pureikyubu/src/mem.cpp

// MI - memory interface.
//
// MI is used in __OSInitMemoryProtection and by few games for debug.
#include "pch.h"

using namespace Debug;

// stubs for MI registers
static void no_write(uint32_t addr, uint32_t data) {}
static void no_read(uint32_t addr, uint32_t* reg) { *reg = 0; }

MIControl mi;

// Load and descramble bootrom.
// This implementation makes working with Bootrom easier, since we do not need to monitor cache transactions ("bursts") from the processor.

void LoadBootrom(HWConfig* config)
{
	mi.BootromPresent = false;
	mi.bootromSize = BOOTROM_SIZE;

	// Load bootrom image

	if (wcslen(config->BootromFilename) == 0)
	{
		Report(Channel::MI, "Bootrom not loaded (not specified)\n");
		return;
	}

	auto bootrom = Util::FileLoad(config->BootromFilename);
	if (bootrom.empty())
	{
		Report(Channel::MI, "Cannot load Bootrom: %s\n", Util::WstringToString(config->BootromFilename).c_str());
		return;
	}

	mi.bootrom = new uint8_t[mi.bootromSize];

	if (bootrom.size() != mi.bootromSize)
	{
		delete[] mi.bootrom;
		mi.bootrom = nullptr;
		return;
	}

	memcpy(mi.bootrom, bootrom.data(), bootrom.size());

	// Determine size of encrypted data (find first empty cache burst line)

	const size_t strideSize = 0x20;
	uint8_t zeroStride[strideSize] = { 0 };

	size_t beginOffset = 0x100;
	size_t endOffset = mi.bootromSize - strideSize;
	size_t offset = beginOffset;

	while (offset < endOffset)
	{
		if (!memcmp(&mi.bootrom[offset], zeroStride, sizeof(zeroStride)))
		{
			break;
		}

		offset += strideSize;
	}

	if (offset == endOffset)
	{
		// Empty cacheline not found, something wrong with the image

		delete[] mi.bootrom;
		mi.bootrom = nullptr;
		return;
	}

	// Descramble

	IPLDescrambler(&mi.bootrom[beginOffset], (offset - beginOffset));
	mi.BootromPresent = true;

	// Show version

	Report(Channel::MI, "Loaded and descrambled valid Bootrom\n");
	Report(Channel::Norm, "%s\n", (char*)mi.bootrom);
}

void MIOpen(HWConfig* config)
{
	Report(Channel::MI, "Flipper memory interface\n");

	mi.ramSize = config->ramsize;
	mi.ram = new uint8_t[mi.ramSize];

	memset(mi.ram, 0, mi.ramSize);

	for (uint32_t ofs = 0; ofs <= 0x28; ofs += 2)
	{
		PISetTrap(16, 0x0C004000 | ofs, no_read, no_write);
	}

	LoadBootrom(config);
}

void MIClose()
{
	if (mi.ram)
	{
		delete[] mi.ram;
		mi.ram = nullptr;
	}

	if (mi.bootrom)
	{
		delete[] mi.bootrom;
		mi.bootrom = nullptr;
	}
}

uint8_t* MITranslatePhysicalAddress(uint32_t physAddr, size_t bytes)
{
	if (!mi.ram || bytes == 0)
		return nullptr;

	if (physAddr < (RAMSIZE - bytes))
	{
		return &mi.ram[physAddr];
	}

	if (physAddr >= BOOTROM_START_ADDRESS && mi.BootromPresent)
	{
		return &mi.bootrom[physAddr - BOOTROM_START_ADDRESS];
	}

	return nullptr;
}

/// <summary>
/// Used for memory access from the CP side, for Vertex Array.
/// </summary>
void* MIGetMemoryPointerForVertexArray(uint32_t phys_addr)
{
	return &mi.ram[phys_addr & RAMMASK];
}