;
;  Copyright (c) 2010 The VP8 project authors. All Rights Reserved.
;
;  Use of this source code is governed by a BSD-style license and patent
;  grant that can be found in the LICENSE file in the root of the source
;  tree. All contributing project authors may be found in the AUTHORS
;  file in the root of the source tree.
;

    EXPORT |vp8_short_inv_walsh4x4_armv6|
    EXPORT |vp8_short_inv_walsh4x4_1_armv6|

    ARM
    REQUIRE8
    PRESERVE8

    AREA    |.text|, CODE, READONLY  ; name this block of code

;short vp8_short_inv_walsh4x4_armv6(short *input, short *output)
|vp8_short_inv_walsh4x4_armv6| PROC

    stmdb       sp!, {r4 - r11, lr}

    ldr         r2, [r0], #4         ; [1  |  0]
    ldr         r3, [r0], #4         ; [3  |  2]
    ldr         r4, [r0], #4         ; [5  |  4]
    ldr         r5, [r0], #4         ; [7  |  6]
    ldr         r6, [r0], #4         ; [9  |  8]
    ldr         r7, [r0], #4         ; [11 | 10]
    ldr         r8, [r0], #4         ; [13 | 12]
    ldr         r9, [r0]             ; [15 | 14]

    qadd16      r10, r2, r8          ; a1 [1+13  |  0+12]
    qadd16      r11, r4, r6          ; b1 [5+9   |  4+8]
    qsub16      r12, r4, r6          ; c1 [5-9   |  4-8]
    qsub16      lr, r2, r8           ; d1 [1-13  |  0-12]

    qadd16      r2, r10, r11         ; a1 + b1 [1  |  0]
    qadd16      r4, r12, lr          ; c1 + d1 [5  |  4]
    qsub16      r6, r10, r11         ; a1 - b1 [9  |  8]
    qsub16      r8, lr, r12          ; d1 - c1 [13 | 12]

    qadd16      r10, r3, r9          ; a1 [3+15  |  2+14]
    qadd16      r11, r5, r7          ; b1 [7+11  |  6+10]
    qsub16      r12, r5, r7          ; c1 [7-11  |  6-10]
    qsub16      lr, r3, r9           ; d1 [3-15  |  2-14]

    qadd16      r3, r10, r11         ; a1 + b1 [3  |  2]
    qadd16      r5, r12, lr          ; c1 + d1 [7  |  6]
    qsub16      r7, r10, r11         ; a1 - b1 [11 | 10]
    qsub16      r9, lr, r12          ; d1 - c1 [15 | 14]

    ; first transform complete

    qsubaddx    r10, r2, r3          ; [c1|a1] [1-2   |   0+3]
    qaddsubx    r11, r2, r3          ; [b1|d1] [1+2   |   0-3]
    qsubaddx    r12, r4, r5          ; [c1|a1] [5-6   |   4+7]
    qaddsubx    lr, r4, r5           ; [b1|d1] [5+6   |   4-7]

    qaddsubx    r2, r10, r11         ; [b2|c2] [c1+d1 | a1-b1]
    qaddsubx    r3, r11, r10         ; [a2|d2] [b1+a1 | d1-c1]
    ldr         r10, c0x00030003
    qaddsubx    r4, r12, lr          ; [b2|c2] [c1+d1 | a1-b1]
    qaddsubx    r5, lr, r12          ; [a2|d2] [b1+a1 | d1-c1]

    qadd16      r2, r2, r10          ; [b2+3|c2+3]
    qadd16      r3, r3, r10          ; [a2+3|d2+3]
    qadd16      r4, r4, r10          ; [b2+3|c2+3]
    qadd16      r5, r5, r10          ; [a2+3|d2+3]

    asr         r12, r2, #3          ; [1  |  x]
    pkhtb       r12, r12, r3, asr #19; [1  |  0]
    lsl         lr, r3, #16          ; [~3 |  x]
    lsl         r2, r2, #16          ; [~2 |  x]
    asr         lr, lr, #3           ; [3  |  x]
    pkhtb       lr, lr, r2, asr #19  ; [3  |  2]

    asr         r2, r4, #3           ; [5  |  x]
    pkhtb       r2, r2, r5, asr #19  ; [5  |  4]
    lsl         r3, r5, #16          ; [~7 |  x]
    lsl         r4, r4, #16          ; [~6 |  x]
    asr         r3, r3, #3           ; [7  |  x]
    pkhtb       r3, r3, r4, asr #19  ; [7  |  6]

    str         r12, [r1], #4
    str         lr, [r1], #4
    str         r2, [r1], #4
    str         r3, [r1], #4

    qsubaddx    r2, r6, r7           ; [c1|a1] [9-10  |  8+11]
    qaddsubx    r3, r6, r7           ; [b1|d1] [9+10  |  8-11]
    qsubaddx    r4, r8, r9           ; [c1|a1] [13-14 | 12+15]
    qaddsubx    r5, r8, r9           ; [b1|d1] [13+14 | 12-15]

    qaddsubx    r6, r2, r3           ; [b2|c2] [c1+d1 | a1-b1]
    qaddsubx    r7, r3, r2           ; [a2|d2] [b1+a1 | d1-c1]
    qaddsubx    r8, r4, r5           ; [b2|c2] [c1+d1 | a1-b1]
    qaddsubx    r9, r5, r4           ; [a2|d2] [b1+a1 | d1-c1]

    qadd16      r6, r6, r10          ; [b2+3|c2+3]
    qadd16      r7, r7, r10          ; [a2+3|d2+3]
    qadd16      r8, r8, r10          ; [b2+3|c2+3]
    qadd16      r9, r9, r10          ; [a2+3|d2+3]

    asr         r2, r6, #3           ; [9  |  x]
    pkhtb       r2, r2, r7, asr #19  ; [9  |  8]
    lsl         r3, r7, #16          ; [~11|  x]
    lsl         r4, r6, #16          ; [~10|  x]
    asr         r3, r3, #3           ; [11 |  x]
    pkhtb       r3, r3, r4, asr #19  ; [11 | 10]

    asr         r4, r8, #3           ; [13 |  x]
    pkhtb       r4, r4, r9, asr #19  ; [13 | 12]
    lsl         r5, r9, #16          ; [~15|  x]
    lsl         r6, r8, #16          ; [~14|  x]
    asr         r5, r5, #3           ; [15 |  x]
    pkhtb       r5, r5, r6, asr #19  ; [15 | 14]

    str         r2, [r1], #4
    str         r3, [r1], #4
    str         r4, [r1], #4
    str         r5, [r1]

    ldmia       sp!, {r4 - r11, pc}
    ENDP        ; |vp8_short_inv_walsh4x4_armv6|


;short vp8_short_inv_walsh4x4_1_armv6(short *input, short *output)
|vp8_short_inv_walsh4x4_1_armv6| PROC

    ldrsh       r2, [r0]             ; [0]
    add         r2, r2, #3           ; [0] + 3
    asr         r2, r2, #3           ; a1 ([0]+3) >> 3
    lsl         r2, r2, #16          ; [a1 |  x]
    orr         r2, r2, r2, lsr #16  ; [a1 | a1]

    str         r2, [r1], #4
    str         r2, [r1], #4
    str         r2, [r1], #4
    str         r2, [r1], #4
    str         r2, [r1], #4
    str         r2, [r1], #4
    str         r2, [r1], #4
    str         r2, [r1]

    bx          lr
    ENDP        ; |vp8_short_inv_walsh4x4_1_armv6|

; Constant Pool
c0x00030003 DCD 0x00030003
    END