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Adds mc6845_assert_light_pen_input. This latches the next character display address into the light pen latch.

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This commit is contained in:
Zsolt Vasvari 2008-02-28 13:25:19 +00:00
parent 8cf42a706d
commit c1eddd0763
2 changed files with 58 additions and 15 deletions
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70
src/emu/video/mc6845.c
View File

@ -50,7 +50,7 @@ struct _mc6845_t
UINT8 cursor_end_ras;
UINT16 start_addr;
UINT16 cursor_addr;
UINT16 light_pen;
UINT16 light_pen_addr;
emu_timer *de_changed_timer;
emu_timer *hsync_on_timer;
@ -98,6 +98,8 @@ static void mc6845_state_save_postload(void *param)
void mc6845_address_w(mc6845_t *mc6845, UINT8 data)
{
assert(mc6845 != NULL);
mc6845->address_latch = data & 0x1f;
}
@ -106,15 +108,17 @@ UINT8 mc6845_register_r(mc6845_t *mc6845)
{
UINT8 ret = 0;
assert(mc6845 != NULL);
switch (mc6845->address_latch)
{
/* 0x0c and 0x0d - Motorola device only */
case 0x0c: ret = (mc6845->start_addr >> 8) & 0xff; break;
case 0x0d: ret = (mc6845->start_addr >> 0) & 0xff; break;
case 0x0e: ret = (mc6845->cursor_addr >> 8) & 0xff; break;
case 0x0f: ret = (mc6845->cursor_addr >> 0) & 0xff; break;
case 0x10: ret = (mc6845->light_pen >> 8) & 0xff; break;
case 0x11: ret = (mc6845->light_pen >> 0) & 0xff; break;
case 0x0c: ret = (mc6845->start_addr >> 8) & 0xff; break;
case 0x0d: ret = (mc6845->start_addr >> 0) & 0xff; break;
case 0x0e: ret = (mc6845->cursor_addr >> 8) & 0xff; break;
case 0x0f: ret = (mc6845->cursor_addr >> 0) & 0xff; break;
case 0x10: ret = (mc6845->light_pen_addr >> 8) & 0xff; break;
case 0x11: ret = (mc6845->light_pen_addr >> 0) & 0xff; break;
/* all other registers are write only and return 0 */
default: break;
@ -128,6 +132,8 @@ void mc6845_register_w(mc6845_t *mc6845, UINT8 data)
{
if (LOG) logerror("M6845 PC %04x: reg 0x%02x = 0x%02x\n", activecpu_get_pc(), mc6845->address_latch, data);
assert(mc6845 != NULL);
switch (mc6845->address_latch)
{
case 0x00: mc6845->horiz_total = data & 0xff; break;
@ -366,15 +372,14 @@ static TIMER_CALLBACK( hsync_off_timer_cb )
}
UINT16 mc6845_get_ma(mc6845_t *mc6845)
static UINT16 get_ma_for_yx(mc6845_t *mc6845, int y, int x)
{
UINT16 ret;
if (mc6845->has_valid_parameters)
{
/* get the current raster positions and clamp them to the visible region */
int y = video_screen_get_vpos(0);
int x = video_screen_get_hpos(0);
/* clamp Y/X to the visible region */
/* since the MA counter stops in the blanking regions, if we are in a
VBLANK, both X and Y are at their max */
@ -385,8 +390,28 @@ UINT16 mc6845_get_ma(mc6845_t *mc6845)
y = mc6845->last_max_y;
ret = (mc6845->start_addr +
(y / (mc6845->max_ras_addr + 1)) * mc6845->horiz_disp +
(x / mc6845->intf->hpixels_per_column)) & 0x3fff;
(y / (mc6845->max_ras_addr + 1)) * mc6845->horiz_disp +
(x / mc6845->intf->hpixels_per_column)) & 0x3fff;
}
else
ret = 0;
return ret;
}
UINT16 mc6845_get_ma(mc6845_t *mc6845)
{
UINT16 ret;
assert(mc6845 != NULL);
if (mc6845->has_valid_parameters)
{
int y = video_screen_get_vpos(mc6845->intf->scrnum);
int x = video_screen_get_hpos(mc6845->intf->scrnum);
ret = get_ma_for_yx(mc6845, y, x);
}
else
ret = 0;
@ -399,10 +424,12 @@ UINT8 mc6845_get_ra(mc6845_t *mc6845)
{
UINT8 ret;
assert(mc6845 != NULL);
if (mc6845->has_valid_parameters)
{
/* get the current vertical raster position and clamp it to the visible region */
int y = video_screen_get_vpos(0);
int y = video_screen_get_vpos(mc6845->intf->scrnum);
if (y > mc6845->last_max_y)
y = mc6845->last_max_y;
@ -416,6 +443,19 @@ UINT8 mc6845_get_ra(mc6845_t *mc6845)
}
void mc6845_assert_light_pen_input(mc6845_t *mc6845)
{
int y, x;
assert(mc6845 != NULL);
/* the light pen address register gets latched on the NEXT display address change */
y = video_screen_get_vpos(mc6845->intf->scrnum);
x = video_screen_get_hpos(mc6845->intf->scrnum) + mc6845->intf->hpixels_per_column;
mc6845->light_pen_addr = get_ma_for_yx(mc6845, y, x);
}
static void update_cursor_state(mc6845_t *mc6845)
{
@ -561,7 +601,7 @@ static void *mc6845_start(running_machine *machine, const char *tag, const void
state_save_register_item(unique_tag, 0, mc6845->cursor_end_ras);
state_save_register_item(unique_tag, 0, mc6845->start_addr);
state_save_register_item(unique_tag, 0, mc6845->cursor_addr);
state_save_register_item(unique_tag, 0, mc6845->light_pen);
state_save_register_item(unique_tag, 0, mc6845->light_pen_addr);
state_save_register_item(unique_tag, 0, mc6845->cursor_state);
state_save_register_item(unique_tag, 0, mc6845->cursor_blink_count);

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

@ -95,6 +95,9 @@ UINT16 mc6845_get_ma(mc6845_t *mc6845);
/* return the current value on the RA0-RA4 pins */
UINT8 mc6845_get_ra(mc6845_t *mc6845);
/* simulates the LO->HI clocking of the light pen pin (pin 3) */
void mc6845_assert_light_pen_input(mc6845_t *mc6845);
/* updates the screen -- this will call begin_update(),
followed by update_row() reapeatedly and after all row
updating is complete, end_update() */