ref: c87f32c7fd1e6ecfc834171df12d7c05cf877a68
dir: /vp8/encoder/arm/armv6/vp8_mse16x16_armv6.asm/
;
; Copyright (c) 2011 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_mse16x16_armv6|
ARM
AREA ||.text||, CODE, READONLY, ALIGN=2
; r0 unsigned char *src_ptr
; r1 int source_stride
; r2 unsigned char *ref_ptr
; r3 int recon_stride
; stack unsigned int *sse
;
;note: Based on vp8_variance16x16_armv6. In this function, sum is never used.
; So, we can remove this part of calculation.
|vp8_mse16x16_armv6| PROC
push {r4-r9, lr}
pld [r0, r1, lsl #0]
pld [r2, r3, lsl #0]
mov r12, #16 ; set loop counter to 16 (=block height)
mov r4, #0 ; initialize sse = 0
loop
; 1st 4 pixels
ldr r5, [r0, #0x0] ; load 4 src pixels
ldr r6, [r2, #0x0] ; load 4 ref pixels
mov lr, #0 ; constant zero
usub8 r8, r5, r6 ; calculate difference
pld [r0, r1, lsl #1]
sel r7, r8, lr ; select bytes with positive difference
usub8 r9, r6, r5 ; calculate difference with reversed operands
pld [r2, r3, lsl #1]
sel r8, r9, lr ; select bytes with negative difference
; calculate partial sums
usad8 r5, r7, lr ; calculate sum of positive differences
usad8 r6, r8, lr ; calculate sum of negative differences
orr r8, r8, r7 ; differences of all 4 pixels
ldr r5, [r0, #0x4] ; load 4 src pixels
; calculate sse
uxtb16 r6, r8 ; byte (two pixels) to halfwords
uxtb16 r7, r8, ror #8 ; another two pixels to halfwords
smlad r4, r6, r6, r4 ; dual signed multiply, add and accumulate (1)
; 2nd 4 pixels
ldr r6, [r2, #0x4] ; load 4 ref pixels
smlad r4, r7, r7, r4 ; dual signed multiply, add and accumulate (2)
usub8 r8, r5, r6 ; calculate difference
sel r7, r8, lr ; select bytes with positive difference
usub8 r9, r6, r5 ; calculate difference with reversed operands
sel r8, r9, lr ; select bytes with negative difference
; calculate partial sums
usad8 r5, r7, lr ; calculate sum of positive differences
usad8 r6, r8, lr ; calculate sum of negative differences
orr r8, r8, r7 ; differences of all 4 pixels
ldr r5, [r0, #0x8] ; load 4 src pixels
; calculate sse
uxtb16 r6, r8 ; byte (two pixels) to halfwords
uxtb16 r7, r8, ror #8 ; another two pixels to halfwords
smlad r4, r6, r6, r4 ; dual signed multiply, add and accumulate (1)
; 3rd 4 pixels
ldr r6, [r2, #0x8] ; load 4 ref pixels
smlad r4, r7, r7, r4 ; dual signed multiply, add and accumulate (2)
usub8 r8, r5, r6 ; calculate difference
sel r7, r8, lr ; select bytes with positive difference
usub8 r9, r6, r5 ; calculate difference with reversed operands
sel r8, r9, lr ; select bytes with negative difference
; calculate partial sums
usad8 r5, r7, lr ; calculate sum of positive differences
usad8 r6, r8, lr ; calculate sum of negative differences
orr r8, r8, r7 ; differences of all 4 pixels
ldr r5, [r0, #0xc] ; load 4 src pixels
; calculate sse
uxtb16 r6, r8 ; byte (two pixels) to halfwords
uxtb16 r7, r8, ror #8 ; another two pixels to halfwords
smlad r4, r6, r6, r4 ; dual signed multiply, add and accumulate (1)
; 4th 4 pixels
ldr r6, [r2, #0xc] ; load 4 ref pixels
smlad r4, r7, r7, r4 ; dual signed multiply, add and accumulate (2)
usub8 r8, r5, r6 ; calculate difference
add r0, r0, r1 ; set src_ptr to next row
sel r7, r8, lr ; select bytes with positive difference
usub8 r9, r6, r5 ; calculate difference with reversed operands
add r2, r2, r3 ; set dst_ptr to next row
sel r8, r9, lr ; select bytes with negative difference
; calculate partial sums
usad8 r5, r7, lr ; calculate sum of positive differences
usad8 r6, r8, lr ; calculate sum of negative differences
orr r8, r8, r7 ; differences of all 4 pixels
subs r12, r12, #1 ; next row
; calculate sse
uxtb16 r6, r8 ; byte (two pixels) to halfwords
uxtb16 r7, r8, ror #8 ; another two pixels to halfwords
smlad r4, r6, r6, r4 ; dual signed multiply, add and accumulate (1)
smlad r4, r7, r7, r4 ; dual signed multiply, add and accumulate (2)
bne loop
; return stuff
ldr r1, [sp, #28] ; get address of sse
mov r0, r4 ; return sse
str r4, [r1] ; store sse
pop {r4-r9, pc}
ENDP
END