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(MESS) maria.c:

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-Timeout rendering added. [Mike Saarna]
-Reorganized DMA penalties to support new rendering code [Mike Saarna, Robert Tuccitto]
This commit is contained in:
Fabio Priuli 2014-09-06 06:38:32 +00:00
parent 8db7baff10
commit 14fb245bf6
1 changed files with 25 additions and 14 deletions
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39
src/mess/video/maria.c
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@ -4,6 +4,10 @@
- some history:
2014-10-03 Mike Saarna, Robert Tuccitto reorganized DMA penalties to
support new rendering timeout code.
2014-08-29 Mike Saarna Timeout rendering added.
2014-08-26 Fabio Priuli Converted to device
@ -161,17 +165,10 @@ void atari_maria_device::draw_scanline()
int d, c, pixel_cell, cells;
int maria_cycles;
if (m_offset == 0)
{
if (READ_MEM(m_dll + 3) & 0x80)
maria_cycles = 40; // DMA + maria interrupt overhead
else
maria_cycles = 19; // DMA
}
else
{
maria_cycles = 16; // DMA
}
// 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;
@ -179,8 +176,10 @@ void atari_maria_device::draw_scanline()
dl = m_dl;
/* DMA */
/* Step through DL's */
while ((READ_MEM(dl + 1) & 0x5f) != 0)
/* 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))
{
/* Extended header */
if (!(READ_MEM(dl + 1) & 0x1f))
@ -210,6 +209,9 @@ void atari_maria_device::draw_scanline()
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)
{
@ -217,7 +219,7 @@ void atari_maria_device::draw_scanline()
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
{
@ -245,6 +247,15 @@ void atari_maria_device::draw_scanline()
}
}
}
// 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
}
// 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.