/*
	PuteBysh: A BytePusher VM
	by Ben "GreaseMonkey" Russell, 2010.
	Public domain.
	
	Tested on FreeBSD 8.1-PRERELEASE.
	
	Keypad is hard-wired to:
		1 2 3 4
		q w e r
		a s d f
		z x c v
	
	Javamannen's audio code has been fixed, now it's a lot smoother.
	
	zzo38's code doesn't appear very well timed (it doesn't frameskip AFAIK
	and the audio tends to stutter) - I should probably prod him about that.
*/

#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>

#include <allegro.h>

// must be divisible by 256
#define BUF_LEN 2048

// CPU_DEBUG: print all non-halt steps
//define CPU_DEBUG

// VUPD_UNLAGGED: draw a pixel after each instruction
//define VUPD_UNLAGGED

// VUPD_LIVE: allow changing of xx---- byte while drawing
// NOTE: REQUIRES VUPD_UNLAGGED TO BE EFFECTIVE, OTHERWISE IT SLOWS DOWN RENDERING
//define VUPD_LIVE

unsigned char *vmmem = NULL;
BITMAP *blah = NULL;

unsigned char *aubuf = NULL;
int aubufpos = 0;

int tick_logic = 0;
int tick_logic_catchup;

void tick_logic_fn(void)
{
	tick_logic++;
}

void cleanup(void)
{
	if(vmmem != NULL)
		free(vmmem);
}

int main(int argc, char *argv[])
{
	if(argc <= 1)
	{
		printf("usage:\n\t%s prog.bytepusher\n", argv[0]);
		return 99;
	}
	
	allegro_init();
	
	printf("install_timer: %i\n",install_timer());
	printf("install_keyboard: %i\n",install_keyboard());
	printf("install_sound: %i\n",install_sound(DIGI_AUTODETECT, MIDI_NONE, NULL));
	set_volume_per_voice(0); // thanks to Javamannen for this suggestion (boosts vol to 100%).
	
	set_color_depth(8);
	set_gfx_mode(GFX_AUTODETECT_WINDOWED, 256, 256, 0, 0);
	
	PALETTE p;
	
	{
		int r,g,b,i;
		
		i = 0;
		for(r = 0x00; r <= 0xFF; r += 0x33)
		for(g = 0x00; g <= 0xFF; g += 0x33)
		for(b = 0x00; b <= 0xFF; b += 0x33)
		{
			p[i].r = r*63/255;
			p[i].g = g*63/255;
			p[i].b = b*63/255;
			i++;
		}
		i--;
		while(++i < 256)
			p[i].r = p[i].g = p[i].b = 0;
	}
	
	set_palette(p);
	
	blah = create_bitmap(256, 256);
	
	// load program about... NOW
	{
		vmmem = malloc(256*256*256+8);
		
		int i;
		for(i = 0; i < 256*256*256+8; i++)
			vmmem[i] = 0;
		
		FILE *fp = fopen(argv[1],"rb");
		fread(vmmem, 1, 256*256*256+8, fp); // slow but saves effort
		fclose(fp);
	}
	
	AUDIOSTREAM *dsp = play_audio_stream(BUF_LEN, 8, 0, 256*60, 256, 128);
	int x,y,vp,pc,sp,dp,i;
	
	install_int_ex(tick_logic_fn, BPS_TO_TIMER(60));
	
	tick_logic_catchup = tick_logic;
	
	while(!key[KEY_ESC])
	{
		int doshowgfx = (tick_logic_catchup == tick_logic);
		
		vmmem[0] = vmmem[1] = 0;
		if(key[KEY_X]) vmmem[1] |= 1;
		if(key[KEY_1]) vmmem[1] |= 2;
		if(key[KEY_2]) vmmem[1] |= 4;
		if(key[KEY_3]) vmmem[1] |= 8;
		if(key[KEY_Q]) vmmem[1] |= 16;
		if(key[KEY_W]) vmmem[1] |= 32;
		if(key[KEY_E]) vmmem[1] |= 64;
		if(key[KEY_A]) vmmem[1] |= 128;
		if(key[KEY_S]) vmmem[0] |= 1;
		if(key[KEY_D]) vmmem[0] |= 2;
		if(key[KEY_Z]) vmmem[0] |= 4;
		if(key[KEY_C]) vmmem[0] |= 8;
		if(key[KEY_4]) vmmem[0] |= 16;
		if(key[KEY_R]) vmmem[0] |= 32;
		if(key[KEY_F]) vmmem[0] |= 64;
		if(key[KEY_V]) vmmem[0] |= 128;
		
		pc = (
			((unsigned int)vmmem[2]<<16)
			|((unsigned int)vmmem[3]<<8)
			|((unsigned int)vmmem[4])
		);
		
#ifdef VUPD_LIVE
		vp = 0;
#else
		vp = (unsigned int)vmmem[5]<<16;
#endif
#ifdef VUPD_UNLAGGED
		if(doshowgfx)
			lock_bitmap(blah);
#endif
		for(y = 0; y < 256; y++)
		for(x = 0; x < 256; x++)
		{
			sp = (
				((unsigned int)vmmem[pc]<<16)
				|((unsigned int)vmmem[pc+1]<<8)
				|((unsigned int)vmmem[pc+2])
			);
			pc += 3;
			dp = (
				((unsigned int)vmmem[pc]<<16)
				|((unsigned int)vmmem[pc+1]<<8)
				|((unsigned int)vmmem[pc+2])
			);
			pc += 3;
			pc = (
				((unsigned int)vmmem[pc]<<16)
				|((unsigned int)vmmem[pc+1]<<8)
				|((unsigned int)vmmem[pc+2])
			);
			vmmem[dp] = vmmem[sp];
#ifdef CPU_DEBUG
			if(dp != sp)
				printf("%06X-[%02X]->%06X => %06X\n",sp,vmmem[sp],dp,pc);
#endif
#ifndef VUPD_UNLAGGED
		}
		
		if(doshowgfx)
		{
			lock_bitmap(blah);
			
			for(y = 0; y < 256; y++)
			for(x = 0; x < 256; x++)
			{
#else
			if(doshowgfx)
			{
#endif
#ifdef VUPD_LIVE
					_putpixel(blah, x,y,vmmem[((unsigned int)vmmem[5]<<16)|vp++]);
#else
					_putpixel(blah, x,y,vmmem[vp++]);
#endif
			}
		
#ifdef VUPD_UNLAGGED
			if(doshowgfx)
				release_bitmap(blah);
#endif
		}
		
		if(aubuf == NULL)
		{
			aubuf = get_audio_stream_buffer(dsp);
			aubufpos = 0;
		}
		
		if(aubuf != NULL)
		{
			pc = (
				((unsigned int)vmmem[6]<<16)
				|((unsigned int)vmmem[7]<<8)
			); // VARIABLE REUSE ABUSE
			
			for(i = 0; i < 256; i++)
				aubuf[aubufpos++] = vmmem[pc++]+0x80;
			
			if(aubufpos == BUF_LEN)
			{
				free_audio_stream_buffer(dsp);
				aubuf = NULL;
			}
		}
		
		if(doshowgfx)
		{
			blit(blah, screen, 0, 0, 0, 0, 256, 256);
			
			while(tick_logic == tick_logic_catchup)
				rest(5);
		}
		
		tick_logic_catchup++;
		
		if(keyboard_needs_poll())
			poll_keyboard();
	}
	
	return 0;
}
END_OF_MAIN()