#include <fxos/os.h>
#include <fxos/target.h>
#include <fxos/memory.h>

#include <cstring>

namespace FxOS {

OS::OS(File &file): m_target()
{
	/* OS files are all at least 1 MB large */
	if(file.size() < 1000000)
		throw std::runtime_error("OS files cannot be < 1MB");

	/* Bind the given file to the internal analysis target */
	m_target.bind_region(MemoryRegion::ROM, file);
	m_target.bind_region(MemoryRegion::ROM_P2, file);

	parse_version();
	parse_syscall_table();
//	parse_footer();
}

void OS::parse_version()
{
	/* Extract the version string at 0x10020 */
	Target &t = m_target;

	char *version = (char *)t.translate(0x80010020, 10);
	m_version = std::string(version, 10);
}

//---
//  Syscalle resolution
//---

int OS::syscall_count() const noexcept
{
	return m_syscall_table.size();
}

uint32_t OS::syscall(int id) const
{
	return m_syscall_table[id];
}

int OS::find_syscall(uint32_t entry) const noexcept
{
	try {
		return m_syscall_addresses.at(entry);
	}
	catch(std::out_of_range &e) {
		return -1;
	}
}

void OS::parse_syscall_table()
{
	Target &t = m_target;

	/* Traverse the syscall table */
	uint32_t syscall_table = t.read_u32(0x8001007c);
	int id = 0;

	while(1)
	{
		uint32_t entry = t.read_u32(syscall_table + 4 * id);

		MemoryRegion const *r = MemoryRegion::region_for(entry);
		if(!r) break;

		m_syscall_table.push_back(entry);
		m_syscall_addresses[entry] = id;

		id++;
	}
}

//---
//  Footer search
//---

uint32_t OS::footer() const noexcept
{
	return m_footer;
}

void OS::parse_footer()
{
	/* Find the footer address (last occurrence of "CASIOABSLangdata") */
	uint32_t start = MemoryRegion::ROM.start;
	uint32_t end = MemoryRegion::ROM.end;

	m_target.search(start, end, "CASIOABSLangdata", 16);
#if 0
	char const *signature = "CASIOABSLangdata";
	void *occ = NULL, *next = memmem(os->data, os->len, signature, 16);
	void *end = os->data + os->len;

	while(next)
	{
		occ = next;
		next = memmem(next + 1, end - (next + 1), signature, 16);
	}

	os->footer = (occ) ? (occ - os->data) : (uint32_t)-1;
#endif
}

} /* namespace FxOS */