// Commander X16 Emulator

// Copyright (c) 2019 Michael Steil

// All rights reserved. License: 2-clause BSD

#ifndef VIA_H

#define VIA_H

#include <stdint.h>

#include <stdbool.h>

#ifdef __cplusplus

extern "C" {

#endif

void via1_init();

uint8_t via1_read(uint8_t reg, bool debug);

void via1_write(uint8_t reg, uint8_t value);

void via1_step(unsigned clocks);

bool via1_irq();

void via2_init();

uint8_t via2_read(uint8_t reg, bool debug);

void via2_write(uint8_t reg, uint8_t value);

void via2_step(unsigned clocks);

bool via2_irq();

// ─── Debugger accessor ───────────────────────────────────────────────────────

// Side-effect-free snapshot of one VIA's state. Safe to call every frame from

// the debugger while the emulation is running.

//

// Register index map (mirrors the MOS 6522 address decoding):

//   0=ORB/IRB  1=ORA/IRA  2=DDRB  3=DDRA

//   4=T1L      5=T1H      6=T1LL  7=T1LH

//   8=T2L      9=T2H(not stored, see timer_count)

//   10=SR      11=ACR     12=PCR  13=IFR  14=IER

//

// `which`: 0 = VIA1, 1 = VIA2.

typedef struct {

	// Whether VIA2 is fitted is a machine-configuration fact (has_via2 in

	// glue.h), not something this module knows -- and reaching for it here

	// would give via.c an external symbol it does not otherwise need, which

	// the standalone VIA tests link without. The caller decides.

	uint8_t  regs[15];         // raw register bytes (indices 0-14, see map above)

	uint16_t timer_count[2];   // live timer counter values (T1=0, T2=1)

	uint16_t timer_latch[2];   // T1 latch = (regs[7]<<8)|regs[6]; T2 latch low = regs[8]

	bool     timer_running[2]; // timer is actively counting

	bool     timer1_m1;        // T1 is in the special -1 state between underflow and reload

	bool     pb7_output;       // PB7 toggle output (used with T1 in one-shot/square-wave mode)

} via_debug_state_t;

void via_debug_get_state(int which, via_debug_state_t *out);

#ifdef __cplusplus

}

#endif

#endif