From 8e120a5c7270fcf4a524dea404c0f2cdcdda3714 Mon Sep 17 00:00:00 2001
From: Benji Dial <benji6283@gmail.com>
Date: Thu, 18 Feb 2021 14:44:06 -0500
Subject: making graphics double-buffered so there isn't flicker when windows
 paint

---
 src/kernel/window.c | 69 ++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 45 insertions(+), 24 deletions(-)

(limited to 'src')

diff --git a/src/kernel/window.c b/src/kernel/window.c
index 10c573f..9d3db28 100644
--- a/src/kernel/window.c
+++ b/src/kernel/window.c
@@ -41,17 +41,42 @@ static struct window {
 static struct window *bottom_window = 0;
 static struct window *top_window = 0;
 
-uint32_t pix_clear_mask;
-
-static inline void put_pix(uint16_t y, uint16_t x, struct pixel px) {
-  uint32_t *const fbp = VBE_MODE_INFO->frame_buf + y * VBE_MODE_INFO->pitch + x * VBE_MODE_INFO->bpp / 8;
-//logf(LOG_INFO, "-- fbp = 0x%h", fbp);
-//logf(LOG_INFO, "-- *fbp -> 0x%h", *fbp);
-  *fbp &= pix_clear_mask;
-  *fbp |= (px.r >> (8 - VBE_MODE_INFO->red_len))   << VBE_MODE_INFO->red_off;
-  *fbp |= (px.g >> (8 - VBE_MODE_INFO->green_len)) << VBE_MODE_INFO->green_off;
-  *fbp |= (px.b >> (8 - VBE_MODE_INFO->blue_len))  << VBE_MODE_INFO->blue_off;
-//logf(LOG_INFO, "-- *fbp <- 0x%h", *fbp);
+static struct pixel *buffer;
+static uint32_t buffer_pages;
+static uint32_t pix_clear_mask;
+
+static void load_mode_params() {
+  if (buffer)
+    free_pages(buffer, buffer_pages);
+
+  const uint32_t fb_len = VBE_MODE_INFO->width * VBE_MODE_INFO->height;
+  buffer_pages = (fb_len * sizeof(struct pixel) - 1) / 4096 + 1;
+  buffer = allocate_kernel_pages(buffer_pages);
+
+  #define MASK(offset, length) ((~((1 << offset) - 1)) - (offset + length == 32 ? 0 : (~((1 << (offset + length)) - 1))))
+  pix_clear_mask = ~(
+    MASK(VBE_MODE_INFO->red_off,   VBE_MODE_INFO->red_len)   |
+    MASK(VBE_MODE_INFO->green_off, VBE_MODE_INFO->green_len) |
+    MASK(VBE_MODE_INFO->blue_off,  VBE_MODE_INFO->blue_len)  |
+    MASK(VBE_MODE_INFO->alpha_off, VBE_MODE_INFO->alpha_len)
+  );
+}
+
+static void blit() {
+  void *row = VBE_MODE_INFO->frame_buf;
+  const struct pixel *from = buffer;
+  for (uint16_t y = 0; y < VBE_MODE_INFO->height; ++y) {
+    uint32_t *out_pix = row;
+    for (uint16_t x = 0; x < VBE_MODE_INFO->width; ++x) {
+      *out_pix &= pix_clear_mask;
+      *out_pix |= (from->r >> (8 - VBE_MODE_INFO->red_len))   << VBE_MODE_INFO->red_off;
+      *out_pix |= (from->g >> (8 - VBE_MODE_INFO->green_len)) << VBE_MODE_INFO->green_off;
+      *out_pix |= (from->b >> (8 - VBE_MODE_INFO->blue_len))  << VBE_MODE_INFO->blue_off;
+      out_pix = (uint32_t *)((void *)out_pix + VBE_MODE_INFO->bpp / 8);
+      ++from;
+    }
+    row += VBE_MODE_INFO->pitch;
+  }
 }
 
 static inline void draw_hz_line(uint16_t y, uint16_t xs, uint16_t xm, struct pixel color) {
@@ -62,7 +87,7 @@ static inline void draw_hz_line(uint16_t y, uint16_t xs, uint16_t xm, struct pix
   if (xm > VBE_MODE_INFO->width)
     xm = VBE_MODE_INFO->width;
   for (uint16_t x = xs; x < xm; ++x)
-    put_pix(y, x, color);
+    buffer[y * VBE_MODE_INFO->width + x] = color;
 }
 
 static inline void draw_vt_line(uint16_t x, uint16_t ys, uint16_t ym, struct pixel color) {
@@ -73,7 +98,7 @@ static inline void draw_vt_line(uint16_t x, uint16_t ys, uint16_t ym, struct pix
   if (ym > VBE_MODE_INFO->height)
     ym = VBE_MODE_INFO->height;
   for (uint16_t y = ys; y < ym; ++y)
-    put_pix(y, x, color);
+    buffer[y * VBE_MODE_INFO->width + x] = color;
 }
 
 static void paint_and_above(const struct window *w) {
@@ -89,7 +114,7 @@ static void paint_and_above(const struct window *w) {
 
     for (uint16_t y = ys; y < ym; ++y)
       for (uint16_t x = xs; x < xm; ++x)
-        put_pix(y + i->ypos, x + i->xpos, i->pixel_buffer_pma[y * i->width + x]);
+        buffer[(y + i->ypos) * VBE_MODE_INFO->width + x + i->xpos] = i->pixel_buffer_pma[y * i->width + x];
 
     draw_hz_line(i->ypos             - 2, i->xpos - 2, i->xpos + i->width + 2, BORDER_COLOR);
     draw_hz_line(i->ypos             - 1, i->xpos - 2, i->xpos + i->width + 2, BORDER_COLOR);
@@ -100,15 +125,15 @@ static void paint_and_above(const struct window *w) {
     draw_vt_line(i->xpos + i->width,      i->ypos,     i->ypos + i->height,    BORDER_COLOR);
     draw_vt_line(i->xpos + i->width  + 1, i->ypos,     i->ypos + i->height,    BORDER_COLOR);
   }
+
+  blit();
   switch_to_task_cr3();
 }
 
 static void paint_bg() {
-  switch_to_kernel_cr3();
   for (uint16_t y = 0; y < VBE_MODE_INFO->height; ++y)
     for (uint16_t x = 0; x < VBE_MODE_INFO->width; ++x)
-      put_pix(y, x, BACKGROUND(x, y));
-  switch_to_task_cr3();
+      buffer[y * VBE_MODE_INFO->width + x] = BACKGROUND(x, y);
 }
 
 static void paint_all() {
@@ -271,15 +296,11 @@ static char *run_command;
 static char *run_command_pass = "";
 
 void init_win() {
-  #define MASK(offset, length) ((~((1 << offset) - 1)) - (offset + length == 32 ? 0 : (~((1 << (offset + length)) - 1))))
-  pix_clear_mask = ~(
-    MASK(VBE_MODE_INFO->red_off,   VBE_MODE_INFO->red_len)   |
-    MASK(VBE_MODE_INFO->green_off, VBE_MODE_INFO->green_len) |
-    MASK(VBE_MODE_INFO->blue_off,  VBE_MODE_INFO->blue_len)  |
-    MASK(VBE_MODE_INFO->alpha_off, VBE_MODE_INFO->alpha_len)
-  );
+  buffer = 0;
+  load_mode_params();
 
   paint_bg();
+  blit();
 
   const file_id_t fid = drives->get_file(drives, RUN_COMMAND_FILE);
   if (!fid)
-- 
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