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Galaxian sound

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- Use DISCRETE_NOTE for pitch generation; it is more accurate (within the one ms where the pitch changes :-) ) and saves a node
- Use DISCRETE_BITS_DECODE and save 2 nodes.
This commit is contained in:
Couriersud 2009-08-16 16:35:46 +00:00
parent 74d1de9d17
commit 4ab4908ac7
1 changed files with 13 additions and 8 deletions
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21
src/mame/audio/galaxian.c
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@ -293,13 +293,18 @@ static DISCRETE_SOUND_START(galaxian)
/* two cascaded LS164 which are reset to pitch latch value,
* thus generating SOUND_CLOCK / (256 - pitch_clock) signal
*/
DISCRETE_TRANSFORM3(NODE_130, SOUND_CLOCK, 256, GAL_INP_PITCH, "012-/")
DISCRETE_COUNTER(NODE_132, 1, 0, NODE_130, 15, DISC_COUNT_UP, 0, DISC_CLK_IS_FREQ)
*
* One possibility to implement this is
* DISCRETE_TRANSFORM3(NODE_130, SOUND_CLOCK, 256, GAL_INP_PITCH, "012-/")
* DISCRETE_COUNTER(NODE_132, 1, 0, NODE_130, 15, DISC_COUNT_UP, 0, DISC_CLK_IS_FREQ)
* but there is a native choice:
*/
DISCRETE_NOTE(NODE_132, 1, SOUND_CLOCK, GAL_INP_PITCH, 255, 15, DISC_CLK_IS_FREQ)
DISCRETE_BIT_DECODE(NODE_133, NODE_132, 0, TTL_OUT) /* QA 74393 */
DISCRETE_BIT_DECODE(NODE_134, NODE_132, 2, TTL_OUT) /* QC 74393 */
DISCRETE_BIT_DECODE(NODE_135, NODE_132, 3, TTL_OUT) /* QD 74393 */
/* from the 74393 (counter 2 above) only QA, QC, QD are used.
* We decode three here and use SUB_NODE(133,x) below to access.
*/
DISCRETE_BITS_DECODE(NODE_133, NODE_132, 0, 3, TTL_OUT) /* QA-QD 74393 */
/************************************************/
/* HIT */
@ -344,7 +349,7 @@ static DISCRETE_SOUND_START(galaxian)
/* FINAL MIX */
/************************************************/
DISCRETE_MIXER5(NODE_279, 1, NODE_133, NODE_134, NODE_134, NODE_135, NODE_120, &galaxian_mixerpre_desc)
DISCRETE_MIXER5(NODE_279, 1, NODE_SUB(133,0), NODE_SUB(133,2), NODE_SUB(133,2), NODE_SUB(133,3), NODE_120, &galaxian_mixerpre_desc)
DISCRETE_MIXER3(NODE_280, 1, NODE_279, NODE_157, NODE_172, &galaxian_mixer_desc)
DISCRETE_OUTPUT(NODE_280, 32767.0/5.0*5)
@ -359,7 +364,7 @@ static DISCRETE_SOUND_START(mooncrst)
/************************************************/
DISCRETE_DELETE(NODE_279, NODE_279)
DISCRETE_REPLACE
DISCRETE_MIXER7(NODE_280, 1, NODE_133, NODE_134, NODE_134, NODE_135, NODE_120, NODE_157, NODE_172, &mooncrst_mixer_desc)
DISCRETE_MIXER7(NODE_280, 1, NODE_SUB(133,0), NODE_SUB(133,2), NODE_SUB(133,2), NODE_SUB(133,3), NODE_120, NODE_157, NODE_172, &mooncrst_mixer_desc)
DISCRETE_SOUND_END
/*************************************