mirror of
https://github.com/holub/mame
synced 2025-06-06 12:53:46 +03:00
(MESS) maria.c: improved DMA accuracy. [Mike Saarna, Robert Tuccitto]
- Last Line DMA value corrected to 6. GCC and Atari docs both show a
difference between Other Line and Last Line as +6 at the lowest part
of the range.
- Blank scanlines are drawn when DMA is off, like real hardware.
- If MARIA hits the DMA limit, the CPU doesn't run until the next
scanline.
This commit is contained in:
Fabio Priuli
parent
0ed3636613
commit
9f7b18a05c
@ -4,8 +4,17 @@
|
||||
|
||||
|
||||
- some history:
|
||||
2014-10-03 Mike Saarna, Robert Tuccitto reorganized DMA penalties to
|
||||
support new rendering timeout code.
|
||||
2014-10-05 Mike Saarna, Robert Tuccitto Last Line DMA value corrected
|
||||
to 6. GCC and Atari docs both show a difference between
|
||||
Other Line and Last Line as +6 at the lowest part of the
|
||||
range.
|
||||
Blank scanlines are drawn when DMA is off, like real
|
||||
hardware.
|
||||
If MARIA hits the DMA limit, the CPU doesn't run until
|
||||
the next scanline.
|
||||
|
||||
2014-09-03 Mike Saarna, Robert Tuccitto reorganized DMA penalties to
|
||||
support new rendering timeout code.
|
||||
|
||||
2014-08-29 Mike Saarna Timeout rendering added.
|
||||
|
||||
@ -165,103 +174,115 @@ void atari_maria_device::draw_scanline()
|
||||
int d, c, pixel_cell, cells;
|
||||
int maria_cycles;
|
||||
|
||||
// All lines in a zone have the same initial DMA startup time. We'll adjust
|
||||
// cycles for the special last zone line later, as those penalties happen after
|
||||
// MARIA is done rendering, or after its hit the maximum rendering time.
|
||||
maria_cycles = 16;
|
||||
|
||||
cells = 0;
|
||||
|
||||
/* Process this DLL entry */
|
||||
dl = m_dl;
|
||||
|
||||
/* DMA */
|
||||
/* Step through DL's while we're within maximum rendering time. max render time = ( scanline length - DMA start ) */
|
||||
/* 426 = ( 454 - 28 ) */
|
||||
|
||||
while (((READ_MEM(dl + 1) & 0x5f) != 0) && (maria_cycles<426))
|
||||
if(m_dmaon)
|
||||
{
|
||||
/* Extended header */
|
||||
if (!(READ_MEM(dl + 1) & 0x1f))
|
||||
{
|
||||
graph_adr = (READ_MEM(dl + 2) << 8) | READ_MEM(dl);
|
||||
width = ((READ_MEM(dl + 3) ^ 0xff) & 0x1f) + 1;
|
||||
hpos = READ_MEM(dl + 4);
|
||||
pal = READ_MEM(dl + 3) >> 5;
|
||||
m_write_mode = (READ_MEM(dl + 1) & 0x80) >> 5;
|
||||
ind = READ_MEM(dl + 1) & 0x20;
|
||||
dl += 5;
|
||||
maria_cycles += 10;
|
||||
}
|
||||
/* Normal header */
|
||||
else
|
||||
{
|
||||
graph_adr = (READ_MEM(dl + 2) << 8) | READ_MEM(dl);
|
||||
width = ((READ_MEM(dl + 1) ^ 0xff) & 0x1f) + 1;
|
||||
hpos = READ_MEM(dl + 3);
|
||||
pal = READ_MEM(dl + 1) >> 5;
|
||||
ind = 0x00;
|
||||
dl += 4;
|
||||
maria_cycles += 8;
|
||||
}
|
||||
// All lines in a zone have the same initial DMA startup time. We'll adjust
|
||||
// cycles for the special last zone line later, as those penalties happen after
|
||||
// MARIA is done rendering, or after its hit the maximum rendering time.
|
||||
maria_cycles = 16;
|
||||
|
||||
/*logerror("%x DL: ADR=%x width=%x hpos=%x pal=%x mode=%x ind=%x\n", m_screen->vpos(), graph_adr, width, hpos, pal, m_write_mode, ind);*/
|
||||
|
||||
for (int x = 0; x < width; x++)
|
||||
/* Process this DLL entry */
|
||||
dl = m_dl;
|
||||
|
||||
/* DMA */
|
||||
/* Step through DL's while we're within maximum rendering time. */
|
||||
/* max render time = ( scanline length - DMA start ) */
|
||||
/* 426 = ( 454 - 28 ) */
|
||||
|
||||
while (((READ_MEM(dl + 1) & 0x5f) != 0) && (maria_cycles<426))
|
||||
{
|
||||
if (maria_cycles >= 426) // ensure we haven't overrun the maximum render time
|
||||
break;
|
||||
|
||||
/* Do indirect mode */
|
||||
if (ind)
|
||||
/* Extended header */
|
||||
if (!(READ_MEM(dl + 1) & 0x1f))
|
||||
{
|
||||
c = READ_MEM(graph_adr + x) & 0xff;
|
||||
data_addr = (m_charbase | c) + (m_offset << 8);
|
||||
if (is_holey(data_addr))
|
||||
continue;
|
||||
graph_adr = (READ_MEM(dl + 2) << 8) | READ_MEM(dl);
|
||||
width = ((READ_MEM(dl + 3) ^ 0xff) & 0x1f) + 1;
|
||||
hpos = READ_MEM(dl + 4);
|
||||
pal = READ_MEM(dl + 3) >> 5;
|
||||
m_write_mode = (READ_MEM(dl + 1) & 0x80) >> 5;
|
||||
ind = READ_MEM(dl + 1) & 0x20;
|
||||
dl += 5;
|
||||
maria_cycles += 10;
|
||||
}
|
||||
/* Normal header */
|
||||
else
|
||||
{
|
||||
graph_adr = (READ_MEM(dl + 2) << 8) | READ_MEM(dl);
|
||||
width = ((READ_MEM(dl + 1) ^ 0xff) & 0x1f) + 1;
|
||||
hpos = READ_MEM(dl + 3);
|
||||
pal = READ_MEM(dl + 1) >> 5;
|
||||
ind = 0x00;
|
||||
dl += 4;
|
||||
maria_cycles += 8;
|
||||
}
|
||||
|
||||
/*logerror("%x DL: ADR=%x width=%x hpos=%x pal=%x mode=%x ind=%x\n", m_screen->vpos(), graph_adr, width, hpos, pal, m_write_mode, ind);*/
|
||||
|
||||
for (int x = 0; x < width; x++)
|
||||
{
|
||||
if (maria_cycles >= 426) // ensure we haven't overrun the maximum render time
|
||||
break;
|
||||
|
||||
/* Do indirect mode */
|
||||
if (ind)
|
||||
{
|
||||
c = READ_MEM(graph_adr + x) & 0xff;
|
||||
data_addr = (m_charbase | c) + (m_offset << 8);
|
||||
if (is_holey(data_addr))
|
||||
continue;
|
||||
|
||||
maria_cycles += 3;
|
||||
if (m_cwidth) // two data bytes per map byte
|
||||
{
|
||||
cells = write_line_ram(data_addr, hpos, pal);
|
||||
hpos += cells;
|
||||
cells = write_line_ram(data_addr+1, hpos, pal);
|
||||
hpos += cells;
|
||||
maria_cycles += 6;
|
||||
maria_cycles += 3;
|
||||
if (m_cwidth) // two data bytes per map byte
|
||||
{
|
||||
cells = write_line_ram(data_addr, hpos, pal);
|
||||
hpos += cells;
|
||||
cells = write_line_ram(data_addr+1, hpos, pal);
|
||||
hpos += cells;
|
||||
maria_cycles += 6;
|
||||
}
|
||||
else
|
||||
{
|
||||
cells = write_line_ram(data_addr, hpos, pal);
|
||||
hpos += cells;
|
||||
maria_cycles += 3;
|
||||
}
|
||||
}
|
||||
else
|
||||
else // direct mode
|
||||
{
|
||||
data_addr = graph_adr + x + (m_offset << 8);
|
||||
if (is_holey(data_addr))
|
||||
continue;
|
||||
cells = write_line_ram(data_addr, hpos, pal);
|
||||
hpos += cells;
|
||||
maria_cycles += 3;
|
||||
}
|
||||
}
|
||||
else // direct mode
|
||||
{
|
||||
data_addr = graph_adr + x + (m_offset << 8);
|
||||
if (is_holey(data_addr))
|
||||
continue;
|
||||
cells = write_line_ram(data_addr, hpos, pal);
|
||||
hpos += cells;
|
||||
maria_cycles += 3;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Last Line post-render DMA cycle penalties...
|
||||
if (m_offset == 0)
|
||||
{
|
||||
maria_cycles += 3; // extra shutdown time
|
||||
if (READ_MEM(m_dll + 3) & 0x80)
|
||||
maria_cycles += 21; // interrupt overhead
|
||||
}
|
||||
// Last Line post-render DMA cycle penalties...
|
||||
if (m_offset == 0)
|
||||
{
|
||||
maria_cycles += 6; // extra shutdown time
|
||||
if (READ_MEM(m_dll + 3) & 0x80)
|
||||
maria_cycles += 17; // interrupt overhead
|
||||
}
|
||||
|
||||
// Spin the CPU for Maria DMA, if it's not already spinning for WSYNC.
|
||||
// MARIA generates the 6502 clock by dividing its own clock by 4. It needs to HALT and unHALT
|
||||
// the 6502 on ths same clock phase, so MARIA will wait until its clock divides evenly by 4.
|
||||
// To spin until an even divisor, we just round-up any would-be truncations by adding 3.
|
||||
if (!m_wsync)
|
||||
m_cpu->spin_until_time(m_cpu->cycles_to_attotime((maria_cycles+3)/4));
|
||||
// If MARIA used up all of the DMA time then the CPU can't run until next line...
|
||||
if (maria_cycles>=426)
|
||||
{
|
||||
m_cpu->spin_until_trigger(TRIGGER_HSYNC);
|
||||
m_wsync = 1;
|
||||
}
|
||||
|
||||
// Spin the CPU for Maria DMA, if it's not already spinning for WSYNC.
|
||||
// MARIA generates the 6502 clock by dividing its own clock by 4. It needs to HALT and unHALT
|
||||
// the 6502 on ths same clock phase, so MARIA will wait until its clock divides evenly by 4.
|
||||
// To spin until an even divisor, we just round-up any would-be truncations by adding 3.
|
||||
if (!m_wsync)
|
||||
m_cpu->spin_until_time(m_cpu->cycles_to_attotime((maria_cycles+3)/4));
|
||||
}
|
||||
|
||||
// draw line buffer to screen
|
||||
m_active_buffer = !m_active_buffer; // switch buffers
|
||||
@ -335,13 +356,13 @@ void atari_maria_device::startdma(int lines)
|
||||
m_holey = (READ_MEM(m_dll) & 0x60) >> 5;
|
||||
m_nmi = READ_MEM(m_dll) & 0x80;
|
||||
/* logerror("DLL=%x\n",m_dll); */
|
||||
draw_scanline();
|
||||
}
|
||||
|
||||
if ((frame_scanline > 15) && (frame_scanline < (lines - 5)))
|
||||
draw_scanline();
|
||||
|
||||
if ((frame_scanline > 16) && (frame_scanline < (lines - 5)) && m_dmaon)
|
||||
{
|
||||
draw_scanline();
|
||||
if (m_offset == 0)
|
||||
{
|
||||
m_dll += 3;
|
||||
|
||||
Loading…
Reference in New Issue
Block a user