ref: d9ca52452bff9481ec1ed4684985a86fb7fc3c3e
dir: /vp8/common/arm/armv6/intra4x4_predict_v6.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_intra4x4_predict_armv6|
ARM
REQUIRE8
PRESERVE8
AREA ||.text||, CODE, READONLY, ALIGN=2
;void vp8_intra4x4_predict(unsigned char *src, int src_stride, int b_mode,
; unsigned char *dst, int dst_stride)
|vp8_intra4x4_predict_armv6| PROC
push {r4-r12, lr}
cmp r2, #10
addlt pc, pc, r2, lsl #2 ; position independent switch
pop {r4-r12, pc} ; default
b b_dc_pred
b b_tm_pred
b b_ve_pred
b b_he_pred
b b_ld_pred
b b_rd_pred
b b_vr_pred
b b_vl_pred
b b_hd_pred
b b_hu_pred
b_dc_pred
; load values
ldr r8, [r0, -r1] ; Above
ldrb r4, [r0, #-1]! ; Left[0]
mov r9, #0
ldrb r5, [r0, r1] ; Left[1]
ldrb r6, [r0, r1, lsl #1]! ; Left[2]
usad8 r12, r8, r9
ldrb r7, [r0, r1] ; Left[3]
; calculate dc
add r4, r4, r5
add r4, r4, r6
add r4, r4, r7
add r4, r4, r12
add r4, r4, #4
ldr r0, [sp, #40] ; load stride
mov r12, r4, asr #3 ; (expected_dc + 4) >> 3
add r12, r12, r12, lsl #8
add r3, r3, r0
add r12, r12, r12, lsl #16
; store values
str r12, [r3, -r0]
str r12, [r3]
str r12, [r3, r0]
str r12, [r3, r0, lsl #1]
pop {r4-r12, pc}
b_tm_pred
sub r10, r0, #1 ; Left
ldr r8, [r0, -r1] ; Above
ldrb r9, [r10, -r1] ; top_left
ldrb r4, [r0, #-1]! ; Left[0]
ldrb r5, [r10, r1]! ; Left[1]
ldrb r6, [r0, r1, lsl #1] ; Left[2]
ldrb r7, [r10, r1, lsl #1] ; Left[3]
ldr r0, [sp, #40] ; load stride
add r9, r9, r9, lsl #16 ; [tl|tl]
uxtb16 r10, r8 ; a[2|0]
uxtb16 r11, r8, ror #8 ; a[3|1]
ssub16 r10, r10, r9 ; a[2|0] - [tl|tl]
ssub16 r11, r11, r9 ; a[3|1] - [tl|tl]
add r4, r4, r4, lsl #16 ; l[0|0]
add r5, r5, r5, lsl #16 ; l[1|1]
add r6, r6, r6, lsl #16 ; l[2|2]
add r7, r7, r7, lsl #16 ; l[3|3]
sadd16 r1, r4, r10 ; l[0|0] + a[2|0] - [tl|tl]
sadd16 r2, r4, r11 ; l[0|0] + a[3|1] - [tl|tl]
usat16 r1, #8, r1
usat16 r2, #8, r2
sadd16 r4, r5, r10 ; l[1|1] + a[2|0] - [tl|tl]
sadd16 r5, r5, r11 ; l[1|1] + a[3|1] - [tl|tl]
add r12, r1, r2, lsl #8 ; [3|2|1|0]
str r12, [r3], r0
usat16 r4, #8, r4
usat16 r5, #8, r5
sadd16 r1, r6, r10 ; l[2|2] + a[2|0] - [tl|tl]
sadd16 r2, r6, r11 ; l[2|2] + a[3|1] - [tl|tl]
add r12, r4, r5, lsl #8 ; [3|2|1|0]
str r12, [r3], r0
usat16 r1, #8, r1
usat16 r2, #8, r2
sadd16 r4, r7, r10 ; l[3|3] + a[2|0] - [tl|tl]
sadd16 r5, r7, r11 ; l[3|3] + a[3|1] - [tl|tl]
add r12, r1, r2, lsl #8 ; [3|2|1|0]
usat16 r4, #8, r4
usat16 r5, #8, r5
str r12, [r3], r0
add r12, r4, r5, lsl #8 ; [3|2|1|0]
str r12, [r3], r0
pop {r4-r12, pc}
b_ve_pred
ldr r8, [r0, -r1]! ; a[3|2|1|0]
ldr r11, c00FF00FF
ldrb r9, [r0, #-1] ; top_left
ldrb r10, [r0, #4] ; a[4]
ldr r0, c00020002
uxtb16 r4, r8 ; a[2|0]
uxtb16 r5, r8, ror #8 ; a[3|1]
ldr r2, [sp, #40] ; stride
pkhbt r9, r9, r5, lsl #16 ; a[1|-1]
add r9, r9, r4, lsl #1 ;[a[1]+2*a[2] | tl+2*a[0] ]
uxtab16 r9, r9, r5 ;[a[1]+2*a[2]+a[3] | tl+2*a[0]+a[1] ]
uxtab16 r9, r9, r0 ;[a[1]+2*a[2]+a[3]+2| tl+2*a[0]+a[1]+2]
add r0, r0, r10, lsl #16 ;[a[4]+2 | 2]
add r0, r0, r4, asr #16 ;[a[4]+2 | a[2]+2]
add r0, r0, r5, lsl #1 ;[a[4]+2*a[3]+2 | a[2]+2*a[1]+2]
uadd16 r4, r4, r0 ;[a[4]+2*a[3]+a[2]+2|a[2]+2*a[1]+a[0]+2]
and r9, r11, r9, asr #2
and r4, r11, r4, asr #2
add r3, r3, r2 ; dst + dst_stride
add r9, r9, r4, lsl #8
; store values
str r9, [r3, -r2]
str r9, [r3]
str r9, [r3, r2]
str r9, [r3, r2, lsl #1]
pop {r4-r12, pc}
b_he_pred
sub r10, r0, #1 ; Left
ldrb r4, [r0, #-1]! ; Left[0]
ldrb r8, [r10, -r1] ; top_left
ldrb r5, [r10, r1]! ; Left[1]
ldrb r6, [r0, r1, lsl #1] ; Left[2]
ldrb r7, [r10, r1, lsl #1] ; Left[3]
add r8, r8, r4 ; tl + l[0]
add r9, r4, r5 ; l[0] + l[1]
add r10, r5, r6 ; l[1] + l[2]
add r11, r6, r7 ; l[2] + l[3]
mov r0, #2<<14
add r8, r8, r9 ; tl + 2*l[0] + l[1]
add r4, r9, r10 ; l[0] + 2*l[1] + l[2]
add r5, r10, r11 ; l[1] + 2*l[2] + l[3]
add r6, r11, r7, lsl #1 ; l[2] + 2*l[3] + l[3]
add r8, r0, r8, lsl #14 ; (tl + 2*l[0] + l[1])>>2 in top half
add r9, r0, r4, lsl #14 ; (l[0] + 2*l[1] + l[2])>>2 in top half
add r10,r0, r5, lsl #14 ; (l[1] + 2*l[2] + l[3])>>2 in top half
add r11,r0, r6, lsl #14 ; (l[2] + 2*l[3] + l[3])>>2 in top half
pkhtb r8, r8, r8, asr #16 ; l[-|0|-|0]
pkhtb r9, r9, r9, asr #16 ; l[-|1|-|1]
pkhtb r10, r10, r10, asr #16 ; l[-|2|-|2]
pkhtb r11, r11, r11, asr #16 ; l[-|3|-|3]
ldr r0, [sp, #40] ; stride
add r8, r8, r8, lsl #8 ; l[0|0|0|0]
add r9, r9, r9, lsl #8 ; l[1|1|1|1]
add r10, r10, r10, lsl #8 ; l[2|2|2|2]
add r11, r11, r11, lsl #8 ; l[3|3|3|3]
; store values
str r8, [r3], r0
str r9, [r3]
str r10, [r3, r0]
str r11, [r3, r0, lsl #1]
pop {r4-r12, pc}
b_ld_pred
ldr r4, [r0, -r1]! ; Above
ldr r12, c00020002
ldr r5, [r0, #4]
ldr lr, c00FF00FF
uxtb16 r6, r4 ; a[2|0]
uxtb16 r7, r4, ror #8 ; a[3|1]
uxtb16 r8, r5 ; a[6|4]
uxtb16 r9, r5, ror #8 ; a[7|5]
pkhtb r10, r6, r8 ; a[2|4]
pkhtb r11, r7, r9 ; a[3|5]
add r4, r6, r7, lsl #1 ; [a2+2*a3 | a0+2*a1]
add r4, r4, r10, ror #16 ; [a2+2*a3+a4 | a0+2*a1+a2]
uxtab16 r4, r4, r12 ; [a2+2*a3+a4+2 | a0+2*a1+a2+2]
add r5, r7, r10, ror #15 ; [a3+2*a4 | a1+2*a2]
add r5, r5, r11, ror #16 ; [a3+2*a4+a5 | a1+2*a2+a3]
uxtab16 r5, r5, r12 ; [a3+2*a4+a5+2 | a1+2*a2+a3+2]
pkhtb r7, r9, r8, asr #16
add r6, r8, r9, lsl #1 ; [a6+2*a7 | a4+2*a5]
uadd16 r6, r6, r7 ; [a6+2*a7+a7 | a4+2*a5+a6]
uxtab16 r6, r6, r12 ; [a6+2*a7+a7+2 | a4+2*a5+a6+2]
uxth r7, r9 ; [ a5]
add r7, r7, r8, asr #15 ; [ a5+2*a6]
add r7, r7, r9, asr #16 ; [ a5+2*a6+a7]
uxtah r7, r7, r12 ; [ a5+2*a6+a7+2]
ldr r0, [sp, #40] ; stride
; scale down
and r4, lr, r4, asr #2
and r5, lr, r5, asr #2
and r6, lr, r6, asr #2
mov r7, r7, asr #2
add r8, r4, r5, lsl #8 ; [3|2|1|0]
str r8, [r3], r0
mov r9, r8, lsr #8
add r9, r9, r6, lsl #24 ; [4|3|2|1]
str r9, [r3], r0
mov r10, r9, lsr #8
add r10, r10, r7, lsl #24 ; [5|4|3|2]
str r10, [r3], r0
mov r6, r6, lsr #16
mov r11, r10, lsr #8
add r11, r11, r6, lsl #24 ; [6|5|4|3]
str r11, [r3], r0
pop {r4-r12, pc}
b_rd_pred
sub r12, r0, r1 ; Above = src - src_stride
ldrb r7, [r0, #-1]! ; l[0] = pp[3]
ldr lr, [r12] ; Above = pp[8|7|6|5]
ldrb r8, [r12, #-1]! ; tl = pp[4]
ldrb r6, [r12, r1, lsl #1] ; l[1] = pp[2]
ldrb r5, [r0, r1, lsl #1] ; l[2] = pp[1]
ldrb r4, [r12, r1, lsl #2] ; l[3] = pp[0]
uxtb16 r9, lr ; p[7|5]
uxtb16 r10, lr, ror #8 ; p[8|6]
add r4, r4, r6, lsl #16 ; p[2|0]
add r5, r5, r7, lsl #16 ; p[3|1]
add r6, r6, r8, lsl #16 ; p[4|2]
pkhbt r7, r7, r9, lsl #16 ; p[5|3]
pkhbt r8, r8, r10, lsl #16 ; p[6|4]
ldr r12, c00020002
ldr lr, c00FF00FF
add r4, r4, r5, lsl #1 ; [p2+2*p3 | p0+2*p1]
add r4, r4, r6 ; [p2+2*p3+p4 | p0+2*p1+p2]
uxtab16 r4, r4, r12 ; [p2+2*p3+p4+2 | p0+2*p1+p2+2]
add r5, r5, r6, lsl #1 ; [p3+2*p4 | p1+2*p2]
add r5, r5, r7 ; [p3+2*p4+p5 | p1+2*p2+p3]
uxtab16 r5, r5, r12 ; [p3+2*p4+p5+2 | p1+2*p2+p3+2]
add r6, r7, r8, lsl #1 ; [p5+2*p6 | p3+2*p4]
add r6, r6, r9 ; [p5+2*p6+p7 | p3+2*p4+p5]
uxtab16 r6, r6, r12 ; [p5+2*p6+p7+2 | p3+2*p4+p5+2]
add r7, r8, r9, lsl #1 ; [p6+2*p7 | p4+2*p5]
add r7, r7, r10 ; [p6+2*p7+p8 | p4+2*p5+p6]
uxtab16 r7, r7, r12 ; [p6+2*p7+p8+2 | p4+2*p5+p6+2]
ldr r0, [sp, #40] ; stride
; scale down
and r7, lr, r7, asr #2
and r6, lr, r6, asr #2
and r5, lr, r5, asr #2
and r4, lr, r4, asr #2
add r8, r6, r7, lsl #8 ; [6|5|4|3]
str r8, [r3], r0
mov r9, r8, lsl #8 ; [5|4|3|-]
uxtab r9, r9, r4, ror #16 ; [5|4|3|2]
str r9, [r3], r0
mov r10, r9, lsl #8 ; [4|3|2|-]
uxtab r10, r10, r5 ; [4|3|2|1]
str r10, [r3], r0
mov r11, r10, lsl #8 ; [3|2|1|-]
uxtab r11, r11, r4 ; [3|2|1|0]
str r11, [r3], r0
pop {r4-r12, pc}
b_vr_pred
sub r12, r0, r1 ; Above = src - src_stride
ldrb r7, [r0, #-1]! ; l[0] = pp[3]
ldr lr, [r12] ; Above = pp[8|7|6|5]
ldrb r8, [r12, #-1]! ; tl = pp[4]
ldrb r6, [r12, r1, lsl #1] ; l[1] = pp[2]
ldrb r5, [r0, r1, lsl #1] ; l[2] = pp[1]
ldrb r4, [r12, r1, lsl #2] ; l[3] = pp[0]
add r5, r5, r7, lsl #16 ; p[3|1]
add r6, r6, r8, lsl #16 ; p[4|2]
uxtb16 r9, lr ; p[7|5]
uxtb16 r10, lr, ror #8 ; p[8|6]
pkhbt r7, r7, r9, lsl #16 ; p[5|3]
pkhbt r8, r8, r10, lsl #16 ; p[6|4]
ldr r4, c00010001
ldr r12, c00020002
ldr lr, c00FF00FF
add r5, r5, r6, lsl #1 ; [p3+2*p4 | p1+2*p2]
add r5, r5, r7 ; [p3+2*p4+p5 | p1+2*p2+p3]
uxtab16 r5, r5, r12 ; [p3+2*p4+p5+2 | p1+2*p2+p3+2]
add r6, r6, r7, lsl #1 ; [p4+2*p5 | p2+2*p3]
add r6, r6, r8 ; [p4+2*p5+p6 | p2+2*p3+p4]
uxtab16 r6, r6, r12 ; [p4+2*p5+p6+2 | p2+2*p3+p4+2]
uadd16 r11, r8, r9 ; [p6+p7 | p4+p5]
uhadd16 r11, r11, r4 ; [(p6+p7+1)>>1 | (p4+p5+1)>>1]
; [F|E]
add r7, r7, r8, lsl #1 ; [p5+2*p6 | p3+2*p4]
add r7, r7, r9 ; [p5+2*p6+p7 | p3+2*p4+p5]
uxtab16 r7, r7, r12 ; [p5+2*p6+p7+2 | p3+2*p4+p5+2]
uadd16 r2, r9, r10 ; [p7+p8 | p5+p6]
uhadd16 r2, r2, r4 ; [(p7+p8+1)>>1 | (p5+p6+1)>>1]
; [J|I]
add r8, r8, r9, lsl #1 ; [p6+2*p7 | p4+2*p5]
add r8, r8, r10 ; [p6+2*p7+p8 | p4+2*p5+p6]
uxtab16 r8, r8, r12 ; [p6+2*p7+p8+2 | p4+2*p5+p6+2]
ldr r0, [sp, #40] ; stride
; scale down
and r5, lr, r5, asr #2 ; [B|A]
and r6, lr, r6, asr #2 ; [D|C]
and r7, lr, r7, asr #2 ; [H|G]
and r8, lr, r8, asr #2 ; [L|K]
add r12, r11, r2, lsl #8 ; [J|F|I|E]
str r12, [r3], r0
add r12, r7, r8, lsl #8 ; [L|H|K|G]
str r12, [r3], r0
pkhbt r2, r6, r2, lsl #16 ; [-|I|-|C]
add r2, r2, r11, lsl #8 ; [F|I|E|C]
pkhtb r12, r6, r5 ; [-|D|-|A]
pkhtb r10, r7, r5, asr #16 ; [-|H|-|B]
str r2, [r3], r0
add r12, r12, r10, lsl #8 ; [H|D|B|A]
str r12, [r3], r0
pop {r4-r12, pc}
b_vl_pred
ldr r4, [r0, -r1]! ; [3|2|1|0]
ldr r12, c00020002
ldr r5, [r0, #4] ; [7|6|5|4]
ldr lr, c00FF00FF
ldr r2, c00010001
mov r0, r4, lsr #16 ; [-|-|3|2]
add r0, r0, r5, lsl #16 ; [5|4|3|2]
uxtb16 r6, r4 ; [2|0]
uxtb16 r7, r4, ror #8 ; [3|1]
uxtb16 r8, r0 ; [4|2]
uxtb16 r9, r0, ror #8 ; [5|3]
uxtb16 r10, r5 ; [6|4]
uxtb16 r11, r5, ror #8 ; [7|5]
uadd16 r4, r6, r7 ; [p2+p3 | p0+p1]
uhadd16 r4, r4, r2 ; [(p2+p3+1)>>1 | (p0+p1+1)>>1]
; [B|A]
add r5, r6, r7, lsl #1 ; [p2+2*p3 | p0+2*p1]
add r5, r5, r8 ; [p2+2*p3+p4 | p0+2*p1+p2]
uxtab16 r5, r5, r12 ; [p2+2*p3+p4+2 | p0+2*p1+p2+2]
uadd16 r6, r7, r8 ; [p3+p4 | p1+p2]
uhadd16 r6, r6, r2 ; [(p3+p4+1)>>1 | (p1+p2+1)>>1]
; [F|E]
add r7, r7, r8, lsl #1 ; [p3+2*p4 | p1+2*p2]
add r7, r7, r9 ; [p3+2*p4+p5 | p1+2*p2+p3]
uxtab16 r7, r7, r12 ; [p3+2*p4+p5+2 | p1+2*p2+p3+2]
add r8, r8, r9, lsl #1 ; [p4+2*p5 | p2+2*p3]
add r8, r8, r10 ; [p4+2*p5+p6 | p2+2*p3+p4]
uxtab16 r8, r8, r12 ; [p4+2*p5+p6+2 | p2+2*p3+p4+2]
add r9, r9, r10, lsl #1 ; [p5+2*p6 | p3+2*p4]
add r9, r9, r11 ; [p5+2*p6+p7 | p3+2*p4+p5]
uxtab16 r9, r9, r12 ; [p5+2*p6+p7+2 | p3+2*p4+p5+2]
ldr r0, [sp, #40] ; stride
; scale down
and r5, lr, r5, asr #2 ; [D|C]
and r7, lr, r7, asr #2 ; [H|G]
and r8, lr, r8, asr #2 ; [I|D]
and r9, lr, r9, asr #2 ; [J|H]
add r10, r4, r6, lsl #8 ; [F|B|E|A]
str r10, [r3], r0
add r5, r5, r7, lsl #8 ; [H|C|G|D]
str r5, [r3], r0
pkhtb r12, r8, r4, asr #16 ; [-|I|-|B]
pkhtb r10, r9, r8 ; [-|J|-|D]
add r12, r6, r12, lsl #8 ; [I|F|B|E]
str r12, [r3], r0
add r10, r7, r10, lsl #8 ; [J|H|D|G]
str r10, [r3], r0
pop {r4-r12, pc}
b_hd_pred
sub r12, r0, r1 ; Above = src - src_stride
ldrb r7, [r0, #-1]! ; l[0] = pp[3]
ldr lr, [r12] ; Above = pp[8|7|6|5]
ldrb r8, [r12, #-1]! ; tl = pp[4]
ldrb r6, [r0, r1] ; l[1] = pp[2]
ldrb r5, [r0, r1, lsl #1] ; l[2] = pp[1]
ldrb r4, [r12, r1, lsl #2] ; l[3] = pp[0]
uxtb16 r9, lr ; p[7|5]
uxtb16 r10, lr, ror #8 ; p[8|6]
add r4, r4, r5, lsl #16 ; p[1|0]
add r5, r5, r6, lsl #16 ; p[2|1]
add r6, r6, r7, lsl #16 ; p[3|2]
add r7, r7, r8, lsl #16 ; p[4|3]
ldr r12, c00020002
ldr lr, c00FF00FF
ldr r2, c00010001
pkhtb r8, r7, r9 ; p[4|5]
pkhtb r1, r9, r10 ; p[7|6]
pkhbt r10, r8, r10, lsl #16 ; p[6|5]
uadd16 r11, r4, r5 ; [p1+p2 | p0+p1]
uhadd16 r11, r11, r2 ; [(p1+p2+1)>>1 | (p0+p1+1)>>1]
; [B|A]
add r4, r4, r5, lsl #1 ; [p1+2*p2 | p0+2*p1]
add r4, r4, r6 ; [p1+2*p2+p3 | p0+2*p1+p2]
uxtab16 r4, r4, r12 ; [p1+2*p2+p3+2 | p0+2*p1+p2+2]
uadd16 r0, r6, r7 ; [p3+p4 | p2+p3]
uhadd16 r0, r0, r2 ; [(p3+p4+1)>>1 | (p2+p3+1)>>1]
; [F|E]
add r5, r6, r7, lsl #1 ; [p3+2*p4 | p2+2*p3]
add r5, r5, r8, ror #16 ; [p3+2*p4+p5 | p2+2*p3+p4]
uxtab16 r5, r5, r12 ; [p3+2*p4+p5+2 | p2+2*p3+p4+2]
add r6, r12, r8, ror #16 ; [p5+2 | p4+2]
add r6, r6, r10, lsl #1 ; [p5+2+2*p6 | p4+2+2*p5]
uxtab16 r6, r6, r1 ; [p5+2+2*p6+p7 | p4+2+2*p5+p6]
; scale down
and r4, lr, r4, asr #2 ; [D|C]
and r5, lr, r5, asr #2 ; [H|G]
and r6, lr, r6, asr #2 ; [J|I]
ldr lr, [sp, #40] ; stride
pkhtb r2, r0, r6 ; [-|F|-|I]
pkhtb r12, r6, r5, asr #16 ; [-|J|-|H]
add r12, r12, r2, lsl #8 ; [F|J|I|H]
add r2, r0, r5, lsl #8 ; [H|F|G|E]
mov r12, r12, ror #24 ; [J|I|H|F]
str r12, [r3], lr
mov r7, r11, asr #16 ; [-|-|-|B]
str r2, [r3], lr
add r7, r7, r0, lsl #16 ; [-|E|-|B]
add r7, r7, r4, asr #8 ; [-|E|D|B]
add r7, r7, r5, lsl #24 ; [G|E|D|B]
str r7, [r3], lr
add r5, r11, r4, lsl #8 ; [D|B|C|A]
str r5, [r3], lr
pop {r4-r12, pc}
b_hu_pred
ldrb r4, [r0, #-1]! ; Left[0]
ldr r12, c00020002
ldrb r5, [r0, r1]! ; Left[1]
ldr lr, c00FF00FF
ldrb r6, [r0, r1]! ; Left[2]
ldr r2, c00010001
ldrb r7, [r0, r1] ; Left[3]
add r4, r4, r5, lsl #16 ; [1|0]
add r5, r5, r6, lsl #16 ; [2|1]
add r9, r6, r7, lsl #16 ; [3|2]
uadd16 r8, r4, r5 ; [p1+p2 | p0+p1]
uhadd16 r8, r8, r2 ; [(p1+p2+1)>>1 | (p0+p1+1)>>1]
; [B|A]
add r4, r4, r5, lsl #1 ; [p1+2*p2 | p0+2*p1]
add r4, r4, r9 ; [p1+2*p2+p3 | p0+2*p1+p2]
uxtab16 r4, r4, r12 ; [p1+2*p2+p3+2 | p0+2*p1+p2+2]
ldr r2, [sp, #40] ; stride
and r4, lr, r4, asr #2 ; [D|C]
add r10, r6, r7 ; [p2+p3]
add r11, r10, r7, lsl #1 ; [p2+3*p3]
add r10, r10, #1
add r11, r11, #2
mov r10, r10, asr #1 ; [E]
mov r11, r11, asr #2 ; [F]
add r9, r7, r9, asr #8 ; [-|-|G|G]
add r0, r8, r4, lsl #8 ; [D|B|C|A]
add r7, r9, r9, lsl #16 ; [G|G|G|G]
str r0, [r3], r2
mov r1, r8, asr #16 ; [-|-|-|B]
add r1, r1, r4, asr #8 ; [-|-|D|B]
add r1, r1, r10, lsl #16 ; [-|E|D|B]
add r1, r1, r11, lsl #24 ; [F|E|D|B]
str r1, [r3], r2
add r10, r11, lsl #8 ; [-|-|F|E]
add r10, r10, r9, lsl #16 ; [G|G|F|E]
str r10, [r3]
str r7, [r3, r2]
pop {r4-r12, pc}
ENDP
; constants
c00010001
DCD 0x00010001
c00020002
DCD 0x00020002
c00FF00FF
DCD 0x00FF00FF
END