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- more accurate horizontal retrace emulation (based on the DOSBox implementation)

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This commit is contained in:
Volker Ruppert 2012-04-08 14:21:18 +00:00
parent fc482db353
commit c24080c92a
2 changed files with 12 additions and 2 deletions
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12
bochs/iodev/vgacore.cc
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@ -427,7 +427,7 @@ void bx_vgacore_c::determine_screen_dimensions(unsigned *piHeight, unsigned *piW
void bx_vgacore_c::calculate_retrace_timing()
{
Bit32u dot_clock[4] = {25175000, 28322000, 25175000, 25175000};
Bit32u htotal, clock, cwidth, vtotal, vrstart, vrend, hfreq, vfreq;
Bit32u htotal, hbstart, hbend, clock, cwidth, vtotal, vrstart, vrend, hfreq, vfreq;
htotal = BX_VGA_THIS s.CRTC.reg[0] + 5;
htotal <<= BX_VGA_THIS s.x_dotclockdiv2;
@ -435,6 +435,11 @@ void bx_vgacore_c::calculate_retrace_timing()
clock = dot_clock[BX_VGA_THIS s.misc_output.clock_select];
hfreq = clock / (htotal * cwidth);
BX_VGA_THIS s.htotal_usec = 1000000 / hfreq;
hbstart = BX_VGA_THIS s.CRTC.reg[2];
BX_VGA_THIS s.hbstart_usec = (1000000 * hbstart * cwidth) / clock;
hbend = (BX_VGA_THIS s.CRTC.reg[3] & 0x1f) + ((BX_VGA_THIS s.CRTC.reg[5] & 0x80) >> 2);
hbend = hbstart + ((hbend - hbstart) & 0x3f);
BX_VGA_THIS s.hbend_usec = (1000000 * hbend * cwidth) / clock;
vtotal = BX_VGA_THIS s.CRTC.reg[6] + ((BX_VGA_THIS s.CRTC.reg[7] & 0x01) << 8) +
((BX_VGA_THIS s.CRTC.reg[7] & 0x20) << 4) + 2;
vrstart = BX_VGA_THIS s.CRTC.reg[16] + ((BX_VGA_THIS s.CRTC.reg[7] & 0x04) << 6) +
@ -512,7 +517,8 @@ Bit32u bx_vgacore_c::read(Bit32u address, unsigned io_len)
retval |= 0x01;
} else {
line_usec = display_usec % BX_VGA_THIS s.htotal_usec;
if (line_usec >= (BX_VGA_THIS s.htotal_usec - 2)) {
if ((line_usec >= BX_VGA_THIS s.hbstart_usec) &&
(line_usec <= BX_VGA_THIS s.hbend_usec)) {
retval |= 0x01;
}
}
@ -1201,6 +1207,8 @@ void bx_vgacore_c::write(Bit32u address, Bit32u value, unsigned io_len, bx_bool
switch (BX_VGA_THIS s.CRTC.address) {
case 0x00:
case 0x02:
case 0x03:
case 0x05:
case 0x06:
case 0x10:
calculate_retrace_timing();

2
bochs/iodev/vgacore.h
View File

@ -209,6 +209,8 @@ protected:
bx_bool y_doublescan;
// h/v retrace timing
Bit32u htotal_usec;
Bit32u hbstart_usec;
Bit32u hbend_usec;
Bit32u vtotal_usec;
Bit32u vblank_usec;
Bit32u vrstart_usec;