from request #628509: ported the Chip-8 emulator as a plugin
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@3996 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Jörg Hohensohn
parent
d8b31814c7
commit
0860a4d6d1
1 changed files with 553 additions and 0 deletions
553
apps/plugins/chip8.c
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553
apps/plugins/chip8.c
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/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Orginal from Vision-8 Emulator / Copyright (C) 1997-1999 Marcel de Kogel
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* Modified for Archos by Blueloop (a.wenger@gmx.de)
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*
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* All files in this archive are subject to the GNU General Public License.
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* See the file COPYING in the source tree root for full license agreement.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "plugin.h"
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/* Only build for (correct) target */
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#ifndef SIMULATOR
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#ifdef HAVE_LCD_BITMAP
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static struct plugin_api* rb; /* here is a global api struct pointer */
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/* plugins have no framebuffer access, we need a copy */
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unsigned char lcd_framebuf[8][64];
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typedef unsigned char byte; /* sizeof(byte)==1 */
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typedef unsigned short word; /* sizeof(word)>=2 */
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struct chip8_regs_struct
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{
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byte alg[16]; /* 16 general registers */
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byte delay,sound; /* delay and sound timer */
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word i; /* index register */
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word pc; /* program counter */
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word sp; /* stack pointer */
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};
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static struct chip8_regs_struct chip8_regs;
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#define chip8_iperiod 10 /* number of opcodes per */
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/* timeslice (1/50sec.) */
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static byte chip8_key_pressed;
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static byte chip8_keys[16]; /* if 1, key is held down */
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static byte chip8_display[64*32]; /* 0xff if pixel is set, */
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/* 0x00 otherwise */
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static byte chip8_mem[4096]; /* machine memory. program */
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/* is loaded at 0x200 */
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#define read_mem(a) (chip8_mem[(a)&4095])
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#define write_mem(a,v) (chip8_mem[(a)&4095]=(v))
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static byte chip8_running; /* Flag for End-of-Emulation */
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#define get_reg_offset(opcode) (chip8_regs.alg+(opcode>>8))
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#define get_reg_value(opcode) (*get_reg_offset(opcode))
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#define get_reg_offset_2(opcode) (chip8_regs.alg+((opcode>>4)&0x0f))
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#define get_reg_value_2(opcode) (*get_reg_offset_2(opcode))
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typedef void (*opcode_fn) (word opcode);
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typedef void (*math_fn) (byte *reg1,byte reg2);
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/****************************************************************************/
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/* Turn sound on */
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/****************************************************************************/
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static void chip8_sound_on (void) { }
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/****************************************************************************/
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/* Turn sound off */
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/****************************************************************************/
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static void chip8_sound_off (void) { }
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static void op_call (word opcode)
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{
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chip8_regs.sp--;
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write_mem (chip8_regs.sp,chip8_regs.pc&0xff);
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chip8_regs.sp--;
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write_mem (chip8_regs.sp,chip8_regs.pc>>8);
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chip8_regs.pc=opcode;
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}
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static void op_jmp (word opcode)
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{
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chip8_regs.pc=opcode;
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}
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static void op_key (word opcode)
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{
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byte key_value,cp_value;
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if ((opcode&0xff)==0x9e)
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cp_value=1;
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else if ((opcode&0xff)==0xa1)
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cp_value=0;
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else
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return;
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key_value=chip8_keys[get_reg_value(opcode)&0x0f];
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if (cp_value==key_value) chip8_regs.pc+=2;
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}
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static void op_skeq_const (word opcode)
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{
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if (get_reg_value(opcode)==(opcode&0xff)) chip8_regs.pc+=2;
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}
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static void op_skne_const (word opcode)
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{
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if (get_reg_value(opcode)!=(opcode&0xff)) chip8_regs.pc+=2;
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}
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static void op_skeq_reg (word opcode)
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{
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if (get_reg_value(opcode)==get_reg_value_2(opcode)) chip8_regs.pc+=2;
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}
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static void op_skne_reg (word opcode)
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{
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if (get_reg_value(opcode)!=get_reg_value_2(opcode)) chip8_regs.pc+=2;
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}
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static void op_mov_const (word opcode)
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{
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*get_reg_offset(opcode)=opcode&0xff;
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}
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static void op_add_const (word opcode)
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{
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*get_reg_offset(opcode)+=opcode&0xff;
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}
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static void op_mvi (word opcode)
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{
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chip8_regs.i=opcode;
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}
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static void op_jmi (word opcode)
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{
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chip8_regs.pc=opcode+chip8_regs.alg[0];
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}
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static void op_rand (word opcode)
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{
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*get_reg_offset(opcode)=rb->rand()&(opcode&0xff);
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}
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static void math_or (byte *reg1,byte reg2)
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{
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*reg1|=reg2;
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}
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static void math_mov (byte *reg1,byte reg2)
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{
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*reg1=reg2;
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}
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static void math_nop (byte *reg1,byte reg2)
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{
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(void)reg1;
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(void)reg2;
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}
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static void math_and (byte *reg1,byte reg2)
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{
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*reg1&=reg2;
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}
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static void math_xor (byte *reg1,byte reg2)
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{
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*reg1^=reg2;
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}
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static void math_add (byte *reg1,byte reg2)
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{
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word tmp;
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tmp=*reg1+reg2;
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*reg1=(byte)tmp;
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chip8_regs.alg[15]=tmp>>8;
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}
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static void math_sub (byte *reg1,byte reg2)
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{
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word tmp;
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tmp=*reg1-reg2;
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*reg1=(byte)tmp;
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chip8_regs.alg[15]=((byte)(tmp>>8))+1;
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}
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static void math_shr (byte *reg1,byte reg2)
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{
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(void)reg2;
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chip8_regs.alg[15]=*reg1&1;
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*reg1>>=1;
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}
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static void math_shl (byte *reg1,byte reg2)
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{
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(void)reg2;
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chip8_regs.alg[15]=*reg1>>7;
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*reg1<<=1;
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}
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static void math_rsb (byte *reg1,byte reg2)
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{
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word tmp;
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tmp=reg2-*reg1;
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*reg1=(byte)tmp;
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chip8_regs.alg[15]=((byte)(tmp>>8))+1;
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}
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static void op_system (word opcode)
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{
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switch ((byte)opcode)
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{
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case 0xe0:
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rb->memset (chip8_display,0,sizeof(chip8_display));
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break;
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case 0xee:
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chip8_regs.pc=read_mem(chip8_regs.sp)<<8;
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chip8_regs.sp++;
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chip8_regs.pc+=read_mem(chip8_regs.sp);
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chip8_regs.sp++;
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break;
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}
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}
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static void op_misc (word opcode)
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{
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byte *reg,i,j;
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reg=get_reg_offset(opcode);
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switch ((byte)opcode)
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{
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case 0x07:
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*reg=chip8_regs.delay;
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break;
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case 0x0a:
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if (chip8_key_pressed)
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*reg=chip8_key_pressed-1;
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else
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chip8_regs.pc-=2;
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break;
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case 0x15:
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chip8_regs.delay=*reg;
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break;
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case 0x18:
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chip8_regs.sound=*reg;
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if (chip8_regs.sound) chip8_sound_on();
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break;
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case 0x1e:
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chip8_regs.i+=(*reg);
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break;
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case 0x29:
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chip8_regs.i=((word)(*reg&0x0f))*5;
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break;
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case 0x33:
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i=*reg;
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for (j=0;i>=100;i-=100) j++;
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write_mem (chip8_regs.i,j);
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for (j=0;i>=10;i-=10) j++;
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write_mem (chip8_regs.i+1,j);
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write_mem (chip8_regs.i+2,i);
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break;
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case 0x55:
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for (i=0,j=(opcode>>8)&0x0f;i<=j;++i)
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write_mem(chip8_regs.i+i,chip8_regs.alg[i]);
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break;
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case 0x65:
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for (i=0,j=(opcode>>8)&0x0f;i<=j;++i)
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chip8_regs.alg[i]=read_mem(chip8_regs.i+i);
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break;
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}
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}
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static void op_sprite (word opcode)
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{
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byte *q;
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byte n,x,x2,y,collision;
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word p;
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x=get_reg_value(opcode)&63;
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y=get_reg_value_2(opcode)&31;
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p=chip8_regs.i;
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q=chip8_display+y*64;
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n=opcode&0x0f;
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if (n+y>32) n=32-y;
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for (collision=1;n;--n,q+=64)
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{
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for (y=read_mem(p++),x2=x;y;y<<=1,x2=(x2+1)&63)
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if (y&0x80) collision&=(q[x2]^=0xff);
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}
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chip8_regs.alg[15]=collision^1;
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}
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static math_fn math_opcodes[16]=
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{
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math_mov,
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math_or,
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math_and,
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math_xor,
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math_add,
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math_sub,
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math_shr,
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math_rsb,
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math_nop,
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math_nop,
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math_nop,
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math_nop,
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math_nop,
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math_nop,
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math_shl,
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math_nop
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};
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static void op_math (word opcode)
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{
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(*(math_opcodes[opcode&0x0f]))
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(get_reg_offset(opcode),get_reg_value_2(opcode));
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}
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static opcode_fn main_opcodes[16]=
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{
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op_system,
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op_jmp,
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op_call,
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op_skeq_const,
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op_skne_const,
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op_skeq_reg,
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op_mov_const,
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op_add_const,
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op_math,
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op_skne_reg,
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op_mvi,
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op_jmi,
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op_rand,
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op_sprite,
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op_key,
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op_misc
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};
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/****************************************************************************/
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/* Update the display */
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/****************************************************************************/
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static void chip8_update_display(void)
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{
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int x,y,i;
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byte w;
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// lcd_clear_display();
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for (y=0;y<=7;++y) /* 32 rows */
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{
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for (x=0;x<64;++x) /* 64 columns */
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{
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w = 0;
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for (i=0;i<=3;i++)
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{
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w = w >> 2;
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if (chip8_display[x+(y*4+i)*64] != 0)
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{
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w += 128+64;
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}
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lcd_framebuf[y][x] = w;
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}
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}
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}
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rb->lcd_bitmap(lcd_framebuf[0], 24, 0*8, 64, 8, true);
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rb->lcd_bitmap(lcd_framebuf[1], 24, 1*8, 64, 8, true);
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rb->lcd_bitmap(lcd_framebuf[2], 24, 2*8, 64, 8, true);
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rb->lcd_bitmap(lcd_framebuf[3], 24, 3*8, 64, 8, true);
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rb->lcd_bitmap(lcd_framebuf[4], 24, 4*8, 64, 8, true);
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rb->lcd_bitmap(lcd_framebuf[5], 24, 5*8, 64, 8, true);
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rb->lcd_bitmap(lcd_framebuf[6], 24, 6*8, 64, 8, true);
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rb->lcd_bitmap(lcd_framebuf[7], 24, 7*8, 64, 8, true);
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rb->lcd_update_rect(24,0,64,64);
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}
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static void chip8_keyboard(void)
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{
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switch (rb->button_get(false))
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{
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case BUTTON_OFF: /* Abort Emulator */
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chip8_running = false;
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break;
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case BUTTON_UP: chip8_keys[2] = 1; break;
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case BUTTON_UP | BUTTON_REL: chip8_keys[2] = 0; break;
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case BUTTON_LEFT: chip8_keys[4] = 1; break;
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case BUTTON_LEFT | BUTTON_REL: chip8_keys[4] = 0; break;
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case BUTTON_RIGHT: chip8_keys[6] = 1; break;
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case BUTTON_RIGHT | BUTTON_REL: chip8_keys[6] = 0; break;
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case BUTTON_DOWN: chip8_keys[8] = 1; break;
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case BUTTON_DOWN | BUTTON_REL: chip8_keys[8] = 0; break;
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case BUTTON_PLAY: chip8_keys[5] = 1; break;
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case BUTTON_PLAY | BUTTON_REL: chip8_keys[5] = 0; break;
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case BUTTON_F1: chip8_keys[1] = 1; break;
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case BUTTON_F1 | BUTTON_REL: chip8_keys[1] = 0; break;
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case BUTTON_F2: chip8_keys[7] = 1; break;
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case BUTTON_F2 | BUTTON_REL: chip8_keys[7] = 0; break;
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case BUTTON_F3: chip8_keys[3] = 1; break;
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case BUTTON_F3 | BUTTON_REL: chip8_keys[3] = 0; break;
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case BUTTON_ON: chip8_keys[9] = 1; break;
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case BUTTON_ON | BUTTON_REL: chip8_keys[9] = 0; break;
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case SYS_USB_CONNECTED:
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#ifdef HAVE_LCD_CHARCELLS
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status_set_param(false);
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#endif
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chip8_running = false;
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break;
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}
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}
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/****************************************************************************/
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/* Execute chip8_iperiod opcodes */
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/****************************************************************************/
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static void chip8_execute(void)
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{
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byte i;
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byte key_pressed=0;
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word opcode;
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for (i = chip8_iperiod ; i ;--i)
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{ /* Fetch the opcode */
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opcode=(read_mem(chip8_regs.pc)<<8)+read_mem(chip8_regs.pc+1);
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chip8_regs.pc+=2;
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(*(main_opcodes[opcode>>12]))(opcode&0x0fff); /* Emulate this opcode */
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}
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/* Update timers */
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if (chip8_regs.delay) --chip8_regs.delay;
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if (chip8_regs.sound) --chip8_regs.sound; /* How could we make sound on the archos? */
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/* Update the machine status */
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chip8_update_display();
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chip8_keyboard();
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rb->sleep(HZ/70); /* ca. 70Hz */
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for (i=key_pressed=0;i<16;++i) /* check if a key was first */
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if (chip8_keys[i]) key_pressed=i+1; /* pressed */
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if (key_pressed && key_pressed!=chip8_key_pressed)
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chip8_key_pressed=key_pressed;
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else
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chip8_key_pressed=0;
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}
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/****************************************************************************/
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/* Reset the virtual chip8 machine */
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/****************************************************************************/
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static void chip8_reset(void)
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{
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static byte chip8_sprites[16*5]=
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{
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0xf9,0x99,0xf2,0x62,0x27,
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0xf1,0xf8,0xff,0x1f,0x1f,
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0x99,0xf1,0x1f,0x8f,0x1f,
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0xf8,0xf9,0xff,0x12,0x44,
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0xf9,0xf9,0xff,0x9f,0x1f,
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0xf9,0xf9,0x9e,0x9e,0x9e,
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0xf8,0x88,0xfe,0x99,0x9e,
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0xf8,0xf8,0xff,0x8f,0x88,
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};
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byte i;
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for (i=0;i<16*5;++i)
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{
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write_mem (i<<1,chip8_sprites[i]&0xf0);
|
||||
write_mem ((i<<1)+1,chip8_sprites[i]<<4);
|
||||
}
|
||||
rb->memset (chip8_regs.alg,0,sizeof(chip8_regs.alg));
|
||||
rb->memset (chip8_keys,0,sizeof(chip8_keys));
|
||||
chip8_key_pressed=0;
|
||||
rb->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;
|
||||
}
|
||||
|
||||
static bool chip8_init(char* file)
|
||||
{
|
||||
int numread;
|
||||
int fd;
|
||||
|
||||
fd = rb->open(file, O_RDONLY);
|
||||
if (fd==-1) return false;
|
||||
numread = rb->read(fd, chip8_mem+0x200, 4096-0x200);
|
||||
if (numread==-1) return false;
|
||||
|
||||
rb->close(fd);
|
||||
return true;
|
||||
}
|
||||
|
||||
bool chip8_run(char* file)
|
||||
{
|
||||
int ok;
|
||||
|
||||
ok = chip8_init(file);
|
||||
if (!ok) {
|
||||
rb->lcd_clear_display();
|
||||
rb->lcd_puts(0, 0, "Error");
|
||||
rb->lcd_update();
|
||||
rb->sleep(HZ);
|
||||
return false;
|
||||
}
|
||||
rb->lcd_clear_display();
|
||||
rb->lcd_puts(0, 0, "Chip8 Emulator ");
|
||||
rb->lcd_puts(0, 1, " (c) by ");
|
||||
rb->lcd_puts(0, 2, "Marcel de Kogel");
|
||||
rb->lcd_puts(0, 3, " Archos: ");
|
||||
rb->lcd_puts(0, 4, " Blueloop ");
|
||||
rb->lcd_puts(0, 5, "---------------");
|
||||
rb->lcd_puts(0, 6, "File OK...");
|
||||
rb->lcd_update();
|
||||
rb->sleep(HZ*1);
|
||||
rb->lcd_clear_display();
|
||||
rb->lcd_drawrect(23,0,66,64);
|
||||
rb->lcd_update();
|
||||
chip8_reset();
|
||||
while (chip8_running) chip8_execute();
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
|
||||
/***************** Plugin Entry Point *****************/
|
||||
|
||||
enum plugin_status plugin_start(struct plugin_api* api, void* parameter)
|
||||
{
|
||||
char* filename;
|
||||
|
||||
/* this macro should be called as the first thing you do in the plugin.
|
||||
it test that the api version and model the plugin was compiled for
|
||||
matches the machine it is running on */
|
||||
TEST_PLUGIN_API(api);
|
||||
rb = api; /* copy to global api pointer */
|
||||
|
||||
if (parameter == NULL)
|
||||
{
|
||||
rb->lcd_puts(0, 0, "Play .ch8 file!");
|
||||
rb->lcd_update();
|
||||
rb->sleep(HZ);
|
||||
return PLUGIN_ERROR;
|
||||
}
|
||||
else
|
||||
{
|
||||
filename = (char*) parameter;
|
||||
}
|
||||
|
||||
/* now go ahead and have fun! */
|
||||
return chip8_run(filename) ? PLUGIN_OK : PLUGIN_ERROR;
|
||||
}
|
||||
|
||||
#endif // #ifdef HAVE_LCD_BITMAP
|
||||
#endif // #ifndef SIMULATOR
|
||||
Loading…
Reference in a new issue