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Fixed Z80 DMA ready signal handling. [Curt Coder]

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This commit is contained in:
Curt Coder 2010-03-07 15:29:29 +00:00
parent ee2134845d
commit 3b241320a3
1 changed files with 29 additions and 21 deletions
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46
src/emu/machine/z80dma.c
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@ -154,7 +154,8 @@ struct _z80dma_t
UINT16 addressB;
UINT16 count;
UINT8 rdy;
int rdy;
int force_ready;
UINT8 reset_pointer;
UINT8 is_read;
@ -227,6 +228,11 @@ static void trigger_interrupt(running_device *device, int level)
}
}
static int is_ready(z80dma_t *z80dma)
{
return (z80dma->force_ready) || (z80dma->rdy == READY_ACTIVE_HIGH(z80dma));
}
/*-------------------------------------------------
z80dma_do_read - perform DMA read
-------------------------------------------------*/
@ -379,7 +385,7 @@ static TIMER_CALLBACK( z80dma_timerproc )
z80dma->dma_enabled = 0; //FIXME: Correct?
z80dma->status = 0x19;
if(!(z80dma->rdy ^ READY_ACTIVE_HIGH(z80dma))) z80dma->status |= 0x02; // ready line status
z80dma->status |= !is_ready(z80dma) << 1; // ready line status
if(TRANSFER_MODE(z80dma) == TM_TRANSFER) z80dma->status |= 0x10; // no match found
@ -404,7 +410,7 @@ static void z80dma_update_status(running_device *device)
attotime next;
/* no transfer is active right now; is there a transfer pending right now? */
pending_transfer = z80dma->rdy & z80dma->dma_enabled;
pending_transfer = is_ready(z80dma) & z80dma->dma_enabled;
if (pending_transfer)
{
@ -418,10 +424,13 @@ static void z80dma_update_status(running_device *device)
next);
}
else
{
if (z80dma->is_read)
{
/* no transfers active right now */
timer_reset(z80dma->timer, attotime_never);
}
}
/* set the busreq line */
devcb_call_write_line(&z80dma->out_busreq_func, pending_transfer ? ASSERT_LINE : CLEAR_LINE);
@ -503,7 +512,10 @@ WRITE8_DEVICE_HANDLER( z80dma_w )
}
else if ((data & 0x83) == 0x83) // WR6
{
z80dma->dma_enabled = 0;
WR6(z80dma) = data;
switch (data)
{
case COMMAND_ENABLE_AFTER_RETI:
@ -517,7 +529,7 @@ WRITE8_DEVICE_HANDLER( z80dma_w )
WR3(z80dma) &= ~0x20;
z80dma->ip = 0;
z80dma->ius = 0;
z80dma->rdy = 0;
z80dma->force_ready = 0;
z80dma->status |= 0x08;
break;
case COMMAND_INITIATE_READ_SEQUENCE:
@ -534,7 +546,7 @@ WRITE8_DEVICE_HANDLER( z80dma_w )
case COMMAND_RESET:
if (LOG) logerror("Reset\n");
z80dma->dma_enabled = 0;
z80dma->rdy = 1;
z80dma->force_ready = 0;
/* Needs six reset commands to reset the DMA */
{
UINT8 WRi;
@ -557,14 +569,11 @@ WRITE8_DEVICE_HANDLER( z80dma_w )
case COMMAND_DISABLE_DMA:
if (LOG) logerror("Disable DMA\n");
z80dma->dma_enabled = 0;
z80dma->rdy = 1 ^ ((WR5(z80dma) & 0x8)>>3);
z80dma_rdy_w(device, z80dma->rdy);
break;
case COMMAND_ENABLE_DMA:
if (LOG) logerror("Enable DMA\n");
z80dma->dma_enabled = 1;
z80dma->rdy = (WR5(z80dma) & 0x8)>>3;
z80dma_rdy_w(device, z80dma->rdy);
z80dma_update_status(device);
break;
case COMMAND_READ_MASK_FOLLOWS:
if (LOG) logerror("Set Read Mask\n");
@ -587,8 +596,8 @@ WRITE8_DEVICE_HANDLER( z80dma_w )
break;
case COMMAND_FORCE_READY:
if (LOG) logerror("Force ready\n");
z80dma->rdy = (WR5(z80dma) & 0x8)>>3;
z80dma_rdy_w(device, z80dma->rdy);
z80dma->force_ready = 1;
z80dma_update_status(device);
break;
case COMMAND_ENABLE_INTERRUPTS:
if (LOG) logerror("Enable IRQ\n");
@ -640,16 +649,14 @@ WRITE8_DEVICE_HANDLER( z80dma_w )
static TIMER_CALLBACK( z80dma_rdy_write_callback )
{
running_device *device = (running_device *)ptr;
int state = param & 0x01;
z80dma_t *z80dma = get_safe_token(device);
/* normalize state */
z80dma->rdy = 1 ^ state ^ READY_ACTIVE_HIGH(z80dma);
z80dma->status = (z80dma->status & 0xFD) | (z80dma->rdy<<1);
z80dma->rdy = param;
z80dma->status = (z80dma->status & 0xFD) | (!is_ready(z80dma) << 1);
z80dma_update_status(device);
if (z80dma->rdy && INT_ON_READY(z80dma))
if (is_ready(z80dma) && INT_ON_READY(z80dma))
{
trigger_interrupt(device, INT_RDY);
}
@ -662,11 +669,10 @@ static TIMER_CALLBACK( z80dma_rdy_write_callback )
WRITE_LINE_DEVICE_HANDLER( z80dma_rdy_w )
{
z80dma_t *z80dma = get_safe_token(device);
int param;
param = (state ? 1 : 0);
if (LOG) logerror("RDY: %d Active High: %d\n", state, READY_ACTIVE_HIGH(z80dma));
timer_call_after_resynch(device->machine, (void *) device, param, z80dma_rdy_write_callback);
timer_call_after_resynch(device->machine, (void *) device, state, z80dma_rdy_write_callback);
}
/*-------------------------------------------------
@ -797,6 +803,7 @@ static DEVICE_START( z80dma )
state_save_register_device_item(device, 0, z80dma->addressB);
state_save_register_device_item(device, 0, z80dma->count);
state_save_register_device_item(device, 0, z80dma->rdy);
state_save_register_device_item(device, 0, z80dma->force_ready);
state_save_register_device_item(device, 0, z80dma->is_read);
state_save_register_device_item(device, 0, z80dma->cur_cycle);
state_save_register_device_item(device, 0, z80dma->latch);
@ -812,6 +819,7 @@ static DEVICE_RESET( z80dma )
z80dma->status = 0;
z80dma->rdy = 0;
z80dma->force_ready = 0;
z80dma->num_follow = 0;
z80dma->dma_enabled = 0;
z80dma->read_num_follow = z80dma->read_cur_follow = 0;