/* VU.H
*
* Real VU meter routines
*
* $Id: vu.c,v 1.2 1997/01/16 18:41:59 pekangas Exp $
*
* Copyright 1996,1997 Housemarque Inc.
*
* This file is part of the MIDAS Sound System, and may only be
* used, modified and distributed under the terms of the MIDAS
* Sound System license, LICENSE.TXT. By continuing to use,
* modify or distribute this file you indicate that you have
* read the license and understand and accept it fully.
*/
#include "lang.h"
#include "mtypes.h"
#include "errors.h"
#include "mmem.h"
#include "sdevice.h"
#include "vu.h"
#include "mutils.h"
RCSID(const char *vu_rcsid = "$Id: vu.c,v 1.2 1997/01/16 18:41:59 pekangas Exp $";)
/* VU meter calculation block size in bytes: */
#define VUBLOCK 128
/* Amount to shift right to convert from bytes to blocks:
(log2 VUBLOCK) */
#define VUBSHIFT 7
sdSample *vuSamples; /* VU sample information */
/****************************************************************************\
*
* Function: int vuInit(void);
*
* Description: Initializes VU-meters, allocating room for MAXSAMPLES
* samples.
*
* Returns: MIDAS error code
*
\****************************************************************************/
int CALLING vuInit(void)
{
int error, i;
/* Allocate memory for sample information structures: */
if ( (error = memAlloc(MAXSAMPLES * sizeof(sdSample), (void**)
&vuSamples)) != OK )
PASSERROR(ID_vuInit)
/* Point all sample VU information initially to NULL to mark it
unallocated: */
for ( i = 0; i < MAXSAMPLES; i++ )
vuSamples[i].sample = NULL;
return OK;
}
/****************************************************************************\
*
* Function: int vuClose(void);
*
* Description: Uninitializes VU-meters
*
* Returns: MIDAS error code
*
\****************************************************************************/
int CALLING vuClose(void)
{
int error, i;
/* Deallocate all sample VU information that is still allocated: */
for ( i = 0; i < MAXSAMPLES; i++ )
{
if ( vuSamples[i].sample != NULL )
{
if ( (error = memFree(vuSamples[i].sample)) != OK )
PASSERROR(ID_vuClose)
vuSamples[i].sample = NULL;
}
}
/* Deallocate sample information structures: */
if ( (error = memFree(vuSamples)) != OK )
PASSERROR(ID_vuClose);
return OK;
}
/****************************************************************************\
*
* Function: int vuPrepare(sdSample *sample, unsigned sampleNumber);
*
* Description: Prepares the VU information for a sample
*
* Input: sdSample *sample pointer to Sound Device sample
* structure for this sample
* unsigned sampleNumber sample number (0 - (MAXSAMPLES-1)),
* usually sound device sample handle
*
* Returns: MIDAS error code.
*
\****************************************************************************/
int CALLING vuPrepare(sdSample *sample, unsigned sampleNumber)
{
sdSample *vuSample = &vuSamples[sampleNumber];
int error;
uchar *src, *dest;
int min, max;
unsigned i, bleft;
/* Copy sample information: */
mMemCopy(vuSample, sample, sizeof(sdSample));
/* If there is no sample data or the sample type is unknown, mark there
is no VU-meter information for this sample and exit: */
if ( (vuSample->sampleLength == 0) || (vuSample->sampleType != smp8bit)
|| (vuSample->samplePos != sdSmpConv) )
{
vuSample->sample = NULL;
return OK;
}
/* FIXME - only 8-bit samples supported! */
/* Allocate memory for VU information: */
if ( (error = memAlloc((vuSample->sampleLength + (VUBLOCK-1)) >> VUBSHIFT,
(void**) &vuSample->sample)) != OK )
PASSERROR(ID_vuPrepare)
/* Point dest to destination buffer and src to sample data: */
dest = vuSample->sample;
src = sample->sample;
bleft = sample->sampleLength;
/* Process all VU information blocks: */
while ( bleft )
{
/* Process VUBLOCK bytes maximum: */
if ( bleft > VUBLOCK )
i = VUBLOCK;
else
i = bleft;
/* Decrease bytes left: */
bleft -= i;
/* Reset minimum and maximum values found: */
min = 255; max = 0;
/* Go through all sample bytes belonging to this block to find the
minimum and maximum values: */
while ( i )
{
if ( *src < min )
min = *src;
if ( *src > max )
max = *src;
src++;
i--;
}
/* Calculate VU-meter value for this block ((max-min)/4, rounded up),
and store it in *dest: */
*(dest++) = (uchar) ((max - min + 2) / 4);
}
return OK;
}
/****************************************************************************\
*
* Function: int vuRemove(unsigned sampleNumber);
*
* Description: Removes and deallocates the VU information for a sample
*
* Input: unsigned sampleNumbe sample number
*
* Returns: MIDAS error code
*
\****************************************************************************/
int CALLING vuRemove(unsigned sampleNumber)
{
int error;
/* Deallocate VU information for this sample if allocated: */
if ( vuSamples[sampleNumber].sample != NULL )
{
if ( (error = memFree(vuSamples[sampleNumber].sample)) != OK )
PASSERROR(ID_vuRemove)
}
/* Mark VU information unallocated: */
vuSamples[sampleNumber].sample = NULL;
return OK;
}
/****************************************************************************\
*
* Function: int vuMeter(unsigned sampleNumber, ulong rate,
* unsigned position, unsigned volume, unsigned *meter);
*
* Description: Calculates the VU-meter value (0-64) for the next 1/50th of
* a second
*
* Input: unsigned sampleNumber sample number
* ulong rate playing rate
* unsigned position sample playing position
* unsigned volume playing volume (0-64)
* unsigned *meter pointer to VU-meter value
*
* Returns: MIDAS error code.
* VU-meter value (0-64) is stored in *meter
*
\****************************************************************************/
int CALLING vuMeter(unsigned sampleNumber, ulong rate, unsigned position,
unsigned volume, unsigned *meter)
{
sdSample *sample = &vuSamples[sampleNumber];
unsigned clippos;
/* Make sure that there is VU information for this sample: */
if ( (sample->sample == NULL) || (sampleNumber >= MAXSAMPLES) )
{
*meter = 0;
return OK;
}
/* Make sure the position is inside the sample: */
if ( position >= sample->sampleLength )
clippos = sample->sampleLength - 1;
else
clippos = position;
/* Just take the VU meter value for current block and scale it with
volume (FIXME?) */
*meter = ((unsigned) sample->sample[clippos >> VUBSHIFT]) * volume / 64;
return OK;
}
/*
* $Log: vu.c,v $
* Revision 1.2 1997/01/16 18:41:59 pekangas
* Changed copyright messages to Housemarque
*
* Revision 1.1 1996/05/22 20:49:33 pekangas
* Initial revision
*
*/
