| /* ------------------------------------------------------------------ |
| * 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); |
| } |