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refactoring peripherals (#21)

This commit is contained in:
Stephen Crane 2023-09-27 11:27:45 +01:00 committed by GitHub
parent 972626cffd
commit 67ff1567af
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4 changed files with 247 additions and 9 deletions

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@ -4,8 +4,8 @@
#include "serialio.h"
#include "acia.h"
void acia::operator=(uint8_t b) {
if (_acc & 1) {
void ACIA::write(Memory::address a, uint8_t b) {
if (a & 1) {
_device->write(b);
return;
}
@ -42,8 +42,8 @@ void acia::operator=(uint8_t b) {
// FIXME: more
}
acia::operator uint8_t() {
if (_acc & 1)
uint8_t ACIA::read(Memory::address a) {
if (a & 1)
return _device->read();
return _device->more()? rdrf | tdre: tdre;

12
acia.h
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@ -1,12 +1,14 @@
#ifndef __ACIA_H__
#define __ACIA_H__
class acia: public Memory::Device {
public:
void operator= (uint8_t);
operator uint8_t();
// Motorola 6850 ACIA
acia(serialio &d): Memory::Device(256), _device(&d) {}
class ACIA {
public:
void write(Memory::address, uint8_t);
uint8_t read(Memory::address);
ACIA(serialio &d): _device(&d) {}
// status bits
//

179
pia.cpp Normal file
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@ -0,0 +1,179 @@
#include <Arduino.h>
#include <memory.h>
#include "pia.h"
// see: https://github.com/mamedev/mame/blob/master/src/devices/machine/6821pia.cpp
// and: https://github.com/mamedev/mame/blob/master/src/devices/machine/6821pia.h
inline bool c1_low_to_high(uint8_t cr) { return cr & 0x02; }
inline bool c1_high_to_low(uint8_t cr) { return !c1_low_to_high(cr); }
inline bool c2_output(uint8_t cr) { return cr & 0x20; }
inline bool c2_input(uint8_t cr) { return !c2_input(cr); }
inline bool c2_low_to_high(uint8_t cr) { return cr & 0x10; }
inline bool c2_high_to_low(uint8_t cr) { return !c2_low_to_high(cr); }
inline bool output_selected(uint8_t cr) { return cr & 0x04; }
void PIA::write(Memory::address a, uint8_t b) {
#if defined(DEBUGGING)
Serial.print(millis());
Serial.print(" > ");
Serial.print(a, 16);
Serial.print(' ');
Serial.println(b, 16);
#endif
switch(a % 4) {
case 0:
output_selected(cra)? write_porta(b): write_ddra(b);
break;
case 1:
write_cra(b);
break;
case 2:
output_selected(crb)? write_portb(b): write_ddrb(b);
break;
case 3:
write_crb(b);
break;
}
}
uint8_t PIA::read(Memory::address a) {
#if defined(DEBUGGING)
Serial.print(millis());
Serial.print(" < ");
Serial.println(a, 16);
#endif
switch (a % 4) {
case 0:
return output_selected(cra)? read_porta(): read_ddra();
case 1:
return read_cra();
case 2:
return output_selected(crb)? read_portb(): read_ddrb();
case 3:
return read_crb();
}
return 0xff;
}
void PIA::checkpoint(Stream &s) {
s.write(crb);
s.write(outb);
s.write(inb);
s.write(ddrb);
s.write(cra);
s.write(outa);
s.write(ina);
s.write(ddra);
s.write(irq_b1);
s.write(irq_b2);
s.write(irq_a1);
s.write(irq_a2);
s.write(cb1);
s.write(cb2);
s.write(ca1);
s.write(ca2);
}
void PIA::restore(Stream &s) {
crb = s.read();
outb = s.read();
inb = s.read();
ddrb = s.read();
cra = s.read();
outa = s.read();
ina = s.read();
ddra = s.read();
irq_b1 = s.read();
irq_b2 = s.read();
irq_a1 = s.read();
irq_a2 = s.read();
cb1 = s.read();
cb2 = s.read();
ca1 = s.read();
ca2 = s.read();
}
void PIA::write_ca1(bool state) {
if (ca1 == state)
return;
if ((state && c1_low_to_high(cra)) || (!state && c1_high_to_low(cra)))
irq_a1 = true;
ca1 = state;
}
void PIA::write_ca2(bool state) {
if (ca2 == state || !c2_input(cra))
return;
if ((state && c2_low_to_high(cra)) || (!state && c2_high_to_low(cra)))
irq_a2 = true;
ca2 = state;
}
void PIA::write_cb1(bool state) {
if (cb1 == state)
return;
if ((state && c1_low_to_high(crb)) || (!state && c1_high_to_low(crb)))
irq_b1 = true;
cb1 = state;
}
void PIA::write_cb2(bool state) {
if (cb2 == state || !c2_input(crb))
return;
if ((state && c2_low_to_high(crb)) || (!state && c2_high_to_low(crb)))
irq_b2 = true;
cb2 = state;
}
uint8_t PIA::read_cra() {
uint8_t b = cra;
if (irq_a1)
b |= IRQ1;
if (irq_a2 && c2_input(cra))
b |= IRQ2;
return b;
}
uint8_t PIA::read_crb() {
uint8_t b = crb;
if (irq_b1)
b |= IRQ1;
if (irq_b2 && c2_input(crb))
b |= IRQ2;
return b;
}
uint8_t PIA::read_porta() {
irq_a1 = irq_a2 = false;
return (ina & ~ddra) | (outa & ddra);
}
uint8_t PIA::read_portb() {
irq_b1 = irq_b2 = false;
return (inb & ~ddrb) | (outb & ddrb);
}

57
pia.h Normal file
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@ -0,0 +1,57 @@
#ifndef __PIA_H__
#define __PIA_H__
// Motorola 6820 / 6821 PIA
// https://en.wikipedia.org/wiki/Peripheral_Interface_Adapter
class PIA {
public:
PIA(): outb(0), inb(0), crb(0), outa(0), ina(0), cra(0), ddrb(0), ddra(0),
ca1(false), ca2(false), cb1(false), cb2(false),
irq_a1(false), irq_a2(false), irq_b1(false), irq_b2(false) {}
virtual void reset() {
outb = inb = crb = ddrb = outa = ina = cra = ddra = 0;
irq_a1 = irq_a2 = irq_b1 = irq_b2 = ca1 = ca2 = cb1 = cb2 = false;
}
// device memory interface
void write(Memory::address, uint8_t);
uint8_t read(Memory::address);
void checkpoint(Stream &);
void restore(Stream &);
// device input (external) interface
void write_porta_in(uint8_t b) { ina = b; }
void write_ca1(bool);
void write_ca2(bool);
void write_portb_in(uint8_t b) { inb = b; }
void write_cb1(bool);
void write_cb2(bool);
static const uint8_t IRQ1 = 0x80;
static const uint8_t IRQ2 = 0x40;
protected:
// overrideable device memory interface
virtual uint8_t read_ddra() { return ddra; }
virtual uint8_t read_porta();
virtual uint8_t read_cra();
virtual uint8_t read_ddrb() { return ddrb; }
virtual uint8_t read_portb();
virtual uint8_t read_crb();
virtual void write_ddra(uint8_t b) { ddra = b; }
virtual void write_porta(uint8_t b) { outa = b; }
virtual void write_cra(uint8_t b) { cra = (b & 0x3f); }
virtual void write_ddrb(uint8_t b) { ddrb = b; }
virtual void write_portb(uint8_t b) { outb = b; }
virtual void write_crb(uint8_t b) { crb = (b & 0x3f); }
private:
uint8_t cra, ina, outa, ddra;
uint8_t crb, inb, outb, ddrb;
bool ca1, ca2, irq_a1, irq_a2;
bool cb1, cb2, irq_b1, irq_b2;
};
#endif