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Made pr8210 serial processing a little more robust.

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This commit is contained in:
Aaron Giles 2009-07-14 05:56:32 +00:00
parent 6f2d3f59e0
commit f5c134ee2a
1 changed files with 14 additions and 17 deletions
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31
src/emu/machine/ldpr8210.c
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@ -54,11 +54,12 @@
/* serial timing, mostly from the service manual, derived from the XTAL */
#define SERIAL_CLOCK XTAL_455kHz
#define SERIAL_0_BIT_TIME ATTOTIME_IN_HZ(SERIAL_CLOCK / 512)
#define SERIAL_1_BIT_TIME ATTOTIME_IN_HZ(SERIAL_CLOCK / 1024)
#define SERIAL_MIDPOINT_TIME ATTOTIME_IN_HZ(SERIAL_CLOCK / 600)
#define SERIAL_MAX_WORD_TIME ATTOTIME_IN_HZ(SERIAL_CLOCK / 11520)
#define SERIAL_REJECT_DUPLICATE_TIME ATTOTIME_IN_HZ(SERIAL_CLOCK / 11520 / 4)
#define SERIAL_0_BIT_TIME ATTOTIME_IN_HZ((double)SERIAL_CLOCK / 512)
#define SERIAL_1_BIT_TIME ATTOTIME_IN_HZ((double)SERIAL_CLOCK / 1024)
#define SERIAL_MIDPOINT_TIME ATTOTIME_IN_HZ((double)SERIAL_CLOCK / 600)
#define SERIAL_MAX_BIT_TIME ATTOTIME_IN_HZ((double)SERIAL_CLOCK / 4096)
#define SERIAL_MAX_WORD_TIME ATTOTIME_IN_HZ((double)SERIAL_CLOCK / 11520)
#define SERIAL_REJECT_DUPLICATE_TIME ATTOTIME_IN_HZ((double)SERIAL_CLOCK / 11520 / 4)
@ -450,12 +451,17 @@ static void pr8210_control_w(laserdisc_state *ld, UINT8 prev, UINT8 data)
if (prev != ASSERT_LINE && data == ASSERT_LINE)
{
attotime curtime = timer_get_time(ld->device->machine);
attotime delta;
attotime delta, overalldelta;
int longpulse;
/* get the time difference from the last assert */
/* and update our internal command time */
delta = attotime_sub(curtime, player->lastbittime);
player->lastbittime = curtime;
/* if we timed out since the first bit, reset the accumulator */
delta = attotime_sub(curtime, player->firstbittime);
if (attotime_compare(delta, SERIAL_MAX_WORD_TIME) > 0)
overalldelta = attotime_sub(curtime, player->firstbittime);
if (attotime_compare(overalldelta, SERIAL_MAX_WORD_TIME) > 0 || attotime_compare(delta, SERIAL_MAX_BIT_TIME) > 0)
{
player->firstbittime = curtime;
player->accumulator = 0x5555;
@ -463,11 +469,6 @@ static void pr8210_control_w(laserdisc_state *ld, UINT8 prev, UINT8 data)
printf("Reset accumulator\n");
}
/* get the time difference from the last assert */
/* and update our internal command time */
delta = attotime_sub(curtime, player->lastbittime);
player->lastbittime = curtime;
/* 0 bit delta is 1.05 msec, 1 bit delta is 2.11 msec */
longpulse = (attotime_compare(delta, SERIAL_MIDPOINT_TIME) < 0) ? 0 : 1;
player->accumulator = (player->accumulator << 1) | longpulse;
@ -501,11 +502,7 @@ static void pr8210_control_w(laserdisc_state *ld, UINT8 prev, UINT8 data)
/* log the command and wait for a keypress */
if (LOG_SERIAL)
{
printf("--- Command = %02X\n", player->pia.porta >> 3);
// while (input_code_pressed(KEYCODE_ENTER)) ;
// while (!input_code_pressed(KEYCODE_ENTER)) ;
}
/* reset the first bit time so that the accumulator clears on the next write */
player->firstbittime = attotime_sub(curtime, SERIAL_MAX_WORD_TIME);