reSIDfp::WaveformGenerator Class Reference

#include <WaveformGenerator.h>

Public Member Functions
void	setWaveformModels (matrix_t *models)
void	setDAC (float *dac)
void	setModel (bool is6581)
void	clock ()
void	synchronize (WaveformGenerator *syncDest, const WaveformGenerator *syncSource) const
	WaveformGenerator ()
void	writeFREQ_LO (unsigned char freq_lo)
void	writeFREQ_HI (unsigned char freq_hi)
void	writePW_LO (unsigned char pw_lo)
void	writePW_HI (unsigned char pw_hi)
void	writeCONTROL_REG (unsigned char control)
void	reset ()
float	output (const WaveformGenerator *ringModulator)
unsigned char	readOSC () const
unsigned int	readAccumulator () const
unsigned int	readFreq () const
bool	readTest () const
bool	readSync () const

Detailed Description

A 24 bit accumulator is the basis for waveform generation. FREQ is added to the lower 16 bits of the accumulator each cycle. The accumulator is set to zero when TEST is set, and starts counting when TEST is cleared.

Waveforms are generated as follows:

• No waveform: When no waveform is selected, the DAC input is floating.
• Triangle: The upper 12 bits of the accumulator are used. The MSB is used to create the falling edge of the triangle by inverting the lower 11 bits. The MSB is thrown away and the lower 11 bits are left-shifted (half the resolution, full amplitude). Ring modulation substitutes the MSB with MSB EOR NOT sync_source MSB.
• Sawtooth: The output is identical to the upper 12 bits of the accumulator.
• Pulse: The upper 12 bits of the accumulator are used. These bits are compared to the pulse width register by a 12 bit digital comparator; output is either all one or all zero bits. The pulse setting is delayed one cycle after the compare. The test bit, when set to one, holds the pulse waveform output at 0xfff regardless of the pulse width setting.
• Noise: The noise output is taken from intermediate bits of a 23-bit shift register which is clocked by bit 19 of the accumulator. The shift is delayed 2 cycles after bit 19 is set high.

Operation: Calculate EOR result, shift register, set bit 0 = result.

               reset  +--------------------------------------------+
                 |    |                                            |
          test--OR-->EOR<--+                                       |
                 |         |                                       |
                 2 2 2 1 1 1 1 1 1 1 1 1 1                         |
Register bits:   2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 <---+
                     |   |       |     |   |       |     |   |
Waveform bits:       1   1       9     8   7       6     5   4
                     1   0

The low 4 waveform bits are zero (grounded).

Constructor & Destructor Documentation

WaveformGenerator()

reSIDfp::WaveformGenerator::WaveformGenerator ( )

inline

Constructor.

Member Function Documentation

clock()

RESID_INLINE void reSIDfp::WaveformGenerator::clock

(

)

SID clocking.

output()

RESID_INLINE float reSIDfp::WaveformGenerator::output

(

const WaveformGenerator *

ringModulator

)

12-bit waveform output as an analogue float value.

Parameters

ringModulator

The oscillator ring-modulating current one.

Returns

output the waveform generator output

readAccumulator()

unsigned int reSIDfp::WaveformGenerator::readAccumulator ( ) const

inline

Read accumulator value.

readFreq()

unsigned int reSIDfp::WaveformGenerator::readFreq ( ) const

inline

Read freq value.

readOSC()

unsigned char reSIDfp::WaveformGenerator::readOSC ( ) const

inline

Read OSC3 value.

readSync()

bool reSIDfp::WaveformGenerator::readSync ( ) const

inline

Read sync value.

readTest()

bool reSIDfp::WaveformGenerator::readTest ( ) const

inline

Read test value.

reset()

void reSIDfp::WaveformGenerator::reset

(

)

SID reset.

setDAC()

void reSIDfp::WaveformGenerator::setDAC ( float *  dac )

inline

Set the analog DAC emulation: 8580 is perfectly linear while 6581 is nonlinear. Must be called before any operation.

Parameters

dac

setModel()

void reSIDfp::WaveformGenerator::setModel ( bool  is6581 )

inline

Set the chip model. Must be called before any operation.

Parameters

is6581

true if MOS6581, false if CSG8580

synchronize()

void reSIDfp::WaveformGenerator::synchronize	(	WaveformGenerator *	syncDest,
		const WaveformGenerator *	syncSource
	)		const

Synchronize oscillators. This must be done after all the oscillators have been clock()'ed, so that they are in the same state.

Parameters

syncDest	The oscillator that will be synced
syncSource	The sync source oscillator

writeCONTROL_REG()

void reSIDfp::WaveformGenerator::writeCONTROL_REG

(

unsigned char

control

)

Write CONTROL REGISTER register.

Parameters

control

control register value

writeFREQ_HI()

void reSIDfp::WaveformGenerator::writeFREQ_HI ( unsigned char  freq_hi )

inline

Write FREQ HI register.

Parameters

freq_hi

high 8 bits of frequency

writeFREQ_LO()

void reSIDfp::WaveformGenerator::writeFREQ_LO ( unsigned char  freq_lo )

inline

Write FREQ LO register.

Parameters

freq_lo

low 8 bits of frequency

writePW_HI()

void reSIDfp::WaveformGenerator::writePW_HI ( unsigned char  pw_hi )

inline

Write PW HI register.

Parameters

pw_hi

high 8 bits of pulse width

writePW_LO()

void reSIDfp::WaveformGenerator::writePW_LO ( unsigned char  pw_lo )

inline

Write PW LO register.

Parameters

pw_lo

low 8 bits of pulse width

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

• WaveformGenerator.h
• WaveformGenerator.cpp