mirror of https://github.com/JorjBauer/aiie.git
151 lines
2.7 KiB
C++
151 lines
2.7 KiB
C++
#include "sy6522.h"
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#include <stdio.h>
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SY6522::SY6522()
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{
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ORB = ORA = 0;
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DDRB = DDRA = 0x00;
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T1_CTR = T2_CTR = 0;
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T1_CTR_LATCH = T2_CTR_LATCH = 0;
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ACR = 0x20; // free-running; FIXME: constant?
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PCR = 0xB0; // FIXME: ?
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IFR = 0x00; // FIXME: ?
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IER = 0x90; // FIXME: ?
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}
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uint8_t SY6522::read(uint8_t address)
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{
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switch (address) {
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case SY_ORB:
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return ORB;
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case SY_ORA:
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return ORA;
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case SY_DDRB:
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return DDRB;
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case SY_DDRA:
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return DDRA;
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case SY_TMR1L:
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// FIXME: also updates IFR?
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return (T1_CTR & 0xFF);
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case SY_TMR1H:
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return (T1_CTR >> 8);
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case SY_TMR1LL:
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return (T1_CTR_LATCH & 0xFF);
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case SY_TMR1HL:
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return (T1_CTR_LATCH >> 8);
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case SY_TMR2L:
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// FIXME: alos udpates IFR?
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return (T2_CTR & 0xFF);
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case SY_TMR2H:
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return (T2_CTR >> 8);
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case SY_SS:
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// FIXME: floating
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return 0xFF;
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case SY_ACR:
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return ACR;
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case SY_PCR:
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return PCR;
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case SY_IFR:
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return IFR;
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case SY_IER:
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return 0x80 | IER;
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case SY_ORANOHS:
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return ORA;
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}
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return 0xFF;
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}
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void SY6522::write(uint8_t address, uint8_t val)
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{
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switch (address) {
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case SY_ORB:
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val &= DDRB;
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ORB = val;
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ay8910[0].write(val, ORA & DDRA);
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return;
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case SY_ORA:
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ORA = val & DDRA;
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return;
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case SY_DDRB:
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DDRB = val;
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return;
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case SY_DDRA:
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DDRA = val;
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return;
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case SY_TMR1L:
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case SY_TMR1LL:
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T1_CTR_LATCH = (T1_CTR_LATCH & 0xFF00) | val;
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return;
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case SY_TMR1H:
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// FIXME: clear interrupt flag
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T1_CTR_LATCH = (T1_CTR_LATCH & 0x00FF) | (val << 8);
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T1_CTR = T1_CTR_LATCH;
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// FIXME: start timer?
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return;
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case SY_TMR1HL:
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T1_CTR_LATCH = (T1_CTR_LATCH & 0x00FF) | (val << 8);
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// FIXME: clear interrupt flag
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return;
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case SY_TMR2L:
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T2_CTR_LATCH = (T2_CTR_LATCH & 0xFF00) | val;
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return;
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case SY_TMR2H:
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// FIXME: clear timer2 interrupt flag
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T2_CTR_LATCH = (T2_CTR_LATCH & 0x00FF) | (val << 8);
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T2_CTR = T2_CTR_LATCH;
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return;
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case SY_SS:
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// FIXME: what is this for?
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return;
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case SY_ACR:
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ACR = val;
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break;
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case SY_PCR:
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PCR = val;
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break;
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case SY_IFR:
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// Clear whatever low bits are set in IFR.
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val |= 0x80;
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val ^= 0x7F;
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IFR &= val;
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break;
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case SY_IER:
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if (val & 0x80) {
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// Set bits based on val
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val &= 0x7F;
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IER |= val;
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// FIXME: start timer if necessary?
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} else {
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// Clear whatever low bits are set in IER.
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val |= 0x80;
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val ^= 0x7F;
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IER &= val;
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// FIXME: stop timer if it's running?
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}
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return;
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case SY_ORANOHS:
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// FIXME: what is this for?
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return;
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}
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}
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void SY6522::update(uint32_t cycles)
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{
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ay8910[0].update(cycles);
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}
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