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Diffstat (limited to 'opencore/codecs_v2/audio/gsm_amr/amr_nb/common/src/pow2.cpp')
| -rw-r--r-- | opencore/codecs_v2/audio/gsm_amr/amr_nb/common/src/pow2.cpp | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/opencore/codecs_v2/audio/gsm_amr/amr_nb/common/src/pow2.cpp b/opencore/codecs_v2/audio/gsm_amr/amr_nb/common/src/pow2.cpp new file mode 100644 index 0000000..637f92d --- /dev/null +++ b/opencore/codecs_v2/audio/gsm_amr/amr_nb/common/src/pow2.cpp @@ -0,0 +1,176 @@ +/* ------------------------------------------------------------------ + * 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: pow2.cpp + +------------------------------------------------------------------------------ +*/ + +/*---------------------------------------------------------------------------- +; INCLUDES +----------------------------------------------------------------------------*/ +#include "pow2.h" +#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 +; Function Prototype declaration +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; LOCAL STORE/BUFFER/POINTER DEFINITIONS +; Variable declaration - defined here and used outside this module +----------------------------------------------------------------------------*/ + + +/* +------------------------------------------------------------------------------ + FUNCTION NAME: Pow2 +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Inputs: + exponent = Integer part whose valid range is: 0 <= value <= 30 (Word16) + fraction = Fractional part whose valid range is 0 <= value < 1 + + pOverflow = pointer to overflow flag + + Outputs: + L_x = Result of the Pow2() computation (Word32) + pOverflow -> 1 if the Pow2() function results in saturation + + Returns: + None + + Global Variables Used: + None + + Local Variables Needed: + None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + This function computes L_x = pow(2.0, exponent.fraction) + + The function Pow2(L_x) is approximated by a table and linear interpolation. + + 1- i = bit10-b15 of fraction, 0 <= i <= 31 + 2- a = bit0-b9 of fraction + 3- L_x = table[i]<<16 - (table[i] - table[i+1]) * a * 2 + 4- L_x = L_x >> (30-exponent) (with rounding) + +------------------------------------------------------------------------------ + REQUIREMENTS + + None + +------------------------------------------------------------------------------ + REFERENCES + + pow2.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 + +------------------------------------------------------------------------------ + PSEUDO-CODE + +Word32 Pow2 ( // (o) : result (range: 0<=val<=0x7fffffff) + Word16 exponent, // (i) : Integer part. (range: 0<=val<=30) + Word16 fraction // (i) : Fractional part. (range: 0.0<=val<1.0) +) +{ + Word16 exp, i, a, tmp; + Word32 L_x; + + L_x = L_mult (fraction, 32); // L_x = fraction<<6 + i = extract_h (L_x); // Extract b10-b16 of fraction + L_x = L_shr (L_x, 1); + a = extract_l (L_x); // Extract b0-b9 of fraction + a = a & (Word16) 0x7fff; + + L_x = L_deposit_h (table[i]); // table[i] << 16 + tmp = sub (table[i], table[i + 1]); // table[i] - table[i+1] + L_x = L_msu (L_x, tmp, a); // L_x -= tmp*a*2 + + exp = sub (30, exponent); + L_x = L_shr_r (L_x, exp); + + return (L_x); +} + +------------------------------------------------------------------------------ + CAUTION [optional] + [State any special notes, constraints or cautions for users of this function] + +------------------------------------------------------------------------------ +*/ + +/*---------------------------------------------------------------------------- +; FUNCTION CODE +----------------------------------------------------------------------------*/ + +OSCL_EXPORT_REF Word32 Pow2( /* (o) : result (range: 0<=val<=0x7fffffff) */ + Word16 exponent, /* (i) : Integer part. (range: 0<=val<=30) */ + Word16 fraction, /* (i) : Fractional part. (range: 0.0<=val<1.0) */ + Flag *pOverflow +) +{ + Word16 exp, i, a, tmp; + Word32 L_x; + + L_x = L_mult(fraction, 32, pOverflow); /* L_x = fraction<<6 */ + + /* Extract b0-b16 of fraction */ + + i = ((Word16)(L_x >> 16)) & 31; /* ensure index i is bounded */ + a = (Word16)((L_x >> 1) & 0x7fff); + + L_x = ((Word32) pow2_tbl[i] << 16); /* pow2_tbl[i] << 16 */ + + /* pow2_tbl[i] - pow2_tbl[i+1] */ + tmp = pow2_tbl[i] - pow2_tbl[i + 1]; + L_x = L_msu(L_x, tmp, a, pOverflow); /* L_x -= tmp*a*2 */ + + exp = 30 - exponent; + L_x = L_shr_r(L_x, exp, pOverflow); + + return (L_x); +} |