Add hires graphics file; draw hires graphics

include/apple2.draw.h

@@ -6,6 +6,7 @@
 
 extern void apple2_draw(apple2 *);
 extern void apple2_draw_40col(apple2 *);
+extern void apple2_draw_hires(apple2 *);
 extern void apple2_draw_lores(apple2 *);
 extern void apple2_draw_pixel(apple2 *, vm_16bit);
 

include/apple2.hires.h

@@ -0,0 +1,8 @@
+#ifndef _APPLE2_HIRES_H_
+#define _APPLE2_HIRES_H_
+
+#include "apple2.h"
+
+extern void apple2_hires_draw(apple2 *, size_t);
+
+#endif

sources.cmake

@@ -6,6 +6,7 @@ set(erc_sources
 	apple2.dec.c
 	apple2.draw.c
 	apple2.enc.c
+	apple2.hires.c
 	apple2.kb.c
 	apple2.lores.c
 	apple2.mem.c

src/apple2.draw.c

@@ -7,6 +7,7 @@
  */
 
 #include "apple2.h"
+#include "apple2.hires.h"
 #include "apple2.lores.h"
 #include "apple2.text.h"
 
@@ -96,6 +97,21 @@ apple2_draw_lores(apple2 *mach)
     }
 }
 
+/*
+ * Draw high-resolution graphics on the screen
+ */
+void
+apple2_draw_hires(apple2 *mach)
+{
+    size_t addr;
+
+    vm_screen_prepare(mach->screen);
+
+    for (addr = 0x2000; addr < 0x4000; addr++) {
+        apple2_hires_draw(mach, addr);
+    }
+}
+
 /*
  * Find the right draw method for the machine, based on its display
  * mode, and use that to refresh the screen.
@@ -106,7 +122,11 @@ apple2_draw(apple2 *mach)
     if (mach->display_mode & DISPLAY_TEXT) {
         apple2_draw_40col(mach);
         return;
+    } else if (mach->memory_mode & MEMORY_HIRES) {
+        apple2_draw_hires(mach);
+        return;
     }
 
+    // The fallback mode is to draw lores graphics
     apple2_draw_lores(mach);
 }

src/apple2.hires.c

@@ -0,0 +1,24 @@
+/*
+ * apple2.hires.c
+ *
+ * High resolution graphics in Apple are a significant change from its
+ * low-resolution graphics. Where one byte can hold the color data for
+ * two onscreen cells in lores graphics, in hires, each _bit_
+ * corresponds to a pixel. The colors you can show depend on the pattern
+ * of high and low bits within a given data byte. Certain rows have
+ * black, purple, or blue available; alternating rows can be black,
+ * green, or orange. 
+ *
+ * Some of this has to do with the space constraints available to the
+ * Apple II: the hires graphics buffer is held between $2000 and $3FFF,
+ * which is only 8k RAM. Some of this has to do with the peculiarities
+ * of the NTSC format, because the Apple II was designed to work with
+ * standard television screens.
+ */
+
+#include "apple2.hires.h"
+
+void
+apple2_hires_draw(apple2 *mach, size_t addr)
+{
+}

tests/apple2.hires.c

@@ -0,0 +1,10 @@
+#include <criterion/criterion.h>
+
+#include "apple2.hires.h"
+#include "apple2.tests.h"
+
+TestSuite(apple2_hires, .init = setup, .fini = teardown);
+
+Test(apple2_hires, draw)
+{
+}