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Diffstat (limited to 'media/libstagefright/codecs/amrnb/common/src/l_shr_r.cpp')
| -rw-r--r-- | media/libstagefright/codecs/amrnb/common/src/l_shr_r.cpp | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/amrnb/common/src/l_shr_r.cpp b/media/libstagefright/codecs/amrnb/common/src/l_shr_r.cpp new file mode 100644 index 0000000..f609a73 --- /dev/null +++ b/media/libstagefright/codecs/amrnb/common/src/l_shr_r.cpp @@ -0,0 +1,214 @@ +/* ------------------------------------------------------------------ + * 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/l_shr_r.c + +------------------------------------------------------------------------------ + REVISION HISTORY + + Description: Created separate file for the L_shr_r function. Sync'ed up + with the current template and fixed tabs. + + Description: Updated template. Changed function interface to pass in a + pointer to overflow flag into the function instead of using a + global flag. Removed code that updates MOPS counter. Changed + function return value name from "L_var_out" to "result". + + Who: Date: + Description: + +------------------------------------------------------------------------------ +*/ + + +/*---------------------------------------------------------------------------- +; 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: L_shr_r +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Inputs: + L_var1 = 32 bit long signed integer (Word32 ) whose value falls + in the range : 0x8000 0000 <= L_var1 <= 0x7fff ffff. + 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 32 bit shift operation resulted in overflow + + Returns: + result = Shifted result w/ rounding (Word32) + + Global Variables Used: + None + + Local Variables Needed: + None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + This function arithmetically shifts the 32 bit input L_var1 right var2 + positions with rounding. If var2 is negative, the function + arithmetically shifts L_var1 left by -var2 and zero fills the -var2 LSB of + the result. The result is saturated in case of underflows or overflows, i.e., + + - If var2 is greater than zero : + if (L_sub(L_shl(L_shr(L_var1,var2),1),L_shr(L_var1,sub(var2,1)))) + is equal to zero + then + L_shr_r(L_var1,var2) = L_shr(L_var1,var2) + else + L_shr_r(L_var1,var2) = L_add(L_shr(L_var1,var2),1) + - If var2 is less than or equal to zero : + L_shr_r(L_var1,var2) = L_shr(L_var1,var2). + +------------------------------------------------------------------------------ + REQUIREMENTS + + None + +------------------------------------------------------------------------------ + REFERENCES + + [1] L_shr_r() function in basic_op2.c, UMTS GSM AMR speech codec, R99 - + Version 3.2.0, March 2, 2001 + +------------------------------------------------------------------------------ + PSEUDO-CODE + +Word32 L_shr_r (Word32 L_var1, Word16 var2) +{ + Word32 L_var_out; + +* The reference ETSI code uses a global flag for Overflow. In the actual +* implementation a pointer to Overflow flag is passed in as a parameter to the +* function L_shr() + + if (var2 > 31) + { + L_var_out = 0; + } + else + { + L_var_out = L_shr (L_var1, var2); +#if (WMOPS) + multiCounter[currCounter].L_shr--; +#endif + if (var2 > 0) + { + if ((L_var1 & ((Word32) 1 << (var2 - 1))) != 0) + { + L_var_out++; + } + } + } +#if (WMOPS) + multiCounter[currCounter].L_shr_r++; +#endif + return (L_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 +----------------------------------------------------------------------------*/ +Word32 L_shr_r(register Word32 L_var1, register Word16 var2, Flag *pOverflow) +{ + Word32 result; + + if (var2 > 31) + { + result = 0; + } + else + { + result = L_shr(L_var1, var2, pOverflow); + + if (var2 > 0) + { + if ((L_var1 & ((Word32) 1 << (var2 - 1))) != 0) + { + result++; + } + } + } + return (result); +} |