reSIDfp::residfp Class Reference

#include <residfp.h>

Public Member Functions
bool	setChipModel (ChipModel model)
ChipModel	getChipModel () const
bool	setCombinedWaveforms (CombinedWaveforms cws)
void	reset ()
void	input (int value)
unsigned char	read (int offset)
void	write (int offset, unsigned char value)
bool	setSamplingParameters (double clockFrequency, SamplingMethod method, double samplingFrequency)
int	clock (unsigned int cycles, short *buf)
void	clockSilent (unsigned int cycles)
void	setFilter6581Curve (double filterCurve)
void	setFilter6581Range (double adjustment)
void	setFilter8580Curve (double filterCurve)
void	enableFilter (bool enable)

Detailed Description

Cycle exact SID emulation

Member Function Documentation

clock()

int residfp::clock	(	unsigned int	cycles,
		short *	buf
	)

Clock SID forward producing audio using chosen output sampling algorithm.

Parameters

cycles	c64 clocks to clock
buf	audio output buffer

Returns

number of samples produced

clockSilent()

void residfp::clockSilent

(

unsigned int

cycles

)

Clock SID forward with no audio production.

Note

You can't mix this method of clocking with the audio-producing clock() because components that don't affect OSC3/ENV3 are not emulated.

Parameters

cycles

c64 clocks to clock.

enableFilter()

void residfp::enableFilter

(

bool

enable

)

Enable filter emulation.

Parameters

enable

false to turn off filter emulation

getChipModel()

ChipModel residfp::getChipModel

(

)

const

Get currently emulated chip model.

input()

void residfp::input

(

int

value

)

16-bit input (EXT IN). Write 16-bit sample to audio input. NB! The caller is responsible for keeping the value within 16 bits. Note that to mix in an external audio signal the signal should be resampled to 1MHz first.

Parameters

value

input level to set

read()

unsigned char residfp::read

(

int

offset

)

Read registers.

Reading a write only register returns the last char written to any SID register. The individual bits in this value start to fade down towards zero after a few cycles. All bits reach zero within approximately $2000 - $4000 cycles on the 6581 and dar longer on the 8580. It has been claimed that this fading happens in an orderly fashion, however sampling of write only registers reveals that this is not the case. NOTE: This is not correctly modeled. The actual use of write only registers has largely been made in the belief that all SID registers are readable. To support this belief the read would have to be done immediately after a write to the same register (remember that an intermediate write to another register would yield that value instead). With this in mind we return the last value written to any SID register for a number of cycles dependent on the chip model without modeling the bit fading.

Parameters

offset

SID register to read

Returns

value read from chip

reset()

void residfp::reset

(

)

SID reset.

setChipModel()

bool residfp::setChipModel

(

ChipModel

model

)

Set chip model.

Parameters

model

chip model to use

Returns

false on unrecognized model

setCombinedWaveforms()

bool residfp::setCombinedWaveforms

(

CombinedWaveforms

cws

)

Set combined waveforms strength.

Parameters

cws	strength of combined waveforms

Returns

false on unrecognized strength value

setFilter6581Curve()

void residfp::setFilter6581Curve

(

double

filterCurve

)

Set filter curve parameter for 6581 model.

See also

Filter6581::setFilterCurve(double)

setFilter6581Range()

void residfp::setFilter6581Range

(

double

adjustment

)

Set filter range parameter for 6581 model

See also

Filter6581::setFilterRange(double)

setFilter8580Curve()

void residfp::setFilter8580Curve

(

double

filterCurve

)

Set filter curve parameter for 8580 model.

See also

Filter8580::setFilterCurve(double)

setSamplingParameters()

bool residfp::setSamplingParameters	(	double	clockFrequency,
		SamplingMethod	method,
		double	samplingFrequency
	)

Setting of SID sampling parameters.

Use a clock freqency of 985248Hz for PAL C64, 1022730Hz for NTSC C64. The default end of passband frequency is pass_freq = 0.9*sample_freq/2 for sample frequencies up to ~ 44.1kHz, and 20kHz for higher sample frequencies.

For resampling, the ratio between the clock frequency and the sample frequency is limited as follows: 125*clock_freq/sample_freq < 16384 E.g. provided a clock frequency of ~ 1MHz, the sample frequency can not be set lower than ~ 8kHz. A lower sample frequency would make the resampling code overfill its 16k sample ring buffer.

The end of passband frequency is also limited: pass_freq <= 0.9*sample_freq/2

E.g. for a 44.1kHz sampling rate the end of passband frequency is limited to slightly below 20kHz. This constraint ensures that the FIR table is not overfilled.

Parameters

clockFrequency	System clock frequency at Hz
method	sampling method to use
samplingFrequency	Desired output sampling rate

Returns

false on unrecognized sampling method

write()

void residfp::write	(	int	offset,
		unsigned char	value
	)

Write registers.

Parameters

offset	chip register to write
value	value to write

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The documentation for this class was generated from the following files:

• residfp.h
• residfp.cpp