1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
|
// license:BSD-3-Clause
// copyright-holders:Juergen Buchmueller
/*****************************************************************************
*
* Xerox AltoII display word task
*
*****************************************************************************/
#include "alto2cpu.h"
/*
* Copied from ALTOCODE24.MU
*
* ;Display Word Task
*
* DWT: T← DWA;
* T←-3+T+1;
* L← AECL+T,BUS=0,TASK; AECL CONTAINS NWRDS AT THIS TIME
* AECL←L, :DWTZ;
*
* DWTY: BLOCK;
* TASK, :DWTF;
*
* DWTZ: L←HTAB-1, BUS=0,TASK;
* HTAB←L, :DOTAB;
*
* DOTAB: DDR←0, :DWTZ;
* NOTAB: MAR←T←DWA;
* L←AECL-T-1;
* ALUCY, L←2+T;
* DWA←L, :XNOMORE;
*
* DOMORE: DDR←MD, TASK;
* DDR←MD, :NOTAB;
*
* XNOMORE:DDR← MD, BLOCK;
* DDR← MD, TASK;
*
* DWTF: :DWT;
*/
//! PROM a38 bit O1 is STOPWAKE' (stop DWT if bit is zero)
#define FIFO_STOPWAKE(a38) (0 == (a38 & disp_a38_STOPWAKE) ? true : false)
/**
* @brief Block the display word task.
*/
void alto2_cpu_device::f1_early_dwt_block()
{
m_dsp.dwt_blocks = true;
// Clear the wakeup for the display word task
m_task_wakeup &= ~(1 << m_task);
LOG((this,LOG_DWT,2," BLOCK %s\n", task_name(m_task)));
// Wakeup the display horizontal task, if it didn't block itself
if (!m_dsp.dht_blocks)
m_task_wakeup |= 1 << task_dht;
}
/**
* @brief Load the display data register
* Pushes the word on the bus to the display FIFO.
* If the FIFO becomes full, the wakeup flag for task_dwt is reset.
*/
void alto2_cpu_device::f2_late_load_ddr()
{
LOG((this,LOG_DWT,2," DDR<- BUS (%#o)\n", m_bus));
m_dsp.fifo[m_dsp.wa] = m_bus;
m_dsp.wa = (m_dsp.wa + 1) % A2_DISP_FIFO;
UINT8 a38 = m_disp_a38[m_dsp.ra * 16 + m_dsp.wa];
if (FIFO_STOPWAKE(a38))
m_task_wakeup &= ~(1 << task_dwt);
LOG((this,LOG_DWT,2, " DWT push %04x into FIFO[%02o]%s\n",
m_bus, (m_dsp.wa - 1) & (A2_DISP_FIFO - 1),
FIFO_STOPWAKE(a38) ? " STOPWAKE" : ""));
}
void alto2_cpu_device::init_dwt(int task)
{
}
void alto2_cpu_device::exit_dwt()
{
// nothing to do yet
}
void alto2_cpu_device::reset_dwt()
{
m_dsp.dwt_blocks = false;
memset(m_dsp.fifo, 0, sizeof(m_dsp.fifo));
m_dsp.wa = 0;
m_dsp.ra = 0;
}
|