      xmm5, XMMWORD [wk(0)]   ; xmm5 = col4
    movdqa      xmm6, XMMWORD [wk(1)]   ; xmm6 = col6

    ; xmm5 = (04 14 24 34 44 54 64 74)
    ; xmm6 = (06 16 26 36 46 56 66 76)
    ; xmm2 = (05 15 25 35 45 55 65 75)
    ; xmm3 = (07 17 27 37 47 57 67 77)

    movdqa      XMMWORD [wk(0)], xmm7   ; wk(0) = (02 03 12 13 22 23 32 33)
    movdqa      XMMWORD [wk(1)], xmm0   ; wk(1) = (42 43 52 53 62 63 72 73)

    movdqa      xmm7, xmm5              ; transpose coefficients(phase 1)
    punpcklwd   xmm5, xmm2              ; xmm5 = (04 05 14 15 24 25 34 35)
    punpckhwd   xmm7, xmm2              ; xmm7 = (44 45 54 55 64 65 74 75)
    movdqa      xmm0, xmm6              ; transpose coefficients(phase 1)
    punpcklwd   xmm6, xmm3              ; xmm6 = (06 07 16 17 26 27 36 37)
    punpckhwd   xmm0, xmm3              ; xmm0 = (46 47 56 57 66 67 76 77)

    movdqa      xmm2, xmm5              ; transpose coefficients(phase 2)
    punpckldq   xmm5, xmm6              ; xmm5 = (04 05 06 07 14 15 16 17)
    punpckhdq   xmm2, xmm6              ; xmm2 = (24 25 26 27 34 35 36 37)
    movdqa      xmm3, xmm7              ; transpose coefficients(phase 2)
    punpckldq   xmm7, xmm0              ; xmm7 = (44 45 46 47 54 55 56 57)
    punpckhdq   xmm3, xmm0              ; xmm3 = (64 65 66 67 74 75 76 77)

    movdqa      xmm6, XMMWORD [wk(0)]   ; xmm6 = (02 03 12 13 22 23 32 33)
    movdqa      xmm0, XMMWORD [wk(1)]   ; xmm0 = (42 43 52 53 62 63 72 73)
    movdqa      XMMWORD [wk(0)], xmm2   ; wk(0) = (24 25 26 27 34 35 36 37)
    movdqa      XMMWORD [wk(1)], xmm7   ; wk(1) = (44 45 46 47 54 55 56 57)

    movdqa      xmm2, xmm1              ; transpose coefficients(phase 2)
    punpckldq   xmm1, xmm6              ; xmm1 = (00 01 02 03 10 11 12 13)
    punpckhdq   xmm2, xmm6              ; xmm2 = (20 21 22 23 30 31 32 33)
    movdqa      xmm7, xmm4              ; transpose coefficients(phase 2)
    punpckldq   xmm4, xmm0              ; xmm4 = (40 41 42 43 50 51 52 53)
    punpckhdq   xmm7, xmm0              ; xmm7 = (60 61 62 63 70 71 72 73)

    movdqa      xmm6, xmm1           ; transpose coefficients(phase 3)
    punpcklqdq  xmm1, xmm5           ; xmm1 = (00 01 02 03 04 05 06 07) = data0
    punpckhqdq  xmm6, xmm5           ; xmm6 = (10 11 12 13 14 15 16 17) = data1
    movdqa      xmm0, xmm7           ; transpose coefficients(phase 3)
    punpcklqdq  xmm7, xmm3           ; xmm7 = (60 61 62 63 64 65 66 67) = data6
    punpckhqdq  xmm0, xmm3           ; xmm0 = (70 71 72 73 74 75 76 77) = data7

    movdqa      xmm5, xmm6
    movdqa      xmm3, xmm1
    psubw       xmm6, xmm7              ; xmm6 = data1 - data6 = tmp6
    psubw       xmm1, xmm0              ; xmm1 = data0 - data7 = tmp7
    paddw       xmm5, xmm7              ; xmm5 = data1 + data6 = tmp1
    paddw       xmm3, xmm0              ; xmm3 = data0 + data7 = tmp0

    movdqa      xmm7, XMMWORD [wk(0)]   ; xmm7 = (24 25 26 27 34 35 36 37)
    movdqa      xmm0, XMMWORD [wk(1)]   ; xmm0 = (44 45 46 47 54 55 56 57)
    movdqa      XMMWORD [wk(0)], xmm6   ; wk(0) = tmp6
    movdqa      XMMWORD [wk(1)], xmm1   ; wk(1) = tmp7

    movdqa      xmm6, xmm2           ; transpose coefficients(phase 3)
    punpcklqdq  xmm2, xmm7           ; xmm2 = (20 21 22 23 24 25 26 27) = data2
    punpckhqdq  xmm6, xmm7           ; xmm6 = (30 31 32 33 34 35 36 37) = data3
    movdqa      xmm1, xmm4           ; transpose coefficients(phase 3)
    punpcklqdq  xmm4, xmm0           ; xmm4 = (40 41 42 43 44 45 46 47) = data4
    punpckhqdq  xmm1, xmm0           ; xmm1 = (50 51 52 53 54 55 56 57) = data5

    movdqa      xmm7, xmm6
    movdqa      xmm0, xmm2
    paddw       xmm6, xmm4              ; xmm6 = data3 + data4 = tmp3
    paddw       xmm2, xmm1              ; xmm2 = data2 + data5 = tmp2
    psubw       xmm7, xmm4              ; xmm7 = data3 - data4 = tmp4
    psubw       xmm0, xmm1              ; xmm0 = data2 - data5 = tmp5

    ; -- Even part

    movdqa      xmm4, xmm3
    movdqa      xmm1, xmm5
    psubw       xmm3, xmm6              ; xmm3 = tmp13
    psubw       xmm5, xmm2              ; xmm5 = tmp12
    paddw       xmm4, xmm6              ; xmm4 = tmp10
    paddw       xmm1, xmm2              ; xmm1 = tmp11

    paddw       xmm5, xmm3
    psllw       xmm5, PRE_MULTIPLY_SCALE_BITS
    pmulhw      xmm5, [GOTOFF(ebx, PW_F0707)]  ; xmm5 = z1

    movdqa      xmm6, xmm4
    movdqa      xmm2, xmm3
    psubw       xmm4, xmm1              ; xmm4 = data4
    psubw       xmm3, xmm5              ; xmm3 = data6
    paddw       xmm6, xmm1              ; xmm6 = data0
    paddw       xmm2, xmm5              ; xmm2 = data2

    movdqa      XMMWORD [XMMBLOCK(4, 0, edx, SIZEOF_DCTELEM)], xmm4
    movdqa      XMMWORD [XMMBLOCK(6, 0, edx, SIZEOF_DCTELEM)], xmm3
    movdqa      XMMWORD [XMMBLOCK(0, 0, edx, SIZEOF_DCTELEM)], xmm6
    movdqa      XMMWORD [XMMBLOCK(2, 0, edx, SIZEOF_DCTELEM)], xmm2

    ; -- Odd part

    movdqa      xmm1, XMMWORD [wk(0)]   ; xmm1 = tmp6
    movdqa      xmm5, XMMWORD [wk(1)]   ; xmm5 = tmp7

    paddw       xmm7, xmm0              ; xmm7 = tmp10
    paddw       xmm0, xmm1              ; xmm0 = tmp11
    paddw       xmm1, xmm5              ; xmm1 = tmp12, xmm5 = tmp7

    psllw       xmm7, PRE_MULTIPLY_SCALE_BITS
    psllw       xmm1, PRE_MULTIPLY_SCALE_BITS

    psllw       xmm0, PRE_MULTIPLY_SCALE_BITS
    pmulhw      xmm0, [GOTOFF(ebx, PW_F0707)]  ; xmm0 = z3

    movdqa      xmm4, xmm7              ; xmm4 = tmp10
    psubw       xmm7, xmm1
    pmulhw      xmm7, [GOTOFF(ebx, PW_F0382)]  ; xmm7 = z5
    pmulhw      xmm4, [GOTOFF(ebx, PW_F0541)]
                ; xmm4 = MULTIPLY(tmp10, FIX_0_541196)
    pmulhw      xmm1, [GOTOFF(ebx, PW_F1306)]
                ; xmm1 = MULTIPLY(tmp12, FIX_1_306562)
    paddw       xmm4, xmm7              ; xmm4 = z2
    paddw       xmm1, xmm7              ; xmm1 = z4

    movdqa      xmm3, xmm5
    psubw       xmm5, xmm0              ; xmm5 = z13
    paddw       xmm3, xmm0              ; xmm3 = z11

    movdqa      xmm6, xmm5
    movdqa      xmm2, xmm3
    psubw       xmm5, xmm4              ; xmm5 = data3
    psubw       xmm3, xmm1              ; xmm3 = data7
    paddw       xmm6, xmm4              ; xmm6 = data5
    paddw       xmm2, xmm1              ; xmm2 = data1

    movdqa      XMMWORD [XMMBLOCK(3, 0, edx, SIZEOF_DCTELEM)], xmm5
    movdqa      XMMWORD [XMMBLOCK(7, 0, edx, SIZEOF_DCTELEM)], xmm3
    movdqa      XMMWORD [XMMBLOCK(5, 0, edx, SIZEOF_DCTELEM)], xmm6
    movdqa      XMMWORD [XMMBLOCK(1, 0, edx, SIZEOF_DCTELEM)], xmm2

;   pop         edi                     ; unused
;   pop         esi                     ; unused
;   pop         edx                     ; need not be preserved
;   pop         ecx                     ; unused
    POPPIC      ebx
    mov         esp, ebp                ; esp <- aligned ebp
    pop         esp                     ; esp <- original ebp
    pop         ebp
    ret

; For some reason, the OS X linker does not honor the request to align the
; segment unless we do this.
    align       32
