ref: 9fdfb8e92823abadc54d825d0603a7e9fd344520
dir: /vp8/encoder/arm/neon/vp8_shortwalsh4x4_neon.asm/
;
; Copyright (c) 2010 The VP8 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.
;
EXPORT |vp8_short_walsh4x4_neon|
ARM
REQUIRE8
PRESERVE8
AREA ||.text||, CODE, READONLY, ALIGN=2
;void vp8_short_walsh4x4_c(short *input, short *output, int pitch)
|vp8_short_walsh4x4_neon| PROC
vld1.16 {d2}, [r0], r2 ;load input
vld1.16 {d3}, [r0], r2
vld1.16 {d4}, [r0], r2
vld1.16 {d5}, [r0], r2
;First for-loop
;transpose d2, d3, d4, d5. Then, d2=ip[0], d3=ip[1], d4=ip[2], d5=ip[3]
vtrn.32 d2, d4
vtrn.32 d3, d5
vtrn.16 d2, d3
vtrn.16 d4, d5
vadd.s16 d6, d2, d5 ;a1 = ip[0]+ip[3]
vadd.s16 d7, d3, d4 ;b1 = ip[1]+ip[2]
vsub.s16 d8, d3, d4 ;c1 = ip[1]-ip[2]
vsub.s16 d9, d2, d5 ;d1 = ip[0]-ip[3]
vadd.s16 d2, d6, d7 ;op[0] = a1 + b1
vsub.s16 d4, d6, d7 ;op[2] = a1 - b1
vadd.s16 d3, d8, d9 ;op[1] = c1 + d1
vsub.s16 d5, d9, d8 ;op[3] = d1 - c1
;Second for-loop
;transpose d2, d3, d4, d5. Then, d2=ip[0], d3=ip[4], d4=ip[8], d5=ip[12]
vtrn.32 d2, d4
vtrn.32 d3, d5
vtrn.16 d2, d3
vtrn.16 d4, d5
vadd.s16 d6, d2, d5 ;a1 = ip[0]+ip[12]
vadd.s16 d7, d3, d4 ;b1 = ip[4]+ip[8]
vsub.s16 d8, d3, d4 ;c1 = ip[4]-ip[8]
vsub.s16 d9, d2, d5 ;d1 = ip[0]-ip[12]
vadd.s16 d2, d6, d7 ;a2 = a1 + b1;
vsub.s16 d4, d6, d7 ;c2 = a1 - b1;
vadd.s16 d3, d8, d9 ;b2 = c1 + d1;
vsub.s16 d5, d9, d8 ;d2 = d1 - c1;
vcgt.s16 q3, q1, #0
vcgt.s16 q4, q2, #0
vsub.s16 q1, q1, q3
vsub.s16 q2, q2, q4
vshr.s16 q1, q1, #1
vshr.s16 q2, q2, #1
vst1.16 {q1, q2}, [r1]
bx lr
ENDP
END