ima_adpcm.c

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		current = pima->samples [k - pima->channels] ;

		diff = step >> 3 ;
		if (bytecode & 1)
			diff += step >> 2 ;
		if (bytecode & 2)
			diff += step >> 1 ;
		if (bytecode & 4)
			diff += step ;
		if (bytecode & 8)
			diff = -diff ;

		current += diff ;

		if (current > 32767)
			current = 32767 ;
		else if (current < -32768)
			current = -32768 ;

		stepindx [chan] += ima_indx_adjust [bytecode] ;

		if (stepindx [chan] < 0)
			stepindx [chan] = 0 ;
		else if (stepindx [chan] > 88)
			stepindx [chan] = 88 ;

		pima->samples [k] = current ;
		} ;

	return 1 ;
} /* wav_w64_ima_decode_block */

static int
wav_w64_ima_encode_block (SF_PRIVATE *psf, IMA_ADPCM_PRIVATE *pima)
{	int		chan, k, step, diff, vpdiff, blockindx, indx, indxstart ;
	short	bytecode, mask ;

	/* Encode the block header. */
	for (chan = 0 ; chan < pima->channels ; chan++)
	{	pima->block [chan*4]	= pima->samples [chan] & 0xFF ;
		pima->block [chan*4+1]	= (pima->samples [chan] >> 8) & 0xFF ;

		pima->block [chan*4+2] = pima->stepindx [chan] ;
		pima->block [chan*4+3] = 0 ;

		pima->previous [chan] = pima->samples [chan] ;
		} ;

	/* Encode the samples as 4 bit. */

	for (k = pima->channels ; k < (pima->samplesperblock * pima->channels) ; k ++)
	{	chan = (pima->channels > 1) ? (k % 2) : 0 ;

		diff = pima->samples [k] - pima->previous [chan] ;

		bytecode = 0 ;
		step = ima_step_size [pima->stepindx [chan]] ;
		vpdiff = step >> 3 ;
		if (diff < 0)
		{	bytecode = 8 ;
			diff = -diff ;
			} ;
		mask = 4 ;
		while (mask)
		{	if (diff >= step)
			{	bytecode |= mask ;
				diff -= step ;
				vpdiff += step ;
				} ;
			step >>= 1 ;
			mask >>= 1 ;
			} ;

		if (bytecode & 8)
			pima->previous [chan] -= vpdiff ;
		else
			pima->previous [chan] += vpdiff ;

		if (pima->previous [chan] > 32767)
			pima->previous [chan] = 32767 ;
		else if (pima->previous [chan] < -32768)
			pima->previous [chan] = -32768 ;

		pima->stepindx [chan] += ima_indx_adjust [bytecode] ;
		if (pima->stepindx [chan] < 0)
			pima->stepindx [chan] = 0 ;
		else if (pima->stepindx [chan] > 88)
			pima->stepindx [chan] = 88 ;

		pima->samples [k] = bytecode ;
		} ;

	/* Pack the 4 bit encoded samples. */

	blockindx = 4 * pima->channels ;

	indxstart = pima->channels ;
	while (blockindx < pima->blocksize)
	{	for (chan = 0 ; chan < pima->channels ; chan++)
		{	indx = indxstart + chan ;
			for (k = 0 ; k < 4 ; k++)
			{	pima->block [blockindx] = pima->samples [indx] & 0x0F ;
				indx += pima->channels ;
				pima->block [blockindx] |= (pima->samples [indx] << 4) & 0xF0 ;
				indx += pima->channels ;
				blockindx ++ ;
				} ;
			} ;
		indxstart += 8 * pima->channels ;
		} ;

	/* Write the block to disk. */

	if ((k = psf_fwrite (pima->block, 1, pima->blocksize, psf)) != pima->blocksize)
		psf_log_printf (psf, "*** Warning : short write (%d != %d).\n", k, pima->blocksize) ;

	memset (pima->samples, 0, pima->samplesperblock * sizeof (short)) ;
	pima->samplecount = 0 ;
	pima->blockcount ++ ;

	return 1 ;
} /* wav_w64_ima_encode_block */

static int
ima_read_block (SF_PRIVATE *psf, IMA_ADPCM_PRIVATE *pima, short *ptr, int len)
{	int		count, total = 0, indx = 0 ;

	while (indx < len)
	{	if (pima->blockcount >= pima->blocks && pima->samplecount >= pima->samplesperblock)
		{	memset (&(ptr [indx]), 0, (size_t) ((len - indx) * sizeof (short))) ;
			return total ;
			} ;

		if (pima->samplecount >= pima->samplesperblock)
			pima->decode_block (psf, pima) ;

		count = (pima->samplesperblock - pima->samplecount) * pima->channels ;
		count = (len - indx > count) ? count : len - indx ;

		memcpy (&(ptr [indx]), &(pima->samples [pima->samplecount * pima->channels]), count * sizeof (short)) ;
		indx += count ;
		pima->samplecount += count / pima->channels ;
		total = indx ;
		} ;

	return total ;
} /* ima_read_block */

static sf_count_t
ima_read_s (SF_PRIVATE *psf, short *ptr, sf_count_t len)
{	IMA_ADPCM_PRIVATE 	*pima ;
	int			readcount, count ;
	sf_count_t	total = 0 ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_ADPCM_PRIVATE*) psf->fdata ;

	while (len > 0)
	{	readcount = (len > 0x10000000) ? 0x10000000 : (int) len ;

		count = ima_read_block (psf, pima, ptr, readcount) ;

		total += count ;
		len -= count ;
		if (count != readcount)
			break ;
		} ;

	return total ;
} /* ima_read_s */

static sf_count_t
ima_read_i (SF_PRIVATE *psf, int *ptr, sf_count_t len)
{	IMA_ADPCM_PRIVATE *pima ;
	short		*sptr ;
	int			k, bufferlen, readcount, count ;
	sf_count_t	total = 0 ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_ADPCM_PRIVATE*) psf->fdata ;

	sptr = psf->u.sbuf ;
	bufferlen = ARRAY_LEN (psf->u.sbuf) ;
	while (len > 0)
	{	readcount = (len >= bufferlen) ? bufferlen : (int) len ;
		count = ima_read_block (psf, pima, sptr, readcount) ;
		for (k = 0 ; k < readcount ; k++)
			ptr [total + k] = ((int) sptr [k]) << 16 ;
		total += count ;
		len -= readcount ;
		if (count != readcount)
			break ;
		} ;

	return total ;
} /* ima_read_i */

static sf_count_t
ima_read_f (SF_PRIVATE *psf, float *ptr, sf_count_t len)
{	IMA_ADPCM_PRIVATE *pima ;
	short		*sptr ;
	int			k, bufferlen, readcount, count ;
	sf_count_t	total = 0 ;
	float		normfact ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_ADPCM_PRIVATE*) psf->fdata ;

	normfact = (psf->norm_float == SF_TRUE) ? 1.0 / ((float) 0x8000) : 1.0 ;

	sptr = psf->u.sbuf ;
	bufferlen = ARRAY_LEN (psf->u.sbuf) ;
	while (len > 0)
	{	readcount = (len >= bufferlen) ? bufferlen : (int) len ;
		count = ima_read_block (psf, pima, sptr, readcount) ;
		for (k = 0 ; k < readcount ; k++)
			ptr [total + k] = normfact * (float) (sptr [k]) ;
		total += count ;
		len -= readcount ;
		if (count != readcount)
			break ;
		} ;

	return total ;
} /* ima_read_f */

static sf_count_t
ima_read_d (SF_PRIVATE *psf, double *ptr, sf_count_t len)
{	IMA_ADPCM_PRIVATE *pima ;
	short		*sptr ;
	int			k, bufferlen, readcount, count ;
	sf_count_t	total = 0 ;
	double 		normfact ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_ADPCM_PRIVATE*) psf->fdata ;

	normfact = (psf->norm_double == SF_TRUE) ? 1.0 / ((double) 0x8000) : 1.0 ;

	sptr = psf->u.sbuf ;
	bufferlen = ARRAY_LEN (psf->u.sbuf) ;
	while (len > 0)
	{	readcount = (len >= bufferlen) ? bufferlen : (int) len ;
		count = ima_read_block (psf, pima, sptr, readcount) ;
		for (k = 0 ; k < readcount ; k++)
			ptr [total + k] = normfact * (double) (sptr [k]) ;
		total += count ;
		len -= readcount ;
		if (count != readcount)
			break ;
		} ;

	return total ;
} /* ima_read_d */

static sf_count_t
ima_seek (SF_PRIVATE *psf, int mode, sf_count_t offset)
{	IMA_ADPCM_PRIVATE *pima ;
	int			newblock, newsample ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_ADPCM_PRIVATE*) psf->fdata ;

	if (psf->datalength < 0 || psf->dataoffset < 0)
	{	psf->error = SFE_BAD_SEEK ;
		return	((sf_count_t) -1) ;
		} ;

	if (offset == 0)
	{	psf_fseek (psf, psf->dataoffset, SEEK_SET) ;
		pima->blockcount = 0 ;
		pima->decode_block (psf, pima) ;
		pima->samplecount = 0 ;
		return 0 ;
		} ;

	if (offset < 0 || offset > pima->blocks * pima->samplesperblock)
	{	psf->error = SFE_BAD_SEEK ;
		return	((sf_count_t) -1) ;
		} ;

	newblock	= offset / pima->samplesperblock ;
	newsample	= offset % pima->samplesperblock ;

	if (mode == SFM_READ)
	{	psf_fseek (psf, psf->dataoffset + newblock * pima->blocksize, SEEK_SET) ;
		pima->blockcount = newblock ;
		pima->decode_block (psf, pima) ;
		pima->samplecount = newsample ;
		}
	else
	{	/* What to do about write??? */
		psf->error = SFE_BAD_SEEK ;
		return	((sf_count_t) -1) ;
		} ;

	return newblock * pima->samplesperblock + newsample ;
} /* ima_seek */

/*==========================================================================================
** IMA ADPCM Write Functions.
*/

static int
ima_writer_init (SF_PRIVATE *psf, int blockalign)
{	IMA_ADPCM_PRIVATE	*pima ;
	int					samplesperblock ;
	unsigned int 		pimasize ;

	if (psf->mode != SFM_WRITE)
		return SFE_BAD_MODE_RW ;

	samplesperblock = 2 * (blockalign - 4 * psf->sf.channels) / psf->sf.channels + 1 ;

	pimasize = sizeof (IMA_ADPCM_PRIVATE) + blockalign + 3 * psf->sf.channels * samplesperblock ;

	if ((pima = calloc (1, pimasize)) == NULL)
		return SFE_MALLOC_FAILED ;

	psf->fdata = (void*) pima ;

	pima->channels			= psf->sf.channels ;
	pima->blocksize			= blockalign ;
	pima->samplesperblock	= samplesperblock ;

	pima->block		= (unsigned char*) pima->data ;
	pima->samples	= (short*) (pima->data + blockalign) ;

	pima->samplecount = 0 ;

	switch (psf->sf.format & SF_FORMAT_TYPEMASK)
	{	case SF_FORMAT_WAV :
		case SF_FORMAT_W64 :
				pima->encode_block = wav_w64_ima_encode_block ;
				break ;

		case SF_FORMAT_AIFF :
				pima->encode_block = aiff_ima_encode_block ;
				break ;

		default :
				psf_log_printf (psf, "ima_reader_init: bad psf->sf.format\n") ;
				return SFE_INTERNAL ;
				break ;
		} ;

	psf->write_short	= ima_write_s ;
	psf->write_int		= ima_write_i ;
	psf->write_float	= ima_write_f ;
	psf->write_double	= ima_write_d ;

	return 0 ;
} /* ima_writer_init */

/*==========================================================================================
*/

static int
ima_write_block (SF_PRIVATE *psf, IMA_ADPCM_PRIVATE *pima, short *ptr, int len)
{	int		count, total = 0, indx = 0 ;

	while (indx < len)
	{	count = (pima->samplesperblock - pima->samplecount) * pima->channels ;

		if (count > len - indx)
			count = len - indx ;

		memcpy (&(pima->samples [pima->samplecount * pima->channels]), &(ptr [total]), count * sizeof (short)) ;
		indx += count ;
		pima->samplecount += count / pima->channels ;
		total = indx ;

		if (pima->samplecount >= pima->samplesperblock)
			pima->encode_block (psf, pima) ;
		} ;

	return total ;
} /* ima_write_block */

static sf_count_t
ima_write_s (SF_PRIVATE *psf, short *ptr, sf_count_t len)
{	IMA_ADPCM_PRIVATE 	*pima ;
	int			writecount, count ;
	sf_count_t	total = 0 ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_ADPCM_PRIVATE*) psf->fdata ;

	while (len)
	{	writecount = (len > 0x10000000) ? 0x10000000 : (int) len ;

		count = ima_write_block (psf, pima, ptr, writecount) ;

		total += count ;
		len -= count ;
		if (count != writecount)
			break ;
		} ;

	return total ;
} /* ima_write_s */

static sf_count_t
ima_write_i (SF_PRIVATE *psf, int *ptr, sf_count_t len)
{	IMA_ADPCM_PRIVATE *pima ;
	short		*sptr ;
	int			k, bufferlen, writecount, count ;
	sf_count_t	total = 0 ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_ADPCM_PRIVATE*) psf->fdata ;

	sptr = psf->u.sbuf ;
	bufferlen = ARRAY_LEN (psf->u.sbuf) ;
	while (len > 0)
	{	writecount = (len >= bufferlen) ? bufferlen : (int) len ;
		for (k = 0 ; k < writecount ; k++)
			sptr [k] = ptr [total + k] >> 16 ;
		count = ima_write_block (psf, pima, sptr, writecount) ;
		total += count ;
		len -= writecount ;
		if (count != writecount)
			break ;
		} ;

	return total ;
} /* ima_write_i */

static sf_count_t
ima_write_f (SF_PRIVATE *psf, float *ptr, sf_count_t len)
{	IMA_ADPCM_PRIVATE *pima ;
	short		*sptr ;
	int			k, bufferlen, writecount, count ;
	sf_count_t	total = 0 ;
	float		normfact ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_ADPCM_PRIVATE*) psf->fdata ;

	normfact = (psf->norm_float == SF_TRUE) ? (1.0 * 0x7FFF) : 1.0 ;

	sptr = psf->u.sbuf ;
	bufferlen = ARRAY_LEN (psf->u.sbuf) ;
	while (len > 0)
	{	writecount = (len >= bufferlen) ? bufferlen : (int) len ;
		for (k = 0 ; k < writecount ; k++)
			sptr [k] = lrintf (normfact * ptr [total + k]) ;
		count = ima_write_block (psf, pima, sptr, writecount) ;
		total += count ;
		len -= writecount ;
		if (count != writecount)
			break ;
		} ;

	return total ;
} /* ima_write_f */

static sf_count_t
ima_write_d (SF_PRIVATE *psf, double *ptr, sf_count_t len)
{	IMA_ADPCM_PRIVATE *pima ;
	short		*sptr ;
	int			k, bufferlen, writecount, count ;
	sf_count_t	total = 0 ;
	double 		normfact ;

	if (! psf->fdata)
		return 0 ;
	pima = (IMA_ADPCM_PRIVATE*) psf->fdata ;

	normfact = (psf->norm_double == SF_TRUE) ? (1.0 * 0x7FFF) : 1.0 ;

	sptr = psf->u.sbuf ;
	bufferlen = ARRAY_LEN (psf->u.sbuf) ;
	while (len > 0)
	{	writecount = (len >= bufferlen) ? bufferlen : (int) len ;
		for (k = 0 ; k < writecount ; k++)
			sptr [k] = lrint (normfact * ptr [total + k]) ;
		count = ima_write_block (psf, pima, sptr, writecount) ;
		total += count ;
		len -= writecount ;
		if (count != writecount)
			break ;
		} ;

	return total ;
} /* ima_write_d */


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