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z80dma: improved end of block test

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This commit is contained in:
Patrick Mackinlay 2023-01-31 16:03:31 +07:00
parent faa0ede657
commit 12e5fa3906
2 changed files with 11 additions and 26 deletions
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35
src/devices/machine/z80dma.cpp
View File

@ -454,16 +454,11 @@ void z80dma_device::do_search()
}
}
int z80dma_device::do_write()
void z80dma_device::do_write()
{
int done;
uint8_t mode;
mode = TRANSFER_MODE;
if (m_byte_counter == 0x0000)
{
//FIXME: Any signal here
}
switch(mode) {
case TM_TRANSFER:
do_transfer_write();
@ -487,19 +482,6 @@ int z80dma_device::do_write()
m_addressB += PORTB_FIXED ? 0 : PORTB_INC ? 1 : -1;
m_byte_counter++;
/*
* HACK: The user manual states that 216+1 bytes are transferred when the
* block length is set to zero, however it also states the maximum length
* is 64Kbytes. For transfers less than the maximum, the value in the block
* length regster is set to N-1.
*/
done = (m_byte_counter == (m_count ? m_count + 1 : m_count));
if (done)
{
//FIXME: interrupt ?
}
return done;
}
@ -509,8 +491,6 @@ int z80dma_device::do_write()
TIMER_CALLBACK_MEMBER(z80dma_device::timerproc)
{
int done;
if (--m_cur_cycle)
{
return;
@ -522,18 +502,20 @@ TIMER_CALLBACK_MEMBER(z80dma_device::timerproc)
{
/* TODO: there's a nasty recursion bug with Alpha for Sharp X1 Turbo on the transfers with this function! */
do_read();
done = 0;
m_is_read = false;
m_cur_cycle = (PORTA_IS_SOURCE ? PORTA_CYCLE_LEN : PORTB_CYCLE_LEN);
}
else
{
done = do_write();
do_write();
m_is_read = true;
m_cur_cycle = (PORTB_IS_SOURCE ? PORTA_CYCLE_LEN : PORTB_CYCLE_LEN);
// param==1 indicates final transfer
m_timer->set_param(m_byte_counter == m_count);
}
if (done)
if (m_is_read && param)
{
m_dma_enabled = 0; //FIXME: Correct?
m_status = 0x09;
@ -560,6 +542,7 @@ TIMER_CALLBACK_MEMBER(z80dma_device::timerproc)
m_count = BLOCKLEN;
m_byte_counter = 0;
m_status |= 0x30;
m_timer->set_param(0);
}
}
}
@ -581,7 +564,7 @@ void z80dma_device::update_status()
attotime const next = attotime::from_hz(clock());
m_timer->adjust(
attotime::zero,
0,
m_timer->param(),
// 1 byte transferred in 4 clock cycles
next);
}
@ -752,6 +735,7 @@ void z80dma_device::write(uint8_t data)
m_count = BLOCKLEN;
m_byte_counter = 0;
m_status |= 0x30;
m_timer->set_param(0);
LOG("Z80DMA Load A: %x B: %x N: %x\n", m_addressA, m_addressB, m_count);
break;
@ -774,6 +758,7 @@ void z80dma_device::write(uint8_t data)
m_dma_enabled = 1;
//"match not found" & "end of block" status flags zeroed here
m_status |= 0x30;
m_timer->set_param(0);
break;
case COMMAND_RESET_PORT_A_TIMING:
LOG("Z80DMA Reset Port A Timing\n");

2
src/devices/machine/z80dma.h
View File

@ -83,7 +83,7 @@ private:
void interrupt_check();
void trigger_interrupt(int level);
void do_read();
int do_write();
void do_write();
void do_transfer_write();
void do_search();