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Added support for driving the VGA display update timer with VSYNC.

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- Using the special value of 0 enables this feature. In that case the vertical
  frequency is used for the display updates. The update() method is called at
  the "vertical retrace end" time and sets the time of the display start. This
  value is used to set the vertical retrace indicator in VGA register 0x03da.
- This feature is not yet enabled if Voodoo support is present. The Voodoo device
  has it's own vertical timer and needs some more testing and possibly some changes.
This commit is contained in:
Volker Ruppert 2024-01-09 21:48:19 +01:00
parent c04fb9a6ba
commit cfa7276cb9
3 changed files with 77 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
bochs/config.cc
View File

@ -1142,11 +1142,17 @@ void bx_init_options()
"If enabled, the VGA timer is based on realtime",
1);
// The value 0 enables support for using vertical frequency (not yet enabled for Voodoo)
#if BX_SUPPORT_VOODOO
#define MIN_UPDATE_FREQ 1
#else
#define MIN_UPDATE_FREQ 0
#endif
bx_param_num_c *vga_update_freq = new bx_param_num_c(display,
"vga_update_frequency",
"VGA Update Frequency",
"Number of VGA updates per emulated second",
1, 75,
MIN_UPDATE_FREQ, 75,
10);
vga_update_freq->set_ask_format ("Type a new value for VGA update frequency: [%d] ");

88
bochs/iodev/display/vgacore.cc
View File

@ -215,23 +215,28 @@ void bx_vgacore_c::init_systemtimer(void)
{
BX_VGA_THIS update_realtime = SIM->get_param_bool(BXPN_VGA_REALTIME)->get();
bx_param_num_c *vga_update_freq = SIM->get_param_num(BXPN_VGA_UPDATE_FREQUENCY);
Bit32u update_interval = (Bit32u)(1000000 / vga_update_freq->get());
BX_INFO(("interval=%u, mode=%s", update_interval, BX_VGA_THIS update_realtime ? "realtime":"standard"));
Bit32u update_interval;
if (vga_update_freq->get() > 0) {
update_interval = (Bit32u)(1000000 / vga_update_freq->get());
BX_INFO(("interval=%u, mode=%s", update_interval, BX_VGA_THIS update_realtime ? "realtime":"standard"));
} else {
update_interval = 0;
BX_INFO(("VGA update interval uses VSYNC, mode=%s", BX_VGA_THIS update_realtime ? "realtime":"standard"));
}
if (BX_VGA_THIS timer_id == BX_NULL_TIMER_HANDLE) {
BX_VGA_THIS timer_id = bx_virt_timer.register_timer(this, vga_timer_handler,
update_interval, 1, 1, BX_VGA_THIS update_realtime, "vga");
100000, 1, 1, BX_VGA_THIS update_realtime, "vga");
vga_update_freq->set_handler(vga_param_handler);
vga_update_freq->set_device_param(this);
}
BX_VGA_THIS vsync_realtime =
(SIM->get_param_enum(BXPN_CLOCK_SYNC)->get() & BX_CLOCK_SYNC_REALTIME) > 0;
BX_INFO(("VSYNC using %s mode", BX_VGA_THIS vsync_realtime ? "realtime":"standard"));
// VGA text mode cursor blink frequency 1.875 Hz
if (update_interval < 266666) {
BX_VGA_THIS s.blink_counter = 266666 / (unsigned)update_interval;
BX_VGA_THIS set_update_timer(update_interval);
if (!BX_VGA_THIS vsync_update_mode) {
BX_VGA_THIS vsync_realtime =
(SIM->get_param_enum(BXPN_CLOCK_SYNC)->get() & BX_CLOCK_SYNC_REALTIME) > 0;
} else {
BX_VGA_THIS s.blink_counter = 1;
BX_VGA_THIS vsync_realtime = BX_VGA_THIS update_realtime;
}
BX_INFO(("VSYNC using %s mode", BX_VGA_THIS vsync_realtime ? "realtime":"standard"));
}
void bx_vgacore_c::vgacore_register_state(bx_list_c *parent)
@ -407,6 +412,9 @@ void bx_vgacore_c::calculate_retrace_timing()
BX_VGA_THIS s.vrstart_usec = BX_VGA_THIS s.htotal_usec * crtcp.vrstart;
BX_VGA_THIS s.vrend_usec = BX_VGA_THIS s.htotal_usec * vrend;
BX_DEBUG(("hfreq = %.1f kHz / vfreq = %d Hz", ((double)hfreq / 1000), vfreq));
if (BX_VGA_THIS vsync_update_mode) {
BX_VGA_THIS set_update_timer(0);
}
}
// static IO port read callback handler
@ -454,7 +462,12 @@ Bit32u bx_vgacore_c::read(Bit32u address, unsigned io_len)
// horizontal or vertical blanking period is active
retval = 0;
display_usec = bx_virt_timer.time_usec(BX_VGA_THIS vsync_realtime) % BX_VGA_THIS s.vtotal_usec;
if (BX_VGA_THIS vsync_update_mode) {
display_usec = bx_virt_timer.time_usec(BX_VGA_THIS vsync_realtime) - BX_VGA_THIS s.display_start_usec;
display_usec = display_usec % BX_VGA_THIS s.vtotal_usec;
} else {
display_usec = bx_virt_timer.time_usec(BX_VGA_THIS vsync_realtime) % BX_VGA_THIS s.vtotal_usec;
}
if ((display_usec >= BX_VGA_THIS s.vrstart_usec) &&
(display_usec <= BX_VGA_THIS s.vrend_usec)) {
retval |= 0x08;
@ -1243,10 +1256,12 @@ bool bx_vgacore_c::skip_update(void)
return 1;
/* skip screen update if the vertical retrace is in progress */
display_usec = bx_virt_timer.time_usec(BX_VGA_THIS vsync_realtime) % BX_VGA_THIS s.vtotal_usec;
if ((display_usec > BX_VGA_THIS s.vrstart_usec) &&
(display_usec < BX_VGA_THIS s.vrend_usec)) {
return 1;
if (!BX_VGA_THIS vsync_update_mode) {
display_usec = bx_virt_timer.time_usec(BX_VGA_THIS vsync_realtime) % BX_VGA_THIS s.vtotal_usec;
if ((display_usec > BX_VGA_THIS s.vrstart_usec) &&
(display_usec < BX_VGA_THIS s.vrend_usec)) {
return 1;
}
}
return 0;
}
@ -1258,6 +1273,11 @@ void bx_vgacore_c::update(void)
static bool cs_visible = 0;
bool cs_toggle = 0;
// Always set display start time if update timer is driven by VSYNC
if (BX_VGA_THIS vsync_update_mode) {
BX_VGA_THIS s.display_start_usec =
bx_virt_timer.time_usec(BX_VGA_THIS vsync_realtime) - BX_VGA_THIS s.vrend_usec;
}
cs_counter--;
/* no screen update necessary */
if ((BX_VGA_THIS s.vga_mem_updated == 0) && (cs_counter > 0))
@ -2295,6 +2315,30 @@ void bx_vgacore_c::vga_timer_handler(void *this_ptr)
bx_gui->flush();
}
void bx_vgacore_c::set_update_timer(Bit32u usec)
{
if (usec == 0) {
usec = BX_VGA_THIS s.vtotal_usec;
if ((usec < 8000) || (usec > 200000)) {
usec = 100000;
}
BX_VGA_THIS vsync_update_mode = true;
} else {
BX_VGA_THIS vsync_update_mode = false;
}
if (usec != BX_VGA_THIS vga_update_interval) {
BX_INFO(("Setting VGA update interval to %d", usec));
bx_virt_timer.activate_timer(BX_VGA_THIS timer_id, usec, 1);
// VGA text mode cursor blink frequency 1.875 Hz
if (usec < 266666) {
BX_VGA_THIS s.blink_counter = 266666 / (unsigned)usec;
} else {
BX_VGA_THIS s.blink_counter = 1;
}
BX_VGA_THIS vga_update_interval = usec;
}
}
#undef LOG_THIS
#define LOG_THIS vgadev->
@ -2302,16 +2346,14 @@ Bit64s bx_vgacore_c::vga_param_handler(bx_param_c *param, bool set, Bit64s val)
{
// handler for runtime parameter 'vga: update_freq'
if (set) {
Bit32u update_interval = (Bit32u)(1000000 / val);
bx_vgacore_c *vgadev = (bx_vgacore_c *)param->get_device_param();
BX_INFO(("Changing timer interval to %d", update_interval));
vga_timer_handler(vgadev);
bx_virt_timer.activate_timer(vgadev->timer_id, update_interval, 1);
if (update_interval < 266666) {
vgadev->s.blink_counter = 266666 / (unsigned)update_interval;
Bit32u update_interval;
if (val > 0) {
update_interval = (Bit32u)(1000000 / val);
} else {
vgadev->s.blink_counter = 1;
update_interval = 0;
}
bx_vgacore_c *vgadev = (bx_vgacore_c *)param->get_device_param();
vgadev->set_update_timer(update_interval);
}
return val;
}

6
bochs/iodev/display/vgacore.h
View File

@ -2,7 +2,7 @@
// $Id$
/////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2001-2023 The Bochs Project
// Copyright (C) 2001-2024 The Bochs Project
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
@ -103,6 +103,7 @@ public:
virtual bool init_vga_extension(void) {return 0;}
virtual void get_crtc_params(bx_crtc_params_t *crtcp, Bit32u *vclock);
virtual void set_update_timer(Bit32u usec);
static void vga_timer_handler(void *);
static Bit64s vga_param_handler(bx_param_c *param, bool set, Bit64s val);
@ -242,6 +243,7 @@ protected:
Bit32u vblank_usec;
Bit32u vrstart_usec;
Bit32u vrend_usec;
Bit64u display_start_usec;
// shift values for extensions
Bit8u plane_shift;
Bit8u dac_shift;
@ -266,8 +268,10 @@ protected:
} s; // state information
int timer_id;
Bit32u vga_update_interval;
bool update_realtime;
bool vsync_realtime;
bool vsync_update_mode;
bx_param_enum_c *vga_ext;
bool pci_enabled;
};