First stab at the sw blitter

1 files changed, 39 insertions, 3 deletions

diff --git a/src/vga.c b/src/vga.c
index 981ad6f..e2fb7f9 100644
--- a/src/vga.c
+++ b/src/vga.c
@@ -1,15 +1,22 @@
 #include <stdlib.h>
+#include <string.h>
 #include <stdint.h>
 #include <dpmi.h>
 #include <sys/nearptr.h>
 #include <pc.h>
 
-uint8_t *open_framebuffer()
+#include "vga.h"
+
+static uint8_t buffer[320 * 200];
+static uint8_t *screen = NULL;
+
+uint8_t open_framebuffer()
 {
     if (__djgpp_nearptr_enable() == 0)
-        return NULL;
+        return 0;
 
-    return (uint8_t *)(0xa0000 + __djgpp_conventional_base);
+    screen = (uint8_t *)(0xa0000 + __djgpp_conventional_base);
+    return 1;
 }
 
 void close_framebuffer()
@@ -36,3 +43,32 @@ void set_palette(const uint8_t *palette)
     for (int i = 0; i < 768; i++)
         outportb(0x3c9, palette[i] >> 2);
 }
+
+void blit(const uint8_t *src, uint16_t x, uint16_t y, uint16_t w, uint16_t h)
+{
+    for (int32_t j = y; j < y + h; j++)
+        for (int32_t i = x; i < x + w; i++)
+        {
+            uint8_t b = *src++;
+
+            /* transparent */
+            if (b == TRANSPARENT)
+                continue;
+
+            /* clipping */
+            if (i < 0 || i >= 320 || j < 0 || j >= 200)
+                continue;
+
+            buffer[i + j * 320] = b;
+        }
+}
+
+void blit_erase(uint8_t c)
+{
+    memset(buffer, c, 320 * 200);
+}
+
+void blit_update()
+{
+    memcpy(screen, buffer, 320 * 200);
+}