#include "arm.h"

#include "isa-inlines.h"

static inline enum RegisterBank _ARMSelectBank(enum PrivilegeMode);

void ARMSetPrivilegeMode(struct ARMCore* cpu, enum PrivilegeMode mode) {
	if (mode == cpu->privilegeMode) {
		// Not switching modes after all
		return;
	}

	enum RegisterBank newBank = _ARMSelectBank(mode);
	enum RegisterBank oldBank = _ARMSelectBank(cpu->privilegeMode);
	if (newBank != oldBank) {
		// Switch banked registers
		if (mode == MODE_FIQ || cpu->privilegeMode == MODE_FIQ) {
			int oldFIQBank = oldBank == BANK_FIQ;
			int newFIQBank = newBank == BANK_FIQ;
			cpu->bankedRegisters[oldFIQBank][2] = cpu->gprs[8];
			cpu->bankedRegisters[oldFIQBank][3] = cpu->gprs[9];
			cpu->bankedRegisters[oldFIQBank][4] = cpu->gprs[10];
			cpu->bankedRegisters[oldFIQBank][5] = cpu->gprs[11];
			cpu->bankedRegisters[oldFIQBank][6] = cpu->gprs[12];
			cpu->gprs[8] = cpu->bankedRegisters[newFIQBank][2];
			cpu->gprs[9] = cpu->bankedRegisters[newFIQBank][3];
			cpu->gprs[10] = cpu->bankedRegisters[newFIQBank][4];
			cpu->gprs[11] = cpu->bankedRegisters[newFIQBank][5];
			cpu->gprs[12] = cpu->bankedRegisters[newFIQBank][6];
		}
		cpu->bankedRegisters[oldBank][0] = cpu->gprs[ARM_SP];
		cpu->bankedRegisters[oldBank][1] = cpu->gprs[ARM_LR];
		cpu->gprs[ARM_SP] = cpu->bankedRegisters[newBank][0];
		cpu->gprs[ARM_LR] = cpu->bankedRegisters[newBank][1];

		cpu->bankedSPSRs[oldBank] = cpu->spsr.packed;
		cpu->spsr.packed = cpu->bankedSPSRs[newBank];

	}
	cpu->privilegeMode = mode;
}

static inline enum RegisterBank _ARMSelectBank(enum PrivilegeMode mode) {
	switch (mode) {
		case MODE_USER:
		case MODE_SYSTEM:
			// No banked registers
			return BANK_NONE;
		case MODE_FIQ:
			return BANK_FIQ;
		case MODE_IRQ:
			return BANK_IRQ;
		case MODE_SUPERVISOR:
			return BANK_SUPERVISOR;
		case MODE_ABORT:
			return BANK_ABORT;
		case MODE_UNDEFINED:
			return BANK_UNDEFINED;
		default:
			// This should be unreached
			return BANK_NONE;
	}
}

void ARMInit(struct ARMCore* cpu) {
	cpu->memory = 0;
	cpu->board = 0;
}

void ARMAssociateMemory(struct ARMCore* cpu, struct ARMMemory* memory) {
	cpu->memory = memory;
}

void ARMAssociateBoard(struct ARMCore* cpu, struct ARMBoard* board) {
	cpu->board = board;
	board->cpu = cpu;
}

void ARMReset(struct ARMCore* cpu) {
	int i;
	for (i = 0; i < 16; ++i) {
		cpu->gprs[i] = 0;
	}
	for (i = 0; i < 6; ++i) {
		cpu->bankedRegisters[i][0] = 0;
		cpu->bankedRegisters[i][1] = 0;
		cpu->bankedRegisters[i][2] = 0;
		cpu->bankedRegisters[i][3] = 0;
		cpu->bankedRegisters[i][4] = 0;
		cpu->bankedRegisters[i][5] = 0;
		cpu->bankedRegisters[i][6] = 0;
		cpu->bankedSPSRs[i] = 0;
	}

	cpu->cpsr.packed = MODE_SYSTEM;
	cpu->spsr.packed = 0;

	cpu->cyclesToEvent = 0;

	cpu->shifterOperand = 0;
	cpu->shifterCarryOut = 0;

	cpu->executionMode = MODE_THUMB;
	_ARMSetMode(cpu, MODE_ARM);

	cpu->board->reset(cpu->board);
}