1 ; 2 ; Copyright (c) 2011 The WebM project authors. All Rights Reserved. 3 ; 4 ; Use of this source code is governed by a BSD-style license 5 ; that can be found in the LICENSE file in the root of the source 6 ; tree. An additional intellectual property rights grant can be found 7 ; in the file PATENTS. All contributing project authors may 8 ; be found in the AUTHORS file in the root of the source tree. 9 ; 10 11 12 EXPORT |vp8_variance8x8_armv6| 13 14 ARM 15 16 AREA ||.text||, CODE, READONLY, ALIGN=2 17 18 ; r0 unsigned char *src_ptr 19 ; r1 int source_stride 20 ; r2 unsigned char *ref_ptr 21 ; r3 int recon_stride 22 ; stack unsigned int *sse 23 |vp8_variance8x8_armv6| PROC 24 25 push {r4-r10, lr} 26 mov r12, #8 ; set loop counter to 8 (=block height) 27 mov r4, #0 ; initialize sum = 0 28 mov r5, #0 ; initialize sse = 0 29 30 loop 31 ; 1st 4 pixels 32 ldr r6, [r0, #0x0] ; load 4 src pixels 33 ldr r7, [r2, #0x0] ; load 4 ref pixels 34 35 mov lr, #0 ; constant zero 36 37 usub8 r8, r6, r7 ; calculate difference 38 sel r10, r8, lr ; select bytes with positive difference 39 usub8 r9, r7, r6 ; calculate difference with reversed operands 40 sel r8, r9, lr ; select bytes with negative difference 41 42 ; calculate partial sums 43 usad8 r6, r10, lr ; calculate sum of positive differences 44 usad8 r7, r8, lr ; calculate sum of negative differences 45 orr r8, r8, r10 ; differences of all 4 pixels 46 ; calculate total sum 47 add r4, r4, r6 ; add positive differences to sum 48 sub r4, r4, r7 ; substract negative differences from sum 49 50 ; calculate sse 51 uxtb16 r7, r8 ; byte (two pixels) to halfwords 52 uxtb16 r10, r8, ror #8 ; another two pixels to halfwords 53 smlad r5, r7, r7, r5 ; dual signed multiply, add and accumulate (1) 54 55 ; 2nd 4 pixels 56 ldr r6, [r0, #0x4] ; load 4 src pixels 57 ldr r7, [r2, #0x4] ; load 4 ref pixels 58 smlad r5, r10, r10, r5 ; dual signed multiply, add and accumulate (2) 59 60 usub8 r8, r6, r7 ; calculate difference 61 add r0, r0, r1 ; set src_ptr to next row 62 sel r10, r8, lr ; select bytes with positive difference 63 usub8 r9, r7, r6 ; calculate difference with reversed operands 64 add r2, r2, r3 ; set dst_ptr to next row 65 sel r8, r9, lr ; select bytes with negative difference 66 67 ; calculate partial sums 68 usad8 r6, r10, lr ; calculate sum of positive differences 69 usad8 r7, r8, lr ; calculate sum of negative differences 70 orr r8, r8, r10 ; differences of all 4 pixels 71 72 ; calculate total sum 73 add r4, r4, r6 ; add positive differences to sum 74 sub r4, r4, r7 ; substract negative differences from sum 75 76 ; calculate sse 77 uxtb16 r7, r8 ; byte (two pixels) to halfwords 78 uxtb16 r10, r8, ror #8 ; another two pixels to halfwords 79 smlad r5, r7, r7, r5 ; dual signed multiply, add and accumulate (1) 80 subs r12, r12, #1 ; next row 81 smlad r5, r10, r10, r5 ; dual signed multiply, add and accumulate (2) 82 83 bne loop 84 85 ; return stuff 86 ldr r8, [sp, #32] ; get address of sse 87 mul r1, r4, r4 ; sum * sum 88 str r5, [r8] ; store sse 89 sub r0, r5, r1, ASR #6 ; return (sse - ((sum * sum) >> 6)) 90 91 pop {r4-r10, pc} 92 93 ENDP 94 95 END 96
