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Added option to programatically set the clock pin. This is needed by at least one MESS driver

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This commit is contained in:
Zsolt Vasvari 2008-03-22 09:49:45 +00:00
parent a5c8f40a68
commit 8fcc91c77f
2 changed files with 24 additions and 1 deletions
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22
src/emu/video/mc6845.c
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@ -79,6 +79,7 @@ struct _mc6845_t
UINT16 light_pen_addr; /* 0x10/0x11 */
/* other internal state */
UINT64 clock;
UINT8 register_address_latch;
UINT8 cursor_state; /* 0 = off, 1 = on */
UINT8 cursor_blink_count;
@ -272,7 +273,7 @@ static void recompute_parameters(mc6845_t *mc6845, int postload)
{
rectangle visarea;
attoseconds_t refresh = HZ_TO_ATTOSECONDS(mc6845->intf->clock) * (mc6845->horiz_char_total + 1) * vert_pix_total;
attoseconds_t refresh = HZ_TO_ATTOSECONDS(mc6845->clock) * (mc6845->horiz_char_total + 1) * vert_pix_total;
visarea.min_x = 0;
visarea.min_y = 0;
@ -548,6 +549,21 @@ void mc6845_assert_light_pen_input(const device_config *device)
}
void mc6845_set_clock(const device_config *device, int clock)
{
mc6845_t *mc6845 = get_safe_token(device);
/* validate arguments */
assert(clock > 0);
if (clock != mc6845->clock)
{
mc6845->clock = clock;
recompute_parameters(mc6845, FALSE);
}
}
static void update_cursor_state(mc6845_t *mc6845)
{
/* save and increment cursor counter */
@ -661,6 +677,9 @@ static void common_start(const device_config *device, int device_type)
assert(mc6845->intf->clock > 0);
assert(mc6845->intf->hpixels_per_column > 0);
/* copy the initial clock */
mc6845->clock = mc6845->intf->clock;
/* get the screen device */
mc6845->screen = device_list_find_by_tag(device->machine->config->devicelist, VIDEO_SCREEN, mc6845->intf->screen_tag);
assert(mc6845->screen != NULL);
@ -689,6 +708,7 @@ static void common_start(const device_config *device, int device_type)
state_save_register_func_postload_ptr(mc6845_state_save_postload, mc6845);
state_save_register_item(unique_tag, 0, mc6845->clock);
state_save_register_item(unique_tag, 0, mc6845->register_address_latch);
state_save_register_item(unique_tag, 0, mc6845->horiz_char_total);
state_save_register_item(unique_tag, 0, mc6845->horiz_disp);

3
src/emu/video/mc6845.h
View File

@ -107,6 +107,9 @@ UINT8 mc6845_get_ra(const device_config *device);
/* simulates the LO->HI clocking of the light pen pin (pin 3) */
void mc6845_assert_light_pen_input(const device_config *device);
/* set the clock (pin 21) of the chip */
void mc6845_set_clock(const device_config *device, int clock);
/* updates the screen -- this will call begin_update(),
followed by update_row() reapeatedly and after all row
updating is complete, end_update() */