some reorganizing

src/app_state.h

@@ -36,3 +36,19 @@ struct User_Input {
 	struct { i32 x; i32 y; } mouse_pos;
 };
 
+struct Window_Data {
+	// Real width and height of the window
+	i32 width;
+	i32 height;
+	bool size_just_changed;
+
+	f32 desired_aspect_ratio;
+};
+
+struct App_State {
+  Window_Data win_data;
+  User_Input user_input;
+
+  u8 *inspected_file;
+  u64 inspected_file_size;
+};

src/mainloop.cpp

@@ -20,10 +20,8 @@ internal inline void monitor_mouse_btn(GLFWwindow *window, u16 *mouse_btn_state,
 	}
 }
 
-internal void run_main_loop(GLFWwindow *window, Arena *arena)
+internal void run_main_loop(GLFWwindow *window, Arena *arena, App_State &app)
 {
-  App_State app {};
-
   f32 delta_time;
   chr::time_point last_saved_time = chr::high_resolution_clock::now();
   

src/mem.cpp

@@ -1,3 +1,5 @@
+// Mostly taken from the raddebugger -- thanks, Ryan.
+
 #define align_pow2(x, b) (((x) + (b) - 1) & ( ~((b) - 1)))
 #define SLLStackPush_N(f,n,next) ((n)->next=(f), (f)=(n))
 #define SLLStackPop_N(f,next) ((f)=(f)->next)
@@ -51,6 +53,7 @@ Arena *arena_alloc_sized(u64 init_res, u64 init_cmt)
     arena->cmt = cmt;
     arena->res = res;
     arena->align = 8;
+    arena->grow = true;
   }
 
   return arena;
@@ -82,7 +85,7 @@ void *arena_push_impl(Arena *arena, u64 size)
   u64 pos_mem = align_pow2(cur->pos, arena->align);
   u64 pos_new = pos_mem + size;
 
-  if (cur->res < pos_new) {
+  if (cur->res < pos_new && arena->grow) {
     Arena *new_block;
     if (size < arena_huge_push_threshold()) {
       new_block = arena_alloc();
@@ -103,7 +106,7 @@ void *arena_push_impl(Arena *arena, u64 size)
 
   if (cur->cmt < pos_new) {
     u64 cmt_new_aligned = align_pow2(pos_new, ARENA_COMMIT_SIZE);
-    u64 cmt_new_clamped = std::min(cmt_new_aligned, cur->res);
+    u64 cmt_new_clamped = min(cmt_new_aligned, cur->res);
     u64 cmt_new_size = cmt_new_clamped - cur->cmt;
     b32x is_cmt_ok = os_commit((u8*)cur + cur->cmt, cmt_new_size);
 
@@ -120,3 +123,77 @@ void *arena_push_impl(Arena *arena, u64 size)
 
   return mem;
 }
+
+template <typename T>
+T *arena_push(Arena *arena)
+{
+  void *mem = arena_push_impl(arena, sizeof(T));
+  return (T *)mem;
+}
+
+template <typename T>
+T *arena_push_array_no_zero(Arena *arena, u64 count)
+{
+  void *mem = arena_push_impl(arena, sizeof(T) * count);
+  return (T *)mem;
+}
+
+template <typename T>
+T *arena_push_array(Arena *arena, u64 count)
+{
+  T *ary = arena_push_array_no_zero<T>(arena, count);
+  memset(ary, 0, sizeof(T) * count);
+  return ary;
+}
+
+u8 *arena_push_contiguous(Arena *arena, u64 size)
+{
+  b32 restore = arena->grow;
+  arena->grow = 0;
+  void *mem = arena_push_impl(arena, size);
+  arena->grow = restore;
+  return (u8 *)mem;
+}
+
+u64 arena_pos(Arena *arena)
+{
+  Arena *cur = arena->cur;
+  u64 pos = cur->base_pos + cur->pos;
+  return pos;
+}
+
+void arena_pop_to(Arena *arena, u64 big_pos_unclamped)
+{
+  u64 big_pos = min(ARENA_HEADER_SIZE, big_pos_unclamped);
+  
+  // unroll the chain
+  Arena *current = arena->cur;
+  for (Arena *prev = 0; current->base_pos >= big_pos; current = prev) {
+    prev = current->prev;
+    os_release(current, current->res);
+  }
+  assert(current);
+  arena->cur = current;
+  
+  // compute arena-relative position
+  u64 new_pos = big_pos - current->base_pos;
+  assert(new_pos <= current->pos);
+  
+  // poison popped memory block
+  asan_poison_memory_region((u8*)current + new_pos, (current->pos - new_pos));
+  
+  // update position
+  current->pos = new_pos;
+}
+
+Temp temp_begin(Arena *arena)
+{
+  u64 pos = arena_pos(arena);
+  Temp temp = {arena, pos};
+  return temp;
+}
+
+void temp_end(Temp temp)
+{
+  arena_pop_to(temp.arena, temp.pos);
+}

src/mem.h

@@ -10,4 +10,10 @@ struct Arena {
   u64 cmt;
   u64 res;
   u64 align;
+  b8 grow;
+};
+
+struct Temp {
+  Arena *arena;
+  u64 pos;
 };

src/render.cpp

@@ -1,22 +1,17 @@
-struct Window_Data {
-	// Real width and height of the window
-	i32 width;
-	i32 height;
-	bool size_just_changed;
-
-	f32 desired_aspect_ratio;
-};
-
-struct App_State {
-  Window_Data win_data;
-  User_Input user_input;
-};
-
 internal void update_and_render(Arena *arena, App_State &app, f32 delta_time)
 {
   ImGui::SetNextWindowPos({ 0, 0 });
   ImGui::SetNextWindowSize({ (f32)app.win_data.width, (f32)app.win_data.height });
+
+  Temp scratch = temp_begin(arena);
+  defer { temp_end(scratch); };
+
+  u64 text_buf_size = min(app.inspected_file_size, 2048);
+  char *text_buf = arena_push_array<char>(scratch.arena, text_buf_size);
+  // TODO: convert file content to human readable
+  
   if (ImGui::Begin("test")) {
+    ImGui::InputTextMultiline("##text_buf", text_buf, text_buf_size);
     ImGui::End();
   }
 }

src/rntviewer.cpp

@@ -23,7 +23,7 @@
 #include "types.h"
 #include "defer.hpp"
 #include "mem.h"
-#include "input.h"
+#include "app_state.h"
 
 namespace chr = std::chrono;
 
@@ -148,7 +148,11 @@ int main(int argc, char **argv)
   }
 
   // Start main loop
-  run_main_loop(window, arena);
+  App_State app {};
+  app.inspected_file = (u8*)fmem;
+  app.inspected_file_size = fsize;
+  
+  run_main_loop(window, arena, app);
 
   return 0;
 }

src/types.h

@@ -10,7 +10,11 @@ using b8 = bool;
 using b32 = int32_t;
 using b32x = int;
 
+using i8 = int8_t;
 using i32 = int32_t;
 using i64 = int64_t;
 
 #define internal static
+
+#define max(a, b) ((a) > (b)) ? (a) : (b)
+#define min(a, b) ((a) < (b)) ? (a) : (b)