You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
99 lines
3.0 KiB
99 lines
3.0 KiB
/*----------------------------------------------------------------------------
|
|
*
|
|
* File:
|
|
* eas_pan.c
|
|
*
|
|
* Contents and purpose:
|
|
* Calculates left and right gain multipliers based on a pan value from -63 to +63
|
|
*
|
|
* NOTES:
|
|
* The _CMX_PARSER and _MFI_PARSER preprocessor symbols determine
|
|
* whether the parser works for those particular file formats.
|
|
*
|
|
* Copyright Sonic Network Inc. 2005
|
|
|
|
* 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.
|
|
*
|
|
*----------------------------------------------------------------------------
|
|
* Revision Control:
|
|
* $Revision: 82 $
|
|
* $Date: 2006-07-10 11:45:19 -0700 (Mon, 10 Jul 2006) $
|
|
*----------------------------------------------------------------------------
|
|
*/
|
|
|
|
#include "eas_pan.h"
|
|
#include "eas_math.h"
|
|
|
|
/*----------------------------------------------------------------------------
|
|
* EAS_CalcPanControl()
|
|
*----------------------------------------------------------------------------
|
|
* Purpose:
|
|
* Assign the left and right gain values corresponding to the given pan value.
|
|
*
|
|
* This routine uses sin/cos approximations for an equal power curve:
|
|
*
|
|
* sin(x) = (2-4*c)*x^2 + c + x
|
|
* cos(x) = (2-4*c)*x^2 + c - x
|
|
*
|
|
* where c = 1/sqrt(2)
|
|
* using the a0 + x*(a1 + x*a2) approach
|
|
*
|
|
* Inputs:
|
|
* pan - pan value (-63 to + 63)
|
|
*
|
|
* Outputs:
|
|
* pGainLeft linear gain multiplier for left channel (15-bit fraction)
|
|
* pGainRight linear gain multiplier for left channel (15-bit fraction)
|
|
*
|
|
* Side Effects:
|
|
*----------------------------------------------------------------------------
|
|
*/
|
|
void EAS_CalcPanControl (EAS_INT pan, EAS_I16 *pGainLeft, EAS_I16 *pGainRight)
|
|
{
|
|
EAS_INT temp;
|
|
EAS_INT netAngle;
|
|
|
|
/* impose hard limit */
|
|
if (pan < -63)
|
|
netAngle = -63;
|
|
else if (pan > 63)
|
|
netAngle = 63;
|
|
else
|
|
netAngle = pan;
|
|
|
|
/*lint -e{701} <avoid multiply for performance reasons>*/
|
|
netAngle = netAngle << 8;
|
|
|
|
/* calculate sin */
|
|
temp = EG1_ONE + FMUL_15x15(COEFF_PAN_G2, netAngle);
|
|
temp = COEFF_PAN_G0 + FMUL_15x15(temp, netAngle);
|
|
|
|
if (temp > SYNTH_FULL_SCALE_EG1_GAIN)
|
|
temp = SYNTH_FULL_SCALE_EG1_GAIN;
|
|
else if (temp < 0)
|
|
temp = 0;
|
|
|
|
*pGainRight = (EAS_I16) temp;
|
|
|
|
/* calculate cos */
|
|
temp = -EG1_ONE + FMUL_15x15(COEFF_PAN_G2, netAngle);
|
|
temp = COEFF_PAN_G0 + FMUL_15x15(temp, netAngle);
|
|
if (temp > SYNTH_FULL_SCALE_EG1_GAIN)
|
|
temp = SYNTH_FULL_SCALE_EG1_GAIN;
|
|
else if (temp < 0)
|
|
temp = 0;
|
|
|
|
*pGainLeft = (EAS_I16) temp;
|
|
}
|
|
|