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Changed retrace handling to be exact.

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@520
This commit is contained in:
Sjoerd van der Berg 2002-11-17 11:19:07 +00:00
parent 04a152a743
commit 073f2bcfe3
1 changed files with 18 additions and 16 deletions
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34
src/hardware/vga_misc.cpp
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@ -18,9 +18,10 @@
#include "dosbox.h"
#include "inout.h"
#include "timer.h"
#include "pic.h"
#include "vga.h"
static Bit8u flip=0;
static Bit32u keep_vretrace;
static bool keeping=false;
@ -34,22 +35,12 @@ Bit8u read_p3d5(Bit32u port);
static Bit8u read_p3da(Bit32u port) {
vga.internal.attrindex=false;
if (vga.config.retrace) {
vga.config.retrace=false;
vga.config.real_start=vga.config.display_start;
keep_vretrace=LastTicks+1;
keeping=true;
flip=0;
return 9;
}
if (keeping) {
if (LastTicks>(keep_vretrace)) keeping=false;
return 9;
} else {
flip++;
if (flip>10) flip=0;
if (flip>5) return 1;
return 0;
}
flip++;
if (flip>10) flip=0;
if (flip>5) return 1;
return 0;
/*
0 Either Vertical or Horizontal Retrace active if set
3 Vertical Retrace in progress if set
@ -58,6 +49,7 @@ static Bit8u read_p3da(Bit32u port) {
static void write_p3d8(Bit32u port,Bit8u val) {
LOG_DEBUG("Write %2X to 3da",val);
/*
3 Vertical Sync Select. If set Vertical Sync to the monitor is the
logical OR of the vertical sync and the vertical display enable.
@ -75,7 +67,6 @@ static void write_p3c2(Bit32u port,Bit8u val) {
IO_FreeReadHandler(0x3b4);
IO_FreeWriteHandler(0x3b5);
IO_FreeReadHandler(0x3b5);
} else {
IO_RegisterWriteHandler(0x3b4,write_p3d4,"VGA:CRTC Index Select");
IO_RegisterReadHandler(0x3b4,read_p3d4,"VGA:CRTC Index Select");
@ -105,6 +96,17 @@ static Bit8u read_p3cc(Bit32u port) {
}
static void EndRetrace(void) {
vga.config.retrace=false;
}
void VGA_StartRetrace(void) {
/* Setup a timer to destroy the vertical retrace bit in a few microseconds */
vga.config.real_start=vga.config.display_start;
vga.config.retrace=true;
PIC_AddEvent(EndRetrace,667);
}
void VGA_SetupMisc(void) {
IO_RegisterReadHandler(0x3da,read_p3da,"VGA Input Status 1");
IO_RegisterReadHandler(0x3ba,read_p3da,"VGA Input Status 1");