scale_sig_opt.s revision b676a05348e4c516fa8b57e33b10548e6142c3f8 
1@/*
2@ ** Copyright 2003-2010, VisualOn, Inc.
3@ **
4@ ** Licensed under the Apache License, Version 2.0 (the "License");
5@ ** you may not use this file except in compliance with the License.
6@ ** You may obtain a copy of the License at
7@ **
8@ **     http://www.apache.org/licenses/LICENSE-2.0
9@ **
10@ ** Unless required by applicable law or agreed to in writing, software
11@ ** distributed under the License is distributed on an "AS IS" BASIS,
12@ ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13@ ** See the License for the specific language governing permissions and
14@ ** limitations under the License.
15@ */
16@
17@void Scale_sig(
18@	       Word16 x[],                           /* (i/o) : signal to scale               */
19@	       Word16 lg,                            /* (i)   : size of x[]                   */
20@	       Word16 exp                            /* (i)   : exponent: x = round(x << exp) */
21@	       )
22@
23@r0 --- x[]
24@r1 --- lg
25@r2 --- exp
26
27          .section  .text
28	  .global   Scale_sig_opt
29
30Scale_sig_opt:
31
32         STMFD         r13!, {r4 - r12, r14}
33	 SUB           r3, r1, #1                  @i = lg - 1
34         CMP           r2, #0                      @Compare exp and 0
35	 RSB           r7, r2, #0                  @exp = -exp
36	 ADD           r10, r2, #16                @16 + exp
37         ADD           r4, r0, r3, LSL #1          @x[i] address
38	 MOV           r8, #0x7fffffff
39	 MOV           r9, #0x8000
40	 BLE           LOOP2
41
42LOOP1:
43
44         LDRSH          r5, [r4]                    @load x[i]
45         MOV           r12, r5, LSL r10
46	 TEQ           r5, r12, ASR r10
47	 EORNE         r12, r8, r5, ASR #31
48	 SUBS          r3, r3, #1
49	 QADD          r11, r12, r9
50	 MOV           r12, r11, ASR #16
51	 STRH          r12, [r4], #-2
52	 BGE           LOOP1
53         BL            The_end
54
55LOOP2:
56
57         LDRSH          r5, [r4]                   @load x[i]
58	 MOV           r6, r5, LSL #16            @L_tmp = x[i] << 16
59	 MOV           r5, r6, ASR r7             @L_tmp >>= exp
60	 QADD          r11, r5, r9
61	 MOV           r12, r11, ASR #16
62	 SUBS          r3, r3, #1
63	 STRH          r12, [r4], #-2
64	 BGE           LOOP2
65
66The_end:
67         LDMFD         r13!, {r4 - r12, r15}
68
69         @ENDFUNC
70         .END
71
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