1 /* ------------------------------------------------------------------
2 * Copyright (C) 1998-2009 PacketVideo
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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
14 * See the License for the specific language governing permissions
15 * and limitations under the License.
16 * -------------------------------------------------------------------
18 /****************************************************************************************
19 Portions of this file are derived from the following 3GPP standard:
22 ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec
23 Available from http://www.3gpp.org
25 (C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC)
26 Permission to distribute, modify and use this file under the standard license
27 terms listed above has been obtained from the copyright holder.
28 ****************************************************************************************/
33 ------------------------------------------------------------------------------
36 Summation function with overflow control
38 ------------------------------------------------------------------------------
42 /*----------------------------------------------------------------------------
44 ----------------------------------------------------------------------------*/
47 /*----------------------------------------------------------------------------
49 ; [Define module specific macros here]
50 ----------------------------------------------------------------------------*/
52 /*----------------------------------------------------------------------------
54 ; [Include all pre-processor statements here. Include conditional
55 ; compile variables also.]
56 ----------------------------------------------------------------------------*/
58 /*----------------------------------------------------------------------------
59 ; LOCAL FUNCTION DEFINITIONS
60 ; [List function prototypes here]
61 ----------------------------------------------------------------------------*/
63 /*----------------------------------------------------------------------------
64 ; LOCAL VARIABLE DEFINITIONS
65 ; [Variable declaration - defined here and used outside this module]
66 ----------------------------------------------------------------------------*/
70 ------------------------------------------------------------------------------
72 ------------------------------------------------------------------------------
73 INPUT AND OUTPUT DEFINITIONS
76 var1 = 16 bit short signed integer (Word16) whose value falls in
77 the range : 0xffff 8000 <= var1 <= 0x0000 7fff.
79 var2 = 16 bit short signed integer (Word16) whose value falls in
80 the range : 0xffff 8000 <= var2 <= 0x0000 7fff.
82 pOverflow = pointer to overflow (Flag)
85 pOverflow -> 1 if the add operation resulted in overflow
88 sum = 16-bit limited sum of var1 and var2 (Word16)
90 Global Variables Used:
93 Local Variables Needed:
96 ------------------------------------------------------------------------------
99 This function performs the addition (var1+var2) with overflow control and
100 saturation; the 16 bit result is set at +32767 when overflow occurs or at
101 -32768 when underflow occurs.
103 ------------------------------------------------------------------------------
108 ------------------------------------------------------------------------------
111 [1] add.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001
113 ------------------------------------------------------------------------------
116 Word16 add (Word16 var1, Word16 var2)
121 sum = (Word32) var1 + var2;
123 * The reference ETSI code uses a global flag for Overflow inside the function
124 * saturate(). In the actual implementation a pointer to Overflow flag is passed in
125 * as a parameter to the function
127 var_out = saturate (sum);
129 multiCounter[currCounter].add++;
134 ------------------------------------------------------------------------------
136 [State any special notes, constraints or cautions for users of this function]
138 ------------------------------------------------------------------------------
141 /*----------------------------------------------------------------------------
143 ----------------------------------------------------------------------------*/
144 OSCL_EXPORT_REF Word16 add_16(Word16 var1, Word16 var2, Flag *pOverflow)
146 /*----------------------------------------------------------------------------
147 ; Define all local variables
148 ----------------------------------------------------------------------------*/
150 sum = (Word32) var1 + var2;
152 /* Saturate result (if necessary). */
153 /* Replaced function call with in-line code */
154 /* to conserve MIPS, i.e., var_out = saturate (sum) */
156 if (sum > 0X00007fffL)
161 else if (sum < (Word32) 0xffff8000L)
167 /* Return the sum as a 16 bit value by type casting Word32 to Word16 */
169 return ((Word16) sum);