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STE sound emulator
[io68 library documentation.]

Detailed Description

STE (MicroWire/LMC/DMA) emulator.


Files

file  mw_io.h
 STE sound IO plugin header.

file  mwemul.h
 STE sound emulator header.


Micro-Wire registers

#define MW_ACTI   0x01
 Microwire enabled.

#define MW_BASH   0x03
 Microwire sample start address, bit 16-23.

#define MW_BASM   (MW_BASH+2)
 Microwire sample start address, bit 8-15.

#define MW_BASL   (MW_BASH+4)
 Microwire sample start address, bit 0-7.

#define MW_CTH   0x09
 Microwire sample counter, bit 16-23.

#define MW_CTM   (MW_CTH+2)
 Microwire sample counter, bit 8-15.

#define MW_CTL   (MW_CTH+4)
 Microwire sample counter, bit 0-7.

#define MW_ENDH   0x0f
 Microwire sample end address, bit 16-23.

#define MW_ENDM   (MW_ENDH+2)
 Microwire sample end address, bit 8-15.

#define MW_ENDL   (MW_ENDH+4)
 Microwire sample end address, bit 0-7.

#define MW_MODE   0x21
 Microwire playing mode.

#define MW_DATA   0x22
 Microwire data register.

#define MW_CTRL   0x24
 Microwire control register.


Initialization functions

unsigned int MW_sampling_rate (unsigned int f)
 Set/Get sampling rate.

int MW_reset (void)
 Micro-Wire hardware reset.

int MW_init (void)
 Micro-Wire first one first initialization.


Emulation functions

void MW_mix (u32 *b, const u8 *mem68, int n)
 Execute Micro-Wire emulation.


Micro-Wire LMC control functions

void MW_set_LMC_mixer (unsigned int n)
 Set LMC mixer type.

void MW_set_LMC_master (unsigned int n)
 Set LMC master volume.

void MW_set_LMC_left (unsigned int n)
 Set LMC left channel volume.

void MW_set_LMC_right (unsigned int n)
 Set LMC right channel volume.

void MW_set_LMC_high (unsigned int n)
 Set high pass filter.

void MW_set_LMC_low (unsigned int n)
 Set low pass filter.


STE sound IO plugin

io68_t mw_io
 STE IO plugin instance.


Micro-Wire internal data

u8 mw [0x40]
 Micro-Wire register array.

u32 mw_ct
 DMA current location (8 bit fixed point).

u32 mw_end
 DMA end point location (8 bit fixed point).

Function Documentation

unsigned int MW_sampling_rate (  unsigned int  f  ) 
 

Set/Get sampling rate.

The MW_sampling_rate() function set Micro-Wire emulator sampling rate. f is given in hz. If f is 0 the current replay is return.

Parameters:
f sampling rate in hz (0 to get current value).
Returns:
new sampling rate

int MW_reset (  void   ) 
 

Micro-Wire hardware reset.

The MW_reset() reset function perform a Micro-Wire reset. It performs following operations :

  • all registers zeroed
  • all internal counter zeroed
  • LMC reset
    • mixer mode YM2149+Micro-Wire
    • master volume to -40db
    • left and right volumes to -20db
    • low-pass filter to 0

Returns:
error-code (always success)
Return values:
0 Success

int MW_init (  void   ) 
 

Micro-Wire first one first initialization.

The MW_init() must be call before all other PL functions. It performs following operations.

  • Init output level (volume) table.
  • Hardware reset
  • Set replay frequency to default (44100 Hz)

Returns:
error-code (always success)
Return values:
0 Success
See also:
MW_reset()

void MW_mix (  u32 *  b,
const u8 *  mem68,
int  n
) 
 

Execute Micro-Wire emulation.

The MW_mix() function processes sample mixing with current internal parameters for n samples. Mixed samples are stored in a large enough (at least n) 32 bit buffer pointed by b. This buffer have to be previously filled with the YM-2149 samples. Typically it is the YM-2149 emulator output buffer. This allows Micro-Wire emulator to honnor the LMC mixer mode.iven LMC mode. This porocess include the mono to stereo expansion. The mem68 starting pointer locates the 68K memory buffer where samples are stored to allow DMA fetch emulation.

Parameters:
b Pointer to YM-2149 source sample directly used for Micro-Wire output mixing.
mem68 Pointer to 68K memory buffer start address
n Number of sample to mix in b buffer
See also:
YM_mix()

YM_get_buffer()

void MW_set_LMC_mixer (  unsigned int  n  ) 
 

Set LMC mixer type.

The MW_set_LMC_mixer() function choose the mixer mode :

  • 0 -12 Db
  • 1 YM+STE
  • 2 STE only
  • 3 reserved ???

Parameters:
n New mixer mode (see above)

void MW_set_LMC_master (  unsigned int  n  ) 
 

Set LMC master volume.

Parameters:
n New volume in range [0..40]=>[-80Db..0Db]
See also:
MW_set_LMC_left()

MW_set_LMC_right()

void MW_set_LMC_left (  unsigned int  n  ) 
 

Set LMC left channel volume.

Set LMC left channel volume in decibel.

Parameters:
n New volume in range [0..20]=>[-40Db..0Db]
See also:
MW_set_LMC_master()

MW_set_LMC_right()

void MW_set_LMC_right (  unsigned int  n  ) 
 

Set LMC right channel volume.

Parameters:
n New volume in range [0..20]=>[-40Db..0Db]
See also:
MW_set_LMC_master()

MW_set_LMC_left()

void MW_set_LMC_high (  unsigned int  n  ) 
 

Set high pass filter.

Parameters:
n New high pass filter [0..12]=>[-12Db..0Db]
See also:
MW_set_LMC_low()
Warning:
Filters are not supported by MicroWire emulator.

void MW_set_LMC_low (  unsigned int  n  ) 
 

Set low pass filter.

Parameters:
n New low pass filter [0..12]=>[-12Db..0Db]
See also:
MW_set_LMC_high()
Warning:
Unsupported by MicroWire emulator.

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