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rockbox/apps/plugins/chip8.c
Daniel Stenberg 1e88be518a Barry Wardell's keymappings for H10 
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@10446 a1c6a512-1295-4272-9138-f99709370657
2006-08-03 20:17:25 +00:00

1332 lines
37 KiB
C
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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Orginal from Vision-8 Emulator / Copyright (C) 1997-1999 Marcel de Kogel
* Modified for Archos by Blueloop (a.wenger@gmx.de)
*
* All files in this archive are subject to the GNU General Public License.
* See the file COPYING in the source tree root for full license agreement.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "plugin.h"
/* Only build for (correct) target */
#ifdef HAVE_LCD_BITMAP
PLUGIN_HEADER
static struct plugin_api* rb; /* here is a global api struct pointer */
#define EXTERN static
#define STATIC static
#define memset rb->memset
#define memcpy rb->memcpy
#define printf DEBUGF
#define rand rb->rand
/* #define CHIP8_DEBUG */
#if (LCD_WIDTH >= 112) && (LCD_HEIGHT >= 64)
#define CHIP8_SUPER /* SCHIP even on the archos recorder (112x64) */
#endif
/****************************************************************************/
/** (S)CHIP-8 core emulation, from Vision-8 + mods by Fdy **/
/** The core is completely generic and can be used outside of Rockbox, **/
/** thus the STATIC, EXTERN etc. Please do not modify. **/
/****************************************************************************/
/** Vision8: CHIP8 emulator *************************************************/
/** **/
/** CHIP8.h **/
/** **/
/** This file contains the portable CHIP8 emulation engine definitions **/
/** **/
/** Copyright (C) Marcel de Kogel 1997 **/
/** You are not allowed to distribute this software commercially **/
/** Please, notify me, if you make any changes to this file **/
/****************************************************************************/
#ifndef __CHIP8_H
#define __CHIP8_H
#ifndef EXTERN
#define EXTERN extern
#endif
typedef unsigned char byte; /* sizeof(byte)==1 */
typedef unsigned short word; /* sizeof(word)>=2 */
struct chip8_regs_struct
{
byte alg[16]; /* 16 general registers */
byte delay,sound; /* delay and sound timer */
word i; /* index register */
word pc; /* program counter */
word sp; /* stack pointer */
};
EXTERN struct chip8_regs_struct chip8_regs;
#ifdef CHIP8_SUPER
#define CHIP8_WIDTH 128
#define CHIP8_HEIGHT 64
EXTERN byte chip8_super; /* != 0 if in SCHIP display mode */
#else
#define CHIP8_WIDTH 64
#define CHIP8_HEIGHT 32
#endif
EXTERN byte chip8_iperiod; /* number of opcodes per */
/* timeslice (1/50sec.) */
EXTERN byte chip8_keys[16]; /* if 1, key is held down */
EXTERN byte chip8_display[CHIP8_WIDTH*CHIP8_HEIGHT];/* 0xff if pixel is set, */
/* 0x00 otherwise */
EXTERN byte chip8_mem[4096]; /* machine memory. program */
/* is loaded at 0x200 */
EXTERN byte chip8_running; /* if 0, emulation stops */
EXTERN void chip8_execute (void); /* execute chip8_iperiod */
/* opcodes */
EXTERN void chip8_reset (void); /* reset virtual machine */
EXTERN void chip8 (void); /* start chip8 emulation */
EXTERN void chip8_sound_on (void); /* turn sound on */
EXTERN void chip8_sound_off (void); /* turn sound off */
EXTERN void chip8_interrupt (void); /* update keyboard, */
/* display, etc. */
#ifdef CHIP8_DEBUG
EXTERN byte chip8_trace; /* if 1, call debugger */
/* every opcode */
EXTERN word chip8_trap; /* if pc==trap, set trace */
/* flag */
EXTERN void chip8_debug (word opcode,struct chip8_regs_struct *regs);
#endif
#endif /* __CHIP8_H */
/** Vision8: CHIP8 emulator *************************************************/
/** **/
/** CHIP8.c **/
/** **/
/** This file contains the portable CHIP8 emulation engine **/
/** SCHIP emulation (C) Frederic Devernay 2005 **/
/** **/
/** Copyright (C) Marcel de Kogel 1997 **/
/** You are not allowed to distribute this software commercially **/
/** Please, notify me, if you make any changes to this file **/
/****************************************************************************/
/* you can
#define STATIC static
#define EXTERN static
and include this file for single-object generation
*/
#ifndef STATIC
#include <stdlib.h> /* for memset, etc. */
#include <string.h>
#define STATIC
#endif
#ifdef CHIP8_DEBUG
#include <stdio.h>
#define DBG_(_x) ((void)(_x))
#else
#define DBG_(_x) ((void)0)
#endif
STATIC struct chip8_regs_struct chip8_regs;
static byte chip8_key_pressed;
STATIC byte chip8_keys[16]; /* if 1, key is held down */
STATIC byte chip8_display[CHIP8_WIDTH*CHIP8_HEIGHT]; /* 0xff if pixel is set, */
/* 0x00 otherwise */
#ifdef CHIP8_SUPER
STATIC byte chip8_super; /* != 0 if in SCHIP display mode */
#endif
STATIC byte chip8_mem[4096]; /* machine memory. program */
/* is loaded at 0x200 */
#define read_mem(a) (chip8_mem[(a)&4095])
#define write_mem(a,v) (chip8_mem[(a)&4095]=(v))
STATIC byte chip8_iperiod;
STATIC byte chip8_running; /* Flag for End-of-Emulation */
#define get_reg_offset(opcode) (chip8_regs.alg+(opcode>>8))
#define get_reg_value(opcode) (*get_reg_offset(opcode))
#define get_reg_offset_2(opcode) (chip8_regs.alg+((opcode>>4)&0x0f))
#define get_reg_value_2(opcode) (*get_reg_offset_2(opcode))
typedef void (*opcode_fn) (word opcode);
typedef void (*math_fn) (byte *reg1,byte reg2);
static void op_call (word opcode)
{
chip8_regs.sp--;
write_mem (chip8_regs.sp,chip8_regs.pc&0xff);
chip8_regs.sp--;
write_mem (chip8_regs.sp,chip8_regs.pc>>8);
chip8_regs.pc=opcode;
#ifdef CHIP8_DEBUG
if(chip8_regs.sp < 0x1c0)
printf("warning: more than 16 subroutine calls, sp=%x\n", chip8_regs.sp);
#endif
}
static void op_jmp (word opcode)
{
chip8_regs.pc=opcode;
}
static void op_key (word opcode)
{
#ifdef CHIP8_DEBUG
static byte tested[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
#endif
byte key, key_value,cp_value;
if ((opcode&0xff)==0x9e) /* skp */
cp_value=1;
else if ((opcode&0xff)==0xa1) /* sknp */
cp_value=0;
else {
DBG_(printf("unhandled key opcode 0x%x\n", opcode));
return;
}
key = get_reg_value(opcode)&0x0f;
#ifdef CHIP8_DEBUG
if (!tested[key]) {
tested[key] = 1;
DBG_(printf("testing key %d\n", key));
}
#endif
key_value=chip8_keys[key];
if (cp_value==key_value)
chip8_regs.pc+=2;
}
static void op_skeq_const (word opcode)
{
if (get_reg_value(opcode)==(opcode&0xff))
chip8_regs.pc+=2;
}
static void op_skne_const (word opcode)
{
if (get_reg_value(opcode)!=(opcode&0xff))
chip8_regs.pc+=2;
}
static void op_skeq_reg (word opcode)
{
if (get_reg_value(opcode)==get_reg_value_2(opcode))
chip8_regs.pc+=2;
}
static void op_skne_reg (word opcode)
{
if (get_reg_value(opcode)!=get_reg_value_2(opcode))
chip8_regs.pc+=2;
}
static void op_mov_const (word opcode)
{
*get_reg_offset(opcode)=opcode&0xff;
}
static void op_add_const (word opcode)
{
*get_reg_offset(opcode)+=opcode&0xff;
}
static void op_mvi (word opcode)
{
chip8_regs.i=opcode;
}
static void op_jmi (word opcode)
{
chip8_regs.pc=opcode+chip8_regs.alg[0];
}
static void op_rand (word opcode)
{
*get_reg_offset(opcode)=rand()&(opcode&0xff);
}
static void math_or (byte *reg1,byte reg2)
{
*reg1|=reg2;
}
static void math_mov (byte *reg1,byte reg2)
{
*reg1=reg2;
}
static void math_nop (byte *reg1,byte reg2)
{
(void)reg1;
(void)reg2;
DBG_(printf("Warning: math nop!\n"));
}
static void math_and (byte *reg1,byte reg2)
{
*reg1&=reg2;
}
static void math_xor (byte *reg1,byte reg2)
{
*reg1^=reg2;
}
static void math_add (byte *reg1,byte reg2)
{
word tmp;
tmp=*reg1+reg2;
*reg1=(byte)tmp;
chip8_regs.alg[15]=tmp>>8;
}
static void math_sub (byte *reg1,byte reg2)
{
word tmp;
tmp=*reg1-reg2;
*reg1=(byte)tmp;
chip8_regs.alg[15]=((byte)(tmp>>8))+1;
}
static void math_shr (byte *reg1,byte reg2)
{
(void)reg2;
chip8_regs.alg[15]=*reg1&1;
*reg1>>=1;
}
static void math_shl (byte *reg1,byte reg2)
{
(void)reg2;
chip8_regs.alg[15]=*reg1>>7;
*reg1<<=1;
}
static void math_rsb (byte *reg1,byte reg2)
{
word tmp;
tmp=reg2-*reg1;
*reg1=(byte)tmp;
chip8_regs.alg[15]=((byte)(tmp>>8))+1;
}
#ifdef CHIP8_SUPER
/* SUPER: scroll down n lines (or half in CHIP8 mode) */
static void scroll_down(word opcode)
{
int n = opcode & 0xf;
byte *dst = chip8_display + CHIP8_WIDTH*CHIP8_HEIGHT -1;
byte *src = dst - n*CHIP8_WIDTH;
while(src >= chip8_display) {
*dst-- = *src--;
}
while(dst >= chip8_display) {
*dst-- = 0;
}
}
/* SUPER: scroll 4 pixels left! */
static void scroll_left(void)
{
byte *dst = chip8_display;
byte *src = dst;
byte *eol = chip8_display + CHIP8_WIDTH;
byte *eoi = chip8_display + CHIP8_WIDTH*CHIP8_HEIGHT;
while(eol <= eoi) {
src+=4;
while(src < eol) {
*dst++ = *src++;
}
*dst++ = 0;
*dst++ = 0;
*dst++ = 0;
*dst++ = 0;
eol += CHIP8_WIDTH;
}
}
static void scroll_right(void)
{
byte *dst = chip8_display + CHIP8_WIDTH*CHIP8_HEIGHT -1;
byte *src = dst;
byte *bol = chip8_display + CHIP8_WIDTH*(CHIP8_HEIGHT-1);
while(bol >= chip8_display) {
src-=4;
while(src >= bol) {
*dst-- = *src--;
}
*dst-- = 0;
*dst-- = 0;
*dst-- = 0;
*dst-- = 0;
bol -= CHIP8_WIDTH;
}
}
#endif
static void op_system (word opcode)
{
switch ((byte)opcode)
{
#ifdef CHIP8_SUPER
case 0xfb:
scroll_right();
break;
case 0xfc:
scroll_left();
break;
case 0xfd:
DBG_(printf("SUPER: quit the emulator\n"));
chip8_reset();
break;
case 0xfe:
DBG_(printf("SUPER: set CHIP-8 graphic mode\n"));
memset (chip8_display,0,sizeof(chip8_display));
chip8_super = 0;
break;
case 0xff:
DBG_(printf("SUPER: set SCHIP graphic mode\n"));
memset (chip8_display,0,sizeof(chip8_display));
chip8_super = 1;
break;
#endif
case 0xe0:
memset (chip8_display,0,sizeof(chip8_display));
break;
case 0xee:
chip8_regs.pc=read_mem(chip8_regs.sp)<<8;
chip8_regs.sp++;
chip8_regs.pc+=read_mem(chip8_regs.sp);
chip8_regs.sp++;
break;
default:
#ifdef CHIP8_SUPER
if ((opcode & 0xF0) == 0xC0)
scroll_down(opcode);
else
#endif
{
DBG_(printf("unhandled system opcode 0x%x\n", opcode));
chip8_running = 3;
}
break;
}
}
static void op_misc (word opcode)
{
byte *reg,i,j;
#ifdef CHIP8_DEBUG
static byte firstwait = 1;
#endif
reg=get_reg_offset(opcode);
switch ((byte)opcode)
{
case 0x07: /* gdelay */
*reg=chip8_regs.delay;
break;
case 0x0a: /* key */
#ifdef CHIP8_DEBUG
if(firstwait) {
printf("waiting for key press\n");
firstwait = 0;
}
#endif
if (chip8_key_pressed)
*reg=chip8_key_pressed-1;
else
chip8_regs.pc-=2;
break;
case 0x15: /* sdelay */
chip8_regs.delay=*reg;
break;
case 0x18: /* ssound */
chip8_regs.sound=*reg;
if (chip8_regs.sound)
chip8_sound_on();
break;
case 0x1e: /* adi */
chip8_regs.i+=(*reg);
break;
case 0x29: /* font */
chip8_regs.i=((word)(*reg&0x0f))*5;
break;
#ifdef CHIP8_SUPER
case 0x30: /* xfont */
chip8_regs.i=((word)(*reg&0x0f))*10+0x50;
break;
#endif
case 0x33: /* bcd */
i=*reg;
for (j=0;i>=100;i-=100)
j++;
write_mem (chip8_regs.i,j);
for (j=0;i>=10;i-=10)
j++;
write_mem (chip8_regs.i+1,j);
write_mem (chip8_regs.i+2,i);
break;
case 0x55: /* str */
for (i=0,j=(opcode>>8)&0x0f; i<=j; ++i)
write_mem(chip8_regs.i+i,chip8_regs.alg[i]);
break;
case 0x65: /* ldr */
for (i=0,j=(opcode>>8)&0x0f; i<=j; ++i)
chip8_regs.alg[i]=read_mem(chip8_regs.i+i);
break;
#ifdef CHIP8_SUPER
case 0x75:
DBG_(printf("SUPER: save V0..V%x (X<8) in the HP48 flags\n", (opcode>>8)&0x0f));
break;
case 0x85:
DBG_(printf("SUPER: load V0..V%x (X<8) from the HP48 flags\n", (opcode>>8)&0x0f));
break;
#endif
default:
DBG_(printf("unhandled misc opcode 0x%x\n", opcode));
break;
}
}
static void op_sprite (word opcode)
{
byte *q;
byte n,x,x2,y,collision;
word p;
x=get_reg_value(opcode);
y=get_reg_value_2(opcode);
p=chip8_regs.i;
n=opcode&0x0f;
#ifdef CHIP8_SUPER
if (chip8_super) {
/*printf("SUPER: sprite(%x)\n", opcode);*/
x &= 128-1;
y &= 64-1;
q=chip8_display+y*CHIP8_WIDTH;
if(n == 0)
{ /* 16x16 sprite */
n = 16;
if (n+y>64)
n=64-y;
for (collision=1;n;--n,q+=CHIP8_WIDTH)
{
/* first 8 bits */
for (y=read_mem(p++),x2=x;y;y<<=1,x2=(x2+1)&(CHIP8_WIDTH-1))
if (y&0x80)
collision&=(q[x2]^=0xff);
x2=(x+8)&(CHIP8_WIDTH-1);
/* last 8 bits */
for (y=read_mem(p++);y;y<<=1,x2=(x2+1)&(CHIP8_WIDTH-1))
if (y&0x80)
collision&=(q[x2]^=0xff);
}
}
else {
/* 8xn sprite */
if (n+y>64)
n=64-y;
for (collision=1;n;--n,q+=CHIP8_WIDTH)
{
for (y=read_mem(p++),x2=x;y;y<<=1,x2=(x2+1)&(CHIP8_WIDTH-1))
if (y&0x80)
collision&=(q[x2]^=0xff);
}
}
}
else {
x &= 64-1;
y &= 32-1;
q=chip8_display+y*CHIP8_WIDTH*2;
if(n == 0)
n = 16;
if (n+y>32)
n=32-y;
for (collision=1;n;--n,q+=CHIP8_WIDTH*2)
{
for (y=read_mem(p++),x2=x*2;y;y<<=1,x2=(x2+2)&(CHIP8_WIDTH-1))
if (y&0x80) {
q[x2]^=0xff;
q[x2+1]^=0xff;
q[x2+CHIP8_WIDTH]^=0xff;
q[x2+CHIP8_WIDTH+1]^=0xff;
collision &= q[x2]|q[x2+1]|q[x2+CHIP8_WIDTH]|q[x2+CHIP8_WIDTH+1];
}
}
}
#else
x &= 64-1;
y &= 32-1;
q=chip8_display+y*CHIP8_WIDTH;
if (n+y>32)
n=32-y;
for (collision=1;n;--n,q+=CHIP8_WIDTH)
{
for (y=read_mem(p++),x2=x;y;y<<=1,x2=(x2+1)&(CHIP8_WIDTH-1))
if (y&0x80)
collision&=(q[x2]^=0xff);
}
#endif
chip8_regs.alg[15]=collision^1;
}
static math_fn math_opcodes[16]=
{
math_mov,
math_or,
math_and,
math_xor,
math_add,
math_sub,
math_shr,
math_rsb,
math_nop,
math_nop,
math_nop,
math_nop,
math_nop,
math_nop,
math_shl,
math_nop
};
static void op_math (word opcode)
{
(*(math_opcodes[opcode&0x0f]))
(get_reg_offset(opcode),get_reg_value_2(opcode));
}
static opcode_fn main_opcodes[16]=
{
op_system,
op_jmp,
op_call,
op_skeq_const,
op_skne_const,
op_skeq_reg,
op_mov_const,
op_add_const,
op_math,
op_skne_reg,
op_mvi,
op_jmi,
op_rand,
op_sprite,
op_key,
op_misc
};
#ifdef CHIP8_DEBUG
STATIC byte chip8_trace;
STATIC word chip8_trap;
/****************************************************************************/
/* This routine is called every opcode when chip8_trace==1. It prints the */
/* current register contents and the opcode being executed */
/****************************************************************************/
STATIC void chip8_debug (word opcode,struct chip8_regs_struct *regs)
{
int i;
byte hextable[16] = "0123456789ABCDEF";
byte v1[3] = "Vx\0";
byte v2[3] = "Vx\0";
v1[1] = hextable[(opcode>>8)&0x0f];
v2[1] = hextable[(opcode>>8)&0x0f];
printf ("PC=%04X: %04X - ",regs->pc,opcode);
switch (opcode>>12) {
case 0:
if ((opcode&0xff0) == 0xc0) {
printf ("SCD %01X ; Scroll down n lines",opcode&0xf);
}
else switch (opcode&0xfff) {
case 0xe0:
printf ("CLS ; Clear screen");
break;
case 0xee:
printf ("RET ; Return from subroutine call");
break;
case 0xfb:
printf("SCR ; Scroll right");
break;
case 0xfc:
printf("SCL ; Scroll left");
break;
case 0xfd:
printf("EXIT ; Terminate the interpreter");
break;
case 0xfe:
printf("LOW ; Disable extended screen mode");
break;
case 0xff:
printf("HIGH ; Enable extended screen mode");
break;
default:
printf ("SYS %03X ; Unknown system call",opcode&0xff);
}
break;
case 1:
printf ("JP %03X ; Jump to address",opcode&0xfff);
break;
case 2:
printf ("CALL %03X ; Call subroutine",opcode&0xfff);
break;
case 3:
printf ("SE %s,%02X ; Skip if register == constant",v1,opcode&0xff);
break;
case 4:
printf ("SNE %s,%02X ; Skip if register <> constant",v1,opcode&0xff);
break;
case 5:
printf ("SE %s,%s ; Skip if register == register",v1,v2);
break;
case 6:
printf ("LD %s,%02X ; Set VX = Byte",v1,opcode&0xff);
break;
case 7:
printf ("ADD %s,%02X ; Set VX = VX + Byte",v1,opcode&0xff);
break;
case 8:
switch (opcode&0x0f) {
case 0:
printf ("LD %s,%s ; Set VX = VY, VF updates",v1,v2);
break;
case 1:
printf ("OR %s,%s ; Set VX = VX | VY, VF updates",v1,v2);
break;
case 2:
printf ("AND %s,%s ; Set VX = VX & VY, VF updates",v1,v2);
break;
case 3:
printf ("XOR %s,%s ; Set VX = VX ^ VY, VF updates",v1,v2);
break;
case 4:
printf ("ADD %s,%s ; Set VX = VX + VY, VF = carry",v1,v2);
break;
case 5:
printf ("SUB %s,%s ; Set VX = VX - VY, VF = !borrow",v1,v2);
break;
case 6:
printf ("SHR %s,%s ; Set VX = VX >> 1, VF = carry",v1,v2);
break;
case 7:
printf ("SUBN %s,%s ; Set VX = VY - VX, VF = !borrow",v1,v2);
break;
case 14:
printf ("SHL %s,%s ; Set VX = VX << 1, VF = carry",v1,v2);
break;
default:
printf ("Illegal opcode");
}
break;
case 9:
printf ("SNE %s,%s ; Skip next instruction iv VX!=VY",v1,v2);
break;
case 10:
printf ("LD I,%03X ; Set I = Addr",opcode&0xfff);
break;
case 11:
printf ("JP V0,%03X ; Jump to Addr + V0",opcode&0xfff);
break;
case 12:
printf ("RND %s,%02X ; Set VX = random & Byte",v1,opcode&0xff);
break;
case 13:
printf ("DRW %s,%s,%X ; Draw n byte sprite stored at [i] at VX,VY. Set VF = collision",v1,v2,opcode&0x0f);
break;
case 14:
switch (opcode&0xff) {
case 0x9e:
printf ("SKP %s ; Skip next instruction if key VX down",v1);
break;
case 0xa1:
printf ("SKNP %s ; Skip next instruction if key VX up",v1);
break;
default:
printf ("%04X ; Illegal opcode", opcode);
}
break;
case 15:
switch (opcode&0xff) {
case 0x07:
printf ("LD %s,DT ; Set VX = delaytimer",v1);
break;
case 0x0a:
printf ("LD %s,K ; Set VX = key, wait for keypress",v1);
break;
case 0x15:
printf ("LD DT,%s ; Set delaytimer = VX",v1);
break;
case 0x18:
printf ("LD ST,%s ; Set soundtimer = VX",v1);
break;
case 0x1e:
printf ("ADD I,%s ; Set I = I + VX",v1);
break;
case 0x29:
printf ("LD LF,%s ; Point I to 5 byte numeric sprite for value in VX",v1);
break;
case 0x30:
printf ("LD HF,%s ; Point I to 10 byte numeric sprite for value in VX",v1);
break;
case 0x33:
printf ("LD B,%s ; Store BCD of VX in [I], [I+1], [I+2]",v1);
break;
case 0x55:
printf ("LD [I],%s ; Store V0..VX in [I]..[I+X]",v1);
break;
case 0x65:
printf ("LD %s,[I] ; Read V0..VX from [I]..[I+X]",v1);
break;
case 0x75:
printf ("LD R,%s ; Store V0..VX in RPL user flags (X<=7)",v1);
break;
case 0x85:
printf ("LD %s,R ; Read V0..VX from RPL user flags (X<=7)",v1);
break;
default:
printf ("%04X ; Illegal opcode", opcode);
}
break;
}
printf ("\n; Registers: ");
for (i=0;i<16;++i) printf ("%02x ",(regs->alg[i])&0xff);
printf ("\n; Index: %03x Stack:%03x Delay:%02x Sound:%02x\n",
regs->i&0xfff,regs->sp&0xfff,regs->delay&0xff,regs->sound&0xff);
}
#endif
/****************************************************************************/
/* Execute chip8_iperiod opcodes */
/****************************************************************************/
STATIC void chip8_execute(void)
{
byte i;
byte key_pressed=0;
word opcode;
for (i = chip8_iperiod ; i ;--i)
{
/* Fetch the opcode */
opcode=(read_mem(chip8_regs.pc)<<8)+read_mem(chip8_regs.pc+1);
#ifdef CHIP8_DEBUG
/* Check if trap address has been reached */
if ((chip8_regs.pc&4095)==chip8_trap)
chip8_trace=1;
/* Call the debugger if chip8_trace!=0 */
if (chip8_trace)
chip8_debug (opcode,&chip8_regs);
#endif
chip8_regs.pc+=2;
(*(main_opcodes[opcode>>12]))(opcode&0x0fff); /* Emulate this opcode */
}
/* Update timers */
if (chip8_regs.delay)
--chip8_regs.delay;
if (chip8_regs.sound)
if (--chip8_regs.sound == 0)
chip8_sound_off();
/* Update the machine status */
chip8_interrupt ();
for (i=key_pressed=0;i<16;++i) /* check if a key was first */
if (chip8_keys[i]) /* pressed */
key_pressed=i+1;
if (key_pressed && key_pressed!=chip8_key_pressed)
chip8_key_pressed=key_pressed;
else
chip8_key_pressed=0;
}
/****************************************************************************/
/* Reset the virtual chip8 machine */
/****************************************************************************/
STATIC void chip8_reset(void)
{
static byte chip8_sprites[0x50]=
{
0xf9,0x99,0xf2,0x62,0x27,
0xf1,0xf8,0xff,0x1f,0x1f,
0x99,0xf1,0x1f,0x8f,0x1f,
0xf8,0xf9,0xff,0x12,0x44,
0xf9,0xf9,0xff,0x9f,0x1f,
0xf9,0xf9,0x9e,0x9e,0x9e,
0xf8,0x88,0xfe,0x99,0x9e,
0xf8,0xf8,0xff,0x8f,0x88,
}; /* 4x5 pixel hexadecimal character font patterns */
#ifdef CHIP8_SUPER
static byte schip_sprites[10*10]=
{
0x3C, 0x7E, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0x7E, 0x3C, /* 0 */
0x18, 0x38, 0x58, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x3C, /* 1 */
0x3E, 0x7F, 0xC3, 0x06, 0x0C, 0x18, 0x30, 0x60, 0xFF, 0xFF, /* 2 */
0x3C, 0x7E, 0xC3, 0x03, 0x0E, 0x0E, 0x03, 0xC3, 0x7E, 0x3C, /* 3 */
0x06, 0x0E, 0x1E, 0x36, 0x66, 0xC6, 0xFF, 0xFF, 0x06, 0x06, /* 4 */
0xFF, 0xFF, 0xC0, 0xC0, 0xFC, 0xFE, 0x03, 0xC3, 0x7E, 0x3C, /* 5 */
0x3E, 0x7C, 0xC0, 0xC0, 0xFC, 0xFE, 0xC3, 0xC3, 0x7E, 0x3C, /* 6 */
0xFF, 0xFF, 0x03, 0x06, 0x0C, 0x18, 0x30, 0x60, 0x60, 0x60, /* 7 */
0x3C, 0x7E, 0xC3, 0xC3, 0x7E, 0x7E, 0xC3, 0xC3, 0x7E, 0x3C, /* 8 */
0x3C, 0x7E, 0xC3, 0xC3, 0x7F, 0x3F, 0x03, 0x03, 0x3E, 0x7C, /* 9 */
}; /* 8x10 pixel font patterns (only 10) */
#endif
byte i;
for (i=0;i<16*5;++i)
{
write_mem (i<<1,chip8_sprites[i]&0xf0);
write_mem ((i<<1)+1,chip8_sprites[i]<<4);
}
#ifdef CHIP8_SUPER
/*
for (i=0; i<100; i++)
write_mem (i+0x50,schip_sprites[i]);
*/
memcpy(chip8_mem+0x50, schip_sprites, 100);
chip8_super = 0;
#endif
memset (chip8_regs.alg,0,sizeof(chip8_regs.alg));
memset (chip8_keys,0,sizeof(chip8_keys));
chip8_key_pressed=0;
memset (chip8_display,0,sizeof(chip8_display));
chip8_regs.delay=chip8_regs.sound=chip8_regs.i=0;
chip8_regs.sp=0x1e0;
chip8_regs.pc=0x200;
chip8_sound_off ();
chip8_running=1;
#ifdef CHIP8_DEBUG
chip8_trace=0;
#endif
}
/****************************************************************************/
/* Start CHIP8 emulation */
/****************************************************************************/
STATIC void chip8 (void)
{
chip8_reset ();
while (chip8_running==1) chip8_execute ();
}
/****************************************************************************/
/** END OF (S)CHIP-8 core emulation, from Vision-8 + mods by Fdy **/
/****************************************************************************/
/* size of the displayed area */
#if (CHIP8_WIDTH == 128) && (LCD_WIDTH < 128)
#define CHIP8_LCDWIDTH 112
#else
#define CHIP8_LCDWIDTH CHIP8_WIDTH
#endif
#if (LCD_WIDTH > CHIP8_LCDWIDTH)
#define CHIP8_X ((LCD_WIDTH - CHIP8_LCDWIDTH)/2)
#else
#define CHIP8_X 0
#endif
#if (LCD_HEIGHT > CHIP8_HEIGHT)
#define CHIP8_Y (((LCD_HEIGHT - CHIP8_HEIGHT)>>4)<<3)
#else
#define CHIP8_Y 0
#endif
/* variable button definitions */
#if CONFIG_KEYPAD == RECORDER_PAD /* only 9 out of 16 chip8 buttons */
#define CHIP8_OFF BUTTON_OFF
#define CHIP8_KEY1 BUTTON_F1
#define CHIP8_KEY2 BUTTON_UP
#define CHIP8_KEY3 BUTTON_F3
#define CHIP8_KEY4 BUTTON_LEFT
#define CHIP8_KEY5 BUTTON_PLAY
#define CHIP8_KEY6 BUTTON_RIGHT
#define CHIP8_KEY7 BUTTON_F2
#define CHIP8_KEY8 BUTTON_DOWN
#define CHIP8_KEY9 BUTTON_ON
#elif CONFIG_KEYPAD == ONDIO_PAD /* even more limited */
#define CHIP8_OFF BUTTON_OFF
#define CHIP8_KEY2 BUTTON_UP
#define CHIP8_KEY4 BUTTON_LEFT
#define CHIP8_KEY5 BUTTON_MENU
#define CHIP8_KEY6 BUTTON_RIGHT
#define CHIP8_KEY8 BUTTON_DOWN
#elif (CONFIG_KEYPAD == IRIVER_H100_PAD) || \
(CONFIG_KEYPAD == IRIVER_H300_PAD)
#define CHIP8_OFF BUTTON_OFF
#define CHIP8_KEY2 BUTTON_UP
#define CHIP8_KEY4 BUTTON_LEFT
#define CHIP8_KEY5 BUTTON_SELECT
#define CHIP8_KEY6 BUTTON_RIGHT
#define CHIP8_KEY8 BUTTON_DOWN
#define CHIP8_RC_OFF BUTTON_RC_STOP
#elif (CONFIG_KEYPAD == IPOD_4G_PAD) || \
(CONFIG_KEYPAD == IPOD_3G_PAD)
#define CHIP8_OFF BUTTON_MENU
#define CHIP8_KEY2 BUTTON_SCROLL_BACK
#define CHIP8_KEY4 BUTTON_LEFT
#define CHIP8_KEY5 BUTTON_PLAY
#define CHIP8_KEY6 BUTTON_RIGHT
#define CHIP8_KEY8 BUTTON_SCROLL_FWD
#elif (CONFIG_KEYPAD == IAUDIO_X5_PAD)
#define CHIP8_OFF BUTTON_POWER
#define CHIP8_KEY2 BUTTON_UP
#define CHIP8_KEY4 BUTTON_LEFT
#define CHIP8_KEY5 BUTTON_SELECT
#define CHIP8_KEY6 BUTTON_RIGHT
#define CHIP8_KEY8 BUTTON_DOWN
#elif (CONFIG_KEYPAD == GIGABEAT_PAD)
#define CHIP8_OFF BUTTON_A
#define CHIP8_KEY2 BUTTON_UP
#define CHIP8_KEY4 BUTTON_LEFT
#define CHIP8_KEY5 BUTTON_MENU
#define CHIP8_KEY6 BUTTON_RIGHT
#define CHIP8_KEY8 BUTTON_DOWN
#elif (CONFIG_KEYPAD == IRIVER_H10_PAD)
#define CHIP8_OFF BUTTON_POWER
#define CHIP8_KEY2 BUTTON_SCROLL_UP
#define CHIP8_KEY4 BUTTON_LEFT
#define CHIP8_KEY5 BUTTON_PLAY
#define CHIP8_KEY6 BUTTON_RIGHT
#define CHIP8_KEY8 BUTTON_SCROLL_DOWN
#endif
static byte chip8_virtual_keys[16];
static byte chip8_keymap[16];
static unsigned long starttimer; /* Timer value at the beginning */
static unsigned long cycles; /* Number of update cycles (50Hz) */
#ifndef SIMULATOR
static bool is_playing;
#endif
/* one frame of bitswapped mp3 data */
static unsigned char beep[]={255,
223, 28, 35, 0,192,210, 35,226, 72,188,242, 1,128,166, 16, 68,146,252,151, 19,
10,180,245,127, 96,184, 3,184, 30, 0,118, 59,128,121,102, 6,212, 0, 97, 6,
42, 65, 28,134,192,145, 57, 38,136, 73, 29, 38,132, 15, 21, 70, 91,185, 99,198,
15,192, 83, 6, 33,129, 20, 6, 97, 33, 4, 6,245,128, 92, 6, 24, 0, 86, 6,
56,129, 44, 24,224, 25, 13, 48, 50, 82,180, 11,251,106,249, 59, 24, 82,175,223,
252,119, 76,134,120,236,149,250,247,115,254,145,173,174,168,180,255,107,195, 89,
24, 25, 48,131,192, 61, 48, 64, 10,176, 49, 64, 1,152, 50, 32, 8,140, 48, 16,
5,129, 51,196,187, 41,177, 23,138, 70, 50, 8, 10,242, 48,192, 3,248,226, 0,
20,100, 18, 96, 41, 96, 78,102, 7,201,122, 76,119, 20,137, 37,177, 15,132,224,
20, 17,191, 67,147,187,116,211, 41,169, 63,172,182,186,217,155,111,140,104,254,
111,181,184,144, 17,148, 21,101,166,227,100, 86, 85, 85, 85};
/* callback to request more mp3 data */
void callback(unsigned char** start, int* size)
{
*start = beep; /* give it the same frame again */
*size = sizeof(beep);
}
/****************************************************************************/
/* Turn sound on */
/****************************************************************************/
static void chip8_sound_on (void)
{
#ifndef SIMULATOR
if (!is_playing)
rb->mp3_play_pause(true); /* kickoff audio */
#endif
}
/****************************************************************************/
/* Turn sound off */
/****************************************************************************/
static void chip8_sound_off (void)
{
#ifndef SIMULATOR
if (!is_playing)
rb->mp3_play_pause(false); /* pause audio */
#endif
}
/****************************************************************************/
/* Update the display */
/****************************************************************************/
static void chip8_update_display(void)
{
int x, lcd_x, y, i;
byte w;
byte* row;
/* frame buffer in hardware fomat */
unsigned char lcd_framebuf[CHIP8_HEIGHT/8][CHIP8_LCDWIDTH];
for (y=0;y<CHIP8_HEIGHT/8;++y)
{
row = lcd_framebuf[y];
for (x=0, lcd_x=0;x<CHIP8_WIDTH;++x,++lcd_x)
{
w = 0;
for (i=0;i<8;i++)
{
w = w >> 1;
if (chip8_display[x+(y*8+i)*CHIP8_WIDTH] != 0)
{
w += 128;
}
}
#if (CHIP8_LCDWIDTH < 128) /* LCD_WIDTH between 112 and 127 */
if (x%8 == 1) {
row[-1] |= w; /* overlay on */
}
else
#endif
*row++ = w;
}
}
#if defined(SIMULATOR) || (LCD_DEPTH > 1)
rb->lcd_set_drawmode(DRMODE_SOLID);
rb->lcd_mono_bitmap(lcd_framebuf[0], CHIP8_X, CHIP8_Y, CHIP8_LCDWIDTH, CHIP8_HEIGHT);
rb->lcd_update();
#else
rb->lcd_blit(lcd_framebuf[0], CHIP8_X, CHIP8_Y>>3, CHIP8_LCDWIDTH, CHIP8_HEIGHT>>3
, CHIP8_LCDWIDTH);
#endif
}
static void chip8_keyboard(void)
{
int i;
int button = rb->button_get(false);
switch (button)
{
#ifdef CHIP8_RC_OFF
case CHIP8_RC_OFF:
#endif
case CHIP8_OFF: /* Abort Emulator */
chip8_running = 0;
break;
case CHIP8_KEY2: chip8_virtual_keys[2] = 1; break;
case CHIP8_KEY2 | BUTTON_REL: chip8_virtual_keys[2] = 0; break;
case CHIP8_KEY4: chip8_virtual_keys[4] = 1; break;
case CHIP8_KEY4 | BUTTON_REL: chip8_virtual_keys[4] = 0; break;
case CHIP8_KEY6: chip8_virtual_keys[6] = 1; break;
case CHIP8_KEY6 | BUTTON_REL: chip8_virtual_keys[6] = 0; break;
case CHIP8_KEY8: chip8_virtual_keys[8] = 1; break;
case CHIP8_KEY8 | BUTTON_REL: chip8_virtual_keys[8] = 0; break;
case CHIP8_KEY5: chip8_virtual_keys[5] = 1; break;
case CHIP8_KEY5 | BUTTON_REL: chip8_virtual_keys[5] = 0; break;
#ifdef CHIP8_KEY1
case CHIP8_KEY1: chip8_virtual_keys[1] = 1; break;
case CHIP8_KEY1 | BUTTON_REL: chip8_virtual_keys[1] = 0; break;
#endif
#ifdef CHIP8_KEY3
case CHIP8_KEY3: chip8_virtual_keys[3] = 1; break;
case CHIP8_KEY3 | BUTTON_REL: chip8_virtual_keys[3] = 0; break;
#endif
#ifdef CHIP8_KEY7
case CHIP8_KEY7: chip8_virtual_keys[7] = 1; break;
case CHIP8_KEY7 | BUTTON_REL: chip8_virtual_keys[7] = 0; break;
#endif
#ifdef CHIP8_KEY9
case CHIP8_KEY9: chip8_virtual_keys[9] = 1; break;
case CHIP8_KEY9 | BUTTON_REL: chip8_virtual_keys[9] = 0; break;
#endif
default:
if (rb->default_event_handler(button) == SYS_USB_CONNECTED)
chip8_running = 2; /* indicates stopped because of USB */
break;
}
for(i=0; i<16; i++) {
chip8_keys[i] = chip8_virtual_keys[chip8_keymap[i]];
}
}
/****************************************************************************/
/* Update keyboard and display, sync emulation with VDP clock */
/****************************************************************************/
static void chip8_interrupt (void)
{
unsigned long newtimer;
unsigned long timer, runtime;
chip8_update_display();
chip8_keyboard();
cycles ++;
runtime = cycles * HZ / 50;
timer = starttimer + runtime;
newtimer = *rb->current_tick;
if (TIME_AFTER(timer, newtimer))
{
rb->sleep(timer - newtimer);
}
else
{
rb->yield();
}
starttimer = newtimer - runtime;
}
static bool chip8_init(char* file)
{
int numread;
int fd;
int len;
int i;
fd = rb->open(file, O_RDONLY);
if (fd==-1) {
rb->lcd_puts(0, 6, "File Error.");
return false;
}
numread = rb->read(fd, chip8_mem+0x200, 4096-0x200);
if (numread==-1) {
rb->lcd_puts(0, 6, "I/O Error.");
return false;
}
rb->close(fd);
/* is there a c8k file (chip8 keys) ? */
for(i=0; i<16; i++) {
chip8_virtual_keys[i] = 0;
chip8_keymap[i] = i;
}
len = rb->strlen(file);
file[len-2] = '8';
file[len-1] = 'k';
fd = rb->open(file, O_RDONLY);
if (fd!=-1) {
rb->lcd_puts(0, 6, "File&Keymap OK.");
numread = rb->read(fd, chip8_keymap, 16);
rb->close(fd);
}
else
{
rb->lcd_puts(0, 6, "File OK.");
}
for(i=0; i<16; i++) {
if (chip8_keymap[i] >= '0'
&& chip8_keymap[i] <= '9')
chip8_keymap[i] -= '0';
else if (chip8_keymap[i] >= 'A'
&& chip8_keymap[i] <= 'F')
chip8_keymap[i] -= 'A' - 10;
else if (chip8_keymap[i] >= 'a'
&& chip8_keymap[i] <= 'f')
chip8_keymap[i] -= 'a' - 10;
else
chip8_keymap[i] %= 16;
}
return true;
}
bool chip8_run(char* file)
{
int ok;
rb->lcd_clear_display();
rb->lcd_puts(0, 0, "SChip8 Emulator");
rb->lcd_puts(0, 1, " (c) by ");
rb->lcd_puts(0, 2, "Marcel de Kogel");
rb->lcd_puts(0, 3, " Rockbox: ");
rb->lcd_puts(0, 4, " Blueloop/Fdy ");
rb->lcd_puts(0, 5, "---------------");
ok = chip8_init(file);
rb->lcd_update();
rb->sleep(HZ*1);
if (!ok)
return false;
rb->lcd_clear_display();
#if (CHIP8_X > 0) && (CHIP8_Y > 0)
rb->lcd_drawrect(CHIP8_X-1,CHIP8_Y-1,CHIP8_LCDWIDTH+2,CHIP8_HEIGHT+2);
#endif
rb->lcd_update();
#ifndef SIMULATOR
/* init sound */
is_playing = rb->mp3_is_playing(); /* would we disturb playback? */
if (!is_playing) /* no? then we can make sound */
{ /* prepare */
rb->mp3_play_data(beep, sizeof(beep), callback);
}
#endif
starttimer = *rb->current_tick;
chip8_iperiod=15;
cycles = 0;
chip8();
if (!ok) {
rb->splash(HZ, true, "Error");
return false;
}
#ifndef SIMULATOR
if (!is_playing)
{ /* stop it if we used audio */
rb->mp3_play_stop(); /* Stop audio playback */
}
#endif
if (chip8_running == 3) {
/* unsupported instruction */
rb->splash(HZ, true, "Error: Unsupported"
#ifndef CHIP8_SUPER
" CHIP-8 instruction. (maybe S-CHIP)"
#else
" (S)CHIP-8 instruction."
#endif
);
return false;
}
return true;
}
/***************** Plugin Entry Point *****************/
enum plugin_status plugin_start(struct plugin_api* api, void* parameter)
{
char* filename;
rb = api; /* copy to global api pointer */
if (parameter == NULL)
{
rb->splash(HZ, true, "Play a .ch8 file!");
return PLUGIN_ERROR;
}
else
{
filename = (char*) parameter;
}
/* now go ahead and have fun! */
if (chip8_run(filename))
if (chip8_running == 0)
return PLUGIN_OK;
else
return PLUGIN_USB_CONNECTED;
else
return PLUGIN_ERROR;
}
#endif /* #ifdef HAVE_LCD_BITMAP */
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