Added the game snake.

games/Makefile

@@ -6,6 +6,7 @@ INITRDDIR:=../initrd
 LOCALBINARIES:=\
 pong \
 conway \
+snake \
 
 BINARIES:=$(addprefix $(INITRDDIR)/,$(LOCALBINARIES))
 

games/snake.cpp

@@ -0,0 +1,179 @@
+#include <libmaxsi/platform.h>
+#include <libmaxsi/io.h>
+#include <libmaxsi/thread.h>
+#include <libmaxsi/keyboard.h>
+#include <libmaxsi/sortix-vga.h>
+#include <libmaxsi/sortix-keyboard.h>
+
+using namespace Maxsi;
+using namespace Maxsi::Keyboard;
+
+const int width = 80;
+const int height = 25;
+
+const int buffersize = height * width;
+
+System::VGA::Frame* frame;
+
+int posx;
+int posy;
+int velx;
+int vely;
+int tailx;
+int taily;
+int taillen;
+int tailmax;
+int animalx;
+int animaly;
+
+char direction[buffersize];
+
+uint16_t animal = '%' | (COLOR8_RED<<8);
+uint16_t snake = ' ' | (COLOR8_GREEN<<12);
+
+// HACK: Sortix has no random number generator yet!
+int random_seed=1337;
+int rand(int max) 
+{
+	int tmpmax=max;
+	random_seed = random_seed + 37 * 1103515245 + 12345;
+	return (unsigned int) (random_seed / 65536) % tmpmax; 
+}
+
+void Clear()
+{
+	// Reset the game data.
+	for ( int i = 0; i < buffersize; i++ ) { frame->text[i] = 0; direction[i] = -1; }
+}
+
+void Reset()
+{
+	Clear();
+	tailx = posx = width/2;
+	taily = posy = height/2;
+	switch ( rand(4) )
+	{
+		case 0: velx = -1; vely = 0; break;
+		case 1: velx = 1; vely = 0; break; 
+		case 2: velx = 0; vely = -1; break;
+		case 3: velx = 0; vely = -1; break;
+	}
+
+	animalx = 2 + rand(width-4);
+	animaly = 2 + rand(height-4);
+
+	taillen = 0;
+	tailmax = 3;
+
+	frame->text[animaly * width + animalx] = animal;
+}
+
+int Init()
+{
+	// Create a VGA frame we can render onto.
+	frame = System::VGA::CreateFrame();
+	if ( frame == NULL )
+	{
+		Print("Could not create VGA frame\n");
+		return -1;
+	}
+
+	System::VGA::ChangeFrame(frame->fd);
+
+	Reset();
+
+	return 0;
+}
+
+void Update()
+{
+	int newvelx = velx;
+	int newvely = vely;
+
+	// Read the keyboard input from the user.
+	unsigned method = System::Keyboard::POLL;
+	uint32_t codepoint;
+	while ( (codepoint = System::Keyboard::ReceieveKeystroke(method) ) != 0 )
+	{
+		bool keyup = codepoint & DEPRESSED;
+		if ( keyup ) { continue; }
+		codepoint &= ~DEPRESSED;
+
+		if ( codepoint == '\n' ) { Reset(); return; }
+		if ( codepoint == 'w' || codepoint == 'W' ) { newvelx = 0; newvely = -1; }
+		if ( codepoint == 'a' || codepoint == 'A' ) { newvelx = -1; newvely = 0; }
+		if ( codepoint == 's' || codepoint == 'S' ) { newvelx = 0; newvely = 1; }
+		if ( codepoint == 'd' || codepoint == 'D' ) { newvelx = 1; newvely = 0; }
+	}
+
+	// Make sure we don't do a 180.
+	if ( !(velx == -1 && newvelx == 1) &&
+	     !(velx == 1 && newvelx == -1) &&
+	     !(vely == -1 && newvely == 1) &&
+	     !(vely == 1 && newvely == -1) )
+	{
+		velx = newvelx; vely = newvely;
+	}
+
+	// Don't collide with the border!
+	if ( posx + velx < 0 || width <= posx + velx ||
+	     posy + vely < 0 || height <= posy + vely ) { Reset(); return; }
+
+	int newx = posx + velx;
+	int newy = posy + vely;
+
+	// Move the tail, if needed.
+	if ( taillen == tailmax )
+	{
+		frame->text[taily * width + tailx] = 0; taillen--;
+		switch ( direction[taily * width + tailx] )
+		{
+			case 0: tailx--; break;
+			case 1: tailx++; break; 
+			case 2: taily--; break;
+			case 3: taily++; break;
+		}
+	}
+
+	// Check for collision.
+	if ( frame->text[newy * width + newx] == snake ) { Reset(); return; }
+
+	// Check for food.
+	if ( newx == animalx && newy == animaly )
+	{
+		tailmax++;
+		animalx = 2 + rand(width-4);
+		animaly = 2 + rand(height-4);
+	}
+
+	frame->text[animaly * width + animalx] = animal;
+
+	// Remember where we are going.
+	int dir = 0;
+	if ( velx < 0 ) { dir = 0; }
+	if ( velx > 0 ) { dir = 1; }
+	if ( vely < 0 ) { dir = 2; }
+	if ( vely > 0 ) { dir = 3; }
+	direction[posy * width + posx] = dir;
+
+	// Move the head.
+	posx = newx;
+	posy = newy;
+	frame->text[posy * width + posx] = snake; taillen++;
+}
+
+int main(int argc, char* argv[])
+{
+	int result = Init();
+	if ( result != 0 ) { return result; }
+
+	// Update the game every 300th milisecond.
+	while ( true )
+	{
+		const int sleepms = 75;
+		Thread::USleep(sleepms * 1000);
+		Update();
+	}
+
+	return 0;
+}