// Copyright (c) 2012 - 2026 kio@little-bat.de
// BSD-2-Clause license
// https://opensource.org/licenses/BSD-2-Clause


#include "Memotech64kRam.h"
#include "Items/Ula/Mmu.h"
#include "Items/Ula/UlaZx81.h"
#include "Machine.h"
#include "Memory.h"
#include "Z80/Z80.h"


/*  To set top of RAM at 64K type:

	POKE 16388,255  (this is not usually needed)
	POKE 16389 255  (this is usually set at 128 for a 32K limit)
	NEW             (the memory is now cleared to start afresh and will
					 now be organised to the new limit)

	To check the current top of RAM type:
	PRINT PEEK 16389

	MODE SWITCH
	---------------------------------------------------------------
		 1    2    3    4
	---------------------------------------------------------------
	A    ON   OFF  OFF  OFF  This mode provides 64K of memory and is for future developments
	B    OFF  ON   OFF  OFF  Memory is provided between 8K and 12K
	C    OFF  OFF  ON   OFF  Memory is provided between 12K and 16K
	D    OFF  OFF  OFF  ON   No memory is available between 8K and 16K
	E    OFF  ON   ON   OFF  Memory is available between 8K and 16K
	---------------------------------------------------------------

	For ZX81 users, switching between modes B, C, D, and E is possible, as long
	as at least one and no more than two switches are ON at the same time. Never
	have more than two switches on at a time, as this can lead to overloading.
*/


namespace zxsp
{

Memotech64kRam::Memotech64kRam(Machine* m, uint dip_switches) :
	ExternalRam(m, isa_Memotech64kRam),
	dip_switches(dip_switches)
{
	machine->ram.grow(64 kB);
	machine->mmu->mapMem(); // map new memory to cpu & to set videoram
	map_dip_switched_ram();
}


Memotech64kRam::~Memotech64kRam()
{
	machine->ram.shrink(machine->model_info->ram_size);

	prev()->romCS(false);
	machine->mmu->mapMem(); // map new memory to cpu & to set videoram
}


/*  Ändere Dip-Switches
	Die Dip-Switches beeinflussen nur das Ram (oder Nicht-Ram) zw. 8k und 16k.
	Außer wenn Switch 1 ON ist, dann all-64k-ram.
	Genaues Error-Checking wird nicht gemacht.
	note: bits[3…0] == dip switch[1…4] lt. Memopak manual
*/
void Memotech64kRam::setDipSwitches(uint sw)
{
	assert(is_locked());

	if (sw == dip_switches) return;
	dip_switches = sw;

	map_dip_switched_ram();
}


/*  Initialisiere dieses Item
	Die "normalen" 48k werden von MmuZx80/81 initialisiert
	Hier werden die unteren 16k nochmal umgebogen.
	Da MmuZx80/81 ab machine.ram[0] benutzt, benutzen wir hier das Ram ab machine.ram[48k]
	Note: Annahme: Ram, das nicht lesbar ist, ist auch nicht beschreibbar.
	Note: wenn im Bereich 8k .. 16k ROM ist, wird es hier durch RAM übersteuert.
		  In der realen Maschine hätten wir hier einen Bus-Konflikt.
*/
// virtual
void Memotech64kRam::powerOn(int32 cc)
{
	ExternalRam::powerOn(cc);
	map_dip_switched_ram();
}


/*	map ram in range 0-8k and 8-16k
 */
void Memotech64kRam::map_dip_switched_ram()
{
	uint8* waitmap = nullptr;
	int	   wm_size = 0;
	if (auto* ula = dynamic_cast<UlaZx81*>(machine->ula))
	{
		waitmap = ula->getWaitmap();
		wm_size = ula->waitmap_size;
	}

	if (dip_switches & 8) // all-64k-ram
	{
		prev()->romCS(true);
		machine->cpu->mapRam(0x0000, 0x4000, &machine->ram[0xC000], waitmap, wm_size);
	}
	else // 0-8k: rom, 8-12 and 12-16k are ram or empty
	{
		prev()->romCS(false);
		if (dip_switches & 4)
			machine->cpu->mapRam(0x2000, 0x1000, &machine->ram[0xe000], waitmap, wm_size); // 8k-12k: Ram
		if (dip_switches & 2)
			machine->cpu->mapRam(0x3000, 0x1000, &machine->ram[0xf000], waitmap, wm_size); // 12k-16k: Ram
	}
}

} // namespace zxsp