ref: 0ced701487583049635386c801b415b4255eec86
dir: /vp8/common/arm/neon/shortidct4x4llm_neon.asm/
;
; Copyright (c) 2010 The WebM 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_idct4x4llm_neon|
ARM
REQUIRE8
PRESERVE8
AREA ||.text||, CODE, READONLY, ALIGN=2
;*************************************************************
;void vp8_short_idct4x4llm_c(short *input, short *output, int pitch)
;r0 short * input
;r1 short * output
;r2 int pitch
;*************************************************************
;static const int cospi8sqrt2minus1=20091;
;static const int sinpi8sqrt2 =35468;
;static const int rounding = 0;
;Optimization note: The resulted data from dequantization are signed 13-bit data that is
;in the range of [-4096, 4095]. This allows to use "vqdmulh"(neon) instruction since
;it won't go out of range (13+16+1=30bits<32bits). This instruction gives the high half
;result of the multiplication that is needed in IDCT.
|vp8_short_idct4x4llm_neon| PROC
ldr r12, _idct_coeff_
vld1.16 {q1, q2}, [r0]
vld1.16 {d0}, [r12]
vswp d3, d4 ;q2(vp[4] vp[12])
vqdmulh.s16 q3, q2, d0[2]
vqdmulh.s16 q4, q2, d0[0]
vqadd.s16 d12, d2, d3 ;a1
vqsub.s16 d13, d2, d3 ;b1
vshr.s16 q3, q3, #1
vshr.s16 q4, q4, #1
vqadd.s16 q3, q3, q2 ;modify since sinpi8sqrt2 > 65536/2 (negtive number)
vqadd.s16 q4, q4, q2
;d6 - c1:temp1
;d7 - d1:temp2
;d8 - d1:temp1
;d9 - c1:temp2
vqsub.s16 d10, d6, d9 ;c1
vqadd.s16 d11, d7, d8 ;d1
vqadd.s16 d2, d12, d11
vqadd.s16 d3, d13, d10
vqsub.s16 d4, d13, d10
vqsub.s16 d5, d12, d11
vtrn.32 d2, d4
vtrn.32 d3, d5
vtrn.16 d2, d3
vtrn.16 d4, d5
vswp d3, d4
vqdmulh.s16 q3, q2, d0[2]
vqdmulh.s16 q4, q2, d0[0]
vqadd.s16 d12, d2, d3 ;a1
vqsub.s16 d13, d2, d3 ;b1
vshr.s16 q3, q3, #1
vshr.s16 q4, q4, #1
vqadd.s16 q3, q3, q2 ;modify since sinpi8sqrt2 > 65536/2 (negtive number)
vqadd.s16 q4, q4, q2
vqsub.s16 d10, d6, d9 ;c1
vqadd.s16 d11, d7, d8 ;d1
vqadd.s16 d2, d12, d11
vqadd.s16 d3, d13, d10
vqsub.s16 d4, d13, d10
vqsub.s16 d5, d12, d11
vrshr.s16 d2, d2, #3
vrshr.s16 d3, d3, #3
vrshr.s16 d4, d4, #3
vrshr.s16 d5, d5, #3
add r3, r1, r2
add r12, r3, r2
add r0, r12, r2
vtrn.32 d2, d4
vtrn.32 d3, d5
vtrn.16 d2, d3
vtrn.16 d4, d5
vst1.16 {d2}, [r1]
vst1.16 {d3}, [r3]
vst1.16 {d4}, [r12]
vst1.16 {d5}, [r0]
bx lr
ENDP
;-----------------
AREA idct4x4_dat, DATA, READWRITE ;read/write by default
;Data section with name data_area is specified. DCD reserves space in memory for 48 data.
;One word each is reserved. Label filter_coeff can be used to access the data.
;Data address: filter_coeff, filter_coeff+4, filter_coeff+8 ...
_idct_coeff_
DCD idct_coeff
idct_coeff
DCD 0x4e7b4e7b, 0x8a8c8a8c
;20091, 20091, 35468, 35468
END