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media/libvpx/vp8/encoder/arm/armv5te/vp8_packtokens_mbrow_armv5.asm@ac0c01689b40 (annotated)

media/libvpx/vp8/encoder/arm/armv5te/vp8_packtokens_mbrow_armv5.asm

Thu, 15 Jan 2015 15:59:08 +0100

author

Michael Schloh von Bennewitz <michael@schloh.com>

date

Thu, 15 Jan 2015 15:59:08 +0100

branch

TOR_BUG_9701

changeset 10

ac0c01689b40

permissions

-rw-r--r--

Implement a real Private Browsing Mode condition by changing the API/ABI;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

michael@0	1	;
michael@0	2	; Copyright (c) 2010 The WebM project authors. All Rights Reserved.
michael@0	3	;
michael@0	4	; Use of this source code is governed by a BSD-style license
michael@0	5	; that can be found in the LICENSE file in the root of the source
michael@0	6	; tree. An additional intellectual property rights grant can be found
michael@0	7	; in the file PATENTS. All contributing project authors may
michael@0	8	; be found in the AUTHORS file in the root of the source tree.
michael@0	9	;
michael@0	10
michael@0	11
michael@0	12	EXPORT |vp8cx_pack_mb_row_tokens_armv5|
michael@0	13	IMPORT |vp8_validate_buffer_arm|
michael@0	14
michael@0	15	INCLUDE vp8_asm_enc_offsets.asm
michael@0	16
michael@0	17	ARM
michael@0	18	REQUIRE8
michael@0	19	PRESERVE8
michael@0	20
michael@0	21	AREA |.text|, CODE, READONLY
michael@0	22
michael@0	23
michael@0	24	; macro for validating write buffer position
michael@0	25	; needs vp8_writer in r0
michael@0	26	; start shall not be in r1
michael@0	27	MACRO
michael@0	28	VALIDATE_POS $start, $pos
michael@0	29	push {r0-r3, r12, lr} ; rest of regs are preserved by subroutine call
michael@0	30	ldr r2, [r0, #vp8_writer_buffer_end]
michael@0	31	ldr r3, [r0, #vp8_writer_error]
michael@0	32	mov r1, $pos
michael@0	33	mov r0, $start
michael@0	34	bl vp8_validate_buffer_arm
michael@0	35	pop {r0-r3, r12, lr}
michael@0	36	MEND
michael@0	37
michael@0	38	; r0 VP8_COMP *cpi
michael@0	39	; r1 vp8_writer *w
michael@0	40	; r2 vp8_coef_encodings
michael@0	41	; r3 vp8_extra_bits
michael@0	42	; s0 vp8_coef_tree
michael@0	43
michael@0	44	|vp8cx_pack_mb_row_tokens_armv5| PROC
michael@0	45	push {r4-r12, lr}
michael@0	46	sub sp, sp, #24
michael@0	47
michael@0	48	; Compute address of cpi->common.mb_rows
michael@0	49	ldr r4, _VP8_COMP_common_
michael@0	50	ldr r6, _VP8_COMMON_MBrows_
michael@0	51	add r4, r0, r4
michael@0	52
michael@0	53	ldr r5, [r4, r6] ; load up mb_rows
michael@0	54
michael@0	55	str r2, [sp, #20] ; save vp8_coef_encodings
michael@0	56	str r5, [sp, #12] ; save mb_rows
michael@0	57	str r3, [sp, #8] ; save vp8_extra_bits
michael@0	58
michael@0	59	ldr r4, _VP8_COMP_tplist_
michael@0	60	add r4, r0, r4
michael@0	61	ldr r7, [r4, #0] ; dereference cpi->tp_list
michael@0	62
michael@0	63	mov r0, r1 ; keep same as other loops
michael@0	64
michael@0	65	ldr r2, [r0, #vp8_writer_lowvalue]
michael@0	66	ldr r5, [r0, #vp8_writer_range]
michael@0	67	ldr r3, [r0, #vp8_writer_count]
michael@0	68
michael@0	69	mb_row_loop
michael@0	70
michael@0	71	ldr r1, [r7, #tokenlist_start]
michael@0	72	ldr r9, [r7, #tokenlist_stop]
michael@0	73	str r9, [sp, #0] ; save stop for later comparison
michael@0	74	str r7, [sp, #16] ; tokenlist address for next time
michael@0	75
michael@0	76	b check_p_lt_stop
michael@0	77
michael@0	78	; actuall work gets done here!
michael@0	79
michael@0	80	while_p_lt_stop
michael@0	81	ldrb r6, [r1, #tokenextra_token] ; t
michael@0	82	ldr r4, [sp, #20] ; vp8_coef_encodings
michael@0	83	mov lr, #0
michael@0	84	add r4, r4, r6, lsl #3 ; a = vp8_coef_encodings + t
michael@0	85	ldr r9, [r1, #tokenextra_context_tree] ; pp
michael@0	86
michael@0	87	ldrb r7, [r1, #tokenextra_skip_eob_node]
michael@0	88
michael@0	89	ldr r6, [r4, #vp8_token_value] ; v
michael@0	90	ldr r8, [r4, #vp8_token_len] ; n
michael@0	91
michael@0	92	; vp8 specific skip_eob_node
michael@0	93	cmp r7, #0
michael@0	94	movne lr, #2 ; i = 2
michael@0	95	subne r8, r8, #1 ; --n
michael@0	96
michael@0	97	rsb r4, r8, #32 ; 32-n
michael@0	98	ldr r10, [sp, #64] ; vp8_coef_tree
michael@0	99
michael@0	100	; v is kept in r12 during the token pack loop
michael@0	101	lsl r12, r6, r4 ; r12 = v << 32 - n
michael@0	102
michael@0	103	; loop start
michael@0	104	token_loop
michael@0	105	ldrb r4, [r9, lr, asr #1] ; pp [i>>1]
michael@0	106	sub r7, r5, #1 ; range-1
michael@0	107
michael@0	108	; Decisions are made based on the bit value shifted
michael@0	109	; off of v, so set a flag here based on this.
michael@0	110	; This value is refered to as "bb"
michael@0	111	lsls r12, r12, #1 ; bb = v >> n
michael@0	112	mul r6, r4, r7 ; ((range-1) * pp[i>>1]))
michael@0	113
michael@0	114	; bb can only be 0 or 1. So only execute this statement
michael@0	115	; if bb == 1, otherwise it will act like i + 0
michael@0	116	addcs lr, lr, #1 ; i + bb
michael@0	117
michael@0	118	mov r7, #1
michael@0	119	ldrsb lr, [r10, lr] ; i = vp8_coef_tree[i+bb]
michael@0	120	add r4, r7, r6, lsr #8 ; 1 + (((range-1) * pp[i>>1]) >> 8)
michael@0	121
michael@0	122	addcs r2, r2, r4 ; if (bb) lowvalue += split
michael@0	123	subcs r4, r5, r4 ; if (bb) range = range-split
michael@0	124
michael@0	125	; Counting the leading zeros is used to normalize range.
michael@0	126	clz r6, r4
michael@0	127	sub r6, r6, #24 ; shift
michael@0	128
michael@0	129	; Flag is set on the sum of count. This flag is used later
michael@0	130	; to determine if count >= 0
michael@0	131	adds r3, r3, r6 ; count += shift
michael@0	132	lsl r5, r4, r6 ; range <<= shift
michael@0	133	bmi token_count_lt_zero ; if(count >= 0)
michael@0	134
michael@0	135	sub r6, r6, r3 ; offset = shift - count
michael@0	136	sub r4, r6, #1 ; offset-1
michael@0	137	lsls r4, r2, r4 ; if((lowvalue<<(offset-1)) & 0x80000000 )
michael@0	138	bpl token_high_bit_not_set
michael@0	139
michael@0	140	ldr r4, [r0, #vp8_writer_pos] ; x
michael@0	141	sub r4, r4, #1 ; x = w->pos-1
michael@0	142	b token_zero_while_start
michael@0	143	token_zero_while_loop
michael@0	144	mov r10, #0
michael@0	145	strb r10, [r7, r4] ; w->buffer[x] =(unsigned char)0
michael@0	146	sub r4, r4, #1 ; x--
michael@0	147	token_zero_while_start
michael@0	148	cmp r4, #0
michael@0	149	ldrge r7, [r0, #vp8_writer_buffer]
michael@0	150	ldrb r11, [r7, r4]
michael@0	151	cmpge r11, #0xff
michael@0	152	beq token_zero_while_loop
michael@0	153
michael@0	154	ldr r7, [r0, #vp8_writer_buffer]
michael@0	155	ldrb r10, [r7, r4] ; w->buffer[x]
michael@0	156	add r10, r10, #1
michael@0	157	strb r10, [r7, r4] ; w->buffer[x] + 1
michael@0	158	token_high_bit_not_set
michael@0	159	rsb r4, r6, #24 ; 24-offset
michael@0	160	ldr r10, [r0, #vp8_writer_buffer]
michael@0	161	lsr r7, r2, r4 ; lowvalue >> (24-offset)
michael@0	162	ldr r4, [r0, #vp8_writer_pos] ; w->pos
michael@0	163	lsl r2, r2, r6 ; lowvalue <<= offset
michael@0	164	mov r6, r3 ; shift = count
michael@0	165	add r11, r4, #1 ; w->pos++
michael@0	166	bic r2, r2, #0xff000000 ; lowvalue &= 0xffffff
michael@0	167	str r11, [r0, #vp8_writer_pos]
michael@0	168	sub r3, r3, #8 ; count -= 8
michael@0	169
michael@0	170	VALIDATE_POS r10, r11 ; validate_buffer at pos
michael@0	171
michael@0	172	strb r7, [r10, r4] ; w->buffer[w->pos++]
michael@0	173
michael@0	174	; r10 is used earlier in the loop, but r10 is used as
michael@0	175	; temp variable here. So after r10 is used, reload
michael@0	176	; vp8_coef_tree_dcd into r10
michael@0	177	ldr r10, [sp, #64] ; vp8_coef_tree
michael@0	178
michael@0	179	token_count_lt_zero
michael@0	180	lsl r2, r2, r6 ; lowvalue <<= shift
michael@0	181
michael@0	182	subs r8, r8, #1 ; --n
michael@0	183	bne token_loop
michael@0	184
michael@0	185	ldrb r6, [r1, #tokenextra_token] ; t
michael@0	186	ldr r7, [sp, #8] ; vp8_extra_bits
michael@0	187	; Add t * sizeof (vp8_extra_bit_struct) to get the desired
michael@0	188	; element. Here vp8_extra_bit_struct == 16
michael@0	189	add r12, r7, r6, lsl #4 ; b = vp8_extra_bits + t
michael@0	190
michael@0	191	ldr r4, [r12, #vp8_extra_bit_struct_base_val]
michael@0	192	cmp r4, #0
michael@0	193	beq skip_extra_bits
michael@0	194
michael@0	195	; if( b->base_val)
michael@0	196	ldr r8, [r12, #vp8_extra_bit_struct_len] ; L
michael@0	197	ldrsh lr, [r1, #tokenextra_extra] ; e = p->Extra
michael@0	198	cmp r8, #0 ; if( L)
michael@0	199	beq no_extra_bits
michael@0	200
michael@0	201	ldr r9, [r12, #vp8_extra_bit_struct_prob]
michael@0	202	asr r7, lr, #1 ; v=e>>1
michael@0	203
michael@0	204	ldr r10, [r12, #vp8_extra_bit_struct_tree]
michael@0	205	str r10, [sp, #4] ; b->tree
michael@0	206
michael@0	207	rsb r4, r8, #32
michael@0	208	lsl r12, r7, r4
michael@0	209
michael@0	210	mov lr, #0 ; i = 0
michael@0	211
michael@0	212	extra_bits_loop
michael@0	213	ldrb r4, [r9, lr, asr #1] ; pp[i>>1]
michael@0	214	sub r7, r5, #1 ; range-1
michael@0	215	lsls r12, r12, #1 ; v >> n
michael@0	216	mul r6, r4, r7 ; (range-1) * pp[i>>1]
michael@0	217	addcs lr, lr, #1 ; i + bb
michael@0	218
michael@0	219	mov r7, #1
michael@0	220	ldrsb lr, [r10, lr] ; i = b->tree[i+bb]
michael@0	221	add r4, r7, r6, lsr #8 ; split = 1 + (((range-1) * pp[i>>1]) >> 8)
michael@0	222
michael@0	223	addcs r2, r2, r4 ; if (bb) lowvalue += split
michael@0	224	subcs r4, r5, r4 ; if (bb) range = range-split
michael@0	225
michael@0	226	clz r6, r4
michael@0	227	sub r6, r6, #24
michael@0	228
michael@0	229	adds r3, r3, r6 ; count += shift
michael@0	230	lsl r5, r4, r6 ; range <<= shift
michael@0	231	bmi extra_count_lt_zero ; if(count >= 0)
michael@0	232
michael@0	233	sub r6, r6, r3 ; offset= shift - count
michael@0	234	sub r4, r6, #1 ; offset-1
michael@0	235	lsls r4, r2, r4 ; if((lowvalue<<(offset-1)) & 0x80000000 )
michael@0	236	bpl extra_high_bit_not_set
michael@0	237
michael@0	238	ldr r4, [r0, #vp8_writer_pos] ; x
michael@0	239	sub r4, r4, #1 ; x = w->pos - 1
michael@0	240	b extra_zero_while_start
michael@0	241	extra_zero_while_loop
michael@0	242	mov r10, #0
michael@0	243	strb r10, [r7, r4] ; w->buffer[x] =(unsigned char)0
michael@0	244	sub r4, r4, #1 ; x--
michael@0	245	extra_zero_while_start
michael@0	246	cmp r4, #0
michael@0	247	ldrge r7, [r0, #vp8_writer_buffer]
michael@0	248	ldrb r11, [r7, r4]
michael@0	249	cmpge r11, #0xff
michael@0	250	beq extra_zero_while_loop
michael@0	251
michael@0	252	ldr r7, [r0, #vp8_writer_buffer]
michael@0	253	ldrb r10, [r7, r4]
michael@0	254	add r10, r10, #1
michael@0	255	strb r10, [r7, r4]
michael@0	256	extra_high_bit_not_set
michael@0	257	rsb r4, r6, #24 ; 24-offset
michael@0	258	ldr r10, [r0, #vp8_writer_buffer]
michael@0	259	lsr r7, r2, r4 ; lowvalue >> (24-offset)
michael@0	260	ldr r4, [r0, #vp8_writer_pos]
michael@0	261	lsl r2, r2, r6 ; lowvalue <<= offset
michael@0	262	mov r6, r3 ; shift = count
michael@0	263	add r11, r4, #1 ; w->pos++
michael@0	264	bic r2, r2, #0xff000000 ; lowvalue &= 0xffffff
michael@0	265	str r11, [r0, #vp8_writer_pos]
michael@0	266	sub r3, r3, #8 ; count -= 8
michael@0	267
michael@0	268	VALIDATE_POS r10, r11 ; validate_buffer at pos
michael@0	269
michael@0	270	strb r7, [r10, r4] ; w->buffer[w->pos++]=(lowvalue >> (24-offset))
michael@0	271	ldr r10, [sp, #4] ; b->tree
michael@0	272	extra_count_lt_zero
michael@0	273	lsl r2, r2, r6
michael@0	274
michael@0	275	subs r8, r8, #1 ; --n
michael@0	276	bne extra_bits_loop ; while (n)
michael@0	277
michael@0	278	no_extra_bits
michael@0	279	ldr lr, [r1, #4] ; e = p->Extra
michael@0	280	add r4, r5, #1 ; range + 1
michael@0	281	tst lr, #1
michael@0	282	lsr r4, r4, #1 ; split = (range + 1) >> 1
michael@0	283	addne r2, r2, r4 ; lowvalue += split
michael@0	284	subne r4, r5, r4 ; range = range-split
michael@0	285	tst r2, #0x80000000 ; lowvalue & 0x80000000
michael@0	286	lsl r5, r4, #1 ; range <<= 1
michael@0	287	beq end_high_bit_not_set
michael@0	288
michael@0	289	ldr r4, [r0, #vp8_writer_pos]
michael@0	290	mov r7, #0
michael@0	291	sub r4, r4, #1
michael@0	292	b end_zero_while_start
michael@0	293	end_zero_while_loop
michael@0	294	strb r7, [r6, r4]
michael@0	295	sub r4, r4, #1 ; x--
michael@0	296	end_zero_while_start
michael@0	297	cmp r4, #0
michael@0	298	ldrge r6, [r0, #vp8_writer_buffer]
michael@0	299	ldrb r12, [r6, r4]
michael@0	300	cmpge r12, #0xff
michael@0	301	beq end_zero_while_loop
michael@0	302
michael@0	303	ldr r6, [r0, #vp8_writer_buffer]
michael@0	304	ldrb r7, [r6, r4]
michael@0	305	add r7, r7, #1
michael@0	306	strb r7, [r6, r4]
michael@0	307	end_high_bit_not_set
michael@0	308	adds r3, r3, #1 ; ++count
michael@0	309	lsl r2, r2, #1 ; lowvalue <<= 1
michael@0	310	bne end_count_zero
michael@0	311
michael@0	312	ldr r4, [r0, #vp8_writer_pos]
michael@0	313	mvn r3, #7
michael@0	314	ldr r7, [r0, #vp8_writer_buffer]
michael@0	315	lsr r6, r2, #24 ; lowvalue >> 24
michael@0	316	add r12, r4, #1 ; w->pos++
michael@0	317	bic r2, r2, #0xff000000 ; lowvalue &= 0xffffff
michael@0	318	str r12, [r0, #vp8_writer_pos]
michael@0	319
michael@0	320	VALIDATE_POS r7, r12 ; validate_buffer at pos
michael@0	321
michael@0	322	strb r6, [r7, r4]
michael@0	323	end_count_zero
michael@0	324	skip_extra_bits
michael@0	325	add r1, r1, #TOKENEXTRA_SZ ; ++p
michael@0	326	check_p_lt_stop
michael@0	327	ldr r4, [sp, #0] ; stop
michael@0	328	cmp r1, r4 ; while( p < stop)
michael@0	329	bcc while_p_lt_stop
michael@0	330
michael@0	331	ldr r6, [sp, #12] ; mb_rows
michael@0	332	ldr r7, [sp, #16] ; tokenlist address
michael@0	333	subs r6, r6, #1
michael@0	334	add r7, r7, #TOKENLIST_SZ ; next element in the array
michael@0	335	str r6, [sp, #12]
michael@0	336	bne mb_row_loop
michael@0	337
michael@0	338	str r2, [r0, #vp8_writer_lowvalue]
michael@0	339	str r5, [r0, #vp8_writer_range]
michael@0	340	str r3, [r0, #vp8_writer_count]
michael@0	341	add sp, sp, #24
michael@0	342	pop {r4-r12, pc}
michael@0	343	ENDP
michael@0	344
michael@0	345	_VP8_COMP_common_
michael@0	346	DCD vp8_comp_common
michael@0	347	_VP8_COMMON_MBrows_
michael@0	348	DCD vp8_common_mb_rows
michael@0	349	_VP8_COMP_tplist_
michael@0	350	DCD vp8_comp_tplist
michael@0	351
michael@0	352	END