add sdl2 demo

src/Makefile

@@ -4,7 +4,7 @@
 CC_NATIVE = gcc
 CFLAGS_NATIVE = -g -std=c89 -Wall -Wextra -Werror -Wno-unused-parameter -I.
 LDFLAGS_NATIVE = 
-LDLIBS_NATIVE =
+LDLIBS_NATIVE = -lSDL2
 
 # WASM build (emscripten)
 CC_WASM = emcc

src/arch/linux/main.c

@@ -1,6 +1,7 @@
 #include "../../debug.h"
 #include "../../test.h"
 #include "../../vm.h"
+#include <SDL2/SDL.h>
 
 int main(int argc, char **argv) {
   VM vm = {0};
@@ -9,9 +10,80 @@ int main(int argc, char **argv) {
   vm.stack_size = STACK_SIZE;
   vm.memory_size = MEMORY_SIZE;
 
-  test_loop_compile(vm.memory);
+  uint32_t end = test_loop_compile(vm.memory);
+  /* test_add_function_compile(vm.memory); */
+  /* test_recursive_function_compile(vm.memory); */
+  uint32_t buffer_size = 640 * 480 * sizeof(uint32_t);
 
-  while (step_vm(&vm)){}
+  Device screen;
+  screen.type = SCREEN;
+  screen.s = (Screen){.width = (uint8_t)480,
+                      .height = (uint8_t)640,
+                      .allocated = {end, buffer_size},
+                      .buffer = &vm.memory[end]};
+  vm.devices[vm.dp++] = screen;
+  vm.mp += buffer_size;
+
+  /* Create window and renderer */
+  SDL_Window *window = SDL_CreateWindow(
+      "Reality Engine VM", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
+      screen.s.width, screen.s.height, SDL_WINDOW_SHOWN | SDL_WINDOW_ALLOW_HIGHDPI);
+
+  SDL_Renderer *renderer = SDL_CreateRenderer(
+      window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
+
+  /* Create texture for 640x480 buffer */
+  SDL_Texture *texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_ARGB8888,
+                                           SDL_TEXTUREACCESS_STREAMING,
+                                           screen.s.width, screen.s.height);
+
+  /* Enable nearest-neighbor scaling (preserves pixel art) */
+  SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "0"); /* "0" = nearest-neighbor */
+
+  while (step_vm(&vm)) {
+    SDL_Event event;
+    while (SDL_PollEvent(&event)) {
+      switch (event.type) {
+      case SDL_QUIT:
+          return 0;
+      case SDL_MOUSEBUTTONDOWN:
+        /* event.button.x, event.button.y, event.button.button */
+        break;
+      case SDL_MOUSEMOTION:
+        /* handleInput(event.motion.x, event.motion.y, 0);  0 for no button */
+        break;
+      case SDL_FINGERDOWN:
+        /* handleInput(event.tfinger.x * screen.s.width, */
+                    /* event.tfinger.y * screen.s.height, 1); // 1 for touch */
+        break;
+      case SDL_FINGERMOTION:
+        /* handleInput(event.tfinger.x * screen.s.width, */
+                    /* event.tfinger.y * screen.s.height, 0); // 0 for no button */
+        break;
+      }
+    }
+
+    SDL_UpdateTexture(texture, NULL, screen.s.buffer,
+                      screen.s.width * sizeof(uint32_t));
+
+    SDL_RenderClear(renderer);
+
+    /* Optional: Set logical size to maintain 640x480 aspect ratio */
+    /* (Scales to fit screen while preserving pixel grid) */
+    SDL_Rect output_rect;
+    SDL_RenderGetViewport(renderer, &output_rect);
+    float scale_x = (float)output_rect.w / screen.s.width;
+    float scale_y = (float)output_rect.h / screen.s.height;
+    float scale = SDL_min(scale_x, scale_y);
+
+    SDL_Rect dstrect = {(int)((output_rect.w - screen.s.width * scale) / 2),
+                        (int)((output_rect.h - screen.s.height * scale) / 2),
+                        (int)(screen.s.width * scale),
+                        (int)(screen.s.height * scale)};
+
+    SDL_RenderCopy(renderer, texture, NULL, &dstrect);
+    SDL_RenderPresent(renderer);
+  }
   core_dump(&vm);
   return 0;
 }

src/opcodes.h

@@ -22,15 +22,31 @@ typedef struct frame_s {
   Slice allocated;           /* start and end of global allocated block */
 } Frame;
 
+typedef struct screen_t {
+  uint8_t width;
+  uint8_t height;
+  Slice allocated;
+  Value *buffer;
+} Screen;
+
+typedef union device_u {
+  uint8_t type;
+  Screen s;
+} Device;
+
 #define MEMORY_SIZE 65536
 #define FRAMES_SIZE 128 
 #define STACK_SIZE 256
+#define DEVICES_SIZE 8
 typedef struct vm_s {
   uint32_t pc; /* Program counter */
-  uint32_t fp; /* Frame pointer (last allocated value) */
+  uint32_t fp; /* Frame pointer (current frame) */
   uint32_t sp; /* stack pointer (top of stack) */
   uint32_t rp; /* return stack pointer (top of stack) */
   uint32_t mp; /* Memory pointer (last allocated value) */
+  uint32_t dp; /* device pointer (last allocated device) */
+  uint8_t devices_size;
+  Device devices[DEVICES_SIZE];
   uint32_t frames_size;
   Frame frames[FRAMES_SIZE]; /* function call frames */
   uint32_t stack_size;
@@ -100,6 +116,14 @@ typedef enum {
   OP_CMP_STRING,     /* cmps : dest = (str == src2) as bool */
 } Opcode;
 
+typedef enum {
+  SCREEN,
+  MOUSE,
+  KEYBOARD,
+  CONTROLLER,
+  AUDIO,
+} Devicecode;
+
 /* defines a uint32 opcode */
 #define OP(opcode, a, b, c) ((opcode << 24) | (a << 16) | (b << 8) | c)