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cpu/hcd62121: Implement missing mov instructions and timer wait (#12099)
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Co-authored-by: George Stagg <georgestagg@gmail.com>
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@qufb @georgestagg
qufb and georgestagg committed Mar 4, 2024
1 parent 1565fb9 commit c13a580
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Showing 2 changed files with 176 additions and 6 deletions.
181 changes: 175 additions & 6 deletions src/devices/cpu/hcd62121/hcd62121.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,7 @@ hcd62121_cpu_device::hcd62121_cpu_device(const machine_config &mconfig, const ch
, m_dseg(0)
, m_sseg(0)
, m_f(0)
, m_time(0)
, m_lar(0)
, m_opt(0)
, m_port(0)
Expand Down Expand Up @@ -1443,11 +1444,18 @@ void hcd62121_cpu_device::execute_run()
break;

case 0xB1: /* unk_B1 reg/i8 - PORTx control/direction? */
case 0xB3: /* unk_B3 reg/i8 - timer/irq related? */
logerror("%02x:%04x: unimplemented instruction %02x encountered\n", m_cseg, m_ip-1, op);
read_op();
break;

case 0xB3: /* timer_set i8 */
{
u8 arg = read_op();

m_time = arg;
}
break;

case 0xB4: /* out koh,reg */
m_koh_cb(m_reg[read_op() & 0x7f]);
break;
Expand Down Expand Up @@ -1710,6 +1718,15 @@ void hcd62121_cpu_device::execute_run()
}
break;

case 0xEA: /* movw reg,pc */
{
u8 reg1 = read_op();

m_reg[reg1 & 0x7f] = m_ip & 0xff;
m_reg[(reg1 + 1) & 0x7f] = m_ip >> 8;
}
break;

case 0xEB: /* movw reg,sp */
{
u8 reg1 = read_op();
Expand All @@ -1719,6 +1736,14 @@ void hcd62121_cpu_device::execute_run()
}
break;

case 0xED: /* movb reg,ds */
m_reg[read_op() & 0x7f] = m_dseg;
break;

case 0xEE: /* movb reg,cs */
m_reg[read_op() & 0x7f] = m_cseg;
break;

case 0xEF: /* movb reg,ss */
m_reg[read_op() & 0x7f] = m_sseg;
break;
Expand All @@ -1736,20 +1761,164 @@ void hcd62121_cpu_device::execute_run()
case 0xF1: /* unk_F1 reg/i8 (out?) */
case 0xF3: /* unk_F3 reg/i8 (out?) */
case 0xF5: /* unk_F5 reg/i8 (out?) */
case 0xF7: /* unk_F7 reg/i8 (out?) */
case 0xF7: /* timer_ctrl i8 */
logerror("%02x:%04x: unimplemented instruction %02x encountered\n", m_cseg, m_ip-1, op);
read_op();
break;

case 0xFC: /* unk_FC - disable interrupts/stop timer?? */
case 0xFD: /* unk_FD */
case 0xFE: /* unk_FE - wait for/start timer */
if (op == 0xFE)
m_icount -= 75000; // TODO: temporary value that makes emulation speed acceptable

logerror("%02x:%04x: unimplemented instruction %02x encountered\n", m_cseg, m_ip-1, op);
break;

case 0xFE: /* timer_wait */
if (m_time & 0x01) {
/*
When timer control is set with operand 0xC0, the CPU periodically reads
from external RAM (address range 0x7c00..0x7fff) at an interval of
832 clock cycles, with the reads themselves taking another 64 clock cycles.
This needs to be explicitly setup, involving writes to unknown segments
0x11 and 0xE1 (see cfx9850.bin @ 00:00fe), otherwise there's only activity
on address lines without any reads.
The total sum of these state reads can be approximated to the closest
power of two to define timeout values. Multiple samples were averaged,
as the state read interval can start at a distinct point in time from
the timer wait execution.
*/
const u64 TIMER_STATE_READ_CYCLES = 832 + 64;
u64 cycles_until_timeout = 0;
switch (m_time) {
case 0x11:
case 0x13:
case 0x15:
case 0x17:
case 0x19:
case 0x1b:
case 0x1d:
case 0x1f:
case 0x31:
case 0x33:
case 0x35:
case 0x37:
case 0x39:
case 0x3b:
case 0x3d:
case 0x3f:
case 0x51:
case 0x53:
case 0x55:
case 0x57:
case 0x59:
case 0x5b:
case 0x5d:
case 0x5f:
case 0x71:
case 0x73:
case 0x75:
case 0x77:
case 0x79:
case 0x7b:
case 0x7d:
case 0x7f:
case 0x91:
case 0x93:
case 0x95:
case 0x97:
case 0x99:
case 0x9b:
case 0x9d:
case 0x9f:
case 0xb1:
case 0xb3:
case 0xb5:
case 0xb7:
case 0xb9:
case 0xbb:
case 0xbd:
case 0xbf:
case 0xd1:
case 0xd3:
case 0xd5:
case 0xd7:
case 0xd9:
case 0xdb:
case 0xdd:
case 0xdf:
// Approximately 814.32us
cycles_until_timeout = 0x4 * TIMER_STATE_READ_CYCLES;
break;
case 0x21:
case 0x23:
case 0x25:
case 0x27:
case 0x29:
case 0x2b:
case 0x2d:
case 0x2f:
case 0x61:
case 0x63:
case 0x65:
case 0x67:
case 0x69:
case 0x6b:
case 0x6d:
case 0x6f:
case 0xa1:
case 0xa3:
case 0xa5:
case 0xa7:
case 0xa9:
case 0xab:
case 0xad:
case 0xaf:
// Approximately 1.63ms
cycles_until_timeout = 0x8 * TIMER_STATE_READ_CYCLES;
break;
case 0x05:
case 0x07:
case 0x0d:
case 0x0f:
case 0x45:
case 0x47:
case 0x4d:
case 0x4f:
case 0xc5:
case 0xc7:
case 0xcd:
case 0xcf:
// Approximately 209.34ms
cycles_until_timeout = 0x400 * TIMER_STATE_READ_CYCLES;
break;
case 0x49:
case 0x4b:
case 0xc9:
case 0xcb:
// Approximately 837.61ms
cycles_until_timeout = 0x1000 * TIMER_STATE_READ_CYCLES;
break;
case 0x41:
case 0x43:
case 0xc1:
case 0xc3:
// Approximately 1.68s
cycles_until_timeout = 0x2000 * TIMER_STATE_READ_CYCLES;
break;
case 0x81:
case 0x83:
// Approximately 100.58s
cycles_until_timeout = 0x7a800 * TIMER_STATE_READ_CYCLES;
break;
default:
logerror("%02x:%04x: unimplemented timer value %02x encountered\n", m_cseg, m_ip-1, m_time);
break;
}
m_icount -= cycles_until_timeout;
} else {
logerror("%02x:%04x: wait for disabled timer? value %02x\n", m_cseg, m_ip-1, m_time);
}
break;

case 0xFF: /* nop */
break;

Expand Down
1 change: 1 addition & 0 deletions src/devices/cpu/hcd62121/hcd62121.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -91,6 +91,7 @@ class hcd62121_cpu_device : public cpu_device
u8 m_dseg;
u8 m_sseg;
u8 m_f;
u8 m_time;
u16 m_lar;
u8 m_reg[0x80];

Expand Down

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