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msm5205.c: Preserve the documentation differences between MSM6585 & MSM5205 now that support has been added to the msm5205.c driver.

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This commit is contained in:
Brian Troha 2012-07-29 20:03:32 +00:00
parent 58f81a0921
commit b43a647b92
1 changed files with 33 additions and 13 deletions
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46
src/emu/sound/msm5205.c
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@ -11,25 +11,45 @@
* for the current sample rate * for the current sample rate
* *
* 01/06/99 * 01/06/99
* separate MSM5205 emulator form adpcm.c and some fix * separate MSM5205 emulator form adpcm.c and some fix
*
* 07/29/12
* added basic support for the MSM6585
*/ */
#include "emu.h" #include "emu.h"
#include "msm5205.h" #include "msm5205.h"
/* /*
*
* MSM 5205 ADPCM chip: MSM 5205 ADPCM chip:
*
* Data is streamed from a CPU by means of a clock generated on the chip. Data is streamed from a CPU by means of a clock generated on the chip.
*
* A reset signal is set high or low to determine whether playback (and interrupts) are occuring A reset signal is set high or low to determine whether playback (and interrupts) are occuring.
*
* MSM6585: is an upgraded MSM5205 voice synth IC.
* TODO: Improvements:
* - convert to modern More precise internal DA converter
* - lowpass filter for MSM6585 Built in low-pass filter
* Expanded sampling frequency
Differences between MSM6585 & MSM5205:
MSM6586 MSM5205
Master clock frequency 640kHz 384kHz
Sampling frequency 4k/8k/16k/32kHz 4k/6k/8kHz
ADPCM bit length 4-bit 3-bit/4-bit
DA converter 12-bit 10-bit
Low-pass filter -40dB/oct N/A
Overflow prevent circuit Included N/A
Timer callback at VCLK low edge on MSM5205 (at rising edge on MSM6585)
TODO:
- convert to modern
- lowpass filter for MSM6585
*/ */
typedef struct _msm5205_state msm5205_state; typedef struct _msm5205_state msm5205_state;