Casio_asm/interpreter/proc.c

#include "proc.h"
#include "../common/event.h"

#if defined(DEBUG)
#include <stdio.h>
#include "../common/opcodeInfo.h"
#endif

//internal functions
void tick(proc_t *proc);
int readOpcode(proc_t *proc, opcode_t *op, opcode_ext_t *opE);
void handleEvent(proc_t *proc, event_t *evt);

void Proc_execute(proc_t *proc, int maxCycles) {
	proc->status=PROC_STATUS_running;
	int i=0;
	do {
		//do a single tick
		tick(proc);
		i++;
		//loop until we either run out of cycles or we somehow kill ourselves
		if(i==maxCycles&&maxCycles!=-1) return;
		if(proc->status&PROC_STATUS_aborted) return;
	} while(Platform_running());
}
void Proc_interrupt(proc_t *proc, integral_t code, integral_t data) {
	#if defined(DEBUG)
	printf("Interrupted with code %.8x\n", code);
	printf("PC was %.8x\n", proc->registers[0].i);
	#endif
	//set the appropriate bits
	proc->status|=PROC_STATUS_running|PROC_STATUS_interrupt|PROC_STATUS_interrupted;
	//push the PC to the stack, followed by the data and interrupt code
	Stack_push(&proc->stack, proc->registers[0]);
	Stack_pushInt(&proc->stack, data);
	Stack_pushInt(&proc->stack, code);
	//jump to interrupt handler
	proc->registers[0].i=proc->intHandler;
	//check if code can run from there
	if((Mmu_checkAccess(&proc->mmu, proc->intHandler)&(MMU_ACCESS_r|MMU_ACCESS_r))!=(MMU_ACCESS_r|MMU_ACCESS_r)) {
		//abort the processor, the interrupt handler is wrong!
		proc->status|=PROC_STATUS_aborted;
	}
}
void interruptIf(proc_t *proc, integral_t code, integral_t data, integral_t type) {
	if(proc->subscribed&type) Proc_interrupt(proc, code|INTERRUPT_hw_mask, data);
}

void initProc(proc_t *proc) {
	#if defined(DEBUG)
	Opcode_registerOpcodes();
	#endif
	
	proc->status=(integral_t) 0;
	proc->subscribed=(integral_t) 0;
	proc->intHandler=(integral_t) -1;
	proc->lastAddress=(integral_t) -1;
	initMMU(&proc->mmu);
	initStack(&proc->stack);
	for(int i=0; i<256; i++) {
		proc->registers[i].i=(integral_t) 0;
	}
	proc->opaque=0;
}

//do a single cycle
void tick(proc_t *proc) {
	opcode_t op;
	opcode_ext_t opE;
	opcode_data_t instruction;
	
	//handle interrupts
	if(proc->status&PROC_STATUS_interrupt) {
		if(!(proc->status&PROC_STATUS_interrupted)) {
			//if we have the interrupt bit but the interrupted bit is cleared
			//clear the interrupt bit and go back where we were
			Stack_pop(&proc->stack, &proc->registers[0]);
			proc->status^=PROC_STATUS_interrupt;
		}
	}
	
	#if defined(DEBUG)&&defined(PC)
	//print the top of the stack
	if(proc->stack.top) printf("Stack top (%d): %d/%f\n", proc->stack.top, proc->stack.elements[proc->stack.top-1], proc->stack.elements[proc->stack.top-1]);
	else printf("Stack is empty\n");
	#endif
	
	//read and decode instruction
	if(readOpcode(proc, &op, &opE)) {
		if(op.op==OP_extend) {
			Proc_decodeInstructionExt(proc, &opE, &instruction);
		} else {
			Proc_decodeInstruction(proc, &op, &instruction);
		}
		
		#if defined(DEBUG)&&defined(PC)
		#define getInst(field) (instruction.ext?opE.field:op.field)
		//find mnemonic
		opcode_info_t info;
		Opcode_getOpByCode(instruction.op, instruction.ext, &info);
		printf("Instruction at %.8x is %s (%d, %s) [%s]\n", proc->registers[0].i, info.name, instruction.op, instruction.ext?"extended":"normal", info.desc);
		
		//print number of explicit arguments
		if(instruction.nArgs==0) printf("Arguments taken from stack\n");
		else if(instruction.nArgs==1) printf("One argument from register %.2x\n", getInst(arg0));
		else if(instruction.nArgs==2) printf("Two arguments from registers %.2x and %.2x\n", getInst(arg0), getInst(arg1));
		else if(instruction.nArgs==3) printf("Immediate argument %.4x\n", getInst(imm)&0xffff);
		
		//print runtime arguments
		if(instruction.argc==0) printf("No runtime arguments\n");
		else if(instruction.argc==1) printf("One runtime argument: %d/%f\n", instruction.arg0.i, instruction.arg0.d);
		else if(instruction.argc==2) printf("Two runtime arguments: %d/%f and %d/%f\n", instruction.arg0.i, instruction.arg0.d, instruction.arg1.i, instruction.arg1.d);
		#endif
		
		//execute instruction
		Proc_executeInstruction(proc, &instruction);
	}
	
	#if defined(DEBUG)&&defined(PC)
	else printf("Couldn't decode instruction\n");
	#endif
	
	//tick and get event
	event_t evt;
	if(proc->status&PROC_STATUS_running) {
		//do a platform tick and read a single event
		Platform_tick(0);
		if(Event_get(&evt)) handleEvent(proc, &evt);
	} else {
		//wait until we unlock ourselves
		//read all events until then
		while(!((proc->status&PROC_STATUS_running)||(proc->status&PROC_STATUS_aborted))) {
			if(Event_wait(&evt)) handleEvent(proc, &evt);
			//if the platform told us to quit, then kill ourselves
			if(!Platform_running()) return;
		}
	}
}

//read an instruction
int readOpcode(proc_t *proc, opcode_t *op, opcode_ext_t *ext) {
	int pc=proc->registers[0].i;
	mmu_t *mmu=&proc->mmu;
	int access=Mmu_checkAccess(mmu, pc);
	int len=1;
	if((access&MMU_ACCESS_r)&&(access&MMU_ACCESS_x)) {
		//we can read and execute the first byte, this is good
		//as we only need execute permission for the first byte
		Mmu_readByte(mmu, &op->bytes[0], pc);
		if(op->op==OP_extend) {
			//we have an extended instruction, read it that way
			ext->bytes[0]=op->bytes[0];
			Mmu_readByte(mmu, &ext->bytes[1], pc+1);
			if(ext->nArgs) {
				Mmu_readByte(mmu, &ext->bytes[2], pc+2);
				if(ext->nArgs==1) {
					len=3;
				} else {
					Mmu_readByte(mmu, &ext->bytes[3], pc+3);
					len=4;
				}
			} else {
				len=2;
			}
		} else {
			//we have a standard instruction
			if(op->nArgs) {
				Mmu_readByte(mmu, &op->bytes[1], pc+1);
				if(op->nArgs==1) {
					len=2;
				} else {
					Mmu_readByte(mmu, &op->bytes[2], pc+2);
					len=3;
				}
			}
		}
		//increment PC
		proc->registers[0].i=pc+len;
		return 1;
	} else {
		#if defined(DEBUG)
		printf("Access is not good: %o at %.8x\n", access&0xff, pc);
		#endif
		//not good, interrupt processor!
		Proc_interrupt(proc, INTERRUPT_illegal_jump, proc->registers[0].i);
		return 0;
	}
}

void handleEvent(proc_t *proc, event_t *evt) {
	switch(evt->type) {
		case EVENT_TYPE_KEYBOARD:
			switch(evt->subtype) {
				case EVENT_TYPE_KEYBOARD_PRESS:
					interruptIf(proc, evt->keyevent.repeat?INTERRUPT_hw_keyrepeat:INTERRUPT_hw_keydown, evt->keyevent.code, PROC_SUBSCRIPTION_keyboard);
					return;
				case EVENT_TYPE_KEYBOARD_RELEASE:
					if(evt->keyevent.repeat) return;
					interruptIf(proc, INTERRUPT_hw_keyup, evt->keyevent.code, PROC_SUBSCRIPTION_keyboard);
					return;
			}
			return;
		case EVENT_TYPE_TIMER:
			interruptIf(proc, INTERRUPT_hw_timer, evt->timerevent.code, PROC_SUBSCRIPTION_timer);
			return;
	}
}