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Diffstat (limited to 'media/libstagefright/codecs/amrnb/common/src/mult_r.cpp')
-rw-r--r-- | media/libstagefright/codecs/amrnb/common/src/mult_r.cpp | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/amrnb/common/src/mult_r.cpp b/media/libstagefright/codecs/amrnb/common/src/mult_r.cpp new file mode 100644 index 0000000..0777e68 --- /dev/null +++ b/media/libstagefright/codecs/amrnb/common/src/mult_r.cpp @@ -0,0 +1,218 @@ +/* ------------------------------------------------------------------ + * Copyright (C) 1998-2009 PacketVideo + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either + * express or implied. + * See the License for the specific language governing permissions + * and limitations under the License. + * ------------------------------------------------------------------- + */ +/**************************************************************************************** +Portions of this file are derived from the following 3GPP standard: + + 3GPP TS 26.073 + ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec + Available from http://www.3gpp.org + +(C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC) +Permission to distribute, modify and use this file under the standard license +terms listed above has been obtained from the copyright holder. +****************************************************************************************/ +/* + + Filename: /audio/gsm_amr/c/src/mult_r.c + +------------------------------------------------------------------------------ + REVISION HISTORY + + Description: Created separate file for the mult_r function. Sync'ed up + with the current template and fixed tabs. + + Description: Passing in a pointer to the overflow flag instead of using + a global flag. + + Description: Made the following changes based on P2/P3 review: + 1) Simplified test to determine if sign extension is necessary + 2) Changed the name of pointer "overflow" to "Poverflow" + 3) Removed code that updates MOPS counter + 4) Updated template and reference section + + Who: Date: + Description: + + +------------------------------------------------------------------------------ + MODULE DESCRIPTION + + Multiplication function with rounding and overflow control + +------------------------------------------------------------------------------ +*/ + +/*---------------------------------------------------------------------------- +; INCLUDES +----------------------------------------------------------------------------*/ +#include "basic_op.h" + +/*---------------------------------------------------------------------------- +; MACROS +; [Define module specific macros here] +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; DEFINES +; [Include all pre-processor statements here. Include conditional +; compile variables also.] +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; LOCAL FUNCTION DEFINITIONS +; [List function prototypes here] +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; LOCAL VARIABLE DEFINITIONS +; [Variable declaration - defined here and used outside this module] +----------------------------------------------------------------------------*/ + + +/* +------------------------------------------------------------------------------ + FUNCTION NAME: mult_r +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Inputs: + var1 = 16 bit short signed integer (Word16) whose value falls in + the range : 0xffff 8000 <= var1 <= 0x0000 7fff. + + var2 = 16 bit short signed integer (Word16) whose value falls in + the range : 0xffff 8000 <= var2 <= 0x0000 7fff. + + pOverflow = pointer to overflow (Flag) + + Outputs: + pOverflow -> 1 if the add operation resulted in overflow + + Returns: + L_product_arr = 16-bit limited product of var1 and var2 (Word16) + + Global Variables Used: + None + + Local Variables Needed: + None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + This function performs the multiplication of var1 by var2 with rounding, and + gives a 16 bit result which is scaled, i.e.: + mult_r(var1,var2) = extract_l(L_shr(((var1 * var2) + 16384),15)) and | + mult_r(-32768,-32768) = 32767 + +------------------------------------------------------------------------------ + REQUIREMENTS + + None + +------------------------------------------------------------------------------ + REFERENCES + + [1] mult_r() function in basicop2.c, UMTS GSM AMR speech codec, R99 - + Version 3.2.0, March 2, 2001 + +------------------------------------------------------------------------------ + PSEUDO-CODE + +Word16 mult_r (Word16 var1, Word16 var2) +{ + Word16 var_out; + Word32 L_product_arr; + + L_product_arr = (Word32) var1 *(Word32) var2; + L_product_arr += (Word32) 0x00004000L; + L_product_arr &= (Word32) 0xffff8000L; + L_product_arr >>= 15; + + if (L_product_arr & (Word32) 0x00010000L) + { + L_product_arr |= (Word32) 0xffff0000L; + } +* The reference ETSI code uses a global flag for Overflow inside the function +* saturate(). In the actual implementation a pointer to Overflow flag is passed in +* as a parameter to the function + + var_out = saturate (L_product_arr); + +#if (WMOPS) + multiCounter[currCounter].mult_r++; +#endif + + return (var_out); +} + +------------------------------------------------------------------------------ + RESOURCES USED [optional] + + When the code is written for a specific target processor the + the resources used should be documented below. + + HEAP MEMORY USED: x bytes + + STACK MEMORY USED: x bytes + + CLOCK CYCLES: (cycle count equation for this function) + (variable + used to represent cycle count for each subroutine + called) + where: (cycle count variable) = cycle count for [subroutine + name] + +------------------------------------------------------------------------------ + CAUTION [optional] + [State any special notes, constraints or cautions for users of this function] + +------------------------------------------------------------------------------ +*/ + +/*---------------------------------------------------------------------------- +; FUNCTION CODE +----------------------------------------------------------------------------*/ + +Word16 mult_r(Word16 var1, Word16 var2, Flag *pOverflow) +{ + + register Word32 L_product_arr; + + L_product_arr = ((Word32) var1) * var2; /* product */ + L_product_arr += (Word32) 0x00004000L; /* round */ + L_product_arr >>= 15; /* shift */ + + /* sign extend when necessary */ + L_product_arr |= (Word32) - (L_product_arr & (Word32) 0x00010000L); + + /* Saturate result (if necessary). */ + /* Replaced function call with in-line code to conserve MIPS, */ + /* i.e., var_out = saturate (L_product_arr) */ + + if (L_product_arr > 0X00007fffL) + { + *pOverflow = 1; + L_product_arr = MAX_16; + } + else if (L_product_arr < (Word32) 0xffff8000L) + { + *pOverflow = 1; + L_product_arr = MIN_16; + } + + return ((Word16) L_product_arr); +} |