IMA/DVI ADPCM
[Advanced]

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Detailed Description

All the IMA/DVI ADPCM functions implemented in the DSP advanced library.

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Benchmark on the AT32UC targets

• coding a 100-element vector: 5,819 cycles (194.0us @ 30MHz) and decoding a 100-element vector: 4,740 cycles (158.0us @ 30MHz).

Functions
void	dsp_adpcm_ima_decode (S16 *out, void *in, int size, S16 *step_index, S16 *predicted_value)
	IMA/DVI ADPCM decoder.
S16	dsp_adpcm_ima_decode_nibble (S8 nibble, S16 *step_index, S16 *predicted_value)
	IMA/DVI ADPCM sample decoder.
void	dsp_adpcm_ima_encode (void *out, S16 *in, int size, S16 *step_index, S16 *predicted_value)
	IMA/DVI ADPCM encoder.
S8	dsp_adpcm_ima_encode_nibble (S16 nibble, S16 *step_index, S16 *predicted_value)
	IMA/DVI ADPCM sample encoder.

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Function Documentation

void dsp_adpcm_ima_decode	(	S16 *	out,
		void *	in,
		int	size,
		S16 *	step_index,
		S16 *	predicted_value
	)

IMA/DVI ADPCM decoder.

Parameters:

	out	A 16-bit data vector that will contain the decoded data.
	in	A 4-bit data vector that contains the IMA/DVI ADPCM encoded data to decode.
	size	The number of data to decode.
	step_index	A pointer on a 16 bits data which contain the current step index of the ADPCM algorithm.
	predicted_value	A pointer on a 16 bits data which contain the current predicted value of the ADPCM algorithm.

S16 dsp_adpcm_ima_decode_nibble	(	S8	nibble,
		S16 *	step_index,
		S16 *	predicted_value
	)

IMA/DVI ADPCM sample decoder.

Parameters:

	nibble	The sample to decode. It must be a 4-bit data.
	step_index	A pointer on a 16 bits data which contain the previous step index of the ADPCM algorithm.
	predicted_value	A pointer on a 16 bits data which contain the previous predicted value of the ADPCM algorithm.

Returns:

A 16-bit data that corresponds to the sample decoded.

void dsp_adpcm_ima_encode	(	void *	out,
		S16 *	in,
		int	size,
		S16 *	step_index,
		S16 *	predicted_value
	)

IMA/DVI ADPCM encoder.

Parameters:

	out	A 4-bit data vector that will contain the encoded data.
	in	A 16-bit data vector that contains the data to encode.
	size	The number of data to encode.
	step_index	A pointer on a 16 bits data which contain the current step index of the ADPCM algorithm.
	predicted_value	A pointer on a 16 bits data which contain the current predicted value of the ADPCM algorithm.

Note:

Can be performed "in-place".

S8 dsp_adpcm_ima_encode_nibble	(	S16	nibble,
		S16 *	step_index,
		S16 *	predicted_value
	)

IMA/DVI ADPCM sample encoder.

Parameters:

	nibble	The sample to encode.
	step_index	A pointer on a 16 bits data which contain the current step index of the ADPCM algorithm.
	predicted_value	A pointer on a 16 bits data which contain the current predicted value of the ADPCM algorithm.

Returns:

A 4-bit data that corresponds to the sample encoded.