#include <fxos/semantics.h>

namespace FxOS {

DataValue::DataValue():
	type(nullptr), determined(false)
{
}

uint32_t DataValue::read(int offset, int size)
{
	if(offset < 0 || size < 0 || (type->size && offset+size >= type->size))
		throw std::logic_error("Invalid read into simulated data");
	if(!size || size & (size - 1))
		throw std::logic_error("Simulated read not a power of 2");

	if(type->kind==DataType::Integral || type->kind==DataType::BitField)
	{
		int shift = (4 - size - offset) << 3;
		uint32_t u = uinteger >> shift;
		return (size == 4) ? u :
		       (size == 2) ? (uint16_t)u :
		       (uint8_t)u;
	}
	else if(type->kind == DataType::Array)
	{
		int elsize = type->arraytype->size;
		int index = offset / elsize;

		if(index >= (int)entries.size())
			throw std::logic_error("Read out of array bounds");

		/* Will throw if reading from two entries simultaneously */
		return entries[index].read(offset % elsize, size);
	}
	else if(type->kind == DataType::Array)
	{
		int index = 0;
		while(offset >= type->attributes[index].size)
		{
			index++;
			offset -= type->attributes[index].size;
		}

		return entries[index].read(offset, size);
	}

	throw std::logic_error("Read into unknown DataValue kind");
}

void DataValue::write(int offset, int size, uint32_t contents)
{
	if(offset < 0 || size < 0 || (type->size && offset+size >= type->size))
		throw std::logic_error("Invalid write into simulated data");
	if(!size || size & (size - 1))
		throw std::logic_error("Simulated write not a power of 2");

	if(type->kind==DataType::Integral || type->kind==DataType::BitField)
	{
		uint32_t mask = (size == 1) ? 0xff :
		                (size == 2) ? 0xffff :
		                0xffffffff;

		int shift = (4 - size - offset) << 3;

		uinteger = (uinteger & ~(mask << shift)) | (contents << shift);
	}
	else if(type->kind == DataType::Array)
	{
		int elsize = type->arraytype->size;
		int index = offset / elsize;

		if(index >= (int)entries.size())
			throw std::logic_error("Write out of array bounds");

		entries[index].write(offset % elsize, size, contents);
	}
	else if(type->kind == DataType::Array)
	{
		int index = 0;
		while(offset >= type->attributes[index].size)
		{
			index++;
			offset -= type->attributes[index].size;
		}

		entries[index].write(offset, size, contents);
	}

	throw std::logic_error("Write into unknown DataValue kind");
}

} /* namespace FxOS */