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midway/omegrace.cpp: Replaced input lookup table with encoder function. (#10728)

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0kmg 2022-12-23 13:39:57 -08:00 committed by GitHub
parent 6120f9a042
commit 61a26b1898
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1 changed files with 9 additions and 28 deletions
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37
src/mame/midway/omegrace.cpp
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@ -109,8 +109,7 @@
15 I encoder 1 (d7-d2) 15 I encoder 1 (d7-d2)
The encoder is a 64 position Grey Code encoder, or a The encoder is a 64 position Gray code encoder.
pot and A to D converter.
Unlike the quadrature inputs on Atari and Sega games, Unlike the quadrature inputs on Atari and Sega games,
Omega Race's controller is an absolute angle. Omega Race's controller is an absolute angle.
@ -126,8 +125,7 @@
16 I encoder 2 (d5-d0) 16 I encoder 2 (d5-d0)
The inputs aren't scrambled as they are on the 1 player The encoder is a 64 position Gray code encoder.
encoder
17 I DIP SW C6 (coin/cocktail settings) 17 I DIP SW C6 (coin/cocktail settings)
@ -269,6 +267,7 @@ private:
TIMER_CALLBACK_MEMBER(periodic_int); TIMER_CALLBACK_MEMBER(periodic_int);
uint8_t vg_go_r(); uint8_t vg_go_r();
static constexpr uint8_t encode_spinner(uint8_t data);
uint8_t spinner1_r(); uint8_t spinner1_r();
uint8_t spinner2_r(); uint8_t spinner2_r();
void outputs_w(uint8_t data); void outputs_w(uint8_t data);
@ -327,38 +326,20 @@ uint8_t omegrace_state::vg_go_r()
* *
*************************************/ *************************************/
/* constexpr uint8_t omegrace_state::encode_spinner(uint8_t data)
* Encoder bit mappings
* The encoder is a 64 way switch, with the inputs scrambled
* on the input port (and shifted 2 bits to the left for the
* 1 player encoder)
*
* 3 6 5 4 7 2 for encoder 1 (shifted two bits left..)
*
* 1 4 3 2 5 0 for encoder 2 (not shifted..)
*/
static const uint8_t spinnerTable[64] =
{ {
0x00, 0x01, 0x05, 0x04, 0x06, 0x07, 0x17, 0x16, data &= 0x3f;
0x14, 0x15, 0x11, 0x10, 0x12, 0x13, 0x1b, 0x1a, return data ^ (data >> 1) ^ 0x3f; // Inverted 6-bit Gray code
0x18, 0x19, 0x1d, 0x1c, 0x1e, 0x1f, 0x3f, 0x3e, }
0x3c, 0x3d, 0x39, 0x38, 0x3a, 0x3b, 0x33, 0x32,
0x30, 0x31, 0x35, 0x34, 0x36, 0x37, 0x27, 0x26,
0x24, 0x25, 0x21, 0x20, 0x22, 0x23, 0x2b, 0x2a,
0x28, 0x29, 0x2d, 0x2c, 0x2e, 0x2f, 0x0f, 0x0e,
0x0c, 0x0d, 0x09, 0x08, 0x0a, 0x0b, 0x03, 0x02
};
uint8_t omegrace_state::spinner1_r() uint8_t omegrace_state::spinner1_r()
{ {
return spinnerTable[m_spinner[0]->read() & 0x3f] << 2; return encode_spinner(m_spinner[0]->read()) << 2;
} }
uint8_t omegrace_state::spinner2_r() uint8_t omegrace_state::spinner2_r()
{ {
return spinnerTable[m_spinner[1]->read() & 0x3f]; return encode_spinner(m_spinner[1]->read());
} }