ref: 9fdfb8e92823abadc54d825d0603a7e9fd344520
dir: /vp8/encoder/arm/neon/fastfdct4x4_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_fast_fdct4x4_neon|
ARM
REQUIRE8
PRESERVE8
AREA ||.text||, CODE, READONLY, ALIGN=2
;void vp8_fast_fdct4x4_c(short *input, short *output, int pitch);
;NOTE:
;The input *src_diff. src_diff is calculated as:
;diff_ptr[c] = src_ptr[c] - pred_ptr[c]; (in Subtract* function)
;In which *src_ptr and *pred_ptr both are unsigned char.
;Therefore, *src_diff should be in the range of [-255, 255].
;CAUTION:
;The input values of 25th block are set in vp8_build_dcblock function, which are out of [-255, 255].
;But, VP8 encoder only uses vp8_short_fdct4x4_c for 25th block, not vp8_fast_fdct4x4_c. That makes
;it ok for assuming *input in [-255, 255] in vp8_fast_fdct4x4_c, but not ok in vp8_short_fdct4x4_c.
|vp8_fast_fdct4x4_neon| PROC
vld1.16 {d2}, [r0], r2 ;load input
ldr r12, _ffdct_coeff_
vld1.16 {d3}, [r0], r2
vld1.16 {d4}, [r0], r2
vld1.16 {d0}, [r12]
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 ;ip[0]+ip[3]
vadd.s16 d7, d3, d4 ;ip[1]+ip[2]
vsub.s16 d8, d3, d4 ;ip[1]-ip[2]
vsub.s16 d9, d2, d5 ;ip[0]-ip[3]
vshl.i16 q3, q3, #1 ; a1, b1
vshl.i16 q4, q4, #1 ; c1, d1
vadd.s16 d10, d6, d7 ;temp1 = a1 + b1
vsub.s16 d11, d6, d7 ;temp2 = a1 - b1
vqdmulh.s16 q6, q5, d0[1]
vqdmulh.s16 q8, q4, d0[0]
vqdmulh.s16 q7, q4, d0[2]
vshr.s16 q6, q6, #1
vshr.s16 q8, q8, #1
vshr.s16 q7, q7, #1 ;d14:temp1 = ( c1 * x_c3)>>16; d15:temp1 = (d1 * x_c3)>>16
vadd.s16 q8, q4, q8 ;d16:temp2 = ((c1 * x_c1)>>16) + c1; d17:temp2 = ((d1 * x_c1)>>16) + d1
vadd.s16 d2, d10, d12 ;op[0] = ((temp1 * x_c2 )>>16) + temp1
vadd.s16 d4, d11, d13 ;op[2] = ((temp2 * x_c2 )>>16) + temp2
vadd.s16 d3, d14, d17 ;op[1] = temp1 + temp2 -- q is not necessary, just for protection
vsub.s16 d5, d15, d16 ;op[3] = temp1 - temp2
;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 d10, d6, d7 ;temp1 = a1 + b1
vsub.s16 d11, d6, d7 ;temp2 = a1 - b1
vqdmulh.s16 q6, q5, d0[1]
vqdmulh.s16 q8, q4, d0[0]
vqdmulh.s16 q7, q4, d0[2]
vshr.s16 q6, q6, #1
vshr.s16 q8, q8, #1
vshr.s16 q7, q7, #1 ;d14:temp1 = ( c1 * x_c3)>>16; d15:temp1 = (d1 * x_c3)>>16
vadd.s16 q8, q4, q8 ;d16:temp2 = ((c1 * x_c1)>>16) + c1; d17:temp2 = ((d1 * x_c1)>>16) + d1
vadd.s16 d2, d10, d12 ;a2 = ((temp1 * x_c2 )>>16) + temp1
vadd.s16 d4, d11, d13 ;c2 = ((temp2 * x_c2 )>>16) + temp2
vadd.s16 d3, d14, d17 ;b2 = temp1 + temp2 -- q is not necessary, just for protection
vsub.s16 d5, d15, d16 ;d2 = temp1 - temp2
vclt.s16 q3, q1, #0
vclt.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
;-----------------
AREA fastfdct_dat, DATA, READONLY
;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 ...
_ffdct_coeff_
DCD ffdct_coeff
ffdct_coeff
; 60547 = 0xEC83
; 46341 = 0xB505
; 25080 = 0x61F8
DCD 0xB505EC83, 0x000061F8
END