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diff --git a/media/libstagefright/codecs/amrnb/common/src/sub.cpp b/media/libstagefright/codecs/amrnb/common/src/sub.cpp
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+/* ------------------------------------------------------------------
+ * 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);
+}