2 ; Copyright (c) 2010 The WebM project authors. All Rights Reserved.
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.
12 EXPORT |vp8cx_pack_tokens_armv5|
13 IMPORT |vp8_validate_buffer_arm|
15 INCLUDE vp8_asm_enc_offsets.asm
21 AREA |.text|, CODE, READONLY
24 ; macro for validating write buffer position
25 ; needs vp8_writer in r0
26 ; start shall not be in r1
28 VALIDATE_POS $start, $pos
29 push {r0-r3, r12, lr} ; rest of regs are preserved by subroutine call
30 ldr r2, [r0, #vp8_writer_buffer_end]
31 ldr r3, [r0, #vp8_writer_error]
34 bl vp8_validate_buffer_arm
40 ; r1 const TOKENEXTRA *p
42 ; r3 vp8_coef_encodings
45 |vp8cx_pack_tokens_armv5| PROC
49 ; Add size of xcount * sizeof (TOKENEXTRA) to get stop
50 ; sizeof (TOKENEXTRA) is 8
51 add r2, r1, r2, lsl #3 ; stop = p + xcount*sizeof(TOKENEXTRA)
53 str r3, [sp, #8] ; save vp8_coef_encodings
54 ldr r2, [r0, #vp8_writer_lowvalue]
55 ldr r5, [r0, #vp8_writer_range]
56 ldr r3, [r0, #vp8_writer_count]
60 ldrb r6, [r1, #tokenextra_token] ; t
61 ldr r4, [sp, #8] ; vp8_coef_encodings
63 add r4, r4, r6, lsl #3 ; a = vp8_coef_encodings + t
64 ldr r9, [r1, #tokenextra_context_tree] ; pp
66 ldrb r7, [r1, #tokenextra_skip_eob_node]
68 ldr r6, [r4, #vp8_token_value] ; v
69 ldr r8, [r4, #vp8_token_len] ; n
71 ; vp8 specific skip_eob_node
74 subne r8, r8, #1 ; --n
76 rsb r4, r8, #32 ; 32-n
77 ldr r10, [sp, #60] ; vp8_coef_tree
79 ; v is kept in r12 during the token pack loop
80 lsl r12, r6, r4 ; r12 = v << 32 - n
84 ldrb r4, [r9, lr, asr #1] ; pp [i>>1]
85 sub r7, r5, #1 ; range-1
87 ; Decisions are made based on the bit value shifted
88 ; off of v, so set a flag here based on this.
89 ; This value is refered to as "bb"
90 lsls r12, r12, #1 ; bb = v >> n
91 mul r6, r4, r7 ; ((range-1) * pp[i>>1]))
93 ; bb can only be 0 or 1. So only execute this statement
94 ; if bb == 1, otherwise it will act like i + 0
95 addcs lr, lr, #1 ; i + bb
98 ldrsb lr, [r10, lr] ; i = vp8_coef_tree[i+bb]
99 add r4, r7, r6, lsr #8 ; 1 + (((range-1) * pp[i>>1]) >> 8)
101 addcs r2, r2, r4 ; if (bb) lowvalue += split
102 subcs r4, r5, r4 ; if (bb) range = range-split
104 ; Counting the leading zeros is used to normalize range.
106 sub r6, r6, #24 ; shift
108 ; Flag is set on the sum of count. This flag is used later
109 ; to determine if count >= 0
110 adds r3, r3, r6 ; count += shift
111 lsl r5, r4, r6 ; range <<= shift
112 bmi token_count_lt_zero ; if(count >= 0)
114 sub r6, r6, r3 ; offset = shift - count
115 sub r4, r6, #1 ; offset-1
116 lsls r4, r2, r4 ; if((lowvalue<<(offset-1)) & 0x80000000 )
117 bpl token_high_bit_not_set
119 ldr r4, [r0, #vp8_writer_pos] ; x
120 sub r4, r4, #1 ; x = w->pos-1
121 b token_zero_while_start
122 token_zero_while_loop
124 strb r10, [r7, r4] ; w->buffer[x] =(unsigned char)0
126 token_zero_while_start
128 ldrge r7, [r0, #vp8_writer_buffer]
131 beq token_zero_while_loop
133 ldr r7, [r0, #vp8_writer_buffer]
134 ldrb r10, [r7, r4] ; w->buffer[x]
136 strb r10, [r7, r4] ; w->buffer[x] + 1
137 token_high_bit_not_set
138 rsb r4, r6, #24 ; 24-offset
139 ldr r10, [r0, #vp8_writer_buffer]
140 lsr r7, r2, r4 ; lowvalue >> (24-offset)
141 ldr r4, [r0, #vp8_writer_pos] ; w->pos
142 lsl r2, r2, r6 ; lowvalue <<= offset
143 mov r6, r3 ; shift = count
144 add r11, r4, #1 ; w->pos++
145 bic r2, r2, #0xff000000 ; lowvalue &= 0xffffff
146 str r11, [r0, #vp8_writer_pos]
147 sub r3, r3, #8 ; count -= 8
149 VALIDATE_POS r10, r11 ; validate_buffer at pos
151 strb r7, [r10, r4] ; w->buffer[w->pos++]
153 ; r10 is used earlier in the loop, but r10 is used as
154 ; temp variable here. So after r10 is used, reload
155 ; vp8_coef_tree_dcd into r10
156 ldr r10, [sp, #60] ; vp8_coef_tree
159 lsl r2, r2, r6 ; lowvalue <<= shift
161 subs r8, r8, #1 ; --n
164 ldrb r6, [r1, #tokenextra_token] ; t
165 ldr r7, [sp, #56] ; vp8_extra_bits
166 ; Add t * sizeof (vp8_extra_bit_struct) to get the desired
167 ; element. Here vp8_extra_bit_struct == 16
168 add r12, r7, r6, lsl #4 ; b = vp8_extra_bits + t
170 ldr r4, [r12, #vp8_extra_bit_struct_base_val]
175 ldr r8, [r12, #vp8_extra_bit_struct_len] ; L
176 ldrsh lr, [r1, #tokenextra_extra] ; e = p->Extra
180 ldr r9, [r12, #vp8_extra_bit_struct_prob]
181 asr r7, lr, #1 ; v=e>>1
183 ldr r10, [r12, #vp8_extra_bit_struct_tree]
184 str r10, [sp, #4] ; b->tree
192 ldrb r4, [r9, lr, asr #1] ; pp[i>>1]
193 sub r7, r5, #1 ; range-1
194 lsls r12, r12, #1 ; v >> n
195 mul r6, r4, r7 ; (range-1) * pp[i>>1]
196 addcs lr, lr, #1 ; i + bb
199 ldrsb lr, [r10, lr] ; i = b->tree[i+bb]
200 add r4, r7, r6, lsr #8 ; split = 1 + (((range-1) * pp[i>>1]) >> 8)
202 addcs r2, r2, r4 ; if (bb) lowvalue += split
203 subcs r4, r5, r4 ; if (bb) range = range-split
208 adds r3, r3, r6 ; count += shift
209 lsl r5, r4, r6 ; range <<= shift
210 bmi extra_count_lt_zero ; if(count >= 0)
212 sub r6, r6, r3 ; offset= shift - count
213 sub r4, r6, #1 ; offset-1
214 lsls r4, r2, r4 ; if((lowvalue<<(offset-1)) & 0x80000000 )
215 bpl extra_high_bit_not_set
217 ldr r4, [r0, #vp8_writer_pos] ; x
218 sub r4, r4, #1 ; x = w->pos - 1
219 b extra_zero_while_start
220 extra_zero_while_loop
222 strb r10, [r7, r4] ; w->buffer[x] =(unsigned char)0
224 extra_zero_while_start
226 ldrge r7, [r0, #vp8_writer_buffer]
229 beq extra_zero_while_loop
231 ldr r7, [r0, #vp8_writer_buffer]
235 extra_high_bit_not_set
236 rsb r4, r6, #24 ; 24-offset
237 ldr r10, [r0, #vp8_writer_buffer]
238 lsr r7, r2, r4 ; lowvalue >> (24-offset)
239 ldr r4, [r0, #vp8_writer_pos]
240 lsl r2, r2, r6 ; lowvalue <<= offset
241 mov r6, r3 ; shift = count
242 add r11, r4, #1 ; w->pos++
243 bic r2, r2, #0xff000000 ; lowvalue &= 0xffffff
244 str r11, [r0, #vp8_writer_pos]
245 sub r3, r3, #8 ; count -= 8
247 VALIDATE_POS r10, r11 ; validate_buffer at pos
249 strb r7, [r10, r4] ; w->buffer[w->pos++]=(lowvalue >> (24-offset))
250 ldr r10, [sp, #4] ; b->tree
254 subs r8, r8, #1 ; --n
255 bne extra_bits_loop ; while (n)
258 ldr lr, [r1, #4] ; e = p->Extra
259 add r4, r5, #1 ; range + 1
261 lsr r4, r4, #1 ; split = (range + 1) >> 1
262 addne r2, r2, r4 ; lowvalue += split
263 subne r4, r5, r4 ; range = range-split
264 tst r2, #0x80000000 ; lowvalue & 0x80000000
265 lsl r5, r4, #1 ; range <<= 1
266 beq end_high_bit_not_set
268 ldr r4, [r0, #vp8_writer_pos]
271 b end_zero_while_start
277 ldrge r6, [r0, #vp8_writer_buffer]
280 beq end_zero_while_loop
282 ldr r6, [r0, #vp8_writer_buffer]
287 adds r3, r3, #1 ; ++count
288 lsl r2, r2, #1 ; lowvalue <<= 1
291 ldr r4, [r0, #vp8_writer_pos]
293 ldr r7, [r0, #vp8_writer_buffer]
294 lsr r6, r2, #24 ; lowvalue >> 24
295 add r12, r4, #1 ; w->pos++
296 bic r2, r2, #0xff000000 ; lowvalue &= 0xffffff
297 str r12, [r0, #vp8_writer_pos]
299 VALIDATE_POS r7, r12 ; validate_buffer at pos
304 add r1, r1, #TOKENEXTRA_SZ ; ++p
306 ldr r4, [sp, #0] ; stop
307 cmp r1, r4 ; while( p < stop)
310 str r2, [r0, #vp8_writer_lowvalue]
311 str r5, [r0, #vp8_writer_range]
312 str r3, [r0, #vp8_writer_count]