instruction.c File Reference

#include "instruction.h"
#include "../common.h"
#include "../decode.h"
#include "../font.h"
#include "exception.h"
#include <stdlib.h>
#include <string.h>

Macros
#define	VERBOSE(c)   (c->flags & C8_FLAG_VERBOSE)
#define	SCHIP_EXCLUSIVE(c)
#define	XOCHIP_EXCLUSIVE(c)
#define	QUIRK_BITWISE(c)
#define	QUIRK_DRAW(c)
#define	QUIRK_LOADSTORE(c)
#define	QUIRK_SHIFT(c)
#define	BORROWS(x, y)   ((((int) x) - y) < 0)
#define	CARRIES(x, y)   ((((int) x) + y) > UINT8_MAX)

Functions
int	c8_parse_instruction (C8 *c8)
	Execute the instruction at c8->pc

Detailed Description

Note

NOT EXPORTED

This file contains the implementation of the instruction parsing and execution for the CHIP-8 interpreter.

Macro Definition Documentation

BORROWS

#define BORROWS	(		x,
			y
	)		((((int) x) - y) < 0)

CARRIES

#define CARRIES	(		x,
			y
	)		((((int) x) + y) > UINT8_MAX)

QUIRK_BITWISE

#define QUIRK_BITWISE

(

c

)

Value:

    if (c->flags & C8_FLAG_QUIRK_BITWISE) {                                                        \
        c->V[0xF] = 0;                                                                             \
    }

QUIRK_DRAW

#define QUIRK_DRAW

(

c

)

Value:

    if (c->flags & C8_FLAG_QUIRK_DRAW) {                                                           \
        if ()                                                                                      \
    }

QUIRK_LOADSTORE

#define QUIRK_LOADSTORE

(

c

)

Value:

    if (c->flags & C8_FLAG_QUIRK_LOADSTORE) {                                                      \
        c->I += x + 1;                                                                             \
    }

QUIRK_SHIFT

#define QUIRK_SHIFT

(

c

)

Value:

    if (c->flags & C8_FLAG_QUIRK_SHIFT) {                                                          \
        y = x;                                                                                     \
    }

SCHIP_EXCLUSIVE

#define SCHIP_EXCLUSIVE

(

c

)

Value:

    if (c->mode == C8_MODE_CHIP8) {                                                                \
        C8_EXCEPTION(C8_INVALID_INSTRUCTION_EXCEPTION,                                             \
                     "SCHIP instruction detected in CHIP-8 mode.\n");                              \
        return C8_INVALID_INSTRUCTION_EXCEPTION;                                                   \
    }

VERBOSE

#define VERBOSE

(

c

)

(c->flags & C8_FLAG_VERBOSE)

XOCHIP_EXCLUSIVE

#define XOCHIP_EXCLUSIVE

(

c

)

Value:

    if (c->mode != C8_MODE_XOCHIP) {                                                               \
        const char* modeStr = (c->mode == C8_MODE_CHIP8) ? "CHIP-8" : "SCHIP";                     \
        C8_EXCEPTION(C8_INVALID_INSTRUCTION_EXCEPTION,                                             \
                     "XOCHIP instruction detected in %s mode.\n",                                  \
                     modeStr);                                                                     \
        return C8_INVALID_INSTRUCTION_EXCEPTION;                                                   \
    }

Function Documentation

c8_parse_instruction()

int c8_parse_instruction

(

C8 *

c8

)

Execute the instruction at c8->pc

This function parses and executes the instruction at the current program counter.

If verbose flag is set, this will print the instruction to stdout as well.

Parameters

c8	the C8 to execute the instruction from

Returns

amount to increase the program counter, or an exception code if an error occurs.