/*
   C-like prototype :
        void j_rev_dct_arm(DCTBLOCK data)

   With DCTBLOCK being a pointer to an array of 64 'signed shorts'

   Copyright (c) 2001 Lionel Ulmer (lionel.ulmer@free.fr / bbrox@bbrox.org)

   Permission is hereby granted, free of charge, to any person obtaining a copy
   of this software and associated documentation files (the "Software"), to deal
   in the Software without restriction, including without limitation the rights
   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   copies of the Software, and to permit persons to whom the Software is
   furnished to do so, subject to the following conditions:

   The above copyright notice and this permission notice shall be included in
   all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
   COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
   IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

*/

#include "libavutil/arm/asm.S"

#define FIX_0_298631336 2446
#define FIX_0_541196100 4433
#define FIX_0_765366865 6270
#define FIX_1_175875602 9633
#define FIX_1_501321110 12299
#define FIX_2_053119869 16819
#define FIX_3_072711026 25172
#define FIX_M_0_390180644 -3196
#define FIX_M_0_899976223 -7373
#define FIX_M_1_847759065 -15137
#define FIX_M_1_961570560 -16069
#define FIX_M_2_562915447 -20995
#define FIX_0xFFFF 0xFFFF

#define FIX_0_298631336_ID      0
#define FIX_0_541196100_ID      4
#define FIX_0_765366865_ID      8
#define FIX_1_175875602_ID     12
#define FIX_1_501321110_ID     16
#define FIX_2_053119869_ID     20
#define FIX_3_072711026_ID     24
#define FIX_M_0_390180644_ID   28
#define FIX_M_0_899976223_ID   32
#define FIX_M_1_847759065_ID   36
#define FIX_M_1_961570560_ID   40
#define FIX_M_2_562915447_ID   44
#define FIX_0xFFFF_ID          48

function ff_j_rev_dct_arm, export=1
        push            {r0, r4 - r11, lr}

        mov             lr, r0                    @ lr = pointer to the current row
        mov             r12, #8                   @ r12 = row-counter
        movrel          r11, const_array          @ r11 = base pointer to the constants array
row_loop:
        ldrsh           r0, [lr, # 0]             @ r0 = 'd0'
        ldrsh           r2, [lr, # 2]             @ r2 = 'd2'

        @ Optimization for row that have all items except the first set to 0
        @ (this works as the int16_t are always 4-byte aligned)
        ldr             r5, [lr, # 0]
        ldr             r6, [lr, # 4]
        ldr             r3, [lr, # 8]
        ldr             r4, [lr, #12]
        orr             r3, r3, r4
        orr             r3, r3, r6
        orrs            r5, r3, r5
        beq             end_of_row_loop           @ nothing to be done as ALL of them are '0'
        orrs            r3, r3, r2
        beq             empty_row

        ldrsh           r1, [lr, # 8]             @ r1 = 'd1'
        ldrsh           r4, [lr, # 4]             @ r4 = 'd4'
        ldrsh           r6, [lr, # 6]             @ r6 = 'd6'

        ldr             r3, [r11, #FIX_0_541196100_ID]
        add             r7, r2, r6
        ldr             r5, [r11, #FIX_M_1_847759065_ID]
        mul             r7, r3, r7                @ r7 = z1
        ldr             r3, [r11, #FIX_0_765366865_ID]
        mla             r6, r5, r6, r7            @ r6 = tmp2
        add             r5, r0, r4                @ r5 = tmp0
        mla             r2, r3, r2, r7            @ r2 = tmp3
        sub             r3, r0, r4                @ r3 = tmp1

        add             r0, r2, r5, lsl #13       @ r0 = tmp10
        rsb             r2, r2, r5, lsl #13       @ r2 = tmp13
        add             r4, r6, r3, lsl #13       @ r4 = tmp11
        rsb             r3, r6, r3, lsl #13       @ r3 = tmp12

        push            {r0, r2, r3, r4}          @ save on the stack tmp10, tmp13, tmp12, tmp11

        ldrsh           r3, [lr, #10]             @ r3 = 'd3'
        ldrsh           r5, [lr, #12]             @ r5 = 'd5'
        ldrsh           r7, [lr, #14]             @ r7 = 'd7'

        add             r0, r3, r5                @ r0 = 'z2'
        add             r2, r1, r7                @ r2 = 'z1'
        add             r4, r3, r7                @ r4 = 'z3'
        add             r6, r1, r5                @ r6 = 'z4'
        ldr             r9, [r11, #FIX_1_175875602_ID]
        add             r8, r4, r6                @ r8 = z3 + z4
        ldr             r10, [r11, #FIX_M_0_899976223_ID]
        mul             r8, r9, r8                @ r8 = 'z5'
        ldr             r9, [r11, #FIX_M_2_562915447_ID]
        mul             r2, r10, r2               @ r2 = 'z1'
        ldr             r10, [r11, #FIX_M_1_961570560_ID]
        mul             r0, r9, r0                @ r0 = 'z2'
        ldr             r9, [r11, #FIX_M_0_390180644_ID]
        mla             r4, r10, r4, r8           @ r4 = 'z3'
        ldr             r10, [r11, #FIX_0_298631336_ID]
        mla             r6, r9, r6, r8            @ r6 = 'z4'
        ldr             r9, [r11, #FIX_2_053119869_ID]
        mla             r7, r10, r7, r2           @ r7 = tmp0 + z1
        ldr             r10, [r11, #FIX_3_072711026_ID]
        mla             r5, r9, r5, r0            @ r5 = tmp1 + z2
        ldr             r9, [r11, #FIX_1_501321110_ID]
        mla             r3, r10, r3, r0           @ r3 = tmp2 + z2
        add             r7, r7, r4                @ r7 = tmp0
        mla             r1, r9, r1, r2            @ r1 = tmp3 + z1
        add             r5, r5, r6                @ r5 = tmp1
        add             r3, r3, r4                @ r3 = tmp2
        add             r1, r1, r6                @ r1 = tmp3

        pop             {r0, r2, r4, r6}          @ r0 = tmp10 / r2 = tmp13 / r4 = tmp12 / r6 = tmp11
                                                  @ r1 = tmp3  / r3 = tmp2  / r5 = tmp1  / r7 = tmp0

        @ Compute DESCALE(tmp10 + tmp3, CONST_BITS-PASS1_BITS)
        add             r8, r0, r1
        add             r8, r8, #(1<<10)
        mov             r8, r8, asr #11
        strh            r8, [lr, # 0]

        @ Compute DESCALE(tmp10 - tmp3, CONST_BITS-PASS1_BITS)
        sub             r8, r0, r1
        add             r8, r8, #(1<<10)
        mov             r8, r8, asr #11
        strh            r8, [lr, #14]

        @ Compute DESCALE(tmp11 + tmp2, CONST_BITS-PASS1_BITS)
        add             r8, r6, r3
        add             r8, r8, #(1<<10)
        mov             r8, r8, asr #11
        strh            r8, [lr, # 2]

        @ Compute DESCALE(tmp11 - tmp2, CONST_BITS-PASS1_BITS)
        sub             r8, r6, r3
        add             r8, r8, #(1<<10)
        mov             r8, r8, asr #11
        strh            r8, [lr, #12]

        @ Compute DESCALE(tmp12 + tmp1, CONST_BITS-PASS1_BITS)
        add             r8, r4, r5
        add             r8, r8, #(1<<10)
        mov             r8, r8, asr #11
        strh            r8, [lr, # 4]

        @ Compute DESCALE(tmp12 - tmp1, CONST_BITS-PASS1_BITS)
        sub             r8, r4, r5
        add             r8, r8, #(1<<10)
        mov             r8, r8, asr #11
        strh            r8, [lr, #10]

        @ Compute DESCALE(tmp13 + tmp0, CONST_BITS-PASS1_BITS)
        add             r8, r2, r7
        add             r8, r8, #(1<<10)
        mov             r8, r8, asr #11
        strh            r8, [lr, # 6]

        @ Compute DESCALE(tmp13 - tmp0, CONST_BITS-PASS1_BITS)
        sub             r8, r2, r7
        add             r8, r8, #(1<<10)
        mov             r8, r8, asr #11
        strh            r8, [lr, # 8]

        @ End of row loop
        add             lr, lr, #16
        subs            r12, r12, #1
        bne             row_loop
        beq             start_column_loop

empty_row:
        ldr             r1, [r11, #FIX_0xFFFF_ID]
        mov             r0, r0, lsl #2
        and             r0, r0, r1
        add             r0, r0, r0, lsl #16
        str             r0, [lr, # 0]
        str             r0, [lr, # 4]
        str             r0, [lr, # 8]
        str             r0, [lr, #12]

end_of_row_loop:
        @ End of loop
        add             lr, lr, #16
        subs            r12, r12, #1
        bne             row_loop

start_column_loop:
        @ Start of column loop
        pop             {lr}
        mov             r12, #8
column_loop:
        ldrsh           r0, [lr, #( 0*8)]         @ r0 = 'd0'
        ldrsh           r2, [lr, #( 4*8)]         @ r2 = 'd2'
        ldrsh           r4, [lr, #( 8*8)]         @ r4 = 'd4'
        ldrsh           r6, [lr, #(12*8)]         @ r6 = 'd6'

        ldr             r3, [r11, #FIX_0_541196100_ID]
        add             r1, r2, r6
        ldr             r5, [r11, #FIX_M_1_847759065_ID]
        mul             r1, r3, r1                @ r1 = z1
        ldr             r3, [r11, #FIX_0_765366865_ID]
        mla             r6, r5, r6, r1            @ r6 = tmp2
        add             r5, r0, r4                @ r5 = tmp0
        mla             r2, r3, r2, r1            @ r2 = tmp3
        sub             r3, r0, r4                @ r3 = tmp1

        add             r0, r2, r5, lsl #13       @ r0 = tmp10
        rsb             r2, r2, r5, lsl #13       @ r2 = tmp13
        add             r4, r6, r3, lsl #13       @ r4 = tmp11
        rsb             r6, r6, r3, lsl #13       @ r6 = tmp12

        ldrsh           r1, [lr, #( 2*8)]         @ r1 = 'd1'
        ldrsh           r3, [lr, #( 6*8)]         @ r3 = 'd3'
        ldrsh           r5, [lr, #(10*8)]         @ r5 = 'd5'
        ldrsh           r7, [lr, #(14*8)]         @ r7 = 'd7'

        @ Check for empty odd column (happens about 20 to 25 % of the time according to my stats)
        orr             r9, r1, r3
        orr             r10, r5, r7
        orrs            r10, r9, r10
        beq             empty_odd_column

        push            {r0, r2, r4, r6}          @ save on the stack tmp10, tmp13, tmp12, tmp11

        add             r0, r3, r5                @ r0 = 'z2'
        add             r2, r1, r7                @ r2 = 'z1'
        add             r4, r3, r7                @ r4 = 'z3'
        add             r6, r1, r5                @ r6 = 'z4'
        ldr             r9, [r11, #FIX_1_175875602_ID]
        add             r8, r4, r6
        ldr             r10, [r11, #FIX_M_0_899976223_ID]
        mul             r8, r9, r8                @ r8 = 'z5'
        ldr             r9, [r11, #FIX_M_2_562915447_ID]
        mul             r2, r10, r2               @ r2 = 'z1'
        ldr             r10, [r11, #FIX_M_1_961570560_ID]
        mul             r0, r9, r0                @ r0 = 'z2'
        ldr             r9, [r11, #FIX_M_0_390180644_ID]
        mla             r4, r10, r4, r8           @ r4 = 'z3'
        ldr             r10, [r11, #FIX_0_298631336_ID]
        mla             r6, r9, r6, r8            @ r6 = 'z4'
        ldr             r9, [r11, #FIX_2_053119869_ID]
        mla             r7, r10, r7, r2           @ r7 = tmp0 + z1
        ldr             r10, [r11, #FIX_3_072711026_ID]
        mla             r5, r9, r5, r0            @ r5 = tmp1 + z2
        ldr             r9, [r11, #FIX_1_501321110_ID]
        mla             r3, r10, r3, r0           @ r3 = tmp2 + z2
        add             r7, r7, r4                @ r7 = tmp0
        mla             r1, r9, r1, r2            @ r1 = tmp3 + z1
        add             r5, r5, r6                @ r5 = tmp1
        add             r3, r3, r4                @ r3 = tmp2
        add             r1, r1, r6                @ r1 = tmp3

        pop             {r0, r2, r4, r6}          @ r0 = tmp10 / r2 = tmp13 / r4 = tmp11 / r6 = tmp12
                                                  @ r1 = tmp3  / r3 = tmp2  / r5 = tmp1  / r7 = tmp0

        @ Compute DESCALE(tmp10 + tmp3, CONST_BITS+PASS1_BITS+3)
        add             r8, r0, r1
        add             r8, r8, #(1<<17)
        mov             r8, r8, asr #18
        strh            r8, [lr, #( 0*8)]

        @ Compute DESCALE(tmp10 - tmp3, CONST_BITS+PASS1_BITS+3)
        sub             r8, r0, r1
        add             r8, r8, #(1<<17)
        mov             r8, r8, asr #18
        strh            r8, [lr, #(14*8)]

        @ Compute DESCALE(tmp11 + tmp2, CONST_BITS+PASS1_BITS+3)
        add             r8, r4, r3
        add             r8, r8, #(1<<17)
        mov             r8, r8, asr #18
        strh            r8, [lr, #( 2*8)]

        @ Compute DESCALE(tmp11 - tmp2, CONST_BITS+PASS1_BITS+3)
        sub             r8, r4, r3
        add             r8, r8, #(1<<17)
        mov             r8, r8, asr #18
        strh            r8, [lr, #(12*8)]

        @ Compute DESCALE(tmp12 + tmp1, CONST_BITS+PASS1_BITS+3)
        add             r8, r6, r5
        add             r8, r8, #(1<<17)
        mov             r8, r8, asr #18
        strh            r8, [lr, #( 4*8)]

        @ Compute DESCALE(tmp12 - tmp1, CONST_BITS+PASS1_BITS+3)
        sub             r8, r6, r5
        add             r8, r8, #(1<<17)
        mov             r8, r8, asr #18
        strh            r8, [lr, #(10*8)]

        @ Compute DESCALE(tmp13 + tmp0, CONST_BITS+PASS1_BITS+3)
        add             r8, r2, r7
        add             r8, r8, #(1<<17)
        mov             r8, r8, asr #18
        strh            r8, [lr, #( 6*8)]

        @ Compute DESCALE(tmp13 - tmp0, CONST_BITS+PASS1_BITS+3)
        sub             r8, r2, r7
        add             r8, r8, #(1<<17)
        mov             r8, r8, asr #18
        strh            r8, [lr, #( 8*8)]

        @ End of row loop
        add             lr, lr, #2
        subs            r12, r12, #1
        bne             column_loop
        beq             the_end

empty_odd_column:
        @ Compute DESCALE(tmp10 + tmp3, CONST_BITS+PASS1_BITS+3)
        @ Compute DESCALE(tmp10 - tmp3, CONST_BITS+PASS1_BITS+3)
        add             r0, r0, #(1<<17)
        mov             r0, r0, asr #18
        strh            r0, [lr, #( 0*8)]
        strh            r0, [lr, #(14*8)]

        @ Compute DESCALE(tmp11 + tmp2, CONST_BITS+PASS1_BITS+3)
        @ Compute DESCALE(tmp11 - tmp2, CONST_BITS+PASS1_BITS+3)
        add             r4, r4, #(1<<17)
        mov             r4, r4, asr #18
        strh            r4, [lr, #( 2*8)]
        strh            r4, [lr, #(12*8)]

        @ Compute DESCALE(tmp12 + tmp1, CONST_BITS+PASS1_BITS+3)
        @ Compute DESCALE(tmp12 - tmp1, CONST_BITS+PASS1_BITS+3)
        add             r6, r6, #(1<<17)
        mov             r6, r6, asr #18
        strh            r6, [lr, #( 4*8)]
        strh            r6, [lr, #(10*8)]

        @ Compute DESCALE(tmp13 + tmp0, CONST_BITS+PASS1_BITS+3)
        @ Compute DESCALE(tmp13 - tmp0, CONST_BITS+PASS1_BITS+3)
        add             r2, r2, #(1<<17)
        mov             r2, r2, asr #18
        strh            r2, [lr, #( 6*8)]
        strh            r2, [lr, #( 8*8)]

        @ End of row loop
        add             lr, lr, #2
        subs            r12, r12, #1
        bne             column_loop

the_end:
        @ The end....
        pop             {r4 - r11, pc}
endfunc

const const_array
        .word FIX_0_298631336
        .word FIX_0_541196100
        .word FIX_0_765366865
        .word FIX_1_175875602
        .word FIX_1_501321110
        .word FIX_2_053119869
        .word FIX_3_072711026
        .word FIX_M_0_390180644
        .word FIX_M_0_899976223
        .word FIX_M_1_847759065
        .word FIX_M_1_961570560
        .word FIX_M_2_562915447
        .word FIX_0xFFFF
endconst
