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author | Andreas Huber <andih@google.com> | 2009-12-08 15:40:06 -0800 |
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committer | Andreas Huber <andih@google.com> | 2009-12-10 12:23:55 -0800 |
commit | 4f1efc098cb5791c3e9f483f2af84aef70d2d0a0 (patch) | |
tree | a2873e84aed3eecb1198f85954e24cddb1bdc380 /media/libstagefright/codecs/amrnb/common/src/sub.cpp | |
parent | c54176addef15699a518b69cd6bbd40ffc95e72e (diff) | |
download | frameworks_av-4f1efc098cb5791c3e9f483f2af84aef70d2d0a0.zip frameworks_av-4f1efc098cb5791c3e9f483f2af84aef70d2d0a0.tar.gz frameworks_av-4f1efc098cb5791c3e9f483f2af84aef70d2d0a0.tar.bz2 |
Initial check in of AMR (NB and WB) decoders based on PV source code.
Diffstat (limited to 'media/libstagefright/codecs/amrnb/common/src/sub.cpp')
-rw-r--r-- | media/libstagefright/codecs/amrnb/common/src/sub.cpp | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/amrnb/common/src/sub.cpp b/media/libstagefright/codecs/amrnb/common/src/sub.cpp new file mode 100644 index 0000000..d936128 --- /dev/null +++ b/media/libstagefright/codecs/amrnb/common/src/sub.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/sub.c + +------------------------------------------------------------------------------ + REVISION HISTORY + + Description: Created separate file for the sub function. Sync'ed up with the + current template and fixed tabs. + + Description: Changed all occurrences of L_diff to diff, deleted "short" in + the definition of var1 and var2, and fixed the range values. + + Description: Changed function prototype passing in a pointer to overflow flag + instead of using global data. + + Description: Changes made per formal review comments. + 1. Changed the parameter name fron "overflow" to "pOverflow" + 2. Updated template + 3. Updated reference section + + Description: Removed conditional code that updates WMOPS counter + + Description: + 1. Modified if-else structure to save cycles by processing + the most common case faster. + + Who: Date: + Description: + +------------------------------------------------------------------------------ + MODULE DESCRIPTION + + Subtraction function with 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: sub +------------------------------------------------------------------------------ + 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 subtract operation resulted in overflow + + Returns: + diff = 16-bit limited difference between var1 and var2 (Word16) + + Global Variables Used: + None + + Local Variables Needed: + None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + This function performs the subtraction (var1-var2) with overflow control and + saturation; the 16 bit result is set at +32767 when overflow occurs or at + -32768 when underflow occurs. + +------------------------------------------------------------------------------ + REQUIREMENTS + + None + +------------------------------------------------------------------------------ + REFERENCES + + [1] sub() function in basicop2.c, UMTS GSM AMR speech codec, R99 - + Version 3.2.0, March 2, 2001 + +------------------------------------------------------------------------------ + + PSEUDO-CODE + + Word16 sub (Word16 var1, Word16 var2) + { + Word16 var_out; + Word32 diff; + + diff = (Word32) var1 - var2; + +* 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 (diff); + + #if (WMOPS) + multiCounter[currCounter].sub++; + #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 sub(Word16 var1, Word16 var2, Flag *pOverflow) +{ + + Word32 diff; + + diff = (Word32) var1 - var2; + + /* Saturate result (if necessary). */ + /* Replaced function call with in-line code */ + /* to conserve MIPS, i.e., var_out = saturate (diff) */ + + + if ((UWord32)(diff - 0xFFFF8000L) > 0x000FFFF) + { + if (diff > (Word32) 0x0007FFFL) + { + diff = MAX_16; + } + else + { + diff = MIN_16; + } + + *pOverflow = 1; + } + + + return ((Word16) diff); +} |