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appleramdac: Cursor lo-byte position delay option.

This commit is contained in:
joevt 2024-04-21 18:43:59 -07:00 committed by Maxim Poliakovski
parent dfd4d82693
commit 5f6b924004
2 changed files with 30 additions and 2 deletions
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10
devices/video/appleramdac.cpp
View File

@ -87,13 +87,18 @@ void AppleRamdac::iodev_write(uint32_t address, uint16_t value) {
case RamdacRegs::MULTI:
switch (this->dac_addr) {
case RamdacRegs::CURSOR_POS_HI:
#ifdef CURSOR_LO_DELAY // HACK: prevents artifacts in some cases, disabled by default
if (this->cursor_timer_id) {
TimerManager::get_instance()->cancel_timer(this->cursor_timer_id);
cursor_timer_id = 0;
}
this->cursor_xpos = (value << 8) | this->cursor_pos_lo;
#else
this->cursor_xpos = (value << 8) | (this->cursor_xpos & 0xff);
#endif
break;
case RamdacRegs::CURSOR_POS_LO:
#ifdef CURSOR_LO_DELAY // HACK: prevents artifacts in some cases, disabled by default
if (this->cursor_timer_id) {
TimerManager::get_instance()->cancel_timer(this->cursor_timer_id);
this->cursor_xpos = (this->cursor_xpos & 0xff00) | (this->cursor_pos_lo & 0x00ff);
@ -101,9 +106,12 @@ void AppleRamdac::iodev_write(uint32_t address, uint16_t value) {
}
this->cursor_pos_lo = value;
this->cursor_timer_id = TimerManager::get_instance()->add_oneshot_timer(
1000000000 / 60, [this]() {
NS_PER_SEC / 60, [this]() {
this->cursor_xpos = (this->cursor_xpos & 0xff00) | (this->cursor_pos_lo & 0x00ff);
});
#else
this->cursor_xpos = (this->cursor_xpos & 0xff00) | (value & 0x00ff);
#endif
break;
case RamdacRegs::MISC_CTRL:
if (bit_changed(this->dac_cr, value, 1)) {

22
devices/video/appleramdac.h
View File

@ -19,6 +19,24 @@ You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
//#define CURSOR_LO_DELAY
/* Uncomment this to add a delay before allowing the low byte of the cursor
position to be latched. In that case, a write to the high byte of the
cursor position latches the low byte immediately since the high byte is
expected to always be the second byte written. This change solves the issue
described below.
The horizontal position of the cursor may be incorrect between the times
when the low byte and the high byte are written. This is true when both
bytes change such as when the position changes from 0xFF to 0x100. This is
usually not a problem since the position usually changes only during a VBL.
In the case of Open Firmware, there is at least 2 ms between writes so
the cursor position could be incorrect for a third of the refresh cycle.
Open Firmware doesn't use VBLs. It also doesn't usually use a hardware
cursor so this change isn't usually useful.
*/
/** Definitions for the Apple RAMDAC ASICs (RaDACal & DACula). */
#ifndef APPLE_RAMDAC_H
@ -107,7 +125,6 @@ protected:
uint16_t cursor_xpos = 0; // horizontal position of the cursor region
uint16_t cursor_ypos = 0;
uint16_t cursor_height = 0;
uint8_t cursor_pos_lo = 0;
uint8_t clk_m[2] = {};
uint8_t clk_pn[2] = {};
uint8_t pll_cr = 0;
@ -118,7 +135,10 @@ protected:
int video_width = 0;
int video_height = 0;
uint32_t fb_pitch = 0;
#ifdef CURSOR_LO_DELAY
uint8_t cursor_pos_lo = 0;
uint32_t cursor_timer_id = 0;
#endif
};
#endif // APPLE_RAMDAC_H