norm_l.cpp revision 4f1efc098cb5791c3e9f483f2af84aef70d2d0a0 
1/* ------------------------------------------------------------------
2 * Copyright (C) 1998-2009 PacketVideo
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
13 * express or implied.
14 * See the License for the specific language governing permissions
15 * and limitations under the License.
16 * -------------------------------------------------------------------
17 */
18/****************************************************************************************
19Portions of this file are derived from the following 3GPP standard:
20
21    3GPP TS 26.073
22    ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec
23    Available from http://www.3gpp.org
24
25(C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC)
26Permission to distribute, modify and use this file under the standard license
27terms listed above has been obtained from the copyright holder.
28****************************************************************************************/
29/*
30 Pathname: ./gsm-amr/c/src/norm_l.c
31
32------------------------------------------------------------------------------
33 REVISION HISTORY
34
35 Description: Created separate file for the norm_l function. Sync'ed up
36          with the current template and fixed tabs.
37
38 Description: Updated module description to be the same as the equivalent
39          assembly file (norm_l.asm).
40
41 Description: Removed conditional code that updates WMOPS counter
42
43 Description: Made the following changes
44              1. Unrolled the search loop to make four comparison per
45                 pass, using only four iterations of the loop and saving
46                 shifts cycles
47              2. Updated header and copyright year
48
49 Description: 1. Support for ARM and Linux-ARM assembly instructions.
50
51 Who:                       Date:
52 Description:
53
54------------------------------------------------------------------------------
55 INPUT AND OUTPUT DEFINITIONS
56
57 Inputs:
58    L_var1 = 32 bit long signed integer (Word32) whose value falls
59             in the range : 0x8000 0000 <= var1 <= 0x7fff ffff.
60
61 Local Stores/Buffers/Pointers Needed:
62    None
63
64 Global Stores/Buffers/Pointers Needed:
65    None
66
67 Outputs:
68    var_out = number of left shifts need to normalize input (Word16)
69
70 Pointers and Buffers Modified:
71    None
72
73 Local Stores Modified:
74    None
75
76 Global Stores Modified:
77    None
78
79------------------------------------------------------------------------------
80 FUNCTION DESCRIPTION
81
82 This function produces the number of left shifts needed to normalize the 32
83 bit variable L_var1 for positive values on the interval with minimum of
84 0x40000000 and maximum of 0x7fffffff, and for negative values on the interval
85 with minimum of 0x80000000 and maximum of 0xc0000000. Note that when L_var1
86 is equal to zero, the output var_out is set to zero.
87
88------------------------------------------------------------------------------
89 REQUIREMENTS
90
91 None
92
93------------------------------------------------------------------------------
94 REFERENCES
95
96 [1] basicop2.c, ETS Version 2.0.0, February 8, 1999
97
98------------------------------------------------------------------------------
99 PSEUDO-CODE
100
101Word16 norm_l (Word32 L_var1)
102{
103    Word16 var_out;
104
105    if (L_var1 == 0)
106    {
107        var_out = 0;
108    }
109    else
110    {
111        if (L_var1 == (Word32) 0xffffffffL)
112        {
113            var_out = 31;
114        }
115        else
116        {
117            if (L_var1 < 0)
118            {
119                L_var1 = ~L_var1;
120            }
121            for (var_out = 0; L_var1 < (Word32) 0x40000000L; var_out++)
122            {
123                L_var1 <<= 1;
124            }
125        }
126    }
127
128#if (WMOPS)
129    multiCounter[currCounter].norm_l++;
130#endif
131    return (var_out);
132}
133
134------------------------------------------------------------------------------
135 RESOURCES USED
136   When the code is written for a specific target processor the
137     the resources used should be documented below.
138
139 STACK USAGE: [stack count for this module] + [variable to represent
140          stack usage for each subroutine called]
141
142     where: [stack usage variable] = stack usage for [subroutine
143         name] (see [filename].ext)
144
145 DATA MEMORY USED: x words
146
147 PROGRAM MEMORY USED: x words
148
149 CLOCK CYCLES: [cycle count equation for this module] + [variable
150           used to represent cycle count for each subroutine
151           called]
152
153     where: [cycle count variable] = cycle count for [subroutine
154        name] (see [filename].ext)
155
156------------------------------------------------------------------------------
157*/
158
159
160/*----------------------------------------------------------------------------
161; INCLUDES
162----------------------------------------------------------------------------*/
163#include    "basic_op.h"
164
165/*----------------------------------------------------------------------------
166; MACROS
167; Define module specific macros here
168----------------------------------------------------------------------------*/
169
170/*----------------------------------------------------------------------------
171; DEFINES
172; Include all pre-processor statements here. Include conditional
173; compile variables also.
174----------------------------------------------------------------------------*/
175
176/*----------------------------------------------------------------------------
177; LOCAL FUNCTION DEFINITIONS
178; Function Prototype declaration
179----------------------------------------------------------------------------*/
180
181/*----------------------------------------------------------------------------
182; LOCAL STORE/BUFFER/POINTER DEFINITIONS
183; Variable declaration - defined here and used outside this module
184----------------------------------------------------------------------------*/
185
186/*----------------------------------------------------------------------------
187; EXTERNAL FUNCTION REFERENCES
188; Declare functions defined elsewhere and referenced in this module
189----------------------------------------------------------------------------*/
190
191/*----------------------------------------------------------------------------
192; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES
193; Declare variables used in this module but defined elsewhere
194----------------------------------------------------------------------------*/
195
196/*----------------------------------------------------------------------------
197; FUNCTION CODE
198----------------------------------------------------------------------------*/
199#if !( defined(PV_ARM_V5) || defined(PV_ARM_GCC_V5) )
200Word16 norm_l(register Word32 L_var1)
201{
202    /*----------------------------------------------------------------------------
203    ; Define all local variables
204    ----------------------------------------------------------------------------*/
205    register Word16 var_out = 0;
206
207    /*----------------------------------------------------------------------------
208    ; Function body here
209    ----------------------------------------------------------------------------*/
210
211    if (L_var1)
212    {
213
214        Word32 y = L_var1 - (L_var1 < 0);
215        L_var1 = y ^(y >> 31);
216
217
218        while (!(0x40000000L & L_var1))
219        {
220            var_out++;
221            if ((0x20000000L & L_var1))
222            {
223                break;
224            }
225            var_out++;
226            if ((0x10000000L & L_var1))
227            {
228                break;
229            }
230            var_out++;
231            if ((0x08000000L & L_var1))
232            {
233                break;
234            }
235            var_out++;
236            L_var1 <<= 4;
237        }
238    }
239
240    /*----------------------------------------------------------------------------
241    ; Return nothing or data or data pointer
242    ----------------------------------------------------------------------------*/
243
244
245    return (var_out);
246}
247#endif
248