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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.
****************************************************************************************/
/*
Pathname: ./audio/gsm-amr/c/src/lsp_lsf.c
Functions: Lsp_lsf
Lsf_lsp
------------------------------------------------------------------------------
REVISION HISTORY
Description: Updated template used to PV coding template.
Description: Deleted variables listed in the Local Stores Needed/Modified
section.
Description: Synchronized file with UMTS version 3.2.0. Updated coding
template and removed unnecessary include files.
Description: Replaced basic_op.h with the header file of the math functions
used in the file.
Description: Changed to accept the pOverflow flag for EPOC compatibility.
Description: Placed table declarations in a .c file, rather than an included
.tab. The tables are now referenced via an extern in this file.
Description: For Lsp_lsf()
1. Eliminated unused include file typedef.h.
2. Replaced array addressing by pointers
Description: Replaced "int" and/or "char" with defined types.
Added proper casting (Word32) to some left shifting operations
Description: Changed round function name to pv_round to avoid conflict with
round function in C standard library.
Description: Added #ifdef __cplusplus around extern'ed table.
Who: Date:
Description:
------------------------------------------------------------------------------
MODULE DESCRIPTION
This file contains the functions that convert line spectral pairs (LSP) to
line spectral frequencies (LSF) and vice-versa.
------------------------------------------------------------------------------
*/
/*----------------------------------------------------------------------------
; INCLUDES
----------------------------------------------------------------------------*/
#include "lsp_lsf.h"
#include "basicop_malloc.h"
#include "basic_op.h"
/*--------------------------------------------------------------------------*/
#ifdef __cplusplus
extern "C"
{
#endif
/*----------------------------------------------------------------------------
; 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 VARIABLE DEFINITIONS
; Variable declaration - defined here and used outside this module
----------------------------------------------------------------------------*/
extern const Word16 table[];
extern const Word16 slope[];
/*--------------------------------------------------------------------------*/
#ifdef __cplusplus
}
#endif
/*
------------------------------------------------------------------------------
FUNCTION NAME: Lsf_lsp
------------------------------------------------------------------------------
INPUT AND OUTPUT DEFINITIONS
Inputs:
lsf = buffer containing normalized line spectral frequencies; valid
range is between 0 and 0.5 (Word16)
lsp = buffer containing line spectral pairs; valid range is between
-1 and 1 (Word16)
m = LPC order (Word16)
Outputs:
lsp contains the newly calculated line spectral pairs
Returns:
None
Global Variables Used:
table = cosine table
Local Variables Needed:
None
------------------------------------------------------------------------------
FUNCTION DESCRIPTION
This function performs the LSF to LSP transformation using the equation:
lsf[i] = arccos(lsp[i])/(2*pi)
The transformation from lsp[i] to lsf[i] is approximated by a look-up table
and interpolation.
------------------------------------------------------------------------------
REQUIREMENTS
None
------------------------------------------------------------------------------
REFERENCES
lsp_lsf.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001
------------------------------------------------------------------------------
PSEUDO-CODE
void Lsf_lsp (
Word16 lsf[], // (i) : lsf[m] normalized (range: 0.0<=val<=0.5)
Word16 lsp[], // (o) : lsp[m] (range: -1<=val<1)
Word16 m // (i) : LPC order
)
{
Word16 i, ind, offset;
Word32 L_tmp;
for (i = 0; i < m; i++)
{
ind = shr (lsf[i], 8); // ind = b8-b15 of lsf[i]
offset = lsf[i] & 0x00ff; // offset = b0-b7 of lsf[i]
// lsp[i] = table[ind]+ ((table[ind+1]-table[ind])*offset) / 256
L_tmp = L_mult (sub (table[ind + 1], table[ind]), offset);
lsp[i] = add (table[ind], extract_l (L_shr (L_tmp, 9)));
}
return;
}
------------------------------------------------------------------------------
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]
------------------------------------------------------------------------------
*/
void Lsf_lsp(
Word16 lsf[], /* (i) : lsf[m] normalized (range: 0.0<=val<=0.5) */
Word16 lsp[], /* (o) : lsp[m] (range: -1<=val<1) */
Word16 m, /* (i) : LPC order */
Flag *pOverflow /* (o) : Flag set when overflow occurs */
)
{
Word16 i, ind, offset;
Word32 L_tmp;
for (i = 0; i < m; i++)
{
ind = lsf[i] >> 8; /* ind = b8-b15 of lsf[i] */
offset = lsf[i] & 0x00ff; /* offset = b0-b7 of lsf[i] */
/* lsp[i] = table[ind]+ ((table[ind+1]-table[ind])*offset) / 256 */
L_tmp = ((Word32)(table[ind + 1] - table[ind]) * offset) >> 8;
lsp[i] = add(table[ind], (Word16) L_tmp, pOverflow);
}
return;
}
/****************************************************************************/
/*
------------------------------------------------------------------------------
FUNCTION NAME: Lsp_lsf
------------------------------------------------------------------------------
INPUT AND OUTPUT DEFINITIONS
Inputs:
lsp = buffer containing line spectral pairs; valid range is between
-1 and 1 (Word16)
lsf = buffer containing normalized line spectral frequencies; valid
range is between 0 and 0.5 (Word16)
m = LPC order (Word16)
Outputs:
lsf contains the newly calculated normalized line spectral frequencies
Returns:
None
Global Variables Used:
table = cosine table
slope = table to used to calculate inverse cosine
Local Variables Needed:
None
------------------------------------------------------------------------------
FUNCTION DESCRIPTION
This function performs the LSP to LSF transformation using the equation:
lsp[i] = cos(2*pi*lsf[i])
The transformation from lsf[i] to lsp[i] is approximated by a look-up table
and interpolation.
------------------------------------------------------------------------------
REQUIREMENTS
None
------------------------------------------------------------------------------
REFERENCES
lsp_lsf.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001
------------------------------------------------------------------------------
PSEUDO-CODE
void Lsp_lsf (
Word16 lsp[], // (i) : lsp[m] (range: -1<=val<1)
Word16 lsf[], // (o) : lsf[m] normalized (range: 0.0<=val<=0.5)
Word16 m // (i) : LPC order
)
{
Word16 i, ind;
Word32 L_tmp;
ind = 63; // begin at end of table -1
for (i = m - 1; i >= 0; i--)
{
// find value in table that is just greater than lsp[i]
while (sub (table[ind], lsp[i]) < 0)
{
ind--;
}
// acos(lsp[i])= ind*256 + ( ( lsp[i]-table[ind] ) *
slope[ind] )/4096
L_tmp = L_mult (sub (lsp[i], table[ind]), slope[ind]);
//(lsp[i]-table[ind])*slope[ind])>>12
lsf[i] = pv_round (L_shl (L_tmp, 3));
lsf[i] = add (lsf[i], shl (ind, 8));
}
return;
}
------------------------------------------------------------------------------
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]
------------------------------------------------------------------------------
*/
void Lsp_lsf(
Word16 lsp[], /* (i) : lsp[m] (range: -1<=val<1) */
Word16 lsf[], /* (o) : lsf[m] normalized (range: 0.0<=val<=0.5) */
Word16 m, /* (i) : LPC order */
Flag *pOverflow /* (o) : Flag set when overflow occurs */
)
{
Word16 i;
Word16 ind;
Word16 temp;
Word32 L_tmp;
Word16 *p_lsp = &lsp[m-1];
Word16 *p_lsf = &lsf[m-1];
OSCL_UNUSED_ARG(pOverflow);
ind = 63; /* begin at end of table -1 */
for (i = m - 1; i >= 0; i--)
{
/* find value in table that is just greater than lsp[i] */
temp = *(p_lsp--);
while (table[ind] < temp)
{
ind--;
}
/* acos(lsp[i])= ind*256 + ( ( lsp[i]-table[ind] ) *
slope[ind] )/4096 */
L_tmp = (Word32)(temp - table[ind]) * slope[ind];
/*(lsp[i]-table[ind])*slope[ind])>>12*/
L_tmp = (L_tmp + 0x00000800) >> 12;
*(p_lsf--) = (Word16)(L_tmp) + (ind << 8);
}
return;
}
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