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Diffstat (limited to 'media/libstagefright/codecs/amrnb/common/src/round.cpp')
-rw-r--r-- | media/libstagefright/codecs/amrnb/common/src/round.cpp | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/amrnb/common/src/round.cpp b/media/libstagefright/codecs/amrnb/common/src/round.cpp new file mode 100644 index 0000000..71d1702 --- /dev/null +++ b/media/libstagefright/codecs/amrnb/common/src/round.cpp @@ -0,0 +1,195 @@ +/* ------------------------------------------------------------------ + * 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/round.c + +------------------------------------------------------------------------------ + REVISION HISTORY + + Description: Created separate file for the round function. Sync'ed up + with the current template and fixed tabs. + + Description: Made changes based on review meeting: + 1. Removed long in Inputs Definitions. + 2. Changed L_var1 to var_out and description in + Output Definitions. + + Description: Added a parameter to the function interface, pOverflow which is + a pointer to the overflow flag. This flag is required by the + L_add() function invoked by round(). + Removed code that updates the MOPS counter. + Created a new return variable result. + + Description: Removed embedded tabs. Included comment in the Pseudo code + Section about using pointer to overflow flag in the actual + implementation instead of using a global flag. + + Description: Changed function name to pv_round to avoid conflict with + round function in C standard library. + + Who: Date: + Description: + +------------------------------------------------------------------------------ + MODULE DESCRIPTION + + Rounding function with saturation. + +------------------------------------------------------------------------------ +*/ + +/*---------------------------------------------------------------------------- +; 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: pv_round +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Inputs: + L_var1 = 32 bit signed integer (Word32) whose value falls + in the range : 0x8000 0000 <= L_var1 <= 0x7fff ffff. + + pOverflow = pointer to overflow (Flag) + + Outputs: + None + + Returns: + result = MS 16 bits of rounded input L_var1. + + Global Variables Used: + None + + Local Variables Needed: + None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + This function rounds the lower 16 bits of the 32 bit input number into the + MS 16 bits with saturation. Shift the resulting bits right by 16 and return + the 16 bit number: + pv_round(L_var1) = extract_h(L_add(L_var1,32768)) + +------------------------------------------------------------------------------ + REQUIREMENTS + + None + +------------------------------------------------------------------------------ + REFERENCES + + [1] round() function in basic_op2.c, UMTS GSM AMR speech codec, R99 - + Version 3.2.0, March 2, 2001 + +------------------------------------------------------------------------------ + PSEUDO-CODE + +Word16 pv_round (Word32 L_var1) +{ + Word16 var_out; + Word32 L_rounded; + +* The reference ETSI code uses a global flag for Overflow in the L_add() function. +* In the actual implementation a pointer to Overflow flag is passed in as a +* parameter to the function. + + L_rounded = L_add (L_var1, (Word32) 0x00008000L); +#if (WMOPS) + multiCounter[currCounter].L_add--; +#endif + var_out = extract_h (L_rounded); +#if (WMOPS) + multiCounter[currCounter].extract_h--; + multiCounter[currCounter].round++; +#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 pv_round(register Word32 L_var1, Flag *pOverflow) +{ + Word16 result; + + L_var1 = L_add(L_var1, (Word32) 0x00008000L, pOverflow); + result = (Word16)(L_var1 >> 16); + + return (result); +} |