Memory buffer fixes

3 files changed, 123 insertions, 168 deletions

diff --git a/examples/screenshot.c b/examples/screenshot.c
index c3c0ebd..11b2385 100644
--- a/examples/screenshot.c
+++ b/examples/screenshot.c
@@ -1,23 +1,34 @@
 #include "../graphics.c"
 
-i64 width          = 0;
-i64 height         = 0;
-b8  has_screenshot = 0;
+enum {
+  MAX_NUM_PIXELS = 10 * 1024 * 1024,
+};
+
+b8       has_screenshot         = 0;
+i64      width                  = 0;
+i64      height                 = 0;
+vec4_f32 pixels[MAX_NUM_PIXELS] = {0};
 
 void update_and_render_frame(void) {
   if (!has_screenshot) {
-    take_screenshot(MAX_NUM_PIXELS, &width, &height, g_platform.sketch);
+    take_screenshot(MAX_NUM_PIXELS, &width, &height, pixels);
     has_screenshot = 1;
   }
 
   handle_main_window_events();
 
-  draw_pixels((Brush) { .quick = 1, }, 0, 0, g_platform.real_width, g_platform.real_height, (Pixel_Buffer) {
-    .width  = width,
-    .height = height,
-    .stride = width,
-    .pixels = g_platform.sketch,
-  });
+  draw_pixels_quick(
+    (Box) {
+      .width  = g_platform.real_width,
+      .height = g_platform.real_height,
+    },
+    (Pixel_Buffer) {
+      .width  = width,
+      .height = height,
+      .stride = width,
+      .pixels = pixels,
+    }
+  );
 
   render_main_window_frame();
 }
diff --git a/graphics.c b/graphics.c
index 95cff6b..670610b 100755
--- a/graphics.c
+++ b/graphics.c
@@ -248,6 +248,10 @@ enum {
   CHAR_NUM_BITS_   = CHAR_NUM_BITS_X_ * CHAR_NUM_BITS_Y_,
 };
 
+static i64 min2_i64_(i64 x, i64 y) {
+  return x < y ? x : y;
+}
+
 static f32 max2_f32_(f32 a, f32 b) {
   return a < b ? b : a;
 }
@@ -344,11 +348,25 @@ void draw_pixels_to_buffer(Pixel_Buffer dst, Box area, Pixel_Buffer src) {
   for (i64 j = j0; j < j1; ++j) {
     i64 src_j = (i64) floor(((j - area.y + .5) * src.height) * h_inv);
     if (src_j < 0 || src_j >= src.height) continue;
-    i64 src_n = src_j * src.stride;
+    vec4_f32 *q = src.pixels + src_j * src.stride;
+    vec4_f32 *p = dst.pixels + j     * dst.stride + i0;
     for (i64 i = i0; i < i1; ++i) {
       i64 src_i = (i64) floor(((i - area.x + .5) * src.width) * w_inv);
       if (src_i < 0 || src_i >= src.width) continue;
-      put_pixel_(dst, src.pixels[src_n + src_i], i, j);
+      vec4_f32 color = q[src_i];
+      if (color.w == 1.f)
+        *p = color;
+      else {
+        vec4_f32 dst_color  = *p;
+        f32      dst_amount = 1. - color.w;
+        *p = (vec4_f32) {
+          .x = dst_color.x * dst_amount + color.x * color.w,
+          .y = dst_color.y * dst_amount + color.y * color.w,
+          .z = dst_color.z * dst_amount + color.z * color.w,
+          .w = max2_f32_(dst_color.w, color.w),
+        };
+      }
+      ++p;
     }
   }
 }
@@ -1948,8 +1966,10 @@ static void scale_and_perform_graphics_request_(Graphics_Context context, Graphi
 
 static Graphics_Context graphics_context_defaults_(Graphics_Context context) {
   if (context.dst.pixels == NULL) {
+    i64 max_height = g_platform.num_pixels / g_platform.frame_width;
+
     context.dst.width  = g_platform.frame_width;
-    context.dst.height = g_platform.frame_height;
+    context.dst.height = min2_i64_(max_height, g_platform.frame_height);
     context.dst.stride = g_platform.frame_width;
     context.dst.pixels = g_platform.pixels;
 
@@ -2076,19 +2096,19 @@ TEST("colors") {
   REQUIRE_EQ((purple.z + 2e-7) * 100, 100);
 }
 
-Pixel_Buffer pixels = {
+static Pixel_Buffer _test_pixels = {
   .width  = 1280,
   .height = 720,
   .stride = 1280,
   .pixels = (vec4_f32[1280 * 720]) {0},
 };
 
-vec4_f32 color = { 1., 1., 1., 1., };
+static vec4_f32 _test_color = { 1., 1., 1., 1., };
 
 BENCHMARK("fill rectangle") {
   BENCHMARK_BEGIN;
   {
-    fill_rectangle_to_buffer(pixels, color, (Box) { .x = 100, .y = 100, .width = 300, .height = 200, });
+    fill_rectangle_to_buffer(_test_pixels, _test_color, (Box) { .x = 100, .y = 100, .width = 300, .height = 200, });
   }
   BENCHMARK_END;
 }
@@ -2096,7 +2116,7 @@ BENCHMARK("fill rectangle") {
 BENCHMARK("fill triangle") {
   BENCHMARK_BEGIN;
   {
-    fill_triangle_to_buffer(pixels, color, (vec2[3]) {
+    fill_triangle_to_buffer(_test_pixels, _test_color, (vec2[3]) {
       { 100, 100 },
       { 300, 100 },
       { 200, 250 },
@@ -2108,7 +2128,7 @@ BENCHMARK("fill triangle") {
 BENCHMARK("fill quad") {
   BENCHMARK_BEGIN;
   {
-    fill_quad_to_buffer(pixels, color, (vec2[4]) {
+    fill_quad_to_buffer(_test_pixels, _test_color, (vec2[4]) {
       { 100, 100 },
       { 300, 100 },
       { 300, 200 },
@@ -2121,7 +2141,7 @@ BENCHMARK("fill quad") {
 BENCHMARK("fill ellipse") {
   BENCHMARK_BEGIN;
   {
-    fill_ellipse_to_buffer(pixels, color, (Box) { .x = 80, .y = 80, .width = 340, .height = 240, });
+    fill_ellipse_to_buffer(_test_pixels, _test_color, (Box) { .x = 80, .y = 80, .width = 340, .height = 240, });
   }
   BENCHMARK_END;
 }
@@ -2129,7 +2149,7 @@ BENCHMARK("fill ellipse") {
 BENCHMARK("fill line") {
   BENCHMARK_BEGIN;
   {
-    fill_line_to_buffer(pixels, color, (vec2[2]) {
+    fill_line_to_buffer(_test_pixels, _test_color, (vec2[2]) {
       { 100, 100 },
       { 300, 200 },
     }, 40);
@@ -2141,7 +2161,7 @@ BENCHMARK("draw text area") {
   BENCHMARK_BEGIN;
   {
     c32 text[] = { 'H', 'e', 'l', 'l', 'o', ',', ' ', 'S', 'a', 'i', 'l', 'o', 'r', '!', };
-    draw_text_area_to_buffer(pixels, color, (Box) { .x = 100, .y = 100, .width = 300, .height = 200, }, (vec2) { 100, 200 }, sizeof text / sizeof *text, text);
+    draw_text_area_to_buffer(_test_pixels, _test_color, (Box) { .x = 100, .y = 100, .width = 300, .height = 200, }, (vec2) { 100, 200 }, sizeof text / sizeof *text, text);
   }
   BENCHMARK_END;
 }
diff --git a/reduced_system_layer.c b/reduced_system_layer.c
index ad5e990..3d6a08d 100755
--- a/reduced_system_layer.c
+++ b/reduced_system_layer.c
@@ -111,6 +111,9 @@
 #/    - macOS support
 #/    - Mobile devices support
 #/
+#/  Bugs
+#/  - Buffer overflow after resizing the window.
+#/
 #/  Done
 #/
 #/  - Examples
@@ -249,7 +252,7 @@ i32 main(i32 argc, c8 **argv);
 #endif
 
 #ifndef STATIC_MEMORY_BUFFER_SIZE
-#define STATIC_MEMORY_BUFFER_SIZE (10 * 1024 * 1024)
+#define STATIC_MEMORY_BUFFER_SIZE (20 * 1024 * 1024)
 #endif
 
 #ifndef MEMORY_CHUNK_SIZE
@@ -288,11 +291,11 @@ i32 main(i32 argc, c8 **argv);
 #endif
 
 #ifndef NUM_FRAMES_AVERAGED
-#define NUM_FRAMES_AVERAGED 400
+#define NUM_FRAMES_AVERAGED 600
 #endif
 
 #ifndef AVERAGE_FRAME_BIAS
-#define AVERAGE_FRAME_BIAS (0.02)
+#define AVERAGE_FRAME_BIAS (0.03)
 #endif
 
 #ifndef MAX_NUM_KEYS
@@ -616,8 +619,8 @@ typedef struct {
   i64 num_sound_samples_elapsed;
 
   i64 num_pixels;
-  i64 sketch_len;
   i64 input_len;
+  i64 input_capacity;
   i64 num_drop_files;
   i64 clipboard_text_len;
   i64 clipboard_image_width;
@@ -626,11 +629,7 @@ typedef struct {
   i64 num_clipboard_sound_samples;
   i64 clipboard_sound_len;
 
-  i64 pixels_capacity;
-  i64 input_capacity;
-
   vec4_f32  *pixels;
-  f32       *sketch;
   Input_Key *input;
   Drop_File *drop_files;
   c8        *clipboard_text;
@@ -713,12 +712,10 @@ extern Platform g_platform;
 
 Platform g_platform = {0};
 
-static i64  _sound_clock_time      = 0;
-static i64  _sound_clock_carry     = 0;
-static i64  _sound_position        = 0;
-static i64  _frame_index           = 0;
-static i64  _drop_files_buffer_len = 0;
-static u8  *_drop_files_buffer     = NULL;
+static i64  _sound_clock_time  = 0;
+static i64  _sound_clock_carry = 0;
+static i64  _sound_position    = 0;
+static i64  _frame_index       = 0;
 
 static f32 _sound_ring     [MAX_NUM_PRIMARY_SOUND_FRAMES] = {0};
 static i64 _frame_duration [NUM_FRAMES_AVERAGED]          = {0};
@@ -792,10 +789,13 @@ void *memory_buffer_allocate(i64 size, i64 alignment, i64 previous_size, void *p
     g_platform.memory_buffer      = memory_buffer_;
   }
 
-  i64  occupied_len = memory_buffer_occupied_len_(g_platform.memory_buffer_size);
-  u64 *occupied     = (u64 *) g_platform.memory_buffer;
+  i64 occupied_len       = memory_buffer_occupied_len_(g_platform.memory_buffer_size);
+  i64 occupied_len_bytes = occupied_len * 8;
+  i64 occupied_len_bits  = occupied_len * 64;
+
+  u64 *occupied = (u64 *) g_platform.memory_buffer;
 
-  if (g_platform.memory_buffer_size <= occupied_len * 64) {
+  if (g_platform.memory_buffer_size <= occupied_len_bytes) {
     LOG_ERROR("Memory buffer too small.");
     return NULL;
   }
@@ -820,7 +820,7 @@ void *memory_buffer_allocate(i64 size, i64 alignment, i64 previous_size, void *p
     return NULL;
   }
 
-  u8 *data = g_platform.memory_buffer + occupied_len * 64;
+  u8 *data = g_platform.memory_buffer + occupied_len_bytes;
 
   i64 prev_num_chunks = 0;
   i64 prev_chunk      = 0;
@@ -835,31 +835,26 @@ void *memory_buffer_allocate(i64 size, i64 alignment, i64 previous_size, void *p
 
   //  Search free space
   i64 i0 = 0;
-  while (i0 < occupied_len && occupied[i0] == ~0ull)
-    ++i0;
-  for (i64 i = i0; i < occupied_len * 64; ++i) {
+  while (i0 < occupied_len_bits && occupied[i0 / 64] == ~0ull)
+    i0 += 64;
+  for (i64 i = i0; i < occupied_len_bits; ++i) {
     b8 is_occupied = 0;
-
     for (i64 j = i; j < i + num_chunks; ++j) {
       if (j >= prev_chunk && j < prev_chunk + prev_num_chunks) continue;
-      if ((occupied[j / 64] & (1ull << (j % 64))) == 0)   continue;
+      if ((occupied[j / 64] & (1ull << (j % 64))) == 0)        continue;
       is_occupied = 1;
       break;
     }
-
-    if (is_occupied) {
+    if (!is_occupied) {
       chunk = i;
       break;
     }
   }
 
-  u8 *src = data + prev_chunk * MEMORY_CHUNK_SIZE;
-  u8 *dst = data + chunk      * MEMORY_CHUNK_SIZE;
-  i64 len = size < previous_size ? size : previous_size;
-
   //  Check if out of memory
+  u8 *dst = data + chunk * MEMORY_CHUNK_SIZE;
   if (dst + size > g_platform.memory_buffer + g_platform.memory_buffer_size) {
-    LOG_ERROR("Out of memory.");
+    LOG_ERROR("Out of memory: %lld bytes", size - previous_size);
     return NULL;
   }
 
@@ -868,6 +863,8 @@ void *memory_buffer_allocate(i64 size, i64 alignment, i64 previous_size, void *p
     occupied[j / 64] |= 1ull << (j % 64);
 
   //  Copy data
+  u8 *src = data + prev_chunk * MEMORY_CHUNK_SIZE;
+  i64 len = size < previous_size ? size : previous_size;
   if (dst > src)
     for (i64 k = len - 1; k >= 0; --k)
       dst[k] = src[k];
@@ -901,6 +898,7 @@ void resize_dynamic_array_exact(i64 *num, void **data, i64 element_size, i64 new
   );
 
   if (new_data == NULL && new_num > 0)
+    //  Out of memory.
     return;
 
   *num  = new_num;
@@ -916,7 +914,8 @@ void resize_dynamic_array_capacity(i64 *num, i64 *capacity, void **data, i64 ele
   if (new_num > *capacity)
     resize_dynamic_array_exact(capacity, data, element_size, new_num);
 
-  *num = new_num;
+  if (new_num <= *capacity)
+    *num = new_num;
 }
 
 //  ================================================================
@@ -982,19 +981,6 @@ static b8 native_little_endian_(void) {
   return ((u8 *) &(u32) { 1 })[0] == 1;
 }
 
-static u32 load32_(void *src) {
-  if (native_little_endian_())
-    return *( u32 * )( src );
-  else {
-    u8 *p = ( u8 * )src;
-    u32 w = *p++;
-    w |= ( u32 )( *p++ ) <<  8;
-    w |= ( u32 )( *p++ ) << 16;
-    w |= ( u32 )( *p++ ) << 24;
-    return w;
-  }
-}
-
 static u64 load64_(void *src) {
   if (native_little_endian_())
     return *( u64 * )( src );
@@ -1040,39 +1026,6 @@ static void store64_(void *dst, u64 w) {
   }
 }
 
-static u64 load48_(void *src) {
-  u8 *p = ( u8 * )src;
-  u64 w = *p++;
-  w |= ( u64 )( *p++ ) <<  8;
-  w |= ( u64 )( *p++ ) << 16;
-  w |= ( u64 )( *p++ ) << 24;
-  w |= ( u64 )( *p++ ) << 32;
-  w |= ( u64 )( *p++ ) << 40;
-  return w;
-}
-
-static void store48_(void *dst, u64 w) {
-  u8 *p = ( u8 * )dst;
-  *p++ = ( u8 )w; w >>= 8;
-  *p++ = ( u8 )w; w >>= 8;
-  *p++ = ( u8 )w; w >>= 8;
-  *p++ = ( u8 )w; w >>= 8;
-  *p++ = ( u8 )w; w >>= 8;
-  *p++ = ( u8 )w;
-}
-
-static u32 rotl32_(u32 w, u32 c) {
-  return ( w << c ) | ( w >> ( 32 - c ) );
-}
-
-static u64 rotl64_(u64 w, u32 c) {
-  return ( w << c ) | ( w >> ( 64 - c ) );
-}
-
-static u32 rotr32_(u32 w, u32 c) {
-  return ( w >> c ) | ( w << ( 32 - c ) );
-}
-
 static u64 rotr64_(u64 w, u32 c) {
   return ( w >> c ) | ( w << ( 64 - c ) );
 }
@@ -1087,11 +1040,6 @@ static i32 blake2b_set_lastnode_(Blake2b_State *S) {
   return 0;
 }
 
-static i32 blake2b_clear_lastnode_(Blake2b_State *S) {
-  S->f[1] = 0ull;
-  return 0;
-}
-
 static i32 blake2b_set_lastblock_(Blake2b_State *S) {
   if( S->last_node ) blake2b_set_lastnode_( S );
 
@@ -1099,64 +1047,12 @@ static i32 blake2b_set_lastblock_(Blake2b_State *S) {
   return 0;
 }
 
-static i32 blake2b_clear_lastblock_(Blake2b_State *S) {
-  if( S->last_node ) blake2b_clear_lastnode_( S );
-
-  S->f[0] = 0ull;
-  return 0;
-}
-
 static i32 blake2b_increment_counter_(Blake2b_State *S, u64 inc) {
   S->t[0] += inc;
   S->t[1] += ( S->t[0] < inc );
   return 0;
 }
 
-static i32 blake2b_param_set_digest_length_(Blake2b_Param *P, u8 digest_length) {
-  P->digest_length = digest_length;
-  return 0;
-}
-
-static i32 blake2b_param_set_fanout_(Blake2b_Param *P, u8 fanout) {
-  P->fanout = fanout;
-  return 0;
-}
-
-static i32 blake2b_param_set_max_depth_(Blake2b_Param *P, u8 depth) {
-  P->depth = depth;
-  return 0;
-}
-
-static i32 blake2b_param_set_leaf_length_(Blake2b_Param *P, u32 leaf_length) {
-  store32_( &P->leaf_length, leaf_length );
-  return 0;
-}
-
-static i32 blake2b_param_set_node_offset_(Blake2b_Param *P, u64 node_offset) {
-  store64_( &P->node_offset, node_offset );
-  return 0;
-}
-
-static i32 blake2b_param_set_node_depth_(Blake2b_Param *P, u8 node_depth) {
-  P->node_depth = node_depth;
-  return 0;
-}
-
-static i32 blake2b_param_set_inner_length_(Blake2b_Param *P, u8 inner_length) {
-  P->inner_length = inner_length;
-  return 0;
-}
-
-static i32 blake2b_param_set_salt_(Blake2b_Param *P, u8 salt[BLAKE2B_SALTBYTES]) {
-  mem_cpy_( P->salt, salt, BLAKE2B_SALTBYTES );
-  return 0;
-}
-
-static i32 blake2b_param_set_personal_(Blake2b_Param *P, u8 personal[BLAKE2B_PERSONALBYTES]) {
-  mem_cpy_( P->personal, personal, BLAKE2B_PERSONALBYTES );
-  return 0;
-}
-
 static i32 blake2b_init0_(Blake2b_State *S) {
   i32 i;
   mem_set_( S, 0, sizeof( Blake2b_State ) );
@@ -1511,11 +1407,6 @@ static void drop_files_clean_(void) {
   }
 
   resize_dynamic_array_exact(&g_platform.num_drop_files, (void **) &g_platform.drop_files, sizeof *g_platform.drop_files, 0);
-  resize_dynamic_array_exact(&_drop_files_buffer_len, (void **) &_drop_files_buffer, 1, 0);
-}
-
-static i64 align_size_(i64 x) {
-  return (x + 7) & ~7ll;
 }
 
 static void drop_files_set_num_(i64 num) {
@@ -1693,6 +1584,8 @@ static void network_cleanup_(void) {
       close(_sockets[i].socket);
       _sockets[i].ready = 0;
     }
+
+  resize_dynamic_array_exact(&_num_sockets, (void **) &_sockets, sizeof *_sockets, 0);
 }
 
 static b8 network_open_(u16 slot, IP_Address address, u16 *local_port) {
@@ -2674,6 +2567,19 @@ static i32 x11_error_handler_(Display *display, XErrorEvent *event) {
   return 0;
 }
 
+void update_main_window_frame_(void) {
+  i64 num_pixels = g_platform.frame_width * g_platform.frame_height;
+
+  if (g_platform.num_pixels < num_pixels)
+    resize_dynamic_array_exact(&g_platform.num_pixels, (void **) &g_platform.pixels, sizeof *g_platform.pixels, num_pixels);
+  if (_pixels_scaled_len < num_pixels)
+    resize_dynamic_array_exact(&_pixels_scaled_len, (void **) &_pixels_scaled, sizeof *_pixels_scaled, num_pixels);
+  if (_pixels_internal_len < num_pixels)
+    resize_dynamic_array_exact(&_pixels_internal_len, (void **) &_pixels_internal, sizeof *_pixels_internal, num_pixels);
+
+  _image.data = (c8 *) _pixels_internal;
+}
+
 void init_main_window(void) {
   for (i64 i = 0; i < NUM_FRAMES_AVERAGED; ++i)
     _frame_duration[i] = (MIN_FRAME_DURATION + MAX_FRAME_DURATION) / 2;
@@ -2851,9 +2757,7 @@ void init_main_window(void) {
     .width            = g_platform.frame_width,
     .height           = g_platform.frame_height,
     .depth            = depth,
-    .xoffset          = 0,
     .format           = ZPixmap,
-    .data             = (c8 *) _pixels_internal,
     .byte_order       = LSBFirst,
     .bitmap_unit      = 32,
     .bitmap_bit_order = LSBFirst,
@@ -2865,6 +2769,8 @@ void init_main_window(void) {
     .blue_mask        = 0x0000ff,
   };
 
+  update_main_window_frame_();
+
   XInitImage(&_image);
 
   _wm_delete_window = XInternAtom(_display, "WM_DELETE_WINDOW", False);
@@ -2915,6 +2821,15 @@ void shutdown_all_systems(void) {
   _window  = 0;
   _display = NULL;
 
+  drop_files_clean_();
+  g_platform.input_len = 0;
+
+  resize_dynamic_array_exact(&_pixels_scaled_len,            (void **) &_pixels_scaled, sizeof *_pixels_scaled,       0);
+  resize_dynamic_array_exact(&_pixels_internal_len,          (void **) &_pixels_internal, sizeof *_pixels_internal,   0);
+  resize_dynamic_array_exact(&g_platform.num_pixels,         (void **) &g_platform.pixels, sizeof *g_platform.pixels, 0);
+  resize_dynamic_array_exact(&g_platform.input_capacity,     (void **) &g_platform.input, sizeof *g_platform.input,   0);
+  resize_dynamic_array_exact(&g_platform.clipboard_text_len, (void **) &g_platform.clipboard_text, 1,                 0);
+
   network_cleanup_();
   sound_cleanup_();
 }
@@ -3466,11 +3381,7 @@ void render_main_window_frame(void) {
     _mapped = 1;
   }
 
-  i64 num_pixels = g_platform.frame_width * g_platform.frame_height;
-  if (_pixels_scaled_len < num_pixels)
-    resize_dynamic_array_exact(&_pixels_scaled_len, (void **) &_pixels_scaled, sizeof *_pixels_scaled, num_pixels);
-  if (_pixels_internal_len < num_pixels)
-    resize_dynamic_array_exact(&_pixels_internal_len, (void **) &_pixels_internal, sizeof *_pixels_internal, num_pixels);
+  update_main_window_frame_();
 
   if (g_platform.frame_width == _image.width && g_platform.frame_height == _image.height) {
     i64 size = g_platform.frame_width * g_platform.frame_height;
@@ -3815,18 +3726,31 @@ i32 wait_main_window_events(void) {
 void render_main_window_frame(void) {
   if (_frame_width == g_platform.frame_width && _frame_height == g_platform.frame_height) {
     i64 size = g_platform.frame_width * g_platform.frame_height;
+    if (size > g_platform.num_pixels)
+      size = g_platform.num_pixels;
+    if (size > _pixels_internal_len)
+      size = _pixels_internal_len;
+
     for (i64 i = 0; i < size; ++i)
       _pixels_internal[i] = 0xff000000u | rgb_u32_from_f32_((vec3_f32) { g_platform.pixels[i].z, g_platform.pixels[i].y, g_platform.pixels[i].x });
   } else {
     i64 size = g_platform.frame_width * g_platform.frame_height;
+    if (size > g_platform.num_pixels)
+      size = g_platform.num_pixels;
+    if (size > _pixels_scaled_len)
+      size = _pixels_scaled_len;
+
     for (i64 i = 0; i < size; ++i)
       _pixels_scaled[i] = rgb_u32_from_f32_((vec3_f32) { g_platform.pixels[i].z, g_platform.pixels[i].y, g_platform.pixels[i].x });
 
     for (i64 j = 0; j < _frame_height; ++j) {
       i64 j0 = (j * g_platform.frame_height) / _frame_height;
+      if ((j0 + 1) * _frame_width > _pixels_internal_len) break;
       for (i64 i = 0; i < _frame_width; ++i) {
         i64 i0 = (i * g_platform.frame_width) / _frame_width;
-        _pixels_internal[j * _frame_width + i] = 0xff000000u | _pixels_scaled[j0 * g_platform.frame_width + i0];
+        i64 n0 = j0 * g_platform.frame_width + i0;
+        if (n0 > _pixels_scaled_len) break;
+        _pixels_internal[j * _frame_width + i] = 0xff000000u | _pixels_scaled[n0];
       }
     }
   }