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Diffstat (limited to 'media/libstagefright/codecs/amrnb/common/src/div_32.cpp')
| -rw-r--r-- | media/libstagefright/codecs/amrnb/common/src/div_32.cpp | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/amrnb/common/src/div_32.cpp b/media/libstagefright/codecs/amrnb/common/src/div_32.cpp new file mode 100644 index 0000000..143e37c --- /dev/null +++ b/media/libstagefright/codecs/amrnb/common/src/div_32.cpp @@ -0,0 +1,209 @@ +/* ------------------------------------------------------------------ + * 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/div_32.c + +------------------------------------------------------------------------------ + REVISION HISTORY + + Description: Updated template. Changed function interface to pass in a + pointer to overflow flag into the function instead of using a + global flag. Removed inclusion of unwanted header files. Changed + the name of input and output variables for clarity. + + Description: + 1. Eliminated unused include files. + 2. Replaced l_extract functionality, code size and speed + do not justify calling this function + 3. Eliminated sub() function call, replace by (-), this knowing + that the result will not saturate. + + Description: Added casting to eliminate warnings + + 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: div_32 +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Inputs: + L_num = 32 bit signed integer (Word32) whose value falls in the + range : 0x0000 0000 < L_num < L_denom + L_denom_hi = 16 bit positive normalized integer whose value falls in + the range : 0x4000 < hi < 0x7fff + L_denom_lo = 16 bit positive integer whose value falls in the range : + 0 < lo < 0x7fff + + pOverflow = pointer to overflow (Flag) + + Outputs: + pOverflow -> 1 if the 32 bit divide operation resulted in overflow + + Returns: + result = 32-bit quotient of of the division of two 32 bit integers + L_num / L_denom (Word32) + + Global Variables Used: + None + + Local Variables Needed: + None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + This function is a fractional integer division of two 32 bit numbers, the + numerator L_num and the denominator L_denom. The denominator is formed by + combining denom_hi and denom_lo. Note that denom_hi is a normalized numbers. + The numerator and denominator must be positive and the numerator must be + less than the denominator. + + The division is done as follows: + 1. Find 1/L_denom by first approximating: approx = 1 / denom_hi. + 2. 1/L_denom = approx * (2.0 - L_denom * approx ). + 3. result = L_num * (1/L_denom). + +------------------------------------------------------------------------------ + REQUIREMENTS + + None + +------------------------------------------------------------------------------ + REFERENCES + + [1] div_32() function in oper_32b.c, UMTS GSM AMR speech codec, R99 - + Version 3.2.0, March 2, 2001 + +------------------------------------------------------------------------------ + PSEUDO-CODE + + +------------------------------------------------------------------------------ + 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 Div_32(Word32 L_num, + Word16 L_denom_hi, + Word16 L_denom_lo, + Flag *pOverflow) +{ + + Word16 approx; + Word16 hi; + Word16 lo; + Word16 n_hi; + Word16 n_lo; + Word32 result; + + /* First approximation: 1 / L_denom = 1/L_denom_hi */ + + approx = div_s((Word16) 0x3fff, L_denom_hi); + + /* 1/L_denom = approx * (2.0 - L_denom * approx) */ + + result = Mpy_32_16(L_denom_hi, L_denom_lo, approx, pOverflow); + /* result is > 0 , and less than 1.0 */ + result = 0x7fffffffL - result; + + hi = (Word16)(result >> 16); + lo = (result >> 1) - (hi << 15); + + result = Mpy_32_16(hi, lo, approx, pOverflow); + + /* L_num * (1/L_denom) */ + + hi = (Word16)(result >> 16); + lo = (result >> 1) - (hi << 15); + + n_hi = (Word16)(L_num >> 16); + n_lo = (L_num >> 1) - (n_hi << 15); + + result = Mpy_32(n_hi, n_lo, hi, lo, pOverflow); + result = L_shl(result, 2, pOverflow); + + return (result); +} + |