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Better support for GH issues #129 and #204 (x86 CPU core is no longer max'ed out).

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This commit is contained in:
tomcw 2014-09-21 21:42:19 +01:00
parent 8098b84a0e
commit a2260510f3
1 changed files with 15 additions and 8 deletions
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23
source/Video.cpp
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@ -275,6 +275,7 @@ static WORD colormixmap[6][6][6];
static int g_nAltCharSetOffset = 0; // alternate character set
static /*bool*/ UINT g_VideoForceFullRedraw = 1;
static bool g_bVideoUpdatedThisFrame = false;
static LPBYTE framebufferaddr = (LPBYTE)0;
static LONG g_nFrameBufferPitch = 0;
@ -2663,6 +2664,7 @@ void VideoResetState ()
g_nAltCharSetOffset = 0;
g_uVideoMode = VF_TEXT;
g_VideoForceFullRedraw = 1;
g_bVideoUpdatedThisFrame = false;
}
@ -2697,19 +2699,22 @@ BYTE VideoSetMode (WORD, WORD address, BYTE write, BYTE, ULONG uExecutedCycles)
g_uVideoMode &= ~VF_PAGE2;
if (oldvalue != g_nAltCharSetOffset+(int)(g_uVideoMode & ~(VF_80STORE | VF_PAGE2)))
{
g_VideoForceFullRedraw = 1;
}
g_VideoForceFullRedraw = 1; // Defer video redraw until VideoEndOfVideoFrame()
if (oldpage2 != SW_PAGE2)
{
if (!g_VideoForceFullRedraw)
// /g_bVideoUpdatedThisFrame/ is used to limit the video update to once per 60Hz frame (CPU clk=1MHz):
// . this easily supports the common double-buffered "flip-immediate" case (eg. Airheart flips at a max of ~15Hz, Skyfox/Boulderdash at a max of ~11Hz)
// . crucially this prevents tight-loop page flipping (GH#129,GH#204) from max'ing out an x86 CPU core (and not providing realtime emulation)
// NB. Deferring the update by just setting /g_VideoForceFullRedraw/ is not an option, since this doesn't provide "flip-immediate"
//
// Ultimately this isn't the correct solution, and proper cycle-accurate video rendering should be done, but this is a much bigger job!
//
if (!g_bVideoUpdatedThisFrame)
{
#if 1
VideoRefreshScreen();
#else
g_VideoForceFullRedraw = 1; // GH#129,GH204: Defer the redraw until the main ContinueExecution() loop (TODO: What effect does this have on other games?)
#endif
g_bVideoUpdatedThisFrame = true;
}
}
@ -2744,6 +2749,8 @@ static void VideoUpdateFlash()
// Called from main-loop every 17030 cycles (ie. 60Hz when CPU = 1MHz)
void VideoEndOfVideoFrame(void)
{
g_bVideoUpdatedThisFrame = false; // Allow page1/2 toggle to result in an immediate video redraw
VideoUpdateFlash(); // TODO: Flash rate should be constant (regardless of CPU speed)
if (!VideoApparentlyDirty())