1 files changed, 77 insertions, 0 deletions
diff --git a/src/snake.S b/src/snake.S
new file mode 100644
index 0000000..00d66e2
--- /dev/null
+++ b/src/snake.S
@@ -0,0 +1,77 @@
+//! @file snake.S
+//!
+//! Type definitions, sizes, and the interface for the snake.
+
+#include "helpers/function.S"
+
+#define OFFSET_snake_t_x 0
+#define SIZE_snake_t_x 4
+
+#define OFFSET_snake_t_y OFFSET_snake_t_x + SIZE_snake_t_x
+#define SIZE_snake_t_y 4
+
+#define OFFSET_snake_t_length OFFSET_snake_t_y + SIZE_snake_t_y
+#define SIZE_snake_t_length 4
+
+#define OFFSET_snake_t_direction OFFSET_snake_t_length + SIZE_snake_t_length
+#define SIZE_snake_t_direction 1
+
+#define OFFSET_snake_t_padding OFFSET_snake_t_direction + SIZE_snake_t_direction
+#define SIZE_snake_t_padding 3
+
+#define SIZE_snake_t OFFSET_snake_t_padding + SIZE_snake_t_padding
+
+#ifndef __STDC_VERSION__
+
+.section .text
+
+  //! @fn void snake_init(snake_t * self, int x, int y, int length)
+  //! @param (%rdi) self    the object to initialize
+  //! @param (%esi) x       the x position of the head of the snake
+  //! @param (%edx) y       the y position of the head of the snake
+  //! @param (%ecx) length  the length of the snake
+  function_begin snake_init
+
+    test %rdi, %rdi
+    jz .Lexit_snake_init
+
+    mov %esi, OFFSET_snake_t_x(%rdi)
+    mov %edx, OFFSET_snake_t_y(%rdi)
+    mov %ecx, OFFSET_snake_t_length(%rdi)
+    xor %al, %al
+    mov %al, OFFSET_snake_t_direction(%rdi)
+
+  function_end
+
+#else
+
+#include <stddef.h>
+
+typedef struct {
+  int x;
+  int y;
+  int length;
+  char direction;
+  char padding[3];
+} snake_t;
+
+static_assert(sizeof(snake_t) == SIZE_snake_t);
+
+static_assert(offsetof(snake_t, x) == OFFSET_snake_t_x);
+static_assert(sizeof(((snake_t*)0)->x) == SIZE_snake_t_x);
+
+static_assert(offsetof(snake_t, y) == OFFSET_snake_t_y);
+static_assert(sizeof(((snake_t*)0)->y) == SIZE_snake_t_y);
+
+static_assert(offsetof(snake_t, length) == OFFSET_snake_t_length);
+static_assert(sizeof(((snake_t*)0)->length) == SIZE_snake_t_length);
+
+static_assert(offsetof(snake_t, direction) == OFFSET_snake_t_direction);
+static_assert(sizeof(((snake_t*)0)->direction) == SIZE_snake_t_direction);
+
+static_assert(offsetof(snake_t, padding) == OFFSET_snake_t_padding);
+static_assert(sizeof(((snake_t*)0)->padding) == SIZE_snake_t_padding);
+
+void snake_init(snake_t * self, int x, int y, int length);
+
+#endif
+\ No newline at end of file