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DMD more fixes, WPC should be finally right after all these years! #338

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Oct 5, 2024
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DMD more fixes, WPC should be finally right after all these years! #338

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948f7e2
cleanups, minor (useless ?) fix to GTS3 alphaseg
vbousquet Sep 19, 2024
603aa7b
DMD: fix WPC incorrectly mixing Snd & DMD FIRQ
vbousquet Oct 5, 2024
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11 changes: 7 additions & 4 deletions docs/dmd.md
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Original file line number Diff line number Diff line change
Expand Up @@ -12,8 +12,7 @@ accurately (mainly for backward compatibility, since this was the only thing ava

All DMD control board use Pulse Width Modulation (PWM) to create shades: they quickly toggle the dots on and
off, and the observer eye perceive a shade between fully off and fully on. The limit between perceiving flicker vs perceiving
a stable shade is called the flicker/fusion limit and has lots of scientific documentation as this is a key point when
designing a display. It depends mainly on 2 factors:
a stable shade is called the [flicker/fusion threshold](https://en.wikipedia.org/wiki/Flicker_fusion_threshold). It depends mainly on 2 factors:
- the speed at which the dots switch on/off (do they ramp up/down quickly or do they fade more slowly),
- the device luminance level, which impacts how the human eye perceive light (Ferry/Porter law).

Expand Down Expand Up @@ -55,9 +54,13 @@ The table below gives the main information (PWM FPS / Display FPS / PWM pattern)

## WPC

WPC simply renders frame at 122.1Hz, expecting the viewer eye to merge the 3 last rasterized frame.
WPC continuously renders frame at 122.1Hz. The game code uses this to render sequences of
either 1 (0/100), 2 (0/50/100), or 3 (0/33/66/100) frames, expecting the viewer eye to
merge these frames into shades. For example, Terminator 2 uses a 2 frame PWM pattern while
Creature from the Black Lagoon uses a 3 frame PWM pattern.

Phantom Haus uses a double height DMD which is therefore rasterized at half frequency: 61.5Hz. As a consequence, the game only uses a PWM pattern limited to 2 frame patterns, likely to avoid flicker.
Phantom Haus uses a double height DMD which is rasterized by the same hardware at half frequency: 61.5Hz.
As a consequence, the game only uses a 2 frame PWM pattern, likely to avoid flicker.


## Alvin G
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12 changes: 6 additions & 6 deletions src/p-roc/p-roc.cpp
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Expand Up @@ -95,12 +95,12 @@ PRMachineType getRomMachineType() {
switch (core_gameData->gen) {
case GEN_WPCALPHA_1:
case GEN_WPCALPHA_2:
case GEN_DE:
case GEN_S4:
case GEN_S11A:
case GEN_S11:
case GEN_S11B2:
case GEN_S11C:
case GEN_DE:
case GEN_S4:
case GEN_S11A:
case GEN_S11:
case GEN_S11B2:
case GEN_S11C:
if (pmoptions.alpha_on_dmd) {
fprintf(stderr, "ROM machine type: kPRMachineWPCAlphanumeric,\nbut using kPRMachineWPC due to alpha_on_dmd option\n");
return kPRMachineWPC;
Expand Down
59 changes: 22 additions & 37 deletions src/wpc/gts3.c
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Expand Up @@ -158,11 +158,9 @@ static WRITE_HANDLER( xvia_0_b_w ) {
// - LCLR H->L / LCLR L->H
// We do not simulate the LCLR signals since the pulse is too short (50us) for the output resolution
//printf("t=%8.5f Col=%3x STRB=%d DATA=%d LCLR=%d\n", timer_get_time(), GTS3locals.lampColumn, data & LSTRB, data & LDATA, data & LCLR);
if (data & ~GTS3locals.u4pb & LSTRB) // Positive edge on LSTRB: shift 12bit register and set bit0 to LDATA
{
if (~GTS3locals.u4pb & data & LSTRB) { // Positive edge on LSTRB: shift 12bit register and set bit0 to LDATA
GTS3locals.lampColumn = ((GTS3locals.lampColumn << 1) & 0x0ffe) | (data & LDATA);
if (GTS3locals.lampColumn == 0x001) // Simple strobe emulation: accumulate lamp matrix until strobe restarts from first column
{
if (GTS3locals.lampColumn == 0x001) { // Simple strobe emulation: accumulate lamp matrix until strobe restarts from first column
memcpy(coreGlobals.lampMatrix, coreGlobals.tmpLampMatrix, sizeof(coreGlobals.tmpLampMatrix));
memset(coreGlobals.tmpLampMatrix, 0, sizeof(coreGlobals.tmpLampMatrix));
}
Expand All @@ -172,11 +170,8 @@ static WRITE_HANDLER( xvia_0_b_w ) {
core_write_pwm_output_lamp_matrix(CORE_MODOUT_LAMP0 + 64, (GTS3locals.lampColumn >> 8) & 0x0F, lampRow, 4);


if (GTS3locals.alphagen)
{ // Alpha generation
//printf("%8.5f Alpha Strobe %02x %05x\n", timer_get_time(), data, GTS3locals.alphaNumColShiftRegister);
if (data & ~GTS3locals.u4pb & DSTRB) // Positive edge on DSTRB: shift 20bit register and set bit0 to DDATA
{
if (GTS3locals.alphagen) { // Alpha generation
if (~GTS3locals.u4pb & data & DSTRB) { // Positive edge on DSTRB: shift 20bit register and set bit0 to DDATA
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol + 20) * 16, 0);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol + 20) * 16 + 8, 0);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol ) * 16 , 0);
Expand All @@ -186,29 +181,21 @@ static WRITE_HANDLER( xvia_0_b_w ) {
// This should never happens but you can drive the hardware to it (multiple resets,...), this will lead to incorrect rendering
// assert((GTS3locals.alphaNumColShiftRegister == 0) || (GTS3locals.alphaNumColShiftRegister == (1 << GTS3locals.alphaNumCol)));
}
if (data & ~GTS3locals.u4pb & DBLNK) // DBlank start (positive edge)
{
if (~GTS3locals.u4pb & data & DBLNK) { // DBlank start (positive edge)
for (int i = 0; i < 20 * 2 * 2; i++)
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + i * 8, 0);
}
else if (GTS3locals.alphaNumCol < 20) {
if (~data & GTS3locals.u4pb & DBLNK) // DBlank end (negative edge)
{
// Basic non dimmed segments emulation: just use the column and value defined during DBLNK
coreGlobals.segments[GTS3locals.alphaNumCol + 20].w = GTS3locals.activeSegments[0].w;
coreGlobals.segments[GTS3locals.alphaNumCol ].w = GTS3locals.activeSegments[1].w;
}
if ((data & DBLNK) == 0)
{
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol + 20) * 16 , GTS3locals.activeSegments[0].b.lo);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol + 20) * 16 + 8, GTS3locals.activeSegments[0].b.hi);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol ) * 16 , GTS3locals.activeSegments[1].b.lo);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol ) * 16 + 8, GTS3locals.activeSegments[1].b.hi);
}
else if (GTS3locals.u4pb & ~data & DBLNK && GTS3locals.alphaNumCol < 20) { // DBlank end (negative edge)
// Non dimmed segments emulation: use the column and value defined during DBLNK
coreGlobals.segments[GTS3locals.alphaNumCol + 20].w = GTS3locals.activeSegments[0].w;
coreGlobals.segments[GTS3locals.alphaNumCol ].w = GTS3locals.activeSegments[1].w;
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol + 20) * 16 , GTS3locals.activeSegments[0].b.lo);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol + 20) * 16 + 8, GTS3locals.activeSegments[0].b.hi);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol ) * 16 , GTS3locals.activeSegments[1].b.lo);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol ) * 16 + 8, GTS3locals.activeSegments[1].b.hi);
}
}
else
{ // DMD generation
else { // DMD generation
GTS3_dmdlocals[0].dstrb = (data & DSTRB) != 0;
}

Expand Down Expand Up @@ -821,25 +808,23 @@ static WRITE_HANDLER(display_control) { GTS3locals.DISPLAY_CONTROL(offset,data);
*/
static WRITE_HANDLER(alpha_display){
/* Adjust the 16 Segment Layout to match the output order expected by core.c */
if (offset & 1) // Hi byte (8..15)
{
if (offset & 1) { // Hi byte (8..15)
GTS3locals.activeSegments[offset >> 1].w &= 0x063F; // Remove bits 6..8 and 11..15
GTS3locals.activeSegments[offset >> 1].w |= ((data & 0x0F) << 11) /* 8..11 => 11..14 */
| ((data & 0x10) << 2) /* 12 => 6 */
| ((data & 0x20) << 3) /* 13 => 8 */
| ((data & 0x40) << 9) /* 14 => 15 */
| ((data & 0x80) ); /* 15 => 7 */
| ((data & 0x10) << 2) /* 12 => 6 */
| ((data & 0x20) << 3) /* 13 => 8 */
| ((data & 0x40) << 9) /* 14 => 15 */
| ((data & 0x80) ); /* 15 => 7 */
}
else // Lo byte (0..7)
{
else { // Lo byte (0..7)
GTS3locals.activeSegments[offset >> 1].w &= 0xF9C0; // Remove bits 0..5 and 9..10
GTS3locals.activeSegments[offset >> 1].w |= ((data & 0x3F) ) /* 0.. 5 => 0.. 5 */
| ((data & 0xC0) << 3); /* 6.. 7 => 9..10 */
| ((data & 0xC0) << 3); /* 6.. 7 => 9..10 */
}
if (((GTS3locals.u4pb & DBLNK) == 0) && (GTS3locals.alphaNumCol < 20)) { // This should never happen since character pattern is loaded to the latch registers while DBLNK is raised
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol + 20) * 16 , GTS3locals.activeSegments[0].b.lo);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol + 20) * 16 + 8, GTS3locals.activeSegments[0].b.hi);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol ) * 16 , GTS3locals.activeSegments[0].b.lo);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol ) * 16 , GTS3locals.activeSegments[1].b.lo);
core_write_pwm_output_8b(CORE_MODOUT_SEG0 + (GTS3locals.alphaNumCol ) * 16 + 8, GTS3locals.activeSegments[1].b.hi);
}
}
Expand Down
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