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 Multiplication function with rounding and overflow control
38 ------------------------------------------------------------------------------
41 /*----------------------------------------------------------------------------
43 ----------------------------------------------------------------------------*/
46 /*----------------------------------------------------------------------------
48 ; [Define module specific macros here]
49 ----------------------------------------------------------------------------*/
51 /*----------------------------------------------------------------------------
53 ; [Include all pre-processor statements here. Include conditional
54 ; compile variables also.]
55 ----------------------------------------------------------------------------*/
57 /*----------------------------------------------------------------------------
58 ; LOCAL FUNCTION DEFINITIONS
59 ; [List function prototypes here]
60 ----------------------------------------------------------------------------*/
62 /*----------------------------------------------------------------------------
63 ; LOCAL VARIABLE DEFINITIONS
64 ; [Variable declaration - defined here and used outside this module]
65 ----------------------------------------------------------------------------*/
69 ------------------------------------------------------------------------------
71 ------------------------------------------------------------------------------
72 INPUT AND OUTPUT DEFINITIONS
75 var1 = 16 bit short signed integer (Word16) whose value falls in
76 the range : 0xffff 8000 <= var1 <= 0x0000 7fff.
78 var2 = 16 bit short signed integer (Word16) whose value falls in
79 the range : 0xffff 8000 <= var2 <= 0x0000 7fff.
81 pOverflow = pointer to overflow (Flag)
84 pOverflow -> 1 if the add operation resulted in overflow
87 L_product_arr = 16-bit limited product of var1 and var2 (Word16)
89 Global Variables Used:
92 Local Variables Needed:
95 ------------------------------------------------------------------------------
98 This function performs the multiplication of var1 by var2 with rounding, and
99 gives a 16 bit result which is scaled, i.e.:
100 mult_r(var1,var2) = extract_l(L_shr(((var1 * var2) + 16384),15)) and |
101 mult_r(-32768,-32768) = 32767
103 ------------------------------------------------------------------------------
108 ------------------------------------------------------------------------------
111 [1] mult_r() function in basicop2.c, UMTS GSM AMR speech codec, R99 -
112 Version 3.2.0, March 2, 2001
114 ------------------------------------------------------------------------------
117 Word16 mult_r (Word16 var1, Word16 var2)
120 Word32 L_product_arr;
122 L_product_arr = (Word32) var1 *(Word32) var2;
123 L_product_arr += (Word32) 0x00004000L;
124 L_product_arr &= (Word32) 0xffff8000L;
125 L_product_arr >>= 15;
127 if (L_product_arr & (Word32) 0x00010000L)
129 L_product_arr |= (Word32) 0xffff0000L;
131 * The reference ETSI code uses a global flag for Overflow inside the function
132 * saturate(). In the actual implementation a pointer to Overflow flag is passed in
133 * as a parameter to the function
135 var_out = saturate (L_product_arr);
138 multiCounter[currCounter].mult_r++;
144 ------------------------------------------------------------------------------
146 [State any special notes, constraints or cautions for users of this function]
148 ------------------------------------------------------------------------------
151 /*----------------------------------------------------------------------------
153 ----------------------------------------------------------------------------*/
155 OSCL_EXPORT_REF Word16 mult_r(Word16 var1, Word16 var2, Flag *pOverflow)
158 register Word32 L_product_arr;
160 L_product_arr = ((Word32) var1) * var2; /* product */
161 L_product_arr += (Word32) 0x00004000L; /* round */
162 L_product_arr >>= 15; /* shift */
164 /* sign extend when necessary */
165 L_product_arr |= (Word32) - (L_product_arr & (Word32) 0x00010000L);
167 /* Saturate result (if necessary). */
168 /* Replaced function call with in-line code to conserve MIPS, */
169 /* i.e., var_out = saturate (L_product_arr) */
171 if (L_product_arr > 0X00007fffL)
174 L_product_arr = MAX_16;
176 else if (L_product_arr < (Word32) - 32768)
179 L_product_arr = MIN_16;
182 return ((Word16) L_product_arr);