1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
|
;********************************************************************
;* *
;* THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE. *
;* USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
;* GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
;* IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
;* *
;* THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2010 *
;* by the Xiph.Org Foundation and contributors http://www.xiph.org/ *
;* *
;********************************************************************
;
; function:
; last mod: $Id$
;
;********************************************************************
AREA |.text|, CODE, READONLY
EXPORT oc_pack_read_arm
EXPORT oc_pack_read1_arm
EXPORT oc_huff_token_decode_arm
oc_pack_read1_arm PROC
; r0 = oc_pack_buf *_b
ADD r12,r0,#8
LDMIA r12,{r2,r3} ; r2 = window
; Stall... ; r3 = available
; Stall...
SUBS r3,r3,#1 ; r3 = available-1, available<1 => LT
BLT oc_pack_read1_refill
MOV r0,r2,LSR #31 ; r0 = window>>31
MOV r2,r2,LSL #1 ; r2 = window<<=1
STMIA r12,{r2,r3} ; window = r2
; available = r3
MOV PC,r14
ENDP
oc_pack_read_arm PROC
; r0 = oc_pack_buf *_b
; r1 = int _bits
ADD r12,r0,#8
LDMIA r12,{r2,r3} ; r2 = window
; Stall... ; r3 = available
; Stall...
SUBS r3,r3,r1 ; r3 = available-_bits, available<_bits => LT
BLT oc_pack_read_refill
RSB r0,r1,#32 ; r0 = 32-_bits
MOV r0,r2,LSR r0 ; r0 = window>>32-_bits
MOV r2,r2,LSL r1 ; r2 = window<<=_bits
STMIA r12,{r2,r3} ; window = r2
; available = r3
MOV PC,r14
; We need to refill window.
oc_pack_read1_refill
MOV r1,#1
oc_pack_read_refill
STMFD r13!,{r10,r11,r14}
LDMIA r0,{r10,r11} ; r10 = stop
; r11 = ptr
RSB r0,r1,#32 ; r0 = 32-_bits
RSB r3,r3,r0 ; r3 = 32-available
; We can use unsigned compares for both the pointers and for available
; (allowing us to chain condition codes) because available will never be
; larger than 32 (or we wouldn't be here), and thus 32-available will never be
; negative.
CMP r10,r11 ; ptr<stop => HI
CMPHI r3,#7 ; available<=24 => HI
LDRHIB r14,[r11],#1 ; r14 = *ptr++
SUBHI r3,#8 ; available += 8
; (HI) Stall...
ORRHI r2,r14,LSL r3 ; r2 = window|=r14<<32-available
CMPHI r10,r11 ; ptr<stop => HI
CMPHI r3,#7 ; available<=24 => HI
LDRHIB r14,[r11],#1 ; r14 = *ptr++
SUBHI r3,#8 ; available += 8
; (HI) Stall...
ORRHI r2,r14,LSL r3 ; r2 = window|=r14<<32-available
CMPHI r10,r11 ; ptr<stop => HI
CMPHI r3,#7 ; available<=24 => HI
LDRHIB r14,[r11],#1 ; r14 = *ptr++
SUBHI r3,#8 ; available += 8
; (HI) Stall...
ORRHI r2,r14,LSL r3 ; r2 = window|=r14<<32-available
CMPHI r10,r11 ; ptr<stop => HI
CMPHI r3,#7 ; available<=24 => HI
LDRHIB r14,[r11],#1 ; r14 = *ptr++
SUBHI r3,#8 ; available += 8
; (HI) Stall...
ORRHI r2,r14,LSL r3 ; r2 = window|=r14<<32-available
SUBS r3,r0,r3 ; r3 = available-=_bits, available<bits => GT
BLT oc_pack_read_refill_last
MOV r0,r2,LSR r0 ; r0 = window>>32-_bits
MOV r2,r2,LSL r1 ; r2 = window<<=_bits
STR r11,[r12,#-4] ; ptr = r11
STMIA r12,{r2,r3} ; window = r2
; available = r3
LDMFD r13!,{r10,r11,PC}
; Either we wanted to read more than 24 bits and didn't have enough room to
; stuff the last byte into the window, or we hit the end of the packet.
oc_pack_read_refill_last
CMP r11,r10 ; ptr<stop => LO
; If we didn't hit the end of the packet, then pull enough of the next byte to
; to fill up the window.
LDRLOB r14,[r11] ; (LO) r14 = *ptr
; Otherwise, set the EOF flag and pretend we have lots of available bits.
MOVHS r14,#1 ; (HS) r14 = 1
ADDLO r10,r3,r1 ; (LO) r10 = available
STRHS r14,[r12,#8] ; (HS) eof = 1
ANDLO r10,r10,#7 ; (LO) r10 = available&7
MOVHS r3,#1<<30 ; (HS) available = OC_LOTS_OF_BITS
ORRLO r2,r14,LSL r10 ; (LO) r2 = window|=*ptr>>(available&7)
MOV r0,r2,LSR r0 ; r0 = window>>32-_bits
MOV r2,r2,LSL r1 ; r2 = window<<=_bits
STR r11,[r12,#-4] ; ptr = r11
STMIA r12,{r2,r3} ; window = r2
; available = r3
LDMFD r13!,{r10,r11,PC}
ENDP
oc_huff_token_decode_arm PROC
; r0 = oc_pack_buf *_b
; r1 = const ogg_int16_t *_tree
STMFD r13!,{r4,r5,r10,r14}
LDRSH r10,[r1] ; r10 = n=_tree[0]
LDMIA r0,{r2-r5} ; r2 = stop
; Stall... ; r3 = ptr
; Stall... ; r4 = window
; r5 = available
CMP r10,r5 ; n>available => GT
BGT oc_huff_token_decode_refill0
RSB r14,r10,#32 ; r14 = 32-n
MOV r14,r4,LSR r14 ; r14 = bits=window>>32-n
ADD r14,r1,r14,LSL #1 ; r14 = _tree+bits
LDRSH r12,[r14,#2] ; r12 = node=_tree[1+bits]
; Stall...
; Stall...
RSBS r14,r12,#0 ; r14 = -node, node>0 => MI
BMI oc_huff_token_decode_continue
MOV r10,r14,LSR #8 ; r10 = n=node>>8
MOV r4,r4,LSL r10 ; r4 = window<<=n
SUB r5,r10 ; r5 = available-=n
STMIB r0,{r3-r5} ; ptr = r3
; window = r4
; available = r5
AND r0,r14,#255 ; r0 = node&255
LDMFD r13!,{r4,r5,r10,pc}
; The first tree node wasn't enough to reach a leaf, read another
oc_huff_token_decode_continue
ADD r12,r1,r12,LSL #1 ; r12 = _tree+node
MOV r4,r4,LSL r10 ; r4 = window<<=n
SUB r5,r5,r10 ; r5 = available-=n
LDRSH r10,[r12],#2 ; r10 = n=_tree[node]
; Stall... ; r12 = _tree+node+1
; Stall...
CMP r10,r5 ; n>available => GT
BGT oc_huff_token_decode_refill
RSB r14,r10,#32 ; r14 = 32-n
MOV r14,r4,LSR r14 ; r14 = bits=window>>32-n
ADD r12,r12,r14 ;
LDRSH r12,[r12,r14] ; r12 = node=_tree[node+1+bits]
; Stall...
; Stall...
RSBS r14,r12,#0 ; r14 = -node, node>0 => MI
BMI oc_huff_token_decode_continue
MOV r10,r14,LSR #8 ; r10 = n=node>>8
MOV r4,r4,LSL r10 ; r4 = window<<=n
SUB r5,r10 ; r5 = available-=n
STMIB r0,{r3-r5} ; ptr = r3
; window = r4
; available = r5
AND r0,r14,#255 ; r0 = node&255
LDMFD r13!,{r4,r5,r10,pc}
oc_huff_token_decode_refill0
ADD r12,r1,#2 ; r12 = _tree+1
oc_huff_token_decode_refill
; We can't possibly need more than 15 bits, so available must be <= 15.
; Therefore we can load at least two bytes without checking it.
CMP r2,r3 ; ptr<stop => HI
LDRHIB r14,[r3],#1 ; r14 = *ptr++
RSBHI r5,r5,#24 ; (HI) available = 32-(available+=8)
RSBLS r5,r5,#32 ; (LS) r5 = 32-available
ORRHI r4,r14,LSL r5 ; r4 = window|=r14<<32-available
CMPHI r2,r3 ; ptr<stop => HI
LDRHIB r14,[r3],#1 ; r14 = *ptr++
SUBHI r5,#8 ; available += 8
; (HI) Stall...
ORRHI r4,r14,LSL r5 ; r4 = window|=r14<<32-available
; We can use unsigned compares for both the pointers and for available
; (allowing us to chain condition codes) because available will never be
; larger than 32 (or we wouldn't be here), and thus 32-available will never be
; negative.
CMPHI r2,r3 ; ptr<stop => HI
CMPHI r5,#7 ; available<=24 => HI
LDRHIB r14,[r3],#1 ; r14 = *ptr++
SUBHI r5,#8 ; available += 8
; (HI) Stall...
ORRHI r4,r14,LSL r5 ; r4 = window|=r14<<32-available
CMP r2,r3 ; ptr<stop => HI
MOVLS r5,#-1<<30 ; (LS) available = OC_LOTS_OF_BITS+32
CMPHI r5,#7 ; (HI) available<=24 => HI
LDRHIB r14,[r3],#1 ; (HI) r14 = *ptr++
SUBHI r5,#8 ; (HI) available += 8
; (HI) Stall...
ORRHI r4,r14,LSL r5 ; (HI) r4 = window|=r14<<32-available
RSB r14,r10,#32 ; r14 = 32-n
MOV r14,r4,LSR r14 ; r14 = bits=window>>32-n
ADD r12,r12,r14 ;
LDRSH r12,[r12,r14] ; r12 = node=_tree[node+1+bits]
RSB r5,r5,#32 ; r5 = available
; Stall...
RSBS r14,r12,#0 ; r14 = -node, node>0 => MI
BMI oc_huff_token_decode_continue
MOV r10,r14,LSR #8 ; r10 = n=node>>8
MOV r4,r4,LSL r10 ; r4 = window<<=n
SUB r5,r10 ; r5 = available-=n
STMIB r0,{r3-r5} ; ptr = r3
; window = r4
; available = r5
AND r0,r14,#255 ; r0 = node&255
LDMFD r13!,{r4,r5,r10,pc}
ENDP
END
|
