From 3fb7fefd1fc9f89b55e5ab934dedeb350a5ba5d1 Mon Sep 17 00:00:00 2001
From: DiabloPhD <djbirdsall@dons.usfca.edu>
Date: Tue, 29 Oct 2024 18:19:05 -0700
Subject: [PATCH 1/5] Pushing Suhani's code

---
 Makefile         |   1 +
 kernel/syscall.c |  20 +++++++++
 kernel/syscall.h |   9 ++++
 user/snake.c     | 114 +++++++++++++++++++++++++++++++++++++++++++++++
 user/user.h      |  10 +++++
 5 files changed, 154 insertions(+)
 create mode 100644 user/snake.c

diff --git a/Makefile b/Makefile
index 2584e4a..c8c8dce 100644
--- a/Makefile
+++ b/Makefile
@@ -127,6 +127,7 @@ UPROGS=\
 	$U/_mkdir\
 	$U/_rm\
 	$U/_sh\
+	$U/_snake\
 	$U/_stressfs\
 	$U/_usertests\
 	$U/_grind\
diff --git a/kernel/syscall.c b/kernel/syscall.c
index ed65409..feaa7f5 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -102,6 +102,15 @@ extern uint64 sys_link(void);
 extern uint64 sys_mkdir(void);
 extern uint64 sys_close(void);
 
+extern void sys_clear_screen(void);
+extern void sys_draw_border(void);
+extern void sys_draw_snake(void);
+extern void sys_draw_food(void);
+extern void sys_update_snake(void);
+extern void sys_check_collision(void);
+extern void sys_place_food(void);
+extern void sys_game_over(void);
+
 // An array mapping syscall numbers from syscall.h
 // to the function that handles the system call.
 static uint64 (*syscalls[])(void) = {
@@ -145,3 +154,14 @@ syscall(void)
     p->trapframe->a0 = -1;
   }
 }
+
+static void (*syscalls[])(void) = {
+    [SYS_clear_screen] sys_clear_screen,
+    [SYS_draw_border] sys_draw_border,
+    [SYS_draw_snake] sys_draw_snake,
+    [SYS_draw_food] sys_draw_food,
+    [SYS_update_snake] sys_update_snake,
+    [SYS_check_collision] sys_check_collision,
+    [SYS_place_food] sys_place_food,
+    [SYS_game_over] sys_game_over,
+};
diff --git a/kernel/syscall.h b/kernel/syscall.h
index bc5f356..5dbdd28 100644
--- a/kernel/syscall.h
+++ b/kernel/syscall.h
@@ -20,3 +20,12 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
+//snake system calls
+#define SYS_clear_screen 22
+#define SYS_draw_border 23
+#define SYS_draw_snake 24
+#define SYS_draw_food 25
+#define SYS_update_snake 26
+#define SYS_check_collision 27
+#define SYS_place_food 28
+#define SYS_game_over 29
\ No newline at end of file
diff --git a/user/snake.c b/user/snake.c
new file mode 100644
index 0000000..6bf07c7
--- /dev/null
+++ b/user/snake.c
@@ -0,0 +1,114 @@
+#include "kernel/types.h"
+#include "kernel/stat.h"
+#include "user/user.h"
+#include "kernel/fcntl.h"
+
+#define WIDTH 20
+#define HEIGHT 10
+#define SNAKE_MAX_LENGTH 100
+
+typedef struct {
+    int x, y;
+} Point;
+
+typedef struct {
+    Point body[SNAKE_MAX_LENGTH];
+    int length;
+    Point direction;
+} Snake;
+
+void clear_screen() {
+    printf("\033[H\033[J");
+}
+
+void draw_border() {
+    for (int i = 0; i < WIDTH + 2; i++) printf("#");
+    printf("\n");
+    for (int i = 0; i < HEIGHT; i++) {
+        printf("#");
+        for (int j = 0; j < WIDTH; j++) printf(" ");
+        printf("#\n");
+    }
+    for (int i = 0; i < WIDTH + 2; i++) printf("#");
+    printf("\n");
+}
+
+void draw_snake(Snake *snake) {
+    for (int i = 0; i < snake->length; i++) {
+        printf("\033[%d;%dH@", snake->body[i].y + 2, snake->body[i].x + 2);
+    }
+}
+
+void draw_food(Point *food) {
+    printf("\033[%d;%dH*", food->y + 2, food->x + 2);
+}
+
+void update_snake(Snake *snake) {
+    for (int i = snake->length - 1; i > 0; i--) {
+        snake->body[i] = snake->body[i - 1];
+    }
+    snake->body[0].x += snake->direction.x;
+    snake->body[0].y += snake->direction.y;
+}
+
+int check_collision(Snake *snake) {
+    Point head = snake->body[0];
+    if (head.x < 0 || head.x >= WIDTH || head.y < 0 || head.y >= HEIGHT) return 1;
+    for (int i = 1; i < snake->length; i++) {
+        if (head.x == snake->body[i].x && head.y == snake->body[i].y) return 1;
+    }
+    return 0;
+}
+
+void place_food(Point *food, Snake *snake) {
+    int valid;
+    do {
+        valid = 1;
+        food->x = rand() % WIDTH;
+        food->y = rand() % HEIGHT;
+        for (int i = 0; i < snake->length; i++) {
+            if (food->x == snake->body[i].x && food->y == snake->body[i].y) {
+                valid = 0;
+                break;
+            }
+        }
+    } while (!valid);
+}
+
+void game_over() {
+    printf("\033[%d;%dHGame Over!\n", HEIGHT / 2 + 2, WIDTH / 2 - 4);
+    exit(0);
+}
+
+int main() {
+    Snake snake;
+    Point food;
+    snake.length = 1;
+    snake.body[0].x = WIDTH / 2;
+    snake.body[0].y = HEIGHT / 2;
+    snake.direction.x = 1;
+    snake.direction.y = 0;
+
+    place_food(&food, &snake);
+
+    clear_screen();
+    draw_border();
+    draw_snake(&snake);
+    draw_food(&food);
+
+    while (1) {
+        if (check_collision(&snake)) game_over();
+        if (snake.body[0].x == food.x && snake.body[0].y == food.y) {
+            if (snake.length < SNAKE_MAX_LENGTH) snake.length++;
+            place_food(&food, &snake);
+        }
+        update_snake(&snake);
+        clear_screen();
+        draw_border();
+        draw_snake(&snake);
+        draw_food(&food);
+        sleep(1);
+    }
+    return 0;
+}
+
diff --git a/user/user.h b/user/user.h
index 2e6fc55..b0eb1b2 100644
--- a/user/user.h
+++ b/user/user.h
@@ -41,3 +41,13 @@ void free(void*);
 int atoi(const char*);
 int memcmp(const void *, const void *, uint);
 void *memcpy(void *, const void *, uint);
+
+// Functions for game-related system calls
+void clear_screen(void);
+void draw_border(void);
+void draw_snake(Snake *snake);
+void draw_food(Point *food);
+void update_snake(Snake *snake);
+int check_collision(Snake *snake);
+void place_food(Point *food, Snake *snake);
+void game_over(void);
\ No newline at end of file

From 1bc90534c09e4de432ec11a5b6b1e7de1122a111 Mon Sep 17 00:00:00 2001
From: Duncan Birdsall <djbirdsall@dons.usfca.edu>
Date: Tue, 29 Oct 2024 18:48:45 -0700
Subject: [PATCH 2/5] Snake is now runnable, but not displaying properly

---
 kernel/syscall.c | 20 --------------------
 kernel/syscall.h |  9 ---------
 kernel/types.h   | 10 ++++++++++
 user/snake.c     | 18 ++++++++----------
 4 files changed, 18 insertions(+), 39 deletions(-)

diff --git a/kernel/syscall.c b/kernel/syscall.c
index feaa7f5..ed65409 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -102,15 +102,6 @@ extern uint64 sys_link(void);
 extern uint64 sys_mkdir(void);
 extern uint64 sys_close(void);
 
-extern void sys_clear_screen(void);
-extern void sys_draw_border(void);
-extern void sys_draw_snake(void);
-extern void sys_draw_food(void);
-extern void sys_update_snake(void);
-extern void sys_check_collision(void);
-extern void sys_place_food(void);
-extern void sys_game_over(void);
-
 // An array mapping syscall numbers from syscall.h
 // to the function that handles the system call.
 static uint64 (*syscalls[])(void) = {
@@ -154,14 +145,3 @@ syscall(void)
     p->trapframe->a0 = -1;
   }
 }
-
-static void (*syscalls[])(void) = {
-    [SYS_clear_screen] sys_clear_screen,
-    [SYS_draw_border] sys_draw_border,
-    [SYS_draw_snake] sys_draw_snake,
-    [SYS_draw_food] sys_draw_food,
-    [SYS_update_snake] sys_update_snake,
-    [SYS_check_collision] sys_check_collision,
-    [SYS_place_food] sys_place_food,
-    [SYS_game_over] sys_game_over,
-};
diff --git a/kernel/syscall.h b/kernel/syscall.h
index 5dbdd28..bc5f356 100644
--- a/kernel/syscall.h
+++ b/kernel/syscall.h
@@ -20,12 +20,3 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
-//snake system calls
-#define SYS_clear_screen 22
-#define SYS_draw_border 23
-#define SYS_draw_snake 24
-#define SYS_draw_food 25
-#define SYS_update_snake 26
-#define SYS_check_collision 27
-#define SYS_place_food 28
-#define SYS_game_over 29
\ No newline at end of file
diff --git a/kernel/types.h b/kernel/types.h
index ee73164..cbef7be 100644
--- a/kernel/types.h
+++ b/kernel/types.h
@@ -8,3 +8,13 @@ typedef unsigned int  uint32;
 typedef unsigned long uint64;
 
 typedef uint64 pde_t;
+
+typedef struct {
+    int x, y;
+} Point;
+
+typedef struct {
+    Point body[100];
+    int length;
+    Point direction;
+} Snake;
diff --git a/user/snake.c b/user/snake.c
index 6bf07c7..a3183e3 100644
--- a/user/snake.c
+++ b/user/snake.c
@@ -7,15 +7,13 @@
 #define HEIGHT 10
 #define SNAKE_MAX_LENGTH 100
 
-typedef struct {
-    int x, y;
-} Point;
-
-typedef struct {
-    Point body[SNAKE_MAX_LENGTH];
-    int length;
-    Point direction;
-} Snake;
+uint32 rand() {
+    uint32 x = uptime();
+    x ^= x << 13;
+    x ^= x >> 17;
+    x ^= x << 5;
+    return x;
+}
 
 void clear_screen() {
     printf("\033[H\033[J");
@@ -107,7 +105,7 @@ int main() {
         draw_border();
         draw_snake(&snake);
         draw_food(&food);
-        sleep(1);
+        sleep(100);
     }
     return 0;
 }

From 9ce58521a5c9495eb91963c1e1c83b2cd00d0dea Mon Sep 17 00:00:00 2001
From: Duncan Birdsall <djbirdsall@dons.usfca.edu>
Date: Wed, 30 Oct 2024 00:08:45 -0700
Subject: [PATCH 3/5] Snake is playable! Must fix console afterwards though.

---
 kernel/console.c | 38 ++++++++++++++++++++++++++++++++++++++
 kernel/defs.h    |  1 +
 kernel/file.c    | 28 ++++++++++++++++++++++++++++
 kernel/file.h    |  1 +
 kernel/syscall.c |  2 ++
 kernel/syscall.h |  1 +
 kernel/sysfile.c | 14 ++++++++++++++
 user/snake.c     | 35 ++++++++++++++++++++++++++++++-----
 user/user.h      | 11 +----------
 user/usys.pl     |  1 +
 10 files changed, 117 insertions(+), 15 deletions(-)

diff --git a/kernel/console.c b/kernel/console.c
index 05dc526..5068282 100644
--- a/kernel/console.c
+++ b/kernel/console.c
@@ -126,6 +126,43 @@ consoleread(int user_dst, uint64 dst, int n)
   return target - n;
 }
 
+//Get current keypress from console with no delay.
+int
+consolekeys(int user_dst, uint64 dst, int n)
+{
+  uint target;
+  int c;
+  char cbuf;
+
+  target = n;
+  acquire(&cons.lock);
+  while(n > 0){
+  
+    if(killed(myproc())){
+        release(&cons.lock);
+        return -1;
+    }
+
+    c = cons.buf[cons.r++ % INPUT_BUF_SIZE];
+    // copy the input byte to the user-space buffer.
+    cbuf = c;
+    if (c != '\033' && c!= '[' && c != 'A' && c != 'B' && c != 'C' && c != 'D'){
+        uartputc_sync(c); uartputc_sync(' '); uartputc_sync(c);
+        cons.r--;
+        break;
+    }
+
+    if(either_copyout(user_dst, dst, &cbuf, 1) == -1)
+      break;
+
+    dst++;
+    --n;
+  }
+  release(&cons.lock);
+
+  return target - n;
+}
+
 //
 // the console input interrupt handler.
 // uartintr() calls this for input character.
@@ -188,5 +225,6 @@ consoleinit(void)
   // connect read and write system calls
   // to consoleread and consolewrite.
   devsw[CONSOLE].read = consoleread;
+  devsw[CONSOLE].keys = consolekeys;
   devsw[CONSOLE].write = consolewrite;
 }
diff --git a/kernel/defs.h b/kernel/defs.h
index a3c962b..e4f7d8c 100644
--- a/kernel/defs.h
+++ b/kernel/defs.h
@@ -30,6 +30,7 @@ struct file*    filealloc(void);
 void            fileclose(struct file*);
 struct file*    filedup(struct file*);
 void            fileinit(void);
+int             filekeys(struct file*, uint64, int n);
 int             fileread(struct file*, uint64, int n);
 int             filestat(struct file*, uint64 addr);
 int             filewrite(struct file*, uint64, int n);
diff --git a/kernel/file.c b/kernel/file.c
index 25fa226..6bdf3c1 100644
--- a/kernel/file.c
+++ b/kernel/file.c
@@ -129,6 +129,34 @@ fileread(struct file *f, uint64 addr, int n)
   return r;
 }
 
+// Read keys from file f.
+// addr is a user virtual address.
+int
+filekeys(struct file *f, uint64 addr, int n)
+{
+  int r = 0;
+
+  if(f->readable == 0)
+    return -1;
+
+  if(f->type == FD_PIPE){
+    r = piperead(f->pipe, addr, n);
+  } else if(f->type == FD_DEVICE){
+    if(f->major < 0 || f->major >= NDEV || !devsw[f->major].keys)
+      return -1;
+    r = devsw[f->major].keys(1, addr, n);
+  } else if(f->type == FD_INODE){
+    ilock(f->ip);
+    if((r = readi(f->ip, 1, addr, f->off, n)) > 0)
+      f->off += r;
+    iunlock(f->ip);
+  } else {
+    panic("fileread");
+  }
+
+  return r;
+}
+
 // Write to file f.
 // addr is a user virtual address.
 int
diff --git a/kernel/file.h b/kernel/file.h
index b076d1d..e3eaaf5 100644
--- a/kernel/file.h
+++ b/kernel/file.h
@@ -33,6 +33,7 @@ struct inode {
 struct devsw {
   int (*read)(int, uint64, int);
   int (*write)(int, uint64, int);
+  int (*keys)(int, uint64, int);
 };
 
 extern struct devsw devsw[];
diff --git a/kernel/syscall.c b/kernel/syscall.c
index ed65409..5d06f87 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -101,6 +101,7 @@ extern uint64 sys_unlink(void);
 extern uint64 sys_link(void);
 extern uint64 sys_mkdir(void);
 extern uint64 sys_close(void);
+extern uint64 sys_keys(void);
 
 // An array mapping syscall numbers from syscall.h
 // to the function that handles the system call.
@@ -126,6 +127,7 @@ static uint64 (*syscalls[])(void) = {
 [SYS_link]    sys_link,
 [SYS_mkdir]   sys_mkdir,
 [SYS_close]   sys_close,
+[SYS_keys]   sys_keys,
 };
 
 void
diff --git a/kernel/syscall.h b/kernel/syscall.h
index bc5f356..5872397 100644
--- a/kernel/syscall.h
+++ b/kernel/syscall.h
@@ -20,3 +20,4 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
+#define SYS_keys  22
diff --git a/kernel/sysfile.c b/kernel/sysfile.c
index 16b668c..3e39708 100644
--- a/kernel/sysfile.c
+++ b/kernel/sysfile.c
@@ -79,6 +79,20 @@ sys_read(void)
   return fileread(f, p, n);
 }
 
+uint64
+sys_keys(void)
+{
+  struct file *f;
+  int n;
+  uint64 p;
+
+  argaddr(1, &p);
+  argint(2, &n);
+  if(argfd(0, 0, &f) < 0)
+    return -1;
+  return filekeys(f, p, n);
+}
+
 uint64
 sys_write(void)
 {
diff --git a/user/snake.c b/user/snake.c
index a3183e3..e9b192e 100644
--- a/user/snake.c
+++ b/user/snake.c
@@ -1,7 +1,6 @@
 #include "kernel/types.h"
 #include "kernel/stat.h"
 #include "user/user.h"
-#include "kernel/fcntl.h"
 
 #define WIDTH 20
 #define HEIGHT 10
@@ -15,6 +14,10 @@ uint32 rand() {
     return x;
 }
 
+void move_cursor() {
+    printf("\033[%d;1H", HEIGHT + 3);
+}
+
 void clear_screen() {
     printf("\033[H\033[J");
 }
@@ -29,16 +32,19 @@ void draw_border() {
     }
     for (int i = 0; i < WIDTH + 2; i++) printf("#");
     printf("\n");
+    move_cursor();
 }
 
 void draw_snake(Snake *snake) {
     for (int i = 0; i < snake->length; i++) {
         printf("\033[%d;%dH@", snake->body[i].y + 2, snake->body[i].x + 2);
     }
+    move_cursor();
 }
 
 void draw_food(Point *food) {
     printf("\033[%d;%dH*", food->y + 2, food->x + 2);
+    move_cursor();
 }
 
 void update_snake(Snake *snake) {
@@ -47,6 +53,7 @@ void update_snake(Snake *snake) {
     }
     snake->body[0].x += snake->direction.x;
     snake->body[0].y += snake->direction.y;
+    move_cursor();
 }
 
 int check_collision(Snake *snake) {
@@ -71,11 +78,14 @@ void place_food(Point *food, Snake *snake) {
             }
         }
     } while (!valid);
+    move_cursor();
 }
 
-void game_over() {
+void game_over(Snake *snake) {
     printf("\033[%d;%dHGame Over!\n", HEIGHT / 2 + 2, WIDTH / 2 - 4);
-    exit(0);
+    printf("\033[%d;%dHYou scored %d!\n", HEIGHT / 2 + 3, WIDTH / 2 - 4, snake->length-1);
+    move_cursor();
+    return;
 }
 
 int main() {
@@ -95,7 +105,22 @@ int main() {
     draw_food(&food);
 
     while (1) {
-        if (check_collision(&snake)) game_over();
+        char input[3]; // Buffer to store escape sequences
+        int n = keys(0, input, 3); // Read up to 3 characters
+        if (n > 0) {
+            if (n == 3 && input[0] == '\033' && input[1] == '[') {
+                switch (input[2]) {
+                    case 'A': if (snake.direction.y == 0) { snake.direction.x = 0; snake.direction.y = -1; } break; // Up
+                    case 'B': if (snake.direction.y == 0) { snake.direction.x = 0; snake.direction.y = 1; } break;  // Down
+                    case 'C': if (snake.direction.x == 0) { snake.direction.x = 1; snake.direction.y = 0; } break; // Right
+                    case 'D': if (snake.direction.x == 0) { snake.direction.x = -1; snake.direction.y = 0; } break; // Left
+                }
+            }
+        }
+        if (check_collision(&snake)){
+            game_over(&snake);
+            break;
+        }
         if (snake.body[0].x == food.x && snake.body[0].y == food.y) {
             if (snake.length < SNAKE_MAX_LENGTH) snake.length++;
             place_food(&food, &snake);
@@ -105,7 +130,7 @@ int main() {
         draw_border();
         draw_snake(&snake);
         draw_food(&food);
-        sleep(100);
+        sleep(3);
     }
     return 0;
 }
diff --git a/user/user.h b/user/user.h
index b0eb1b2..1ce2bcd 100644
--- a/user/user.h
+++ b/user/user.h
@@ -22,6 +22,7 @@ int getpid(void);
 char* sbrk(int);
 int sleep(int);
 int uptime(void);
+int keys(int, void*, int);
 
 // ulib.c
 int stat(const char*, struct stat*);
@@ -41,13 +42,3 @@ void free(void*);
 int atoi(const char*);
 int memcmp(const void *, const void *, uint);
 void *memcpy(void *, const void *, uint);
-
-// Functions for game-related system calls
-void clear_screen(void);
-void draw_border(void);
-void draw_snake(Snake *snake);
-void draw_food(Point *food);
-void update_snake(Snake *snake);
-int check_collision(Snake *snake);
-void place_food(Point *food, Snake *snake);
-void game_over(void);
\ No newline at end of file
diff --git a/user/usys.pl b/user/usys.pl
index 01e426e..520f65f 100755
--- a/user/usys.pl
+++ b/user/usys.pl
@@ -36,3 +36,4 @@ sub entry {
 entry("sbrk");
 entry("sleep");
 entry("uptime");
+entry("keys");

From ca942ecfb39800eac51fe0c8924e07fe05881ab5 Mon Sep 17 00:00:00 2001
From: Duncan Birdsall <djbirdsall@dons.usfca.edu>
Date: Wed, 30 Oct 2024 02:20:00 -0700
Subject: [PATCH 4/5] Almost working!

---
 kernel/console.c | 2 +-
 user/snake.c     | 8 ++------
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/kernel/console.c b/kernel/console.c
index 5068282..108668c 100644
--- a/kernel/console.c
+++ b/kernel/console.c
@@ -145,9 +145,9 @@ consolekeys(int user_dst, uint64 dst, int n)
 
     c = cons.buf[cons.r++ % INPUT_BUF_SIZE];
     // copy the input byte to the user-space buffer.
+    cons.w = cons.e;
     cbuf = c;
     if (c != '\033' && c!= '[' && c != 'A' && c != 'B' && c != 'C' && c != 'D'){
-        uartputc_sync(c); uartputc_sync(' '); uartputc_sync(c);
         cons.r--;
         break;
     }
diff --git a/user/snake.c b/user/snake.c
index e9b192e..2691f5e 100644
--- a/user/snake.c
+++ b/user/snake.c
@@ -32,19 +32,16 @@ void draw_border() {
     }
     for (int i = 0; i < WIDTH + 2; i++) printf("#");
     printf("\n");
-    move_cursor();
 }
 
 void draw_snake(Snake *snake) {
     for (int i = 0; i < snake->length; i++) {
         printf("\033[%d;%dH@", snake->body[i].y + 2, snake->body[i].x + 2);
     }
-    move_cursor();
 }
 
 void draw_food(Point *food) {
     printf("\033[%d;%dH*", food->y + 2, food->x + 2);
-    move_cursor();
 }
 
 void update_snake(Snake *snake) {
@@ -53,7 +50,6 @@ void update_snake(Snake *snake) {
     }
     snake->body[0].x += snake->direction.x;
     snake->body[0].y += snake->direction.y;
-    move_cursor();
 }
 
 int check_collision(Snake *snake) {
@@ -78,7 +74,6 @@ void place_food(Point *food, Snake *snake) {
             }
         }
     } while (!valid);
-    move_cursor();
 }
 
 void game_over(Snake *snake) {
@@ -119,7 +114,7 @@ int main() {
         }
         if (check_collision(&snake)){
             game_over(&snake);
-            break;
+            return 0;
         }
         if (snake.body[0].x == food.x && snake.body[0].y == food.y) {
             if (snake.length < SNAKE_MAX_LENGTH) snake.length++;
@@ -130,6 +125,7 @@ int main() {
         draw_border();
         draw_snake(&snake);
         draw_food(&food);
+        move_cursor();
         sleep(3);
     }
     return 0;

From 8f630f4434f90f2f9198f00ff34ff7a7754f4321 Mon Sep 17 00:00:00 2001
From: Duncan Birdsall <djbirdsall@dons.usfca.edu>
Date: Wed, 30 Oct 2024 02:31:09 -0700
Subject: [PATCH 5/5] Issue with overflow somewhere

---
 kernel/types.h | 2 +-
 user/snake.c   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/types.h b/kernel/types.h
index cbef7be..8f1bcf1 100644
--- a/kernel/types.h
+++ b/kernel/types.h
@@ -14,7 +14,7 @@ typedef struct {
 } Point;
 
 typedef struct {
-    Point body[100];
+    Point body[sizeof(Point)*20];
     int length;
     Point direction;
 } Snake;
diff --git a/user/snake.c b/user/snake.c
index 2691f5e..b7b81e0 100644
--- a/user/snake.c
+++ b/user/snake.c
@@ -4,7 +4,7 @@
 
 #define WIDTH 20
 #define HEIGHT 10
-#define SNAKE_MAX_LENGTH 100
+#define SNAKE_MAX_LENGTH 20
 
 uint32 rand() {
     uint32 x = uptime();