Double buffer framebuffer drawing

src/kernel/drivers/framebuffer.c

@@ -2,10 +2,9 @@
 #include <memory.h>
 #include <multiboot.h>
 #include <framebuffer.h>
+#include <stdlib.h>
 
 gfx_context kernel_fb;
-gfx_context subcontext;
-
 
 void putpixel(gfx_context *ctx, uint64_t x, uint64_t y, uint32_t clr)
 {
@@ -13,16 +12,24 @@ void putpixel(gfx_context *ctx, uint64_t x, uint64_t y, uint32_t clr)
     uint64_t loc = \
         y * ctx->pitch + \
         x * ctx->bpp;
-    uint32_t *fb = incptr(P2V(ctx->addr), loc);
+    uint32_t *fb = incptr(ctx->buffer, loc);
-
     *fb = clr;
 }
 
-
+void flip(gfx_context *ctx)
+{
+    for(uint64_t y = 0; y < ctx->height; y++)
+    {
+        memcpy(
+            incptr(ctx->addr, y*ctx->pitch),
+            incptr(ctx->buffer, y*ctx->pitch),
+            ctx->width*ctx->bpp);
+    }
+}
 
 gfx_context *framebuffer_make_subcontext(gfx_context *ctx, uint64_t x, uint64_t y, uint64_t width, uint64_t height)
 {
-    gfx_context *out = &subcontext;
+    gfx_context *out = malloc(sizeof(gfx_context));
     uint64_t loc = \
         y * ctx->pitch + \
         x * ctx->bpp;
@@ -33,6 +40,7 @@ gfx_context *framebuffer_make_subcontext(gfx_context *ctx, uint64_t x, uint64_t
     out->pitch = ctx->pitch;
     out->addr = incptr(ctx->addr, loc);
     out->size = ctx->pitch * (height);
+    out->buffer = calloc(1, out->size);
 
     return out;
 }
@@ -43,11 +51,12 @@ void framebuffer_init(struct fbinfo *fbinfo)
     kernel_fb.height = fbinfo->framebuffer_height;
     kernel_fb.bpp = fbinfo->framebuffer_bpp/8;
     kernel_fb.pitch = fbinfo->framebuffer_pitch;
-    kernel_fb.addr = (void *)fbinfo->framebuffer_addr;
+    kernel_fb.addr = P2V(fbinfo->framebuffer_addr);
     kernel_fb.size = kernel_fb.pitch * (kernel_fb.height);
+    kernel_fb.buffer = calloc(1, kernel_fb.size);
 
     for(uintptr_t p = (uintptr_t)kernel_fb.addr; p < ((uintptr_t)kernel_fb.addr + kernel_fb.size); p += PAGE_SIZE)
     {
-        vmm_set_page(kernel_P4, (uint64_t)P2V(p), p, PAGE_WRITE | PAGE_PRESENT);
+        vmm_set_page(kernel_P4, p, V2P(p), PAGE_WRITE | PAGE_PRESENT);
     }
 }

src/kernel/drivers/terminal/fbterm.c

@@ -113,7 +113,7 @@ static void drawCharacter(gfx_context *ctx, uint64_t x, uint64_t y, uint32_t clr
     uint64_t loc = \
         y * ctx->pitch + \
         x * ctx->bpp;
-    uint32_t *fb = incptr(P2V(ctx->addr), loc);
+    uint32_t *fb = incptr(ctx->buffer, loc);
     for(int row = 0; row < 16; row++)
     {
         for(int col = 0; col < 8; col++)
@@ -143,6 +143,7 @@ void fbterm_init(gfx_context *ctx)
 {
     term_fb = framebuffer_make_subcontext(ctx, 20, 20, 8*VGA_COLS+8, 16*VGA_ROWS+8);
     draw_border(term_fb, RGB(255, 0, 0));
+    flip(term_fb);
     term_fb = framebuffer_make_subcontext(ctx, 24, 24, 8*VGA_COLS, 16*VGA_ROWS);
     setup = 1;
 }
@@ -163,4 +164,5 @@ void fbterm_flush(struct vga_cell *buffer)
             drawCharacter(term_fb, col*8, row*16, 0xFFFFFF, 0, (char)buffer[i++].c);
         }
     }
+    flip(term_fb);
 }

src/kernel/include/framebuffer.h

@@ -13,11 +13,13 @@ typedef struct {
     size_t size;
 } gfx_context;
 
+// drivers/framebuffer.c
 extern gfx_context kernel_fb;
 
 #define RGB(r, g, b) (((uint32_t) (r<<16) + (g<<8) + (b)))
 
+// drivers/framebuffer.c
 void putpixel(gfx_context *ctx, uint64_t x, uint64_t y, uint32_t clr);
+void flip(gfx_context *ctx);
 gfx_context *framebuffer_make_subcontext(gfx_context *ctx, uint64_t x, uint64_t y, uint64_t width, uint64_t height);
-
 void framebuffer_init(struct fbinfo *fbinfo);